Temperature of mesospheric ice retrieved from the O-H stretch band

Abstract

For the first time, the temperature of mesospheric ice particles is retrieved directly from ice infrared extinction spectra measured in the solar occultation regime. The position of ice O-H stretch band peak varies from 3230cm -1 at T = 120K to 3246cm -1 at T = 155K, which enables the retrieval of ice temperature by fitting a model spectrum to a measured one. The retrieved temperature is independent of cloud vertical and horizontal patchiness and has a random uncertainty of <12K. The retrieval is sensitive to chosen particle shape: cubes, hexagons and spheroids of certain forms give same result. Spheres and rectangular prisms (aspect ratio ≥2) change temperature by 3-4K. For nearly 400 ice spectra analyzed the retrieved temperature for cubes ranges from 120K to 150K with the distribution maximum centered at ∼135K. The standard temperature for same ice spectra retrieved from the gas phase differs considerably and sometimes reaches values of 200K and above. Copyright 2009 by the American Geophysical Union.