OTREC Atmospheric Science Field Experiment

Aug 22 2019

Prof. Adam Sobel, along with a team of APAM students, are part of an NSF-sponsored Organization of Tropical East Pacific Convection (OTREC) field campaign conducted by an international team of atmospheric scientists from now until the end of September, based in Costa Rica and Colombia.

A field campaign is a coordinated scientific effort to take targeted measurements over a specific period, to answer questions that can’t be answered using data from the routine global operational network. In OTREC, the primary platform is an airplane, the National Center for Atmospheric Research GV (pronounced “gee five”) whose primary instruments in this instance are a downward-pointing cloud radar and a large number of dropsondes (essentially the same as radiosondes, but without the balloon, so that they fall down from the plane instead of rising up from the ground). The aircraft observations are being supplemented by additional radiosonde launches and other surface-based observations from several sites in Costa Rica and Colombia.

The goal of OTREC is to better understand atmospheric convection – tall systems of rain-producing clouds – on both sides of Central America, over both the eastern Pacific and western Caribbean. At these longitudes, the sea near and south of the equator is typically quite cold relative to the rest of the Tropics, but very warm a bit further north (such as near Liberia, Costa Rica, where the largest group of OTREC scientists is based). The strong spatial contrast in sea surface temperature between these two adjacent regions is unique in the Tropics, and provides an ideal environment to test hypotheses about what controls the convection and associated rainfall in the intertropical convergence zone (ITCZ), or climatological belt of rainy weather, as well as the weather systems that pass through it. Yet there are very few in situ atmospheric measurements made in this region, due to the absence of land masses, so OTREC will fill an important gap during this special two-month period. The lessons learned will help us understand both the day-to-day weather and the long-term climate of this region and, by extension, the globe.

Blog: Trekkies in the Clouds: The OTREC Atmospheric Science Field Experiment in Costa Rica



Photo taken from the NCAR GV at 8:51 local time (1451 UTC) on August 12, 2019. Position 5.3N, 88.7W).