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About
The Combined Scheme approach (hereafter, CoSch, Vila et al, 2009) provides a new high-resolution, gauge-satellite-based analysis of daily precipitation over continental South America. This methodology is based on a combination of additive and multiplicative bias correction schemes to get the lowest bias when compared with the observed values (rain gauges). In this case, realtime TRMM Multisatellite Precipitation Analysis (TMPA, Huffman, 2007), (in which no rain gauges are incorporated) is used as a high-quality rainfall algorithm, whereas a daily rain gauge database is used to correct the bias on a daily basis over South America. In a second step, and considering that TRMM mission ended in 2015 and Global Precipitation Measurement (GPM) started in the same year, the replacement of the TMPA algorithm for Integrated Multi-satellitE Retrievals will be considered for GPM (IMERG) once that algorithm can be reprocessed for a suitable number of years to perform a reliable validation.
This project is financed by the InsuResilience Investment Fund (IIF) through the Centro de Gestão de Pesquisa, Desenvolvimento e Inovação (CGPDI), funded by the German Federal Ministry for Economic Cooperation and Development (BMZ) through KfW.
The overall objective of the IIF is to contribute to the adaptation to climate change by improving access to and the use of insurance in developing countries. The specific objective of the Fund is to reduce the vulnerability of poor households as well as micro, small and medium enterprises (MSME) to extreme weather events.
Characteristics
The initial reprocess the entire database from 2000 involve two different tasks:
- a. Collect and run quality control of global and regional rain gauge data: as described in the Interim Report for the Climate Insurance Fund (CIF), the upgrade of the historical dataset involves two different actions: The first one is to reprocess the current dataset available at CPTEC/INPE from GTS and Brazilian regional networks to include all Latin American countries for the following period: March 2000 – present. A basic QC process was performed.
In order to improve the amount of gauge data, a second action was performed: The Global Historical Climatology Network - Daily (GHCN-Daily) dataset was downloaded and processed to extract daily precipitation data to increase the number of records in the current database and extend the geographical coverage from southern Argentina and Chile to Mexico . GHCN-Daily integrates daily climate observations from approximately 30 different data sources and quality assurance checks are applied to the full dataset.
Figure 1 shows the rainfall field obtained with CoSch for March 3, 2000. All black dots represent the position of raingauges.
- b. Reprocess daily accumulated satellite-based rainfall fields from 2000 to present: In Mexico, Central and South America, the daily gauge data (24 hours accumulation) is calculated from 12:00 UTC of previous day to 12:00 of the current day. The TMPA algorithm is performed over 3-hour periods for 0.25 degrees spatial resolution. In order to merge both dataset in CoSch, daily accumulations for the same period was done for TMPA-RT. This algorithm was considered because no rain gauges are incorporated. Table 1 summarizes the characteristics of the dataset:
| Combined Scheme file characteristics | Value |
|---|---|
| Spatial resolution | 0,25° |
| Spatial coverage | Southern Argentina and Chile to Mexico |
| Temporal resolution | Daily |
| Temporal coverage | March 2000 - Present |
| Geographical Coverage | 33 N - 60 S, 120 W - 30 W |
| Number of lines | 372 |
| Number of columns | 360 |
| Numeric Format |
- Generic binary, real*4 , little-endian byte order - netCDF |
| Name format | CoSch_yyyymmdd1200.bin |
| File size | 535,680 bytes (binary, uncompressed) |
