Evaluating the Suitability of CPTEC Reanalysis Data Over the LBA Study Area as Atmospheric Forcing for use in SALDAS and Regional Parameter Optimization Studies

The availability of reliable atmospheric forcing data is a critical component of the South American Land Data Assimilation System (SALDAS) because it is the primary driver for the participating Land Surface Models (LSM) in the system. Because SALDAS, is built on the framework of the NASA/LIS (Land Information System) and is therefore distributed, the recently released CPTEC/INPE (Centro de Previsão do Tempo e Estudos Climáticos/Instituto Nacional de Pesquisas Espaciais) South American Regional Reanalysis (SARR) has been selected as the primary atmospheric forcing dataset for use with the SALDAS. The SARR integrates upper air and surface observations from several sources over South America, including vertical soundings from RACCI-LBA and SALLJEX-PROSUR field campaigns over the Amazon and the low level jet regions along the Andes respectively. The SARR is based on the Eta model Regional Physical-space Statistical System (RPSAS) data assimilation scheme applied at 40Km horizontal resolution and 38 vertical levels, and currently spans the time period 2000-2004. In this study, the SARR is validated against surface observations across the the LBA study area, including flux tower measurements, with two main objectives: (a) to evaluate how well the SARR atmospheric forcing compares with observed point and area-averaged values, in order to investigate the feasibility of transferring LSM parameters derived at LBA towers sites to surrounding areas; and (b) to evaluate how SALDAS Runs made with SARR forcing over the LBA region compare with the expected hydroclimatology of the Amazon as a regional entity. This study is being carried out jointly by the CD-36 group in the LBA-Eco Synthesis Phase and by the SALDAS initiative, which is part of the GLDAS project at the GSFC/NASA Hydrological Sciences Branch.