Influence of land surface on transition from dry to wet season in Amazonia
Abstract
Analysis of the fifteen years of European Centre for Medium Range Weather Forecasts
(ECMWF) reanalysis suggests that the transition from dry to wet season in Southern
Amazonia is initially driven by increases of surface latent heat flux. These fluxes
rapidly reduce Convective Inhibition Energy (CINE) and increase Convective Available
Potential Energy (CAPE), consequently providing favourable conditions for increased
rainfall even before the large-scale circulation has changed. The increase of rainfall
presumably initiates the reversal of the crossequatorial flow, leading to large-scale
net moisture convergence over Southern Amazonia. An analysis of early and late wet
season onsets on an interannual scale shows that a longer dry season with lower rainfall
reduces surface latent heat flux in the dry and earlier transition periods compared
to that of a normal wet season onset. These conditions result in a higher CINE and
a lower CAPE, causing a delay in the increase of local rainfall in the initiating
phase of the transition and consequently in the wet season onset. Conversely, a wetter
dry season leads to a higher surface latent heat flux and weaker CINE, providing a
necessary condition for an earlier increase of local rainfall and an earlier wet season
onset. Our results imply that if land use change in Amazonia reduces rainfall during
dry and transition seasons, it could significantly delay the wet season onset and
prolong the dry season.
Type
Journal articlePermalink
https://hdl.handle.net/10161/14970Published Version (Please cite this version)
10.1007/s00704-004-0046-7Publication Info
Fu, R; & Li, W (2004). Influence of land surface on transition from dry to wet season in Amazonia. Theoretical & Applied Climatology, 78(1-3). pp. 97-110. 10.1007/s00704-004-0046-7. Retrieved from https://hdl.handle.net/10161/14970.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Wenhong Li
Associate Professor of Climate
Dr. Li's research interests focus primarily on climate dynamics, land-atmosphere interaction,
hydroclimatology, and climate modeling. Her current research is to understand how
the hydrological cycle changes in the current and future climate and their impacts
on the ecosystems, subtropical high variability and change, unforced global temperature variability,
and climate and health issues.

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