Abstract:

This paper compares surface-station temperature observations over Argentina with gridpoint analyses available in the NCEP-NCAR reanalysis dataset. The primary objective is to determine whether the maximum and minimum surface temperatures from the reanalysis can be used to compute statistics on the occurence of extreme events. The extreme range of topography and geography of Argentina is viewed as a severe test for the reanalysis data. Good agreement, on both the daily and monthly timescales, between the station data and the reanalysis gridpoint data is found over the low-elevation regions in central and eastern Argentina. The agreement is relatively poor for summertime maximum temperatures over northern Argentina. The reanalysis data underestimate the intensity of extreme warm events over northern and southern Argentina and overestimate extreme cold events during winter over central Argentina. High-elevation areas in western Argentina have the poorest correspondence throughout the year. Thus, the NCEP-NCAR reanalysis data have to be used with caution for studies of the magnitude of day-to-day temperature changes. The results of this study indicate that the NCEP-NCAR reanalysis data are sufficient for determining the timing of midlatitude events but are not sufficient for determining the amplitude and frequency in the subtropics and in regions of high relief. The use of anomalies tends to improve the amount of agreement between the reanalysis data and station observations.