CM-SAF surface radiation

23rd GIST meeting Offenbach 1

CM-SAF surface radiation

Deutscher Wetterdienst

23rd GIST meeting in Offenbach

29.04.2005

R. Hollmann, R.W. Mueller, H.D. Behr, P. Albert, A. Gratzki,

MeteoSwiss


Outline of talk

Introduction

CM-SAF Surface radiation budget

Algorithms used

results with MSG

cloud mask validation

Conclusion


Motivation

Mandate of CM-SAF:● support climate monitoring at regional scale

● the generation of a thematic climate data record in an

operational off - line environment

● the generation of long-term validated, homogeneous and consistent data sets

Beside the mandate of CM-SAF the Solar-Energy Community benefits from the CM-SAF radiation products


Surface Radiation budget products● Products:

– SOL: surface outgoing longwave – SDL: surface downwelling longwave – SIS: surface incoming shortwave– SAL: surface albedo– SRB: surface radiation budget (SNL/SNS)

● 15x15 km sinusoidal projection.

● Monthly and daily mean (AVHRR, MSG), mean diurnal cycle (only MSG)

● Covered area: 30° N to 80° N, 60° W to 60° E● Operational processing and delivery of NOAA-AVHRR based

products has been started 01.01.2005● MSG based products are currently pre-operational (~available for

public Aug/Sep 2005 (tbc))


I2004

I2007

I2008

I2005

I2006

I2009

Initial Operations Phase

Full Operations Phase

V2

V3

Area Extension

EPS

Merging

MSG

(rad & clouds)

HCP

(ATOVS & MSG)

V1NOAA(rad & clouds)

CM-SAF: Schedule & Versioning

CM-SAF Surface Radiation Budget:

23rd GIST


Beta-user?!

• Passive House Institute, (J. Schnieders), Darmstadt, Germany

• Fraunhofer Institute for Solar Energy Systems (Chr. Reise), Freiburg, Germany

• DWD, Regional Office Hamburg, solar energy specific radiation maps

• Scientific User‘s (tbc):

• RADAGAST (within AMMA framework), A. Slingo, Reading, UK• DLR (M. Schrödter-Homscheidt), Oberpfaffenhofen, Germany• Spain Met. Service (J. L. Camacho, Guerrero)

• Looking for more beta-user!!! -> -> have a look at http:\\www.cmsaf.dwd.de


RTM library libRadtran for MLB-LUTs

Bernhard Mayer (DLR) and Arve Kylling (NILU)

SHDOM for cloud LUTs

Frank Evans

AVHHR TOA-flux with ERBE ADM (DWD), cloud products, nowcasting SAF (SMHI).

TOA-flux for GERB/SEVIRI is calculated by RMIB.

Overview SIS Algorithm


Overview SIS Algorithm

cloudmask

Cloud-free ?

Clear-skyAtmospheric state

Ozon, H2O, Aerosole

CLOUD-LUT Relation G-TOA for

clear-sky atmospheric states(9SZW) and 10 CODs

CLEAR-SKY: MLB-LUTG for clear-sky

atmospheric states

TOAflux

G G

SAT

ADM

AVHRRGERB/SEVIRI


Example MSG productsMonthly mean 2004,07: top SDL, SOL; bottom SIS, SAL


Example productsMonthly mean 2004,07: top SNL; bottom SNS


Example productsMonthly mean diurnal cycle of SIS for April 2005

Rem.: at the moment no GERB-data are available -> the SIS-Algorithm is run with the SEVIRI only based TOA albedo


Overview Longwave

SOL: Based on Plancks radiation law for black bodies.

Surface temperature from GME analysis

SDL: Adaption of Gupta algorithm

T and H2O from GME analysis

Cloudmask and –height retrieved from AVHRR or MSG with nowcasting-SAF algorithms (SMHI, MeteoFrance)


Overview Validation

4-5 stations: Payerne, Carpentras, Lindenberg, Cabauw (Ny-Alesund).

Ongoing validation of the operational products

Validation of reference months.

Base for Initial operations phase. To analyse comparable results with the goal to improve the algorithm.To track the effect of changes in the algorithm.


CARPENTRAS

0

50

100

150

200

250

300

350

400

July 2004 October 2004 July 2004 October 2004

SIS SDL

W/m

2 in_situ W/m2

sat W/m2

Overview Validation

Mean absolute bias of monthly means over all stations and months

(4 stations, 2 month) .

2.759.5SDL

2.52.9SIS

27.6SOL

BIAS in %BIAS in

W/m²


Overview Validation

First validation of MMDC: July 2004, Carpentras-Station

Green: surface obsblack: MSG derived


Conclusion Validation

10 W/m² „target accuracy“ für monthly means (SIS,SOL,SDL) are in general achieved. Problems in the Alpine region, especially for the longwave radiation.

Support for heterogeneous terrain by MeteoSwiss.

Planned:

Routine (Automatized) quality check with reference data set.

Validation for more stations and month.

Acknow.: For providing data for validation to MeteoSwiss, MeteoFrance, KNMI, DWD, AWI


Validation of MSG cloud fraction

● Comparison of MSG cloud fraction with Synop observations● April, May, October 2004


MSG SYNOP

rel. differencedifference



● Better agreement over land than over sea

● Day / night dependence?

● Best agreement where number of SYNOP observations is highest



Outlook:

• Operational production based on NOAA-AVHRR since Jan 2005

• Operational production based on MSG will start Aug/Sep 2005 (tbc)

• Surface Radiation Processing;• mean differences for SIS ~ 10 W/m² • mean differences for SDL ~ 10 W/m²

• Ongoing validation;• selected reference target stations with quick data availability • TOA albedo comparison MSG/GERB vs. AVHRR• improvement of LUT-approach• new background maps for aerosol properties• merging of both data set

• User Workshop 29-31. August 2005 in Nuremberg (Germany).

CM-SAF Surface Radiation Budget: Conclusion & outlook



Clear-sky MLB-LUT

MLB-LUT: G for 2 SZA different AOD, ssa, gg

USS-stand. profile, surf. albedo 0.2

G interpolatedAerosol-space

GADS/OPAC or MPI Hamburg

Aerosol climatology

LAT,LON

AODssa, gg

GME H2OO3 profile correction absorb

constituents H2O,O3

Surface albedoFMI or background

H2O, O3

Albedo correction of effect surface albedo

G

MLB: modified Lambert Beer relationship (Mueller et al. 2004)


Cloudy-sky ‘traditional’ LUT

LUT: TOA flux – G ratiofor 9 SZA, 10 COD, 5 H2O,

7 Albedo, 3 O3, 5 atm. profile

G interpolated, no aerosols

LAT,LON

AODssa, gg

GME H2OO3 profile

Correction for Aerosols

surfacealbedo FMIor background-alb

H2O, O3

Albedo

G

GADS/OPAC or MPI Hamburg

Aerosol Climatology

TOAflux

SATADM

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CM-SAF surface radiation