This paper presents a comparison of reanalyses results for air temperature at 1000 hPa and atmospheric pressure reduced to sea level at the high latitudes of the southern hemisphere, during the period of 1979-2000. The data used comprised three sets of reanalyses, NCEP-NCAR 1 and 2, and ECMWF/ERA-40. The differences between them become significant and increase from ~60º south, reaching particularly high values at the center of the Antarctic continent. Considering the average for the 22 years, the difference in temperature for the reanalyses in the extreme cases reached up to 12ºC in the autumn (March, April and May), and winter (June, July and (August), and for the reduced pressure, up to 30 hPa, in these same seasons. In the coastal Antarctic region the comparison with data from two surface weather stations indicated differences between the average seasonal temperatures actually measured, and those of the reanalyses. The most northern station, Bellinghausen (62º12' S e 058º56' W), presented smaller differences, up to 1.8ºC, and Mirny (66º33' S e 093º01' E), up to 4.5ºC; this is in agreement with the herein proposed increase of the differences according to the latitude. As a possible explanation for these differences among sets of reanalyses and between them and the measured surface data, we suggest: faulty quality control of the input data from Antarctica, and; the difference between the Antarctic atmosphere, particularly in the cases of extreme cold, with that of the standard atmosphere that is used globally to reduce pressure and temperature to other levels in the atmosphere. The magnitude of the differences reported has the potential to hamper the study of temporal series of meteorological data and of climatic variations for Antarctica
Antactica; Reanalyses; Climatology
