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Regionale Niederschlagsänderungen in Namibia bei anthropogen verstärktem Treibhauseffekt - Abschätzungen mit statistischem Downscaling

Projektleitung an der Universität Würzburg:

Beteiligte Wissenschaftlerinnen und Wissenschaftler:

This project tends to assess the future regional rainfall amounts for Namibia under conditions of
man-made enhanced greenhouse warming. Relations between large-scale atmospheric circulation
and Namibian summer-rainfall are established by methods of statistical downscaling. For this
purpose geopotential heights of several atmospheric levels (source: NCEP Reanalysis project) and
monthly rainfall data of Namibia are linked by stepwise multiple regression analysis for every
summer months November - March during a calibration period (1951-80). After verifying these
relations in an independent period (1981-97), regression models with sufficient quality are applied
to assess local rainfall for different greenhouse gas-scenarios using simulated ECHAM3-T42
geopotential heights data. Results for climate conditions of a threefold CO2-concentration
compared to preindustrial times show an increase of rainfall in December, significant increases in
January and February especially in the eastern part of Namibia, but a distinct decrease in March.
These results point to an intensified, but shorter rainy season under conditions of enhanced
greenhouse warming. Assessments of rainfall with regression models with a reversed calibration
(1968-97) and verification period (1951-67) support these findings. Results of
canonical correlation analyses between EOFs of geopotential heights and Namibian rainfall,
confirm an increase in January and decrease of rainfall in March. For December and February the
canonical models do not reconstruct reliable results in the verification period and are not used to
assess future Namibian rainfall for these months.

    statistisches Downscaling
    anthropogene Klimaänderungen

Laufzeit: von 08.1997 bis 07.2000



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