Characteristics of the Amazonian mesoscale convective systems observed from satellite and radar during the WETAMC/LBA experiment

Abstract

An objective tracking of mesoscale convective systems (MCSs) observed in full‐resolution Geostationary Operational Environmental Satellite (GOES) satellite images has been applied during the Wet Season Atmospheric Mesoscale Campaign/Large‐Scale Biosphere–Atmosphere (WETAMC/LBA) experiment in Amazonia from January to February 1999 to document the characteristics of the convective cloud organization in the southwestern Amazon region. The same tracking methodology was also applied to the National Aeronautical Space Administration (NASA) Tropical Ocean Global Atmosphere (TOGA) C‐Band radar data in order to estimate the propagation of the convective rain cells from constant altitude plan position indicators (CAPPI) at a height of 2 km. The convective activity showed two different patterns named Easterly and Westerly regimes according to the wind flow in the 700–850‐hPa layer. During the Easterly regime, MCSs and rain cells had closely related propagations. MCS as well as rain cell propagations were associated mostly to the midlevel mean flow. During the Westerly regime, the propagations of both MCSs and rain cells were much more disorganized, there was no clear relationship with the mean atmospheric flow at any level, although the rain cells have a slight tendency to propagate eastward, and the low‐level rain cells propagated quite independently of the high‐level cloud cover. MCS initiations were mostly driven by topography, that is, high escarpment and relatively high elevation.