Impact of satellite‐based data on fgge general circulation statistics

Abstract

AbstractTo assess the influence that data from satellites and other FGGE special observing systems can have on analyses of the large‐scale circulation, the NASA GLA analysis/forecast system was run in two different parallel modes. In the first, data from all of the FGGE observing systems were utilized (denoted the FGGE analysis), and in the second (the NOSAT analysis) only conventional upper air and surface reports were used. Global wind and temperature fields extracted from month‐long assimilations during the first Special Observing Period are similar in the two cases but showed some differences, especially over the southern hemisphere oceans where satellites play a significant role in filling data voids. Winds are a little stronger in general in the NOSAT case, suggesting a damping effect from the inclusion of satellite‐based data.The GLA model was also integrated for the same period without any data inserted (model CLIMATE run). an independent objective analysis based only on rawinsonde and pilot balloon data (STATION analysis) was performed as well. Stronger zonal winds in the model CLIMATE run and differences in features between the NOSAT and STATION cases attest to some influence of the GLA model and analysis technique on the resulting fields.Momentum and heat budget computations were performed for the FGGE, NOSAT and STATION cases. Integrated values of kinetic and potential energy terms in both zonal mean and eddy forms, as well as various conversions between terms, though similar among the cases, demonstrate overall a small decrease in the vigour of the circulation with the inclusion of satellite observations.