Developments in the Latest Version of the RegCM Jeremy Pal Contributors: Filippo Giorgi, Xunqiang Bi, Nellie Elguindi, Elfatih Eltahir, Raquel Francisco,

Developments in the Latest Developments in the Latest Version of the RegCMVersion of the RegCM

Jeremy PalJeremy PalContributors: Filippo Giorgi, Xunqiang Contributors: Filippo Giorgi, Xunqiang

Bi, Nellie Elguindi, Elfatih Eltahir, Raquel Bi, Nellie Elguindi, Elfatih Eltahir, Raquel Francisco, Sonia Seneviratne, Eric Small, Francisco, Sonia Seneviratne, Eric Small,

Fabien Solmon, and many moreFabien Solmon, and many more

Latest DevelopmentsLatest Developments

►User-friendlinessUser-friendliness►PreprocessorPreprocessor

Terrain and landuseTerrain and landuse Initial and boundary conditionsInitial and boundary conditions

►Model PhysicsModel Physics Large-scale and convective precipitationLarge-scale and convective precipitation Land-surface and oceanLand-surface and ocean

►PostprocessorPostprocessor Output formatsOutput formats

Latest Developments: Input/OutputLatest Developments: Input/Output► User-FriendlyUser-Friendly► Landuse and TopographyLanduse and Topography

USGS GLCC 30 second (~1-km) Landuse dataUSGS GLCC 30 second (~1-km) Landuse data► Based on AVHRRBased on AVHRR► Now 20 vegetation types (previously 13)Now 20 vegetation types (previously 13)

USGS GTOPO30 30 second (~1-km) Elevation dataUSGS GTOPO30 30 second (~1-km) Elevation data► Initial and Boundary ConditionsInitial and Boundary Conditions

Reanalysis Data: NCEP and ECMWFReanalysis Data: NCEP and ECMWF GCM Data: HadCM and CCM3GCM Data: HadCM and CCM3 SST Data: 1SST Data: 1° ° CAC Optimal Interpolation and 1CAC Optimal Interpolation and 1°° Hadley Centre Hadley Centre

► Rotated Mercator Map ProjectionRotated Mercator Map Projection Suitable for most latitudesSuitable for most latitudes

► More Compact Data formatsMore Compact Data formats GrADS compatible (real*4 direct access)GrADS compatible (real*4 direct access) NetCDF Processors (real*4 and integer*2)NetCDF Processors (real*4 and integer*2) Vis5DVis5D

Improvements to Structure & InputImprovements to Structure & Input

RotatedRotatedMercatorMercatorProjectionProjection

GLCCGLCCVegetationVegetation

Reanalysis Reanalysis & GCM & GCM

Initial and Initial and Boundary Boundary ConditionsConditions

Hadley & OISea Surface

Temperatures

USGSUSGSTopographyTopography

Latest Developments: Core ModelLatest Developments: Core Model► Tracer/Aerosol Scheme [Qian et al (2001); Solmon]Tracer/Aerosol Scheme [Qian et al (2001); Solmon]► Zeng et al (1998) Ocean Flux ModelZeng et al (1998) Ocean Flux Model► SUBEX Large-scale Precipitation Scheme (Pal et al SUBEX Large-scale Precipitation Scheme (Pal et al

2000)2000)► Emanuel (1991) Convection SchemeEmanuel (1991) Convection Scheme► Sub-grid Land Surface and Precipitation Sub-grid Land Surface and Precipitation

Parameterization [Giorgi et al (2003); Pal and Parameterization [Giorgi et al (2003); Pal and Elguindi]**Elguindi]**

► Non-Hydrostatic [Bi]**Non-Hydrostatic [Bi]**► Parallel Code [Ye and Bi]**Parallel Code [Ye and Bi]**** To be released by the end of the summer.** To be released by the end of the summer.


2000)2000)► Covection: FC80 Closure; Emanuel (1991) SchemeCovection: FC80 Closure; Emanuel (1991) Scheme► Sub-grid Land Surface and Precipitation Sub-grid Land Surface and Precipitation



Tracer/Aerosol SchemeTracer/Aerosol Scheme► TransportTransport

Advection/DiffusionAdvection/Diffusion ConvectionConvection

► EmissionsEmissions► Removal processesRemoval processes

Precipitation (large-scale Precipitation (large-scale and convective)and convective)

Dry depositionDry deposition

► Chemistry scheme for Chemistry scheme for SulfatesSulfates

► Direct and indirect Direct and indirect radiative effectsradiative effects

RegionalRegionalClimate ModelClimate Model

RadiativeRadiativeTransferTransferPackagePackage

Aerosol ModelAerosol ModelSource, Transport,Source, Transport,

RemovalRemovalR

adia

tive F

luxes

Heati

ng R

ate

Aero

sol R

adia

tive

Forc

ing

Clo

uds,

Tem

pera

ture

,W

ate

r V

apor

Winds, PBL Processes

Clouds, Precipitation

Aeros

ol

Conce

ntra

tion

Adapted from Qian et al (2001)Adapted from Qian et al (2001)

Anthropogenic Aerosols overAnthropogenic Aerosols overEast Asia (Giorgi et al. 2002)East Asia (Giorgi et al. 2002)

► Summer cooling has been observed in recent Summer cooling has been observed in recent decades over many regions of East Asia.decades over many regions of East Asia.

► At the same time, anthropogenic sulfate and fossil At the same time, anthropogenic sulfate and fossil fuel soot emissions have drastically increased due to fuel soot emissions have drastically increased due to the economic development of the region.the economic development of the region.

► This study investigates the impact of sulfur and soot This study investigates the impact of sulfur and soot emissions from fossil fuel burning on the regional emissions from fossil fuel burning on the regional climate of East Asia.climate of East Asia. Intercomparison of 5-year simulations (1993-1997) with Intercomparison of 5-year simulations (1993-1997) with

and without aerosol effects.and without aerosol effects.

Anthropogenic Aerosols over East Anthropogenic Aerosols over East AsiaAsia

►In recent decades, the anthropogenic sulfate In recent decades, the anthropogenic sulfate and fossil fuel soot emission over east Asia and fossil fuel soot emission over east Asia have drastically increased.have drastically increased.

►At the same time, summer cooling has been At the same time, summer cooling has been observed over the major emissions regions.observed over the major emissions regions.

►This study assesses the surface climatic effects This study assesses the surface climatic effects of this emissions.of this emissions.

Sulfur emission over East AsiaSulfur emission over East Asia(g (g SS m m-2-2 yr yr-1-1))

Temperature difference between Temperature difference between betweenbetweenthe periods 1981-1998 and 1951-1980.the periods 1981-1998 and 1951-1980.

Effects of Aerosols onTemperature and Precipitation

Temperature DifferencesTemperature Differences Precipitation DifferencesPrecipitation Differences

Summary of Impacts of East Asian Summary of Impacts of East Asian Anthropogenic EmissionsAnthropogenic Emissions

►The anthropogenic emissions over East Asia The anthropogenic emissions over East Asia tend to cause surface cooling and inhibit tend to cause surface cooling and inhibit precipitation.precipitation.

►Some features of the simulated aerosol-induced Some features of the simulated aerosol-induced surface cooling are consistent with temperature surface cooling are consistent with temperature trends observed in recent decades over trends observed in recent decades over different regions of East Asia.different regions of East Asia.




► Non-Hydrostatic [Bi]**Non-Hydrostatic [Bi]**► Parallel Code [Ye and Bi]**Parallel Code [Ye and Bi]**► ** To be released by the end of the summer.** To be released by the end of the summer.

RegCM: RegCM: BATSBATSRegCM: RegCM: BATS-ZengBATS-ZengZeng et al (1998) Zeng et al (1998) Ocean Flux SchemeOcean Flux Scheme

► The old bulk aerodynamic The old bulk aerodynamic algorithm uses the Monin-algorithm uses the Monin-Obukhov similarity relations Obukhov similarity relations without special treatments of without special treatments of convective or very stable convective or very stable conditions.conditions. Overestimate latent heat in both Overestimate latent heat in both

weak and strong wind conditionsweak and strong wind conditions

► The new algorithm describes all The new algorithm describes all stability conditions and includes stability conditions and includes a gustiness velocity to account a gustiness velocity to account for the additional flux induced for the additional flux induced by boundary layer scale by boundary layer scale variabilityvariability

RegCM: RegCM: ZengZeng





Importance of CloudsImportance of Clouds► Correctly simulating the surface solar radiation is Correctly simulating the surface solar radiation is

crucial in simulating the hydrologic cycle.crucial in simulating the hydrologic cycle.► The response of climate to changes in CO2, soil The response of climate to changes in CO2, soil

moisture, vegetation, etc., is largely dependent on moisture, vegetation, etc., is largely dependent on cloud feedbacks.cloud feedbacks. E.g. The IPCC report indicates that the representation of E.g. The IPCC report indicates that the representation of

cloud characteristics accounts for a large portion of the cloud characteristics accounts for a large portion of the uncertainty in climate change predictions.uncertainty in climate change predictions.

► In most climate models clouds and precipitation are In most climate models clouds and precipitation are represented in two formsrepresented in two forms Resolvable (large-scale)Resolvable (large-scale) Unresolvable (convective)Unresolvable (convective)

SurfaceSurfaceTemperatureTemperature

(RegCM vs OBS)(RegCM vs OBS)

Large-Scale Clouds Large-Scale Clouds and Precipitationand Precipitation

► The model had an on-off tendency The model had an on-off tendency with clouds.with clouds. No middle groundNo middle ground

► Clouds only form when the gridcell Clouds only form when the gridcell is supersaturated.is supersaturated. Clouds often exist at relative Clouds often exist at relative

humidities below one.humidities below one.

► Fractional cloud cover (Fractional cloud cover (FCFC) is 80% ) is 80% when cloud water exists and 0% when cloud water exists and 0% otherwise.otherwise. FCFC varies between 0 and 100%. varies between 0 and 100%.

► Raindrop accretion & evaporation Raindrop accretion & evaporation are not accounted for.are not accounted for.

Incident SolarIncident Solar(RegCM vs OBS)(RegCM vs OBS)

SUBEX: SUBEX: Map of DomainMap of DomainLanduse and ElevationLanduse and Elevation

SUBEX:SUBEX: Incident Surface Solar Incident Surface Solar (NASA-SRB)(NASA-SRB)

Old Model vs. ObservationsOld Model vs. Observations New Model vs. ObservationsNew Model vs. Observations

SUBEX:SUBEX: Mean Surface Mean Surface Temperature (USHCN)Temperature (USHCN)


SUBEX:SUBEX: Precipitation (USHCN)Precipitation (USHCN)


SUBEX:SUBEX: June & June & July 1993 FloodJuly 1993 Flood

RegCM: RegCM: Old ModelOld ModelRegCM: RegCM: New ModelNew Model

USHCN ObservationsUSHCN Observations

SUBEX:SUBEX: Summary of Results Summary of Results

►SUBEX provides a more accurate SUBEX provides a more accurate representation of the fields describing the representation of the fields describing the energy and water budgets.energy and water budgets.

►The improvements are seen in mean The improvements are seen in mean conditions as well as the variability at the conditions as well as the variability at the daily to interannual scalesdaily to interannual scales

►This suggests that SUBEX improves the This suggests that SUBEX improves the model sensitivity which is critical to climate model sensitivity which is critical to climate change and process studies.change and process studies.





Convective ProcessesConvective Processes

►Convective processes occur at horizontal Convective processes occur at horizontal scales on the order of 1-km.scales on the order of 1-km. RCMs and GCMs typically run at resolutions 1-2 RCMs and GCMs typically run at resolutions 1-2

orders of magnitude greater.orders of magnitude greater. Most models are thus required to parameterize Most models are thus required to parameterize

convection making the assumption that the convection making the assumption that the statistical properties of convection can be deduced statistical properties of convection can be deduced from the large-scale (resolved) variables.from the large-scale (resolved) variables.

►In models, an inadequate representation of In models, an inadequate representation of convective can significantly increase the convective can significantly increase the uncertainty of the model predictions.uncertainty of the model predictions.

Grell Scheme DescriptionGrell Scheme Description

► Simplified form of the Arakawa & Schubert (1974) Simplified form of the Arakawa & Schubert (1974) convection schemeconvection scheme

► Convective clouds consist of an updraft and Convective clouds consist of an updraft and downdraft circulation.downdraft circulation.

► The updraft and downdraft origins occur at the The updraft and downdraft origins occur at the levels of maximum and minimum moist static levels of maximum and minimum moist static energy.energy.

► The scheme is activated when a lifted parcel attains The scheme is activated when a lifted parcel attains moist convection.moist convection.

Grell Scheme Closure AssumptionsGrell Scheme Closure Assumptions

Quasi-EquilibriumQuasi-EquilibriumAssumption (Arakawa &Assumption (Arakawa &Schubert 1980; AS74):Schubert 1980; AS74):► Convection stabilizes the Convection stabilizes the

environment as fast as the environment as fast as the large-scale destabilizes it.large-scale destabilizes it.

► Designed to represent Designed to represent Type II (Tropical) Type II (Tropical) convectionconvection which tends to which tends to be the most common form be the most common form of convection.of convection.

► Default in Grell Scheme.Default in Grell Scheme.

Fritsch & Chappell (1980)Fritsch & Chappell (1980)Closure Assumption (FC80)Closure Assumption (FC80)

► Convection removes the Convection removes the available buoyant energy available buoyant energy at a given time-scale.at a given time-scale.

► Designed to represent Designed to represent Type I (explosive) Type I (explosive) convectionconvection which typically which typically occurs in mid-latitudes.occurs in mid-latitudes.

Convective Convective Closure Closure

Assumptions:Assumptions: June & July 1993 June & July 1993

FloodFlood

RegCM: RegCM: AS74AS74

USHCN ObservationsUSHCN Observations

RegCM: RegCM: FC80FC80

Emanuel Convection SchemeEmanuel Convection Scheme

►Arguably a more physical representation of Arguably a more physical representation of convection than the Grell and Anthes-Kuo convection than the Grell and Anthes-Kuo schemes.schemes.

►Designed to represent the effects of all moist Designed to represent the effects of all moist convection, including shallow, non-convection, including shallow, non-precipitating cumulus.precipitating cumulus.

►Includes the tracer transport options.Includes the tracer transport options.►More testing of the Emanuel Scheme within More testing of the Emanuel Scheme within

the RegCM3 is required.the RegCM3 is required. Stable only at small timesteps.Stable only at small timesteps.





Subgrid Topography Subgrid Topography and Landuse Schemeand Landuse Scheme

► Land surfaces are characterized by Land surfaces are characterized by pronounced spatial heterogeneity pronounced spatial heterogeneity that span a wide range of scales that span a wide range of scales (down to 100s of meters).(down to 100s of meters).

► Topography and landuse exert a Topography and landuse exert a strong forcing on atmospheric strong forcing on atmospheric circulations and land-atmosphere circulations and land-atmosphere exchanges.exchanges.

► Current climate models cannot Current climate models cannot capture the full range of scales, capture the full range of scales, thus intermediate techniques can thus intermediate techniques can be used.be used.

10-km10-km

60-km60-km

60-km60-kmLanduseLanduse

10-km10-kmLanduseLanduse

10-km10-kmTopographyTopography

60-km60-kmTopographyTopography

General MethodologyGeneral Methodology► Disaggregate atmospheric fields from the coarse grid Disaggregate atmospheric fields from the coarse grid

to the fine grid surface.to the fine grid surface. Extension of approach of Seth et al. (1994)Extension of approach of Seth et al. (1994) Landuse, topography, and soil texture are characterized Landuse, topography, and soil texture are characterized

on the fine grid.on the fine grid. Disaggregation technique is based on the elevation Disaggregation technique is based on the elevation

differences between the coarse grid and the fine grid.differences between the coarse grid and the fine grid.

► Perform surface physics computations.Perform surface physics computations.► Reaggregate the surface fields from the fine grid to Reaggregate the surface fields from the fine grid to

the coarse grid.the coarse grid.► We apply this method to a regional climate model We apply this method to a regional climate model

(named RegCM) using BATS.(named RegCM) using BATS.

Summary of RegCM3 InputSummary of RegCM3 Input►User-friendlyUser-friendly►Lateral Boundary and Initial ConditionsLateral Boundary and Initial Conditions

Reanalysis: 1. ECMWF; 2. NCEPReanalysis: 1. ECMWF; 2. NCEP GCM: 1. HadCM3; 2. CCM3GCM: 1. HadCM3; 2. CCM3

►Sea-surface temperatures:Sea-surface temperatures: 1. CAC OI; 1. CAC OI;2. Hadley Centre.2. Hadley Centre.

►Landuse:Landuse: USGS GLCC (Loveland et al 1999) USGS GLCC (Loveland et al 1999)►Topography:Topography: USGS GTOPO30 USGS GTOPO30►Map Projections:Map Projections: 1. Rotated Mercator; 1. Rotated Mercator;

2. Lambert Conformal; 3. Polar Stereographic2. Lambert Conformal; 3. Polar Stereographic

Summary of RegCM3 CoreSummary of RegCM3 Core► Dynamics:Dynamics: 1. MM5 Hydrostatic Dynamics (Grell 1. MM5 Hydrostatic Dynamics (Grell

et al. 1994); et al. 1994); 2. Non-hydrostatic (Bi)2. Non-hydrostatic (Bi)► Radiation:Radiation: CCM3 (Kiehl 1996) CCM3 (Kiehl 1996)► Large-Scale Clouds & Precipitaion:Large-Scale Clouds & Precipitaion: SUBEX (Pal SUBEX (Pal

et al 2000)et al 2000)► Cumulus convection:Cumulus convection: 1. Grell (1993); 2. Anthes- 1. Grell (1993); 2. Anthes-

Kuo (1977); 3. Emanuel (1991)Kuo (1977); 3. Emanuel (1991)► Tracers/Aerosols:Tracers/Aerosols: Qian et al (2001); Solmon Qian et al (2001); Solmon► Boundary Layer:Boundary Layer: Holtslag (1990) Holtslag (1990)► Land Surface:Land Surface: 1. BATS (Dickinson et al. 1986); 1. BATS (Dickinson et al. 1986);

2. Subgrid BATS (Giorgi et al 2003)2. Subgrid BATS (Giorgi et al 2003)► Ocean Fluxes:Ocean Fluxes: 1. Zeng et al (1998; 2. BATS 1. Zeng et al (1998; 2. BATS► Parallel Code (Ye & Bi)Parallel Code (Ye & Bi)

Documents

Developments in the Latest Version of the RegCM Jeremy Pal Contributors: Filippo Giorgi, Xunqiang Bi, Nellie Elguindi, Elfatih Eltahir, Raquel Francisco,