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| Titel |
Regional vegetation impacts on tropical precipitation: observational evidence |
| VerfasserIn |
Dominick Spracklen, Stephen Arnold |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055164
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| Zusammenfassung |
| Climate model studies typically predict that large-scale deforestation results in substantial
declines in regional precipitation. Observational studies that have attempted to confirm these
modelling predictions have yielded conflicting results, likely due to the masking of
land-cover induced changes by large temporal and spatial variability in precipitation. Here we
explore the effect of tropical vegetation on precipitation using satellite remote sensed
observations and a Lagrangian atmospheric transport model. We calculate daily 1oÃ1o
precipitation for the period 1998 to 2009 from the Tropical Rainfall Monitoring Mission
(TRMM) 3B42 3-hour 0.25oÃ0.25o satellite product, globally between 50oS and 50oN .
Kinematic five-day atmospheric back trajectories, arriving daily at the centre of each grid
square were calculated for the same period using meteorological analyses from the European
Centre for Medium-range Weather Forecasts (ECMWF). For each back trajectory we
calculated cumulative exposure of the air mass to vegetation by overlaying the back trajectory
on MODIS satellite-observed leaf area index (LAI). We compared air masses with the
same initial moisture content (defined by specific humidity from ECMWF analysis)
and found that over large regions of the tropics air masses that passed over more
vegetation produced significantly more precipitation. Over the Amazon basin satellite
observed precipitation increased by between 0.03 and 0.18 mm day-1 per unit of LAI
(m2/m2) exposure with correlations significant at the 98% level (p |
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