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GEOSCCHEM: The Agony and The Ecstasy Bob Yantosca Software Engineer Atmospheric Chemistry Modeling Group Harvard University Group Meeting / Telecon

06 October

2004 06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

2 Topics 1.

Transition to GEOSC4 Met Fields 2. A Summary of Recent Scientific Upgrades to GEOSCCHEM 3. GEOSCCHEM v7C01C02: New User Interface! 4. Future Directions Appendix: ICARTT NRT Simulations

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

3 Part

1 Transition to GEOSC4

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

4 Transition to GEOSC4 GEOSC4 Overview ? As of October 31, 2002, GEOSC4 is now the operational data product generated by NASA GMAO ? GEOSC4 is very different than GEOSC3 in many ways: ? GEOSC4 uses a different GCM than before (NCAR fvCCM) ? GEOSC4 is a hybrid grid (55 vertical levels) ? GEOSC4 has a

1 x 1.25 horizontal grid (not

1 x 1!) ? Several GEOSC4 quantities have different units than GEOSC3 ? Some GEOSC4 fields did not exist in GEOSC3 ? Et cetera … ? GEOSCCHEM had to evolve to deal with GEOSC4!!

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

5 Transition to GEOSC4 Comparison of GEOS vertical layers in the PBL GEOSC3 has

8 levels up to ~850 hPa, but GEOSC4 only has

4 850 hPa

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

6 Transition to GEOSC4 Differences from GEOSC3 ? Some GEOSC4 quantities can be very different than GEOSC3, for example: ? Cloud optical depth &

cloud mass fluxes ? Surface wetness, snow cover, roughness height ? Precipitation fields ? How does this impact a GEOSCCHEM simulation? ? Cloud optical depth ? affects J-Values ? Cloud mass fluxes ? affects cloud convection ? Surface wetness &

snow cover ? affects dust mobilization ? Roughness height ? affects dry deposition ? Precipitation ? affects rainout &

washout

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

7 Transition to GEOSC4 Slide from J. Logan &

S. Wu ???? GEOSC4 July mean Cld Frac GEOSC3 July mean Cld Frac GEOSC4 July mean OPTD GEOSC3 July mean OPTD Cloud frac does not show up as cloud opt depth!

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

8 Transition to GEOSC4 GEOSC3 Column OPTD, July

2001 GEOSC4 Column OPTD, July

2003 Slide from J. Logan &

S. Wu Larger O1D over Asian Subcontient!

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

9 Transition to GEOSC4

0 4 GWET = surface wetness ranges from

0 (dry) to

1 (totally wet) GWET has important implications for dust mobilization. Where it'

s wet you don'

t have dust, but mud C this suppresses dust mobilization! GEOSC4 is much wetter in Africa, SE Asia &

Americas! -0.33

0 0.78 [unitless] GEOSC3 GWET at

0 GMT 2002/07/01 GEOSC4 GWET at

0 GMT 2002/07/01 Abs Diff GEOSC4 C GEOSC3

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

10 Transition to GEOSC4 Roughness height (Z0) is a function of land type and is used for dry deposition computations. The differences in roughness height indicate that GEOSC4 uses a much different land-surface model than GEOSC3. (Don'

t know if it'

s better!) GEOSC3 Z0 at

0 GMT 2002/07/01 GEOSC4 Z0 at

0 GMT 2002/07/01 Abs Diff GEOSC4 C GEOSC3 -1.96

0 1.27 [m] 0.0 1.30 2.60 [m]

06 October

2004 GEOS-CHEM: The Agony and the Ecstacy

11 Transition to GEOSC4 Differences in the WINDS ? Synoptic values (GEOSC3) ? Averaged values (GEOSC4) ? U and V winds, Specific Humidity, Temperature, Vis. Albedo ? GEOSC4 winds required brand-new transport code ? We added a totally new version of TPCORE (cf. S-J Lin) ? We also installed the LLNL P-Fixer (cf. Phil Cameron-Smith) ? TPCORE mass-flux diags were rewritten for GEOSC4 ? Brendan Field recently did this;