Characterizing Wet Season Precipitation in the Central Amazon Using a
Mesoscale Convective System Tracking Algorithm
Abstract
To comprehensively characterize convective precipitation in the central
Amazon region, we utilize the Python FLEXible object TRacKeR
(PyFLEXTRKR) to track mesoscale convective systems (MCSs) observed
through satellite measurements and simulated by the Weather Research and
Forecasting (WRF) model at convection-permitting resolution. This study
spans a two-month period during the wet seasons of 2014 and 2015. We
observe a strong correlation between MCS track density and accumulated
precipitation in the Amazon basin. Key factors contributing to
precipitation, such as MCS properties (number, size, rainfall intensity,
and movement), are thoroughly examined. Our analysis reveals that while
the overall model produces fewer MCSs with smaller mean sizes compared
to observations, it tends to overpredict total precipitation due to
excessive rainfall intensity for heavy rainfall events (≥ 10 mm h-1) and
longer traveled distances than observed. These biases in simulated MCS
properties vary with the strength of constraints on convective
background environment. Moreover, while the wet bias from heavy
(convective) rainfall outweighs the dry bias in light (stratiform)
rainfall, the latter can be crucial, particularly when MCS cloud cover
is significantly underestimated. A relevant case study for April 1, 2014
highlights the influence of environmental conditions on the MCS
lifecycle and identifies an unrealistic model representation in
convective precipitation features.