1

The GEMS production systems and retrospective reanalysis

Adrian Simmons

2

• ERA-40

• ENVISAT cal/val and assimilation experience

• Development of analysis of CO2 from AIRS radiances

• Development of fast RT models

• Other developments of the ECMWF forecasting system

GEMS production systems and reanalysis will build on several ECMWF activities, including:

3

• A reanalysis from September 1957 to August 2002

• Based on cycle 23r4 of ECMWF forecasting system- operational from June 2001 to January 2002

• Six-hourly 3D-Var analysis- operations uses 12-hourly 4D-Var

• T159 horizontal resolution (~125km grid)- operations uses T511 (~39km grid)

• Uses full 60-level resolution

The ERA-40 data assimilation system

4

Trend and variability in two-metre temperature over land

CRUTEM2v from Jones and Moberg (2003)CRUTEM2v from Jones and Moberg (2003)

Linear trend: CRUTEM2v 0.171OC/decade

ERA-40 0.169OC/decade

ERA-40

5

Linear trend in two-metre temperature (OC/decade)

CRUTEM2v from Jones and Moberg (2003)ERA-40

6

Trend and variability in lower stratospheric temperature

Linear trend: MSU-4 - 0.39OC/decade

ERA-40 - 0.30OC/decade

NCEP - 0.82OC/decade

MSU-4 data analyzed by Mears et al. (2003)ERA-40 equivalent from Ben Santer, PCMDI

7

Total ozone (following Pascal Simon, Météo-France)

Blue: ERA-40 (TOMS and SBUV data assimilated 1979-1988 and

1991-2002)

Red: Ground-based

measurements (NOAA/CMDL)

8

Equatorial specific humidity

Model simulation

10

100

1

hPa

One year

ERA-40

10

100

1

hPa

One year

9

Humidity and rainfall over the tropical oceans

Year

ERA-40

24 - 36h forecast

24h forecast

SSM/I retrievals from Remote Sensing Systems

10

• ERA-40 production system was based on ECMWF’s prepIFS software for preparing and managing experimentation with its forecasting system

• prepIFS is available to Member-State users of the ECMWF forecasting system

• ERA-40 system was used remotely by Reading University and KNMI for studies of data denial

• Updated system will be available to GEMS partners

• GEMS funding will enable ECMWF to provide better support for external users than possible for ERA-40

Remote use of data assimilation system

11

• An interim reanalysis- Start next year, T159L60 (L91?), latest version of forecasting system

- Run from 1991 (tbd) onwards, continued in close to real time

- Basis for future developments (including GEMS)

• Experimentation- To validate new versions of forecasting system

- High-resolution 4D-Var analyses for specific cases

- Observing system experiments

• Development of observational data base and processing software

• An extensive new reanalysis in 2008 or beyond

Reanalysis plans beyond ERA-40

12

TOMS

With MIPAS

No MIPAS

Total ozone 1 October 2003

13

26 Aug 2003 11 Sept 2003 22 Sept 2003

Sonde With MIPAS No MIPAS

Ozone profiles at Neumayer (71S, 8W)

14

With MIPAS

No MIPAS

ECMWFTOMS

Ozone in the tropics 1 August 2003

15

CO2 assimilation from AIRS - Stratosphere

16

Monthly mean distribution for May 2003 is shown on the left, and the upper boundary for the error estimate is shown on the right.

CO2 assimilation from AIRS - Troposphere

17

• Standard RTTOV software has been adapted to

include variable CO2

• RTIASI has been extended to include variable CO2,

CH4, N2O and CO; work on aerosols is planned

• RTTOV is being developed to handle limb-sounded

radiances from MIPAS (as part of development for a

capability for direct assimilation of these radiances)

Fast RT code development

18

• 91-level model with improved resolution of tropopause and stratopause/mesosphere, plus work on gravity-wave parametrization and treatment of biases in data assimilation – to address stratospheric problems

• Work on humidity analysis, assimilation of rain-affected microwave radiances – to reduce spin-down

• Model has been extended to handle extra fields

• Work to extend Jb is planned for 2004

• Work on parametrization of convection and vertical diffusion to enable tracer transfer is planned for 2004

Forecasting-system development