RegCM Simulation of Low Level Jet in South America

The figures below show a vertical slice through the meridional wind field at approximately 15 S and from 100W to 15W
across South America. The diurnal cycle, averaged for the month of January 1983 is given from top to bottom:
2 AM, 6AM, 2PM, 6PM local times. On the left are meridional winds from the NCEP reanalysis and on the right the same
filelds from the RegCM.
Note: contour intervals are 2 m/s for the NCEP data and 3 m/s for the RegCM field.

Both the Reanalyses and the model show two low level jet cores, one .an eastern jet which does not show a strong
diurnal cycle and an Andes jet which shows a substantial diurnal cycle. The RegCM fields
show more intense jets, with a peak of 12 m/s versus 6 m/s in the Reanalyses for the eastern jet, and a peak
of 9 m/s versus 6 m/s in the Reanalyses for the Andes jet. An analysis is currently being prepared of the seasonal
evolution of these jets and their associated moisture transports using the RegCM.