Regional climate projections in two alpine river basins: Upper Danube and Upper Brahmaputra
Projections from coarse-grid global circulation models are not suitable for regional estimates of water balance or trends of extreme precipitation and temperature, especially not in complex terrain. Thus, downscaling of global to regionally resolved projections is necessary to provide input to integ...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2011-04-01
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| Series: | Advances in Science and Research |
| Online Access: | http://www.adv-sci-res.net/7/11/2011/asr-7-11-2011.pdf |
| Summary: | Projections from coarse-grid global circulation models are not suitable for
regional estimates of water balance or trends of extreme precipitation and
temperature, especially not in complex terrain. Thus, downscaling of global
to regionally resolved projections is necessary to provide input to
integrated water resources management approaches for river basins like the
Upper Danube River Basin (UDRB) and the Upper Brahmaputra River Basin
(UBRB).
<br><br>
This paper discusses the application of the regional climate model COSMO-CLM
as a dynamical downscaling tool. To provide accurate data the COSMO-CLM
model output was post-processed by statistical means. This downscaling chain
performs well in the baseline period 1971 to 2000. However, COSMO-CLM
performs better in the UDRB than in the UBRB because of a longer application
experience and a less complex climate in Europe.
<br><br>
Different climate change scenarios were downscaled for the time period
1960–2100. The projections show an increase of temperature in both basins
and for all seasons. The values are generally higher in the UBRB with the
highest values occurring in the region of the Tibetan Plateau. Annual
precipitation shows no substantial change. However, seasonal amounts show
clear trends, for instance an increasing amount of spring precipitation in
the UDRB. Again, the largest trends for different precipitation statistics
are projected in the region of the Tibetan Plateau. Here, the projections
show up to 50% longer dry periods in the months June to September with a
simultaneous increase of about 10% for the maximum amount of
precipitation on five consecutive days. For the Assam region in India, the
projections also show an increase of 25% in the number of consecutive dry
days during the monsoon season leading to prolonged monsoon breaks. |
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| ISSN: | 1992-0628 1992-0636 |