Update and TOA Radiation

Vacations in August have limited the posting, but the validation experiments are continuing. The experiments are moving well, and the system performance will be discussed in another post. Here are some of the validation comparisons for TOA radiation of some reanalyses to CERES ERBE-like data from Terra and Aqua. In the figures, the GEOS5 validation experiment is labeled d5_b10p15 (d is the 1/2 degree resolution, beta10 patch15 is the version of the data assimilation system).

The first figure is the zonal mean of the TOA LW and SW fluxes in Jan and Jul 2004. CERES observations are in red, GEOS5 is blue, JRA-25 is black and NCEP RII is green. GEOS5 shows somewhat smaller bias in the tropics LW, and also mid latitude SW. The July upward SW in the tropics seems biased high compared to the obs and other reanalyses, but otherwise, it seems in the range of the reanalyses. (Click on thumbnails to see the full figure)



The next two figures show the monthly mean maps of the comparisons. to CERES Terra. The differences between the CERES-Terra and CERES-Aqua are provided as a reference. In TOA LW, JRA-25 seems systematically biased high, while NCEP RII has strong positive and negative variations. GEOS5 leans to a high bias, but not as high as JRA. JRA and NCEP also show large positive bias in the tropics, which impling a dry upper troposphere or low cloud top. Newman et al (2000) have evaluated the interal consistency of several reanalyses, between OLR, precipitation and upper level divergence. In addition, they note that the correspondence among the reanalyses is quite low. The reanalyses OLR are all different from each other.



The shortwave biases of the reanalyses generally are similar. The exception seems to be the polar warm season. For example, TOA SW in Antarctica January is high for NCEP RII and GEOS5, but low for JRA.




Newman M., P. D. Sardeshmukh, J. W. Bergman, 2000: An Assessment of the NCEP, NASA, and ECMWF Reanalyses over the Tropical West Pacific Warm Pool. Bull. Amer. Meteror. Soc. 81, 41–48.

Smith, G. L.; Wielicki, B. A.; Barkstrom, B. R.; Lee, R. B.; Priestley, K. J.; Charlock, T. P.; Minnis, P.; Kratz, D. P.; Loeb, N.; 2004: Clouds and Earth Radiant Energy System (CERES): An overview, Advances In Space Research, 33, 1125-1131.

Wielicki, B.A., B.R. Barkstrom, E.F. Harrison, R.B. Lee, G. Louis Smith, and J.E. Cooper, 1996: Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment. Bull. Amer. Meteor. Soc., 77, 853–868.