| Popis: |
The University of Illinois Fe (iron) Boltzmann temperature lidar was operated at the South Pole (90°S) from November 1999 to October 2001, and then at the Rothera Station (67.5°S, 68.0°W) from December 2002 to March 2005. This lidar transmits two UV wavelengths at 372 and 374 nm, and is able to measure the middle and upper atmosphere temperature, Fe density, polar mesospheric clouds (PMC), and polar stratospheric clouds (PSCs). In this paper, we analyze the PSC data collected in the winters and springs of 2003 and 2004 at Rothera, and compare them with the PSC data collected at the South Pole in the 2000 and 2001. PSCs were observed in the range of 15-28 km during the seasons from May/June to October at both locations. The PSC backscatter ratio, width, and altitude at Rothera are comparable to those at the South Pole. However, Rothera PSCs occur less frequently (~17.7%) and in shorter periods, compared to PSCs at the South Pole (~64.9%). At Rothera, PSC occurrence frequency in 2004 is only half of that in 2003, which is likely due to warmer stratospheric temperatures in 2004 associated with changes of the polar vortex. These are the first ground-based lidar observations of PSC at Rothera, and also the first in West Antarctica. |
