The products and validation of GAME reanalysis and JRA-25 part 1: surface fluxes

The Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) reanalysis datasets are the products of four-dimensional data assimilations (4DDA) of meteorological observations made from April 1998 to October 1998. These datasets were created using the most recently updated 4DDA schemes of the Japan Meteorological Agency (JMA) during the GAME reanalysis project (1999-2001) as well as radiosonde observations made during the intensive observation period of the GAME project (April 1998-October 1998). Two versions of reanalyses products have been released officially: Ver. 1.1 and Ver. 1.5. One of the greatest differences between the two versions is the representation of snow cover: Ver. 1.1 used climatological snow data, while Ver. 1.5 used satellite-derived snow information. Here, we describe how snow cover modifications and land surface schemes differ between the two versions and how changes in surface processes affect surface fluxes. The use of satellite-derived snow information produced a difference in surface fluxes over the Tibetan Plateau, especially for May. We also compare surface fluxes estimated by the long-term reanalysis (JRA25) product of the JMA as well as GAME reanalysis product with in situ observations by the Asian Automatic Weather Station (AWS) Network (AAN). Radiosonde observations made 4 times daily were incorporated into the atmospheric field of the 4DDA GAME reanalysis and resulted in a good correspondence between the reanalyses products and surface observations, especially for July. The use of satellite-derived snow information as a boundary condition also had improved flux results over the Tibetan Plateau in May.