Sensitivity and Feedback Analysis of Spatio-Temporal Variability of
Rainfall to Land Cover Change across the Amazon Basin
Abstract
Amazon Basin deforestation has been driven by agricultural expansion and
other developments. Interactions between deforestation, fire, climate,
and drought have led to changes in precipitation patterns and river
discharge. Previous work suggests that these changes are amplified by
land use. Therefore, it is important to understand the degree of change
in precipitation patterns and rainy season characteristics. We used long
term daily gauge measurements and remote sensing data to analyze the
variability and seasonality of rainfall patterns over the Amazon Basin.
We focused on the PERSIANN-CDR and CHIRPS precipitation datasets from
1983 to 2018 to quantify trends in predefined indices. The indices that
were analyzed to assess variability of precipitation are NDD (Number of
dry days); NXE (number of extreme events) during both wet and dry
seasons; ORS (Onset of Rainy Season); and ERS (End of Rainy Season). We
analyzed the trends for statistical significance and spatial similarity
to identify hot spots of change. To connect pattern to process, we also
simulated the land-atmosphere system using WRF to assess coupling
strength and causality. We are running the simulation using CFSR 2010,
with grid resolution of 16 km with the convection scheme active to
capture small scale convective rainfall. Previous evidence has suggested
an increasing trend on NDD during the dry season, a shift to a later
onset and later cessation of the rainy season window, and an increasing
trend in the NXE during both wet and dry seasons. The significance and
spatial distribution of changes may vary over the region, but we
anticipate that in the area with the largest percent of deforestation we
will see the highest amount of changes in precipitation.