Three‐dimensional structure and evolution of stratospheric HNO3 based on UARS Microwave Limb Sounder measurements

摘要: [1] The Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) measured the global distribution of stratospheric HNO3 through more than seven complete annual cycles in both hemispheres. Here we present an overview seasonal, interhemispheric, and interannual variations throughout lower middle stratosphere from 420 to 960 K potential temperature based on UARS MLS version 6 measurements. The data have much better precision a larger vertical range previous sets also been corrected account for oversight retrieval algorithms that led earlier versions overestimate abundances by as 35% at some levels stratosphere. exhibits little vertical, or variability tropics. For first ∼1.5 years mission, however, persistent enhancement is seen low latitudes attribute perturbations reactive nitrogen chemistry under conditions high aerosol loading eruption Mount Pinatubo. signature Pinatubo-induced considerably weaker 465 it higher altitudes, northern Southern Hemisphere. increase toward pole hemispheres all seasons, with exception severely denitrified region inside Antarctic vortex. A pronounced seasonal cycle up least (∼34 km), winter maximum summer minimum. Large timing, magnitude, duration enhanced wintertime Even coldest Arctic winters, depletion modest limited horizontal extent. In contrast, virtually removal gas-phase occurs highest southern July every year Indications denitrification are 740 K, well above altitude which dehydration observed, providing further evidence can proceed absence dehydration.