Abstract
Subtropical cutoff-lows (COLs) are low pressure systems at middle and upper atmospheric levels, with a cold core and are detached equatorward from the jet streams. The mass divergence downstream of COLs can organize ascendant movement and provoke precipitation. Due to the COLs contribution to weather changes and few studies found in literature, the purpose of this study is to describe the synoptic and energetic evolution of the COL that caused extreme rainfall over the Atacama Desert between March 24th and 26th, 2015. For the study, we used the reanalysis from NCEP-DOE, the precipitation data from TRMM and satellite information from GOES-13. From the results, we note that the horizontal advection of anticyclonic relative vorticity is important in amplifying the ridge that enters the southwest/south sector of the trough at 300 hPa causing the cold air to become trapped in lower latitudes, thereby contributing to the formation of the COL. Lorenz's energetic cycle showed that the environment, into which the COL was inserted, was important to the lifecycle of COL. For example, in the COL phase, the baroclinic and barotropic processes and flow in boundary acted as a source of kinetic energy (KE).
Keywords:
cutoff-low; Atacama Desert; synoptic analysis; Lorenz's energy cycle
