Analysis of a 4 year radiosonde data set at Dome C for characterizing temperature and moisture conditions of the Antarctic atmosphere

A 4 year set of vertical profiles of pressure, temperature and relative humidity derived from 1113 radiosounding measurements performed at Dome C (Antarctica) at 12: 00 UTC of each day, from late March 2005 to March 2009, were analyzed using an updated procedure for removing the most important temperature and humidity errors and dry biases. The monthly mean vertical profiles of pressure, temperature, and moisture parameters were determined, providing evidence of the strong seasonal variations in temperature occurring within the ground layer and in the tropopause region. The results are presented for use in the analysis of the ground-based measurements of both short- and long-wave radiation budget terms routinely performed at this site, and to better investigate the water vapor role in the Antarctic Plateau surface-atmosphere system. The evaluation of atmospheric water vapor content W (precipitable water) is of great relevance for astronomical studies, to verify that high atmospheric transmission conditions exist, especially in the submillimeter and millimeter range, for the exceptionally dry air characteristics of the Dome C atmosphere. The monthly mean data sets of moisture parameters were analyzed to determine the monthly mean vertical profiles of absolute humidity, and to evaluate the daily values of W, varying from less than 0.30 mm (from June to October) to more than 0.60 mm in January, on average. The monthly mean percentiles of W indicate that this parameter is expected to be lower than 0.20 mm on at least 25% of days from May to October, indicating that very high atmospheric transparency conditions should occur in the infrared-millimeter spectral range on at least 40 days during austral autumn and winter.