Monday, 21 January 2008
A new satellite derived precipitation data set for studying trends in extreme events
Exhibit Hall B (Ernest N. Morial Convention Center)
While several data sets of precipitation developed from in-situ, satellite, numerical weather prediction and climate model, or merged analysis have emerged over the past decade and focused on studying the long term/large scale trends in the global rainfall, much less attention has been placed on the possible trends in the distribution of short-term rainfall which contribute to longer-term drought and flood conditions. In the most recent climate studies, many investigators conclude that this sort of change is more likely to be attributed to the global warming scenario rather than trends averaged over long temporal and spatial scales. In a project that has been ongoing for the past three years, a new passive microwave satellite-based daily, 0.25 degree resolution data set has been developed using all available sensors with a common retrieval scheme. The time period of the data set is 1992 – 2006 (15 years in length). It has been developed based on hourly rainfall estimates from the satellites, combined using an optimal interpolation scheme. Preliminary analysis indicates that the global rainfall from this new data set performs as well as those from more established techniques such as the GPCP and CMORPH data sets. Because the global daily data set is based on hourly “snapshot” input data (which is preserved in the final product generation), this intermediate product can be used to develop probability distribution functions (PDF's) of instantaneous rain rates at any 0.25 degree grid box on the earth. Thus, changes in the PDF's over time can be investigated and related to other annual to inter-annual climate forcing. Additionally, the data set will offer the ability to examine the diurnal cycle of precipitation and any changes that might be occurring over the 15-year period. Therefore, it is the purpose of this poster to highlight the new data set and its utility for studying trends in short term precipitation frequency and intensity as well as its suitability for the study of other important climate elements such as the diurnal cycle.
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