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| Titel |
Land use radiative impact on temperature and precipitation response in the Eurasian regions |
| VerfasserIn |
Alexey V. Eliseev, Igor I. Mokhov |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250032685
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| Zusammenfassung |
| Simulations with the climate model of intermediate complexity IAP RAS CM (A.M. Obukhov
Institute of Atmospheric Physics RAS, Moscow) are performed for the 16th–21st centuries
forced by the historical reconstructions and future projections of anthropogenic and natural
forcings including long–lived greenhouse gases, tropospheric and stratospheric sulphates,
total solar irradiance, and land use. Future projections of the external anthropogenic forcings
are based on the SRES emission scenarios except the land use forcing which is prescribed in
accordance to the scenarios developed in the framework of the Land Use Harmonization
(LUH) project.
Land use exerts negative radiative forcing in most agricultural regions, in particular, in
the Eurasian extratropics. At the top of the atmosphere, this forcing is stronger in
summer than in winter reaching --6 W m-2 in the central Eurasia in the late
20th century. However, in the regions with semi–desert natural vegetation, weak
positive radiative forcing develops (e.g., about 1 W m-2 in the Middle East). On a
global mean basis, the top–of–the atmosphere radiative forcing in the IAP RAS
CM attains -0.11 W m-2 in the late 20th century. Additional radiative forcing
developing in the 21st century is small and its magnitude does not exceed 1 W m-2
everywhere.
Land use radiative forcing causes a decrease of globally and annually averaged surface
air temperature by - 0.07 K and precipitation by 7% during the 20th century. In
turn, other anthropogenic and natural forcings cause warming amounting 0.7 K
and precipitation increase attaining 4% during the same period. Combined forcing
(land use+other forcings), results in temperature and precipitation increase in the
20th century which are about 0.6 K and - 3%, correspondingly, and agree with
observations.
While warming dominates in Eurasia during the 20th century under combined forcing,
regional cooling in the regions of strong negative radiative forcing is exhibited. In addition
land use retards warming in the northernmost Eurasia by several tenths of kelvin. Land use
radiative forcing modifies seasonal features of surface air temperature response in the
extratropical Eurasia. Namely, other anthropogenic forcings, accounted in these simulations,
lead to general decrease of annual temperature range under annual mean warming, land use
imposes similar decrease of annual temperature range, but under annual mean cooling. In
addition, surface cooling suppresses precipitation, especially in summer. Spatial patterns
of temperature and precipitation trend in the 20th century reasonably agrees with
observations.
In the 21st century, land use radiative impact on surface air temperature and precipitation
for the LUH scenarios is small as a whole. In this century, IAP RAS CM simulates strong
annual mean warming in the Eurasian interior reaching 2 - 4 K, 4 - 6 K, and
4 - 7 K for the SRES scenarios B1, A1B, and A2 respectively. In line with the results
obtained for the 20th century, the warming is strongest during the cold part of the year.
Annual precipitation increases by 5 - 25% depending on region and anthropogenic
scenario. |
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