Implications of Meteoritic Dust In The Upper Stratosphere

Significant levels of extinction in the upper stratosphere and mesosphere have recently been observed by remote sensing observations. Comparisons are made with observations from SAGE II, the NOAA lidar located in Mauna Loa, HI and model-derived profiles from Whole Atmosphere Community Climate Model (WACCM) coupled with the Community Aerosol and Radiation Model for Atmospheres (CARMA). This comparison strongly suggests that the observed extinction is in part from meteoritic dust and needs to be accounted for in the retrievals of stratospheric observations by remote sensing instruments. Without this correction, the amount of scattering in the upper atmosphere is underestimated by as much as 12%. Such extinction biases retrieval algorithms for extinction profile measurements used to make assessments of upper atmospheric optical depth and may lead to an underestimate of the entire radiative forcing of this region. Possible solutions for these problem may include calibrating instruments in higher regions of the atmosphere where the molecular extinction becomes dominant or including information about the extinction of this aerosol within retrievals.