Radiosonde temperature measurements in strong inversions: Correction for thermal lag based on an experiment at the South Pole

• Main Authors: Ashwin Mahesh, Von P. Walden, Stephen, G. Warren
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1997
• Subjects: Antarctic; South Pole; The Antarctic; Antarc*; South pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.546.5744; http://www.atmos.washington.edu/~sgw/PAPERS/1997_JAOT.pdf

Very steep shallow temperature inversions occur during most of the year in the near-surface layer on the Antarctic Plateau. A radiosonde carried by a balloon rising at a few meters per second does not measure such inversions accurately because the response time of the thermistor is several seconds. To quantify this error, the authors flew a radiosonde on a tethered kite on several occasions in winter at South Pole Station immediately prior to the routine launch of the same sonde on a weather balloon. In all cases, the equilibrated temperatures measured by the tethered sonde at a given pressure level were higher than those from the balloon-borne sonde throughout most of the inversion layer. Assuming that the tethered sonde data represent the true atmospheric temperature profile, a procedure can be developed to correct the temperature data from routine radiosonde soundings for the finite response time of the thermistor. The authors devise an accurate deconvolution method to retrieve the true atmospheric temperature profile from the radiosonde data when the thermistor response time is known. However, a simple technique of shifting the profile a few seconds back in time gives results that are nearly equivalent to the deconvolution. Additional temperature errors result at the South Pole because the radiosonde is launched immediately after being brought out of a warm room, making it necessary to further adjust data from the lowest few tens of meters. It is found that the temperature errors cause a 0.3 W m22 error