CEOP received strong support by the IGOSpartners and the CEOS space agencies. ThroughCEOP, CEOS will be able to contribute greatly tothe understanding and prediction of the water cyclethrough the integrated use of satellites of CEOSmembers in cooperation with the IGOS partnership.CEOP represents a unique opportunity to improvethe scientific basis needed to achieve overall watercycle documentation and prediction goals.

Continued on page 2.

NEWS NEWSWorld Climate Research Programme__WCRP

Vol. 10, No. 4 November 2000

Global Energy and Water Cycle Experiment

MARK YOUR CALENDAR!

4TH INTERNATIONAL SCIENTIFICCONFERENCE ON THE GLOBALENERGY AND WATER CYCLE

Paris, France10–14 September 2001

For the Latest Conference Information:http://www.ipsl.jussieu.fr/gewex

EARLY LBARESULTS

SHOW MAJORCLOUD AND

PRECIPITATIONCHARACTER

DIFFERENCESIN THE AMAZON

During the rainy season, the daily detection of cloud-to-ground lightning activity for the TRMM-LBAdomain of the Amazon shows a factor of four increase during 850 hPa easterly wind regime periods (yellowboxes). The marked oscillations associated with these different convective regimes are apparent in theBrazilian Lightning Detection Network data (installed by NASA/MSFC) radar data and also in TRMMsatellite Lightning Imaging Sensor (LIS) data. See page 3. (Figure courtesy of W. Petersen, Colorado StateUniversity and R. Blakeslee, NASA/MSFC.)

CEOP RECEIVES SUPPORTAT IGOS-P AND CEOS

MEETINGS HELD IN RIO

Toshio KoikeUniversity of Tokyo

At the 8th Integrated Global Observing Strategy(IGOS) Partners meeting and the 14th Committeeon Earth Observation Satellites (CEOS) Plenarymeeting held in Rio de Janeiro, Brazil during theweek of November 6, 2000, the World ClimateResearch Programme (WCRP) presented a pro-posal on the Coordinated Enhanced Observing Period(CEOP) Project and a presentation on the develop-ment of an IGOS water cycle theme. An integratedwater cycle observational system would bring to-gether the capabilities of both satellite-based andground-based (remote and in situ) observing sys-tems to support the needs of the research andprediction communities.

November 20002

COMMENTARY: GEWEX SUPPORTSNEW WATER CYCLE INITIATIVES

Soroosh SorooshianGEWEX Scientific Steering Group

Worldwide interest in addressing societal waterresource needs (both in terms of quantity and qual-ity) has been given a special level of urgency. TheMarch 2000 World Water Forum in the Hague, TheNetherlands, which involved over 50 ministers andclose to 4,000 participants, is a strong testament tothe importance placed on this issue. This renewedfocus on water places the physical and biologicalaspects of the hydrologic cycle as a central topic.In this context, a number of international activitiesare being initiated that will hopefully result in amuch-needed increase in research funding in theseareas.

The water cycle initiatives should be viewed ashaving two major components: (1) the physical andbiological aspects which address a better under-standing of the elements of the hydrological cycleand closing of the water balance at various spatialand temporal scales; and (2) the water resourcesmanagement needs, where issues of supply, de-mand, scarcity, quality, and public health are to beaddressed. In order to adequately address thesecond component, it is critical that the hydrologiccycle—in its entirety—be better understood in or-der that the degree of information uncertainty issignificantly reduced.

For its part, GEWEX has been a major interna-tional program that has focused on many elementsof the water cycle during the last several years,with special emphasis on “implementing” global rep-resentations of the key parameters of the watercycle, process studies in regional campaigns world-wide, and upgrades to the land-surface and cloudparameterizations in regional and global models. Initialdata sets, model upgrades, and regional campaignresults were delivered during Phase 1 of GEWEXactivities. Phase 2 implementation is addressing jointinteractions of parameters, significant exploitationof the new satellite sensors, a collective approachby our regional experiments on closing the waterand energy budgets, and an increased emphasis onapplying the results to water resource problems.These activities can form the basis for “jump-start-ing” the plans of the new water cycle initiatives asthe key science questions begin to be addressed.

CEOS contributions to CEOP which were dis-cussed at the meetings include: (a) supporting theimplementation of a CEOP Satellite Data Integra-tion Center, (b) establishing a CEOP Satellite WorkingGroup, and (c) providing field campaigns at refer-ence sites with proper access to satellite observations.

Detailed, specific requirements will be preparedby CEOP and directed to the cognizant space agen-cies for their consideration at the CEOS Plenary tobe held Kyoto, Japan in 2001. The first step inthe preparation of a water cycle theme proposal isa planning workshop that will be held in Los Ange-les, California in the USA.

CEOP RECEIVES SUPPORT(Continued from Page 1)

With respect to the interface between the twoabove-mentioned components, many challenges lieahead. At the international level, both WMO andUNESCO—through their respective hydrologic andwater resource programs—have been in the fore-front in helping nations deal with water resourcesmanagement issues. Undoubtedly, a gap still re-mains between advances in the physical and biologicalaspects and those aspects dealing with the opera-tion and implementation of such knowledge. As anexperienced implementing project, GEWEX has ex-pressed its readiness and willingness to work on theinterface between these two components. ThroughGEWEX’s Hydrometeorology Panel (GHP), a newinitiative to build partnerships with programs suchas HELP, IHDP (International Human DimensionProgram), and IGBP is under way. We expect anenhancement and expansion of current GEWEXactivities to place a greater emphasis on providingrelevant hydrologic information that would result inmore effective management of water resources.

CONTENTS

Commentary – GEWEX Supports New Water Cycle Initiatives 2LBA Initial Results and Status 3Global Aerosol Climatology Project Advances 5Use of Reanalysis Land Surface Water Budget Variables in Hydrologic Studies 6GLASS Implementation Underway 9Workshop/Meeting Summaries

First Meeting of WRAP 10Sixth GHP Meeting 11Water and Energy Budget Workshop 12CEOP Workshop 14

GEWEX/WCRP Meetings Calendar 15

3November 2000

LBA INITIAL RESULTS AND STATUS

Carlos A. Nobre1 andMaria Assuncão F. Silva Dias2

1Centro de Previsão de Tempo e EstudosClimaticos, Instituto Nacional de Pesquisas

Espaciais2Instituto Astronômico e Geofisico, Universidade

de São Paulo

Over 200 investigators are involved in 85 Large-Scale Biosphere Atmosphere Experiment in Amazonia(LBA) studies related to physical climate, atmo-spheric chemistry and composition, carbon storageand exchange, biogeochemical cycles, land surfacehydrology and water chemistry, and land use andland cover changes. The First LBA Scientific Con-ference was held in Belem, Brazil on 26–29 June2000. Over 260 papers were presented and 7thematic workshops were conducted at this verysuccessful conference, which highlighted initial resultsof ongoing investigations with LBA and provided aforum to place LBA in the context of broaderAmazonian and tropical ecosystems science. Asecond conference is planned for mid-2002 in Manaus.LBA results will be published in a special issue ofthe Journal of Geophysical Research in 2001.

The overall timeframe for LBA is 1996–2005. Between 1996 and 1998, severalpreliminary activities took place, including theinstallation of the measurement and monitoringcomponents. LBA data collection activities beganwith an intensive observing period in January–March1999 with the combined Wet Season AtmosphericMesoscale Campaign (WET–AMC) and LBA TropicalRainfall Measuring Mission (TRMM) Validation ex-periment over SW Amazonia (Rondonia), followedby a smaller campaign from September to Novem-ber to study atmospheric processes during the wet-uptransistion period from the dry to wet season, andthe role of aerosols from biomass burning. Overthe past 18 months, ten continuous monitoring sites,including flux towers for water, energy, and carbonfluxes have been established covering a range ofclimatic conditions and vegetation types in Amazonia.These continuous measurements will run through2004 and will also include measurements from TRMM,Terra, ENVISAT, Chinese-Brazilian Earth ResourcesSatellite, and Landsat-7 platforms.

Scientific results from the first 2 years ofLBA research have shown very distinct fea-tures of atmospheric evolution in the AmazonRegion, in particular, of the cloud and precipi-tation regime. The character of precipitation overAmazonia varies from a very continental behaviorin the beginning of the rainy season to a moremaritime regime during the rainy season. Moreimportant, during the rainy season there is an alter-nation between a more maritime and more continentalregime associated with large scale controls, such asthe presence or absence of large scale low-levelconvergence provided by approaching mid-latitudefrontal boundaries or even the establishment of theSouth Atlantic Convergence Zone. Rainfall is morecontinuous throughout the day and occurs also atnight when a large scale forcing is present. Radarprofiles indicate low reflectivities in the upper halfof the troposphere and a minimum of lightning isdetected. In the absence of large scale forcing,convective systems form in the afternoon, are moreisolated, have large reflectivities above the 0oC iso-therm, and lightning is observed. Large scale forcingis seen locally in the southern half of the Amazonbasin as a low level westerly regime; while duringthe break periods the low level flow is dominatedby easterlies. The changes in lightning flash den-sity between the easterly and westerly wind regimesare significant as they indicate marked changes incloud vertical structure (see figure on page 1).Similar regime variability in the lightning flash den-sities have also been observed by the TRMM LIS.The differences in sub-grid convective cloud struc-ture between the wind regimes is verified from theprecipitation radar on the TRMM satellite and theTRMM-LBA ground-based field radar data (Petersenet al., 2000; Cifelli et al., 2000).

Large seasonal variability in the Amazon Basinhas been observed for concentrations of aerosolparticles, cloud condensation nuclei (CCN) and tracegases. This seasonal variability is mostly causedby biomass burning emissions in the dry season(July–October). In terms of aerosol concentrations,typical wet season values detected by NOAA 14sensors, are 10–15 micrograms per cubic meter(µg/m3) for particles less than 10 micrometers, whilein the dry season very high concentrations in therange of 250–400 µg/m3 are observed over largeareas in Amazonia. In terms of aerosol opticaldepth measurements using a network of sun-photometers, background aerosol columnamounts to 0.10–0.15 at 550 nanometers in thewet season. In the dry season, values of 2.5–3

November 20004

are observed over large areas. Taking into ac-count that Smoke Clouds Aerosol and Radiation-BrazilExperiment (SCAR-B ) measurements show a di-rect radiative forcing of -80 watts/m2 per unit ofoptical depth, this high aerosol loading accounts for200 to 250 w/m2 of radiation deficit at 500 nm.This large aerosol direct radiative forcing hascertainly had an impact on the Amazonian eco-system that still remains to be addressed. Also,the large atmospheric aerosol loading appearsto be altering the precipitation regime in areasheavily impacted by biomass burning emissions.In measurements from southeast Asia, a signficantreduction in precipitation was observed due to en-hanced CCN amounts. Similar mechanisms aresuggested to be also occurring in Amazonian re-gions that are heavily impacted by biomass burning.There is a possibility that the large amounts ofaerosols in the end of the dry season are delayingthe beginning of the wet season in Amazonia by afew weeks. Further experiments are planned toassess this important issue.

Early results from LBA hydrological studies areadvancing the application of models for water man-agement. A water budget closure system(WBC-LBA) for computing high-resolution waterbalance elements is being established. By integrat-ing existing scientific tools, such as algorithms thatproduce high-resolution climatology fields, waterbalance and river transport models, and a recentlyestablished GIS-based WWW site that serves as adata repository for participating hydrometeorologicalagencies, the WBC-LBA will produce high resolu-tion gridded fields for precipitation, temperature andother climatic variables, evapotranspiration, soil water,drainage basin storage, runoff and river dischargethat are consistent with the observational record ofdata collected at hydrometeorological monitoring sta-tions. Runoff and convergence field predictionswill be tested by an atmospheric model applied overthe experimental domain. Both retrospective (1960–present) and LBA contemporary time frames willbe analyzed.

A new version of the HYDrological RoutingAlgorithm (HYDRA) is being developed for theAmazon, which will simulate time-varying flow andstorage of water in hydrological systems, includingrivers, floodplains, wetlands, lakes, and human-madereservoirs.

A hydrological model for Brazilian macrobasins is also being developed which will inte-

grate existing meteorological, topographic, veg-etation and pedological data, together withremote sensing derived products. The modelwill be used primarily as a real-time monitoring toolcapable of providing updated information about soilmoisture and river discharges to support severaleconomic activities related to water management.In addition, the model’s results will be used in off-line mode to initialize weather forecast models. Toprovide guidance to policy makers in planning miti-gation actions, seasonal forecasts will be used inthe model to try to assess the impact of extremeclimatic events.

Research is underway to understand and modelthe influence of land-cover change on the streamflowof Amazonian river basins with areas of approxi-mately 10,000 km2. To achieve that goal, theresearch will try to quantify the influence of bothclimate and land-cover change on river flow inmesoscale Amazonia to understand processes gov-erning those influences, and to define the range ofbasin size over which land use affects the hydrol-ogy of rivers. The results will be expressed in theform of a mathematical model, checked against theresponse of river flow, driven by measurements ofrainfall, energy sources and terrain characteristics,derived initially from ground-based measurementsand eventually from satellites. The model will beapplicable to mesoscale basins in other physiographicregions of the Amazon Basin.

By the end of 2000, microscale basins will beset up close to Manaus to gain understanding of thecarbon exchanges between soil vegetation and at-mosphere on a pristine forest. The hydrologicalcomponent will try to understand the main mecha-nisms of runoff generation on tropical basins, thefunctioning of deep root in the dry season and therole of interception in the partitioning of energy.This research will be crucial to conceptualizemacroscale hydrological models. Additonal infor-mation about LBA is available at http://www3.cptec.inpe.br/lba/index.html.

References

Cifelli, R. C., W. A. Petersen, L. D. Carey, and S. A. Rutledge,2000. Radar observations of the kinematic, microphysical andprecipitation characteristics of two MCSs in TRMM/LBA. J.Geophys. Res. Submitted.

Petersen, W. A., Rutledge, S., Blakeslee, R. and Cifelli, R.,2000. Convective Regimes during TRMM-LBA: An integratedview from the TRMM Satellite and Brazilian Lightning Detec-tion Network. To be submitted for publication.

5November 2000

GLOBAL AEROSOL CLIMATOLOGYPROJECT ADVANCES

Michael Mishchenko1, Joyce Penner2, andDonald Anderson3

1Goddard Institute for Space Studies2University of Michigan/Ann Arbor

3NASA Headquarters

The NASA/GEWEX Global Aerosol Climatol-ogy Project (GACP) held its third Science Teammeeting 11–13 October 2000 in Lanham-Seabrook,Maryland. The main objective of the meeting wasto assess the progress achieved by individual inves-tigators, as well as by the project as a whole, andto discuss future program directions. As usual, theagenda of the meeting was quite full and consistedof individual progress reports, four invited presenta-tions, and several plenary discussions. The individualprogress reports were grouped by the followingcategories: (i) Satellite retrievals, (ii) Radiation bal-ance/direct aerosol effect, (iii) Field data, (iv) Modelingstudies, and (v) Indirect aerosol effects. The ple-nary discussions focused on the following topics: (i)Status (Where are we? What do we want for ourfinal product? Are there areas where additionalcoordination would enhance the product?); (ii) Uti-lization of field data to enhance aerosol satelliteretrievals/modeling studies; (iii) How to put togethera global aerosol climatology; and, (iv) Planning forthe next phase of GACP.

The meeting began with a summary of the sat-ellite component of GACP presented by MichaelMishchenko. Several changes and improvements inthe two-channel retrieval algorithm and the resultsof global aerosol retrievals for the period of NOAA-9 observations were summarized. The entire data

set is available at the GACP web site http://gacp.giss.nasa.gov. The figure below depicts theaerosol column optical thickness (τ). The Ang-strom exponent (A) averaged over the Northernand Southern hemispheres as well as over the en-tire globe was also presented. The globalaverage of (τ) is close to 0.15 and the globalaverage of (A), not shown, is close to 0.8.The aerosol optical thickness is systematicallylarger in the Northern than in the Southernhemisphere due to the significant Sahara dustcontribution.

Joyce Penner summarized the results of themodeling intercomparison project. The project wasconducted under the auspices of the Intergovern-mental Panel on Climate Change and included theparticipation of 11 different modeling groups. Themodels were first compared to a set of ground-based observations (average error of order 25%),but the comparison with the other species was notas good. However, even for sulfate, the total bur-den varied by more than a factor of 2. Five groupswere able to model all the major aerosol compo-nents (sulfate, organic carbon, black carbon, dustand sea salt) and were able to provide enoughinformation to develop estimates of optical depth. Astandard set of sources were specified for theintercomparison, and optical depths were estimatedoffline so that all results used the same extinctioncoefficients and relative humidity. Thus, differencesbetween the models are directly related to differ-ences in predicted aerosol concentrations. Opticaldepths were compared to 3 different sets of satel-lite-derived optical depths. The comparison showedthat the average difference between the mod-els and satellite-retrieved optical depth was0.05, while the average difference between theretrievals was also of this order. Differences of

Aerosol optical thickness averaged over Northern and Southern Hemisphere as well as the entire globe.

November 20006

about this same order of magnitude can alsoresult from uncertainties in source strengthsof dimethylsulfide emissions and sea salt. Themodeled optical depths as well as the satellite-retrieved optical depth for the month of January areshown on the back page.

Invited presentations by Ralph Kahn and YoramKaufman focused on recent aerosol retrievals usingMISR and MODIS data and demonstrated a signifi-cant improvement of the retrieval capability of thenew generation of satellite instruments compared toone- and two-channel algorithms based on AVHRRdata. James Hansen summarized the results of aworkshop on long-term monitoring of troposphericaerosols held on September 13 and 14, 2000 atGFDL. The workshop emphasized the need forspecialized aerosol instruments on NOAA NPOESSplatforms capable of retrieving detailed aerosol char-acteristics (bi-modal size distribution, refractive index/chemical composition, optical thickness, number con-centration, and single-scattering albedo) with theaccuracy required for global long-term monitoringof the direct and indirect aerosol forcing of climateand identifying its anthropogenic component. Jean-Louis Brenguier described the results of theParameterization of the Aerosol Indirect ClimaticEffect (PACE) workshop held on 1–3 May 2000 atthe Goddard Institute for Space Studies and co-sponsored by GACP. PACE is a joint project fundedby the European Commission. The main objectiveof the project is to combine in situ/ground-basedmeasurements, satellite observations, and advancedmodeling in order to specifically study the indirectaerosol effect on climate and develop parameterizationssuitable for use in global circulation models.

The final discussion focused on the need tosummarize the current status of developing a uni-fied aerosol climatology for the entire period ofAVHRR observations and to define future programdirections. It was pointed out that significant progresshas been achieved in the development of multi-channel retrieval algorithms, critical assessment ofpotential information content of the existing satellitedata sets and their limitations, reconciling differ-ences in aerosol scenarios predicted by differentmodeling groups, and using field data for validatingsatellite and modeling results. The expected re-sult of the first phase of GACP will be threesatellite climatologies of aerosol properties(based on one- and two-channel AVHRR re-trievals and on TOMS data) and potentiallyseveral climatologies based on various trans-port-chemistry models. Given large calibration

uncertainties in the AVHRR data and the limi-tations of one- and two-channel retrievalstrategies, the satellite climatologies may needto be recalibrated by using more advanced glo-bal MISR and MODIS retrievals as a benchmark.A concerted effort will be required to mergeall satellite and modeling products into a singleaerosol climatology suitable for use in globalcirculation models.

References

Higurashi, A., and T. Nakajima, 1999. Development of a two channelaerosol retrieval algorithm on global scale using NOAA/AVHRR. J.Atmos. Sci., 56, 924-941.

Mishchenko, M. I., I. V. Geogdzhayev, B. Cairns, W. B. Rossow, andA. A. Lacis, 1999. Aerosol retrievals over the ocean by use of chan-nels 1 and 2 AVHRR data: sensitivity analysis and preliminary re-sults. Appl. Opt., 38, 7325-7341.

Stowe, L. L., A. M. Ignatov, and R. R. Singh, 1997. Development,validation, and potential enhancements to the second-generation op-erational aerosol product at the NOAA/NESDIS. J. Geophys. Res.,102, 16,923-16,934.

USE OF REANALYSIS LAND SURFACEWATER BUDGET VARIABLES IN

HYDROLOGIC STUDIES

E. P. Maurer, B. Nijssen, andD. P. Lettenmaier

Dept. of Civil and Environmental EngineeringUniversity of Washington, Seattle, WA

Reanalyses provide the land surface modelingcommunity with a comprehensive global set of landsurface water and energy fluxes and associatedstate variables at a sub-daily time interval overextended periods of one or more decades. Forexample, the NCEP/NCAR reanalysis (Kalnaý etal., 1996) has been completed for 1948–2000 andthe more recent NCEP/DOE reanalysis (Kanamitsuet al., 2000) has been completed for 1979–2000.Because global data based directly on observationsfor most land surface moisture and energy fluxesare either not available, or are plagued by sparseobservation networks, the use of reanalysis "data"for characterization of continental to global scalehydrologic features is an attractive (and in somecases the only) option, notwithstanding known bi-ases in reanalysis surface variables (see Kalnay etal., 1996).

One example of the use of reanalysis data formodel evaluation is illustrated by Irannejad et al.

7November 2000

(2000), who summarize the methodology to be ap-plied in the AMIP II Diagnostic Subproject 12(DSP12) to evaluate the performance of alterna-tive land surface schemes (LSS) coupled toatmospheric models. The stated purpose of thatstudy is "...to analyse the surface energy and waterbudgets as a function of LSS complexity." Ac-knowledging the paucity of global observationaldata sets against which the different LSS formu-lations included in DSP12 can be compared, Irannejadet al. (2000) consider NCEP/NCAR Reanalysis,NCEP/DOE Reanalysis, and Variable Filtration Ca-pacity (VIC) model output from a global study ofNijssen et al. (2000) as posssible validation datasets.

Preliminary comparisions of the two NCEPreanalyses with the off-line VIC simulations(in which the model was forced with observedprecipitation, temperature, and other surfaceforcings derived from these variables) leadIrannejad et al. (2000) to indicate that theVIC-derived latent heat is generally biaseddownward relative to the reanalyses. In fact,we will show that, for several reasons, thelatent heat from both NCEP reanalyses areprobably biased upward, and that extremecaution must be taken if such "data" are tobe used for model evaluation (See back pagefigure).

The VIC model (see Nijssen et al., 1997; 2000for summaries) is similar to other land surfaceschemes to the extent that it represents land sur-face moisture and energy fluxes over large areas.As shown by Nijssen et al. (1997), Maurer et al.(2000) and others, a distinguishing feature of themodel is its ability to reproduce streamflow formajor continental rivers. Therefore, when forcedwith observed precipitation, the land surface waterbudget is closed, at least in the long-term average.Depending on the quality of the precipitation andstreamflow data used, the large-area estimates oflong-term mean evapotranspiration produced by theVIC model can be assumed to be quite accurate.Nijssen et al. (2000), which was the source of theVIC output used by Irannejad et al. (2000), showthat the global VIC surface fluxes generally lie inthe middle of the range of several global waterbalance climatologies (see Table 1). For instance,the annual average evapotranspiration from globalland areas simulated by VIC was 483 mm, and forthe climatologies varied from 424 to 562 mm, witha mean of 495 mm. For the NCEP reanalyses,

the range is 631–713 mm, much higher than therange of the climatologies.

Within the Mississippi River basin, where muchmore detailed (and presumably accurate) surface dataare available than in the global data used by Nijssenet al. (2000), the results are even more illuminating,and suggest why the reanalysis latent heat predic-tions may be biased upward. The left panels of thefigure on the back page show that the precipitationfor both reanalyses over the Mississippi River isbiased upward relative to observations. Certain im-provements in the NCEP/DOE as compared withthe NCEP/NCAR reanalysis reduce this precipitationbias somewhat, but a major source of the upwardbias, which has to do with the convective param-eterization in the underlying model, remains.Furthermore, neither reanalysis closes its land sur-face water budget; soil moisture nudging is used toforce the model's soil moisture toward climatology inNCEP/NCAR, and soil moisture in the NCEP/DOEreanalysis is adjusted using inferred infiltration basedon a pentad precipitation database. As shown in thefigure on the next page, in both cases the (absolute)magnitude of the nudging is significant. For theperiod 1988–97 over the Mississippi River basin theadjustment averages 1.6 mm/d for NCEP/NCAR and0.5 mm/d for NCEP/DOE. The result is that thereanalysis evapotranspiration tends to be biased up-ward, because much of the excess moisture(precipitation and surface imbalance due to nudging)is evaporated.

Although this analysis is comprehensive withrespect to all terms in the surface water bal-

Table 1. Comparison of water balance over globalland areas (excepting Antartica and Greenland)

Model (M) or Climatology (C) P ET R

VIC (M) 727 483 244

NCEP/NCAR Reanalysis (M) 631

NCEP/DOE Reanalysis (M) 650

DOE (VIC Grids) (M) 713

Lvovitch (C) 834 540 294

Baumgartner & Reichel (C) 746 480 266

Korzun (C) 727a 424b 303

Oki et al. (C) 727a 562b 165

Oki (C) 727a 483b 244

Means 769 495c 252

a precipitation climatology from Global Precipitation Climatology Project (gauge-only) productb based on cited runoff and GPCC precipitationc excluding reanalysis products

November 20008

ance only for the Mississippi River basin, itseems likely that the apparent upward bias glo-bally has a similar cause. By contrast, theVIC simulations are forced to close the sur-face water balance, and as shown by Nijssen etal. (2000), the model is able to reproduce rea-sonably well (and certainly much better thanthe reanalyses) global runoff from many largecontinental rivers. We believe, therefore, thatit is quite likely that the latent heat predictedby VIC, both within the Misssissippi River basinand globally, provides more accurate estimatesthan do the reanalyses, which we believe arebiased upwards.

The results presented by Irannejad et al. (2000)and evaluated herein suggest that the caution pre-viously noted by various authors regarding use ofreanalysis surface variables be reiterated. Kalnayet al. (1996) note that in the NCEP/NCAR reanaly-sis, the precipitation used to drive the land surfacemodel is a class "C" variable (meaning that it isonly remotely related to observations) as are otherland surface fluxes, including latent and sensibleheat, that are predicted by the land surface scheme.Kalnay et al. (1996) recommend that class "C"variables be used with caution since they have nodirect relationship to observations and are highlyinfluenced by the assimilation model. Betts et al.

(1996) in an early assessment of the NCEP/NCARreanalysis, observed the now well-known precipita-tion biases. It is not surprising, therefore, that theNCEP reanalyses tend to give high values for la-tent heat.

Finally, there is some hope that ongoingand planned reanalysis efforts will produce betterestimates of land surface fluxes that might bemore appropriate for model evaluation than arecurrently available products. ECMWF has re-cently initiated a new reanalysis effort, whichincludes data assimilation protocols that shouldresult in more reliable surface products. NCEPis in the planning stages for a regional reanaly-sis effort, which will include assimilation ofobserved precipitation in such a way that thesurface water budget should close, or at leastnearly close, with precipitation that is close toobservations. If these new products fulfill theirpromise, they may meet the need for globallycoherent moisture and energy flux productsthat can be used for model evaluation.

References

Betts, A. K., S. Y. Hong, and H. L. Pan, 1996. Comparisonof NCEP-NCAR reanalysis with 1987 FIFE data. Mon.Weather Rev. 124, 1480-1498.

Irannejad, P., A. Henderson-Sellers, T. Phillips, and K.McGuffie, 2000. Analysis of AMIP II models' simulationsof land surface climates. GEWEX News. Vol. 10, No.3.

Kalnay, E., M. Kanamitsu, R. Kistler, W. Collins, D. Deaven,L. Gandin, M. Iredell, S. Saha, G. White, J. Woolen, Y.Zhu, A. Leetmaa, R. Reynolds, M. Chelliah, W. Ebisuaki,W. Higgins, J. Janowiak, K.C. Mo., R. Jenne, and D.Joseph, 1996. The NCEP/NCAR 40-Year Reanalysis Project.Bull. Am. Meteorol. Soc. 77, 437-471.

Kanamitsu, M., W. Ebisuaki, J. Woolen, J. Potter, and M.Fiorino, 2000. An overview of NCEP/DOE Reanalysis-2.Second WCRP International Conference on ReanalysesProc. WCRP 109.

Maurer, E. P., G. M. O'Donnell, D. P. Lettenmaier, and J.O. Roads, 2000. Evaluation of the land surface waterbudget in NCEP/NCAR and NCEP/DOE AMIP-II Reanlaysesusing and off-line Hydrologic Model. J. Geophys. Res (inreview).

Nijssen, B., D. P. Lettenmaier, X. Liang, S. W. Wetzel andE. F. Wood, 1997. Streamflow simulation for Continental-scale watersheds. Water Resources Res., 33(4), 711-724.

Nijssen, B., R. Schnur, and D. P. Lettenmaier, 2000. Globalretrospective estimation of soil moisture using the VICland surface model, 1980-1993. J. Climate (in press).

Comparison of reanalysis average monthly water budgetcomponents with VIC simulations over the MississsippiRiver basin for 1988-97. Precipitation for VIC is ob-served, other VIC values are output of model forced withsurface observations.

9November 2000

GLASS IMPLEMENTATION UNDERWAY

Jan PolcherLaboratoire de Météorologie Dynamique du

CNRS

The Global Land-Atmosphere System Study(GLASS) Project Implementation Plan defines the ac-tivities planned for the next several years. GLASSwill coordinate Land Surface Scheme (LSS)intercomparisons from local to global scales and fromoff-line to fully coupled forcing. Building around thenew GLASS structure and the excellent legacy of theProject for Intercomparison of Land-Surface Param-eterization Schemes (PILPS) and the Global SoilWetness Project (GSWP), the above timeline shows,not only the planned schedule, but indicates the LSSfocus areas of carbon processes, remote sensing anddata assimilation. The following summarizes the GLASSimplementation plans.

Local Off-Line Action Group LSS's (PILPS)(A. Henderson-Sellers, A. Pitman): PILPS willcontinue Phase 2 projects. Emphasis will be given toexperiments associated with an improved understandingof how CO

2 is being represented in the current

generation of LSS’s.

Global Off-Line Action Group (GSWP) ( P.Dirmeyer, T. Oki): GSWP 1.5 will be run with anupdated version of the ISLSCP-1 data and the GSWP-2 effort will be broadened to include many aspects

of the carbon cycle. A key activity will be toencourage the entire LSS community to providediagnostics corresponding to satellite observations.The software for these diagnostics will be provided.

Local Coupled Off-Line Action Group (H.Gupta, P. Houser, P. Viterbo): This group willconcentrate on the Atmospheric Radiation Measure-ment (ARM)/Cloud and Radiation Testbed (CART)site data, distribute a simplified single column modeland extend the PILPS experiments by including thecoupling to the atmosphere. Parameter estimationprocedure will ensure that the effective parametersare the same in all schemes.

Coupled On-Line Action Group (P. Cox, R.Koster): Priority issues are intercomparison projectsthat would quantify the impact of (i) surface pro-cesses on the predictability of the hydrological cycle,and (ii) land-use and climate change on surfaceprocesses and climate.

Infrastructure Action Group (J. Polcher, T.Oki): The Assistance for Land-surface ModelingActivities (ALMA) group will provide an infrastruc-ture to facilitate land-surface scheme inter-comparisons. Standardization of the experimentalset-ups will allow participants to reuse and ex-change the tools needed to conduct the simulationand perform the post-processing. PILPS-2e is thefirst intercomparison within the ALMA framework.

GLASS structure and timeline for scientific tasks

November 200010

WORKSHOP/MEETING SUMMARIES

FIRST MEETING OF THE WRAPWORKING GROUP

29–30 August 2000Palisades, New York

Rick LawfordGCIP/GAPP Project Office

The inaugural meeting of the GEWEX WaterResources Applications Project (WRAP) workinggroup took place at the International Research In-stitute (IRI) at Columbia University. The workinggroup was established by the GEWEX Hydrom-eteorology Panel (GHP) to promote dialogue betweenGHP and the water resources community regardingcurrent and future contributions of GEWEX to watermanagement. The principal objectives of the meet-ing were: (1) to determine the scope of WRAP;(2) to develop a strategy and plan for its activities;and (3) to plan a meeting to bring together GEWEXexpertise and water resource managers.

The meeting began with presentations aimed atbringing participants to a common level of under-standing of the water resource applications andactivities of GEWEX. There were presentations onBALTEX, GAME, GCIP/GAPP, MAGS-II and GRDC

Transition of research results to water resourceapplications. Adapted from K.P. Georgakas, A.P. Georgakasand N.E. Graham, GEWEX News, 1988, Vol. 8, No. 3, pp 5-7.

that showed how these projects involve water re-sources. One example is a study exploring how theuse of ensemble and probability forecasts for theMississippi River basin (see figure) are meeting theneeds of water resource managers.

There were also a number of presentations onrelated programs. They included a presentation onHydrology for Environment, Life and Policy (HELP)that emphasized HELP use of a multidisciplinary,"bottoms-up" process to define its activities. Itbuilds upon existing networks and is complementaryto other international water-related projects. HELPneeds hydrologic research that is directly respon-sive to water-related policy.

The ambitious World Water Development Re-port (WWDR), being prepared under the auspicesof UNESCO and funded primarily by Japan, willassess the state of the world’s freshwater resources,both on a global basis and through case studies ofindividual basins. Among other things, the reportwill review the methodology of Integrated WaterResources Management (IWRM) and implementa-tion of IWRM at the basin scale. WWDR emphasizesa balanced approach between the assessment ofneed and availability of water. Coping with water-related stress through adaptation of natural ecosystemsand human societies is an important part of thisstrategy. If the first report is successful and theproject becomes financially self sufficient, these reportswill be completed every 2 years.

The WMO-Hydrology program features a pro-gram for regional Hydrological Cycle ObservingSystems. It was noted that data from this initiativeare freely available over the internet.

It was clear that a number of the goals andstrategies employed by IRI have potential applica-tion in WRAP. Areas of mutual research interestsinclude water resources monitoring and diagnostics(floods, droughts, areas of vulnerability, observedpredictability), water resources forecasting (statis-tical and dynamic) and water resource managementissues.

Based on the discussions and agreements reachedat the WRAP meeting:

• GEWEX/WRAP, in collaboration with theContinental Scale Experiments (CSE), willparticipate in regional WWDR workshops

11November 2000

SIXTH GHP MEETING

11-15 September, 2000Angra dos Reis, Brazil

Sam BenedictWCRP

The sixth annual meeting of the GEWEX Hy-drometeorology Panel (GHP) was hosted by CarlosNobre, representing the Large-Scale Biosphere-At-mosphere Experiment in Amazonia (LBA). A seriesof technical presentations were made on topics thatcovered research of relevance to the global hydro-logical issues being promoted by WCRP and GEWEX.A focused workshop on the status of the GHPWater and Energy Budget Study (WEBS) was heldon the first day of the meeting. Additional timewas given to the status of the GHP Water Re-sources Application Project (WRAP). Each CSEupdated their implementation status and the GHPworking group for the GHP/GEWEX CoordinatedEnhanced Observing Period (CEOP) reported on itsprogress. Discussions were also underaken to re-fine further actions required to ensure a successfulCEOP process. A review of contributions to GHPby national and international projects and organiza-tions, including those within and outside the GEWEXframework, was given by representatives for theInternational Satellite Land-Surface ClimatologyProject (ISLSCP); the International Association ofHydrological Sciences (IAHS); the National Cli-mate Research Program of Korea; the limitedinternational regional study, designated Coupling theTropical Atmosphere and the Hydrological Cycle(CATCH) in West Africa; the Global PrecipitationClimatology Project (GPCP); the Global Precipita-tion Climatology Center (GPCC); the GEWEX GlobalLand-Atmosphere System Study (GLASS); and oth-ers. The work of the GHP Working Group onData Management was also reviewed.

From plenary sessions and breakout groups, thesteps necessary for GHP to achieve its objectiveswere established. Steps were determined for sig-nificant improvement in the simulation of water andenergy fluxes and reservoirs over land on diurnal-to-annual temporal scales, the prediction of theseon temporal scales up to seasonal and interannual,and documentation of the seasonal advance of themonsoon system and better understanding of thephysical transport mechanisms and their possiblephysical connections.

and case studies. (Basins of high interest toWWDR include Rio de la Plata Basin and basinsin the GAME area).

• HELP will be encouraged to develop mechanismsfor working more closely with GEWEX. Fur-thermore, GEWEX will be a principal source ofhydrologic and hydrometeorological expertise forHELP, within the limits of geography, expertiseand resources.

• GEWEX/WRAP will organize the following meet-ings:

• 2001 or 2002: Applications of GEWEX prod-ucts for water resource management.

• 2003: Special IUGG Workshop on the role ofGEWEX hydrology and hydrometeorology sci-ence in improved water resources management.

• WRAP will facilitate regional workshops on wa-ter resources that are coordinated with or organizedby the CSEs. Where possible and appropriate,these workshops should involve other regionalhydrologic expertise such as Flow Regimes fromInternational Experimental and Network Data.

• WRAP will develop an overview of the waterresource needs through the CSEs. Each CSEwas encouraged to hold one or more “scopingdiagnostic” workshops in which they would, basedon input from regional water resource managers,define the important water resource issues andopportunities for their basin, and find the re-search needed to address these particular problems.(In cases where the basin is both a CSE and aHELP basin these scoping exercises should in-volve HELP and also address social and institutionalissues of interest to HELP). It is recommendedthat GHP add a scoping workshop or study asone of its criteria for CSEs.

For a complete listing of GEWEXreports and documents, consult the

GEWEX Web Site:http://www.gewex.com

November 200012

Dr. S. Sorooshian, Chairman of the GEWEX-Scientific Steering Group (SSG) characterizedthe main science and implementation questionsfor GHP in terms of the key uncertainties fac-ing GEWEX and the broader WCRP climateresearch community. These questions includewhether (a) the global hydrological cycle is ac-celerating, (b) the extent to which models canreproduce extreme events such as floods anddroughts, (c) the ability of models to describethe diurnal cycle (e.g., of precipitation) and (d)the process for evaluations that go from theglobal scale down to the regional scale. Thelatter focuses especially on how downscaling tosmaller grid scales can be adapted to current pa-rameterization formulations, and how these factorsimpact the process and need for GHP to close thewater and energy budgets over the CSE regions.

Milestones to be set for GHP, that are attain-able in the context of the next phase of GEWEX,included: (a) providing sufficient point measurementsnecessary for model validations at local scales withineach CSE; (b) establishing basin budgets from largescale diagnostics (monthly/annual) that would leadto a characterization of diagnostic water and en-ergy budgets for each CSE; (c) assessing modelcapabilities to simulate water and energy budgetvariables at all relevant space and time scales foreach CSE; (d) applying GEWEX deliverables toevaluate reanalysis products; and (e) confirmingWEBS results including, with the support of theGEWEX Radiation Panel (GRP), a goal to quantifyfluxes to within 10 W/m2. The action to documentthese plans in an article suitable for publication inthe Bulletin of American Meteorological Societyor similar journal was also accepted. The plansaddress the central challenge of the second phaseof GEWEX to exploit the new and more diversemeasurements of the new Earth Observing Systemplatforms and the application of scientific results ofthe CSEs to improve climate prediction capabilities.Dr. Sorooshian also noted that to accomplish thiswork, GHP must take the lead in promoting theparticipation of the hydrological modeling commu-nity and supporting operational environmental servicesin their efforts to develop improved and more accu-rate hydrometeorological predictions.

WATER AND ENERGY BUDGETWORKSHOP

11 September 2000Angra dos Reis, Brazil

Ronald StewartMeteorological Services Canada

A 1-day workshop was held on the Water andEnergy Budget Study (WEBS) just before the an-nual GHP meeting. WEBS is a critical effort withinGHP in that it strives to collectively assess ourability to develop observations of basic climate vari-ables, assess our ability to simulate those observationswith atmospheric and hydrologic models, assess ourability to develop budgets from observations andmodels, and clarify levels of uncertainty in thesebudgets at annual, seasonal, diurnal, interannual andlonger time scales over the various continental-scaleexperiments of GEWEX as well as other areas.

The workshop’s specific objectives were tosummarize WEBS activities within the various CSEsand other activities of GHP; to clarify our ability tocharacterize, model and understand water and en-ergy parameters over such regions; and to movetowards syntheses of the individual and GHP-wideefforts. Some of the activities are summarizedhere.

A number of WEBS activities are underwaywithin the Large-Scale Biosphere-Atmosphere Projectin Amazonia (LBA). These are associated withspecific field campaigns to better observe waterand energy fluxes and reservoirs and with the analysisof operational and reanalysis model information. Forexample, Marengo (2000) is using the NCEP re-analysis as well as observational information tocharacterize the annual cycle of critical water bud-get parameters and their variations. In general,there is presently considerable difficulty in the bal-ancing of atmospheric motions with stream flowinformation, due to a considerable degree of uncer-tainty in the measurement of basic parameters. Plansfor improved measurements over the basin shouldhelp to alleviate such uncertainties in the future.

Many WEBS-related activities are taking placewithin GCIP/GAPP to understand the water andenergy balance for the Mississippi River basin. Toaccomplish this it is important to define individualcomponents of moisture fluxes at high space and

13November 2000

time resolution. Some preliminary results indicatethat the effects of the low level jet may be en-hanced by larger scale processes that simultaneouslycontribute to the moisture flux. The water cycleand the carbon cycle are highly coupled asindicated by observations showing that the maxi-mum uptake of carbon occurs when transpirationis at a maximum. For example, measurementsin Illinois indicate 50 percent of annual waterloss through evaporation occurs in the summermonths. Furthermore, with wet soils and mid-day radiation exceeding 650 Wm -2,evapotranspiration can exceed 4 mm/day incrops; GCIP is developing many basin-scaleobservational products of critical parametersfor models.

Particular emphasis is being placed on the sys-tematic evaluation of both high resolution regionalmodels, as well as lower resolution global models.In addition, model outputs summarized on maps ofseasonal and annual averages for water and energyvariables are being brought together for a compre-hensive journal article that will include an assessmentof GCIP's capability to characterize, model andunderstand the water and energy balance over thecentral United States. Based on this comparisonthe global spectral model balances the waterbudget to within 40% while the new regionalmodels balance the budget within 20%. Ac-cording to John Roads (personal communication)the differences between the model energy bud-gets are probably balanced to within 30%.

WEBS-related activities in MAGS span a widerange of studies from hillslopes of tens of meters inlength through small catchments of a few kilome-ters in area to basins of the order of 106 km2.These studies use a variety of observational andmodeling approaches. There is considerable capa-bility to close budgets at the small scales using bothobservational and modeling techniques, despite widevariations in surface conditions and the effects ofvariable slopes. Integration of an observationallybased atmospheric balance study with a large scalehydrological modeling study was used to examineour potential to close the water budget for theMackenzie basin (Strong et al., 2000). While someissues remain unresolved, the studies suggeststhat it is feasible to close the Mackenzie bud-get within the error of measurement at theinterannual time scale using monthly observa-

tions and model results. Other water balancestudies, particularly, for the 1994/1995 water year,have been carried out using numerical weather pre-diction, as well as regional climate models; suchstudies show general agreement with availablemeasurements for some parameters but problemswith others (such as orographic precipitation).

A number of WEBS-related studies have al-ready been carried out within BALTEX. Examplesinclude Heise (1996) for the atmosphere and sur-face and Omstedt and Rutgersson (2000) for theBaltic Sea. The first study relied upon short-rangeforecast information and it documented the annualcycle of the atmospheric water budget, the surfaceenergy budget over the sea, and the atmosphericenergy budget and compared these against availableobservation. In general, model and observa-tional results were comparable. Omsted andRutgersson used observations to demonstratethe close balance between the gain of the BalticSea by precipitation and the inflow of rivers.At the Max-Planck-Institute a water budget studyover the BALTEX area was performed where theresults of 10-year runs from the global climate modeland the regional model were compared. Resultsshow an enhancement of evaporation and precipita-tion by the regional model over land and the oppositeover the Baltic Sea. As well, a regional modelintercomparison was performed with 8 models run-ning in various modes (assimilation, forecast andclimate) and the results are presently in the processof being published.

The GEWEX Asian Monsoon Experiment(GAME) has undertaken a number of studies thatdeal with energy and water balances in each of theareas of study. A considerable amount of budgetanalysis has been undertaken using the EuropeanCentre for Medium-range Weather Forecasts(ECMWF) reanalysis products and validating themwith point measurements. As regional reanalysisproducts using GAME measurements become avail-able from Japan Meteorological Agency (JMA)additional WEBS analysis will be undertaken. Ex-tensive analysis of the effects of land cover onheat fluxes have been undertaken in Thailand. Thisanalysis has shown that latent heat fluxes are largerand sensible heat fluxes smaller over the rice pad-dies than over the forested areas. As part of theGAME effort flux measurements are being madein each region. Closing the budget for theseregions has proven to be a challenge. Theimbalance in energy budgets at individual tow-

November 200014

ers range from 5 to 25% in Tibet to 25 to30% in Siberia and 30% in Thailand.

This was an important workshop that allowedthe various efforts within GHP to illustrate theircurrent efforts in regards to WEBS. Substantialprogress is being made within the regional GHPactivities to characterize individual components ofthe regional water and energy fluxes and reservoirsand to examine the overall budgets. An effort willbe made to better collectively summarize the obser-vational and modeling activities that are taking placewithin the various regions on this issue. In addition,some of the CSEs have already embarked on theproduction of collective scientific articles to sum-marize their overall capabilities to observe and modelwater and energy fluxes and reservoirs. It is alsocritical to improve the global perspective. We shouldmake better use of GEWEX and other global dataproducts as well as rely upon the examination ofreanalysis products; such global products have tobe compared against regional ones. Also, moreattention needs to be paid towards the developmentand application of physically based indices for char-acterization and interpretation purposes. All ofthese efforts will eventually be summarized within aGHP-wide article that will highlight our collectivecapabilities to address water and energy balancesregionally and globally.

References

Heise, E., 1996. An investigation of water and energy budgetfor the BALTEX region based on short-range numerical weatherpredictions. Tellus, 48A, 693-707.

Marengo, J., 2000. On the atmospheric water balance andmoisture cycling rate in the Amazon basin: characteristics andvariability (to be submitted to J. Climate).

Omstedt, A.T., and A. Rutgersson, 2000. Closing the waterand heat cycles of the Baltic Sea. Meteorol. Z., 9, 59-66.

Strong, G.S., B. Proctor, M. Wang, R. Soulis and C.D. Smith,2000. Closing the Mackenzie basin water balance, water years94/95 through 96/97. Atmos.-Ocean (Submitted).

CEOP WORKSHOP SUMMARY

14-15 September 2000Angra dos Reis, Brazil

John LeeseGCIP Office

At the 6th GEWEX Hydrometeorology Panel(GHP) Meeting held 11-15 September 2000, therewas a Coordinated Enhanced Observation Period(CEOP) Workshop with broad GHP membershipparticipation. The planning for CEOP has had oneguiding goal—to understand and model the influ-ence of continental hydroclimate processes on thepredictability of global atmospheric circulation andchanges in water resources, with a particular focuson the heat source and sink regions that drive andmodify the climate system and anomalies. TheGHP agreed to focus the CEOP scientific ef-fort within two major activities. They aresimulation and prediction, and monsoon sys-tems.

The objective of the simulation and predictiontask is to use enhanced observations to documentand improve the simulation and prediction of waterand energy fluxes and reservoirs over land on diur-nal to annual temporal time scales, as well as theprediction of these on temporal scales up to sea-sonal (for water resource applications). The workshopparticipants identified what can be done and thesewere distilled to key items for an implementationstrategy. Among the key items for an implementa-tion strategy were the following:

• Build greater involvement of both the me-teorological and hydrological modelingcommunity in CEOP by promoting it at theupcoming WGNE and GMPP sessions andholding a CEOP Workshop that brings thebroader community of observationists, pro-cess studies and modelers together.

• Specify what CEOP will provide to GEWEXPanels, WCRP Project Panels and the datawe need from these groups.

• Update global data sets to include CEOPperiod (including ISLSCP).

• Provide high resolution regional model datasetsbased around monsoon regions as well as

NEW SHORTWAVE RADIATIONBUDGET CD-ROM AVAILABLE FOR

1984-1994

From the University of Maryland, surfaceand top-of-atmosphere shortwave radiationdata are provided based on ISCCP D1 data.To request a CD-ROM, send an e-mail tosrb@atmos.umd.edu

15November 2000

other energy sources and sinks to the atmo-sphere.

• Provide Model Location Time Series (MOLTS)around regions and areas relevant to CEOPquestions.

• Validate the low-resolution global model outputwith the "high quality," high-resolution dataused in CSE regional models.

The second major CEOP activity identified atthe 6th GHP session was to document the seasonalmarch of the monsoon systems and better under-stand their physical driving mechanisms and theirpossible physical connections. Again, from the dis-cussions on what can be done, several key itemsfor the monsoon systems implementation strategywere the following: (1) articulate a few key scienceissues relevant to the objective; (2) make use ofensemble predictions with "enhanced" initial condi-tions (IC)/boundary conditions (BC); (3) carry outa series of ensemble seasonal simulations with IC/BC; and (4) conduct empirical (diagnostic) studies.

The GHP agreed that the implementationof CEOP will begin with a short build up periodof about three months, starting on 1 July 2001,to produce an initial seasonal dataset. TheEnhanced Observing Period will cover twoannual cycles from 1 October 2001 through30 September 2003. The CEOP Research Phasewill begin in a formal sense with the availabilityof the initial seasonal data set about the end ofSeptember 2002.

The International CEOP Workshop, scheduledfor 27 February to 1 March 2001, in Greenbelt,Maryland will contribute to this planning effort.

GEWEX/WCRP MEETINGSCALENDAR

For calendar updates, see the GEWEX Web site:http://www.gewex.com

4–5 December 2000—LBA-HYDRONET WORKSHOP,Cachoeira Paulista, SP Brazil

11–13 December 2000—ISCCP WORKING GROUP ON DATAMANAGEMENT AND SCIENCE ADVISORY TEAM MEET-ING, NASA Goddard Institute for Space Studies, New York City,NY, USA.

8–10 January 2001—WORKSHOP TO DEVELOP AN INTE-GRATED GLOBAL OBSERVING STRATEGY FOR THEWATER CYCLE, Los Angeles, California, USA.

14–19 January 2001—81ST AMERICAN METEOROLOGI-CAL SOCIETY MEETING, Albuquerque, New Mexico, USA.Special symposia include: Global Aerosol Climatology; Sympo-siums on Global Change Studies and Integrated Observing Systems.

29 January–2 February 2001—GEWEX SCIENTIFIC STEER-ING GROUP MEETING, Barcelona, Spain.

27 February–1 March 2001—INTERNATIONAL CEOPWORKSHOP, NASA/GSFC, Greenbelt, Maryland, USA.

5–7 March 2001—GAME TROPICS WORKSHOP, Phuket,Thailand.

7–9 March 2001—INTERNATIONAL WORKSHOP ONGAME- ASIAN AUTOMATIC WEATHER STATION (AWS)NETWORK (AAN)/RADIATION. For more information: http://erc2.suiri.tsukuba.ac.jp/Project/aan/aan.html.

19–24 March 2001—WCRP JOINT SCIENTIFIC COMMIT-TEE MEETING, Boulder, Colorado, USA.

4–6 April 2001 —GAPP PRINCIPAL INVESTIGATORS MEET-ING AND GAPP IMPLEMENTATION PLAN WORKSHOP,Potomac, Maryland, USA.

2–6 July 2001—THIRD STUDY CONFERENCE ON BALTEX,Aland, Finland. For information consult website: http://w3.gkss.de/baltex/.

10–13 July 2001—CHALLENGES OF A CHANGING EARTH--A GLOBAL CHANGE OPEN SCIENCE CONFERENCE, RAIConference Center, Amsterdam, The Netherlands. Abstractsare due 31 March 2001. For information:http://www.sciconf.igbp.kva.se/fr.html.

14–15 July 2001—JOINT ISLSCP/BAHC SCIENCE PANELMEETING, Amsterdam, The Netherlands.

18–27 July 2001—SIXTH SCIENTIFIC ASSEMBLY OF THEINTERNATIONAL ASSOCIATION OF HYDROLOGICALSCIENCES (IAHS)-S5 SOIL-VEGETATION-ATMOSPHERETRANSFER SCHEMES AND LARGE SCALE HYDROLOGI-CAL MODELS, Maastricht, The Netherlands.

10–14 September 2001—FOURTH INTERNATIONAL SCI-ENTIFIC CONFERENCE ON THE GLOBAL ENERGY ANDWATER CYCLE, Institut Pierre Simon Laplace, Collège deFrance, Paris, France. For information: http://www.ipsl.jussieu.fr/gewex.

1–2 October 2001—SIXTH GAME INTERNATIONAL SCI-ENCE PANEL MEETING, Aichi Trade Center, Nagoya, Japan.

3–5 October 2001—FIFTH INTERNATIONAL STUDY CON-FERENCE ON GEWEX IN ASIA AND GAME, Nagoya, Japan.

November 200016

MODELS AND SATELLITE-DERIVED OPTICAL DEPTH AVERAGE 0.05 DIFFERENCES

Aerosol optical depth derived from AVHRR sat-ellite analysis following Nakajima et al. (1999)(labeled result 1 and result 2), Mishchenko etal. (1999) and Stowe et al. (1997) for Janu-ary. The results from Nakajima refer to 1990,while those from Mishchenko and Stowe referto an average over the years 1985 to 1988.The results derived from the models which par-ticipated in the GACP and IPCC-sponsoredworkshop are also shown. The case labeledsummed sensitivity study shows the derivedoptical depth for the ECHAM/GRANTOURmodel using a factor of two increase in theDMS flux and the monthly average sea saltfluxes derived using the SSM/I wind fields (Seepage 5).

REANALYSIS COMPARISONS PROVIDE PROMISE FORCLOSING BUDGETS

Left panels: Average precipitation in mm/day over theMississippi River basin for summer (June, July, Au-gust) for 1988-97 for NCEP/NCAR and NCEP/DOE re-analyses, and gridded observed values (used in theVIC model). Right panels: 10-year average (1988-97)latent heat differences between NCEP/NCAR (upper)and NCEP/DOE (lower) reanalyses and VIC over theMississippi River basin. VIC was forced by observedprecipitation, and closely reproduced observed runoff(See page 6).

GEWEX NEWS

Published by the International GEWEXProject Office (IGPO)

Mail: International GEWEX Project Office1010 Wayne Avenue, Suite 450Silver Spring, MD 20910, USA

Tel: (301) 565-8345Fax: (301) 565-8279

E-mail: gewex@cais.comWWW Site: http://www.gewex.com

Dr. Paul D. Try, DirectorEditor: Dr. Paul F. Twitchell

Assistant Editor: Dawn P. Erlich