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| Titel |
A combined drought index from the Global Precipitation Climatology Centre (GPCC) |
| VerfasserIn |
Markus Ziese, Udo Schneider, Anja Meyer-Christoffer, Peter Finger, Kirstin Schamm, Andreas Becker, Bruno Rudolf |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075471
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| Zusammenfassung |
| Since its start in 1989 the Global Precipitation Climatology Centre (GPCC) performs global analyses of monthly precipitation for the earth’s land-surface on the basis of in-situ measurements. Meanwhile, the data set has continuously grown both in temporal coverage (original start of the evaluation period was 1986), as well as extent and quality of the underlying data base. The high spatio-temporal variability of precipitation requires a high density of measurement data.
Data collected from national meteorological and hydrological services are the core of the GPCC data base, and are extended by global and regional data collections. Also the GPCC receives SYNOP and CLIMAT reports via WMO-GTS, which are mainly applied for near-real-time products. For quality control a high effort is undertaken to remove miscoded and temporal or spatial dislocated data before interpolation.
Based on the GPCC-products the GPCC–Drought Index (GPCC-DI) is a combination of SPI and SPEI in order to gain a global coverage of the drought index. Even the correction of the SPI as used at DWD does not allow calculating this index in very dry regions like deserts, because the precipitation distribution described by the gamma function is inaccurate. On the other hand, the SPEI can not be calculated in cold regions, because a simple temperature based parameterization of the evapotranspiration doesn’t work. A nearly global coverage is possible with the application of the SPI-DWD in cold regions, whereas the SPEI can be calculated in dry regions. The GPCC-DI uses the SPI-DWD, if only this index can be calculated, and the SPEI vice versa. If both drought indices can be calculated, the GPCC-DI uses the mean of both drought indices.
Monthly precipitation totals were taken from the GPCC ‘First Guess Product’, which is based on accumulated SYNOP reports. Parameters of the precipitation distribution were derived from the GPCC ‘Full Data Reanalysis’, which is based on monthly totals collected from national meteorological and hydrological services, regional and global data collections as well as SYNOP and CLIMAT reports. Monthly mean temperatures were taken from the ‘CPC Monthly Global Surface Air Temperature Data Set’.
Examples of both of the used drought indices and the combined GPCC-DI will be shown as well as examples of the input data. The calculation of the GPCC-DI will be starting operationally in 2013. It will be available 10 to 13 days after the end of each month. Just as the other GPCC products, this drought index will be available free of charge from the GPCC website (gpcc.dwd.de). The temperature data are available freely from the CPC. |
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