Climatology of the upper mesosphere temperature above South Pole (90°S): Mesospheric cooling during 2002

Abstract

Polar mesospheric temperature measurements obtained above South Pole from 1991 through 2002 are shown, and their long‐term behavior ‐climatology‐ has been deduced. The variation of this temperature during the polar night shows an annual amplitude of 14 K about the mean yearly value. A strong and highly significant correlation is found between the mean yearly temperature and the solar activity ‐expressed as the F10.7 flux‐, giving a 13 K change per 100 unit F10.7 change. The mean measured 2002 polar night temperatures are about 35 K cooler than the mean for the previous 11 years and well outside their excursions about this mean. This observed mesospheric cooling is in keeping with the disturbed lower atmosphere reported for this period. Other effects from the latter include both a smaller austral ozone depletion hole than has been recorded in previous years and higher than average minimum temperatures in the south polar region. The observed mesospheric cooling resembles the cooling observed at Northern midlatitudes during stratospheric warmings.

Observations of stratospheric warmings and mesospheric coolings by the TIMED SABER instrument

“…They also found no connection between the solar 10.7 cm flux (F107) and airglow temperature. This is in contrast to the results of Hernandez [2003], who found a strong correlation with F107. He also suggests a correlation between winter OH* temperatures over the South Pole and the size of the springtime Antarctic ozone hole [Hernandez, 2004].…”

Dynamical coupling of the stratosphere and mesosphere in the 2002 Southern Hemisphere major stratospheric sudden warming

“…The mesospheric cooling around the major warming is in better agreement between the model (from 185 K on day 265 to 170 K on day 270) and the observation (from 190 K on day to 265 to 170 K on day 275). Above the South Pole, the OH temperature drop (near 85 km) reported by Hernandez [2003] is from 180 K to 168 K (10-day averages) in the period of mid-July and mid-August. The model temperature at 87.5°S and 85 km is in general 40 K warmer than this observation but also displays a cooling of similar magnitude (230 K to 210 K).…”

“…Mesospheric cooling [Hernandez, 2003;T. D. Kawahara, private communication] and mesospheric jet reversal [Dowdy et al, 2004] were observed above Antarctica prior to the unprecedented major SSW in the Southern Hemisphere (SH) in 2002 [Baldwin et al, 2003].…”

Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements

“…These changes can range from the zonal mean wind reversal (Dowdy et al, 2004) to the cooling of the MLT temperature (Hernandez, 2003;Liu and Roble, 2005). Dowdy et al (2004) used three medium frequency (MF) radars located at Davis (69 • S, 78 • W), Syowa (69 • S, 40 • W) and Rothera (68 • S, 68 • W) to study the dynamics of the MLT during the SH 2002 SSW.…”