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

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

[1]  John C. Gille,et al.  Accuracy and precision of the nitric acid concentrations determined by the limb infrared monitor of the stratosphere experiment on NIMBUS 7 , 1984 .

[2]  L. Froidevaux,et al.  Polar Vortex Conditions During The 1995-96 Arctic Winter: MLS ClO and HNO3 , 1996 .

[3]  L. Thomason,et al.  A global climatology of stratospheric aerosol surface area density deduced from Stratospheric Aerosol and Gas Experiment II measurements: 1984–1994 , 1997 .

[4]  Peter Barthol,et al.  CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere - CRISTA , 1999, Optical Remote Sensing of the Atmosphere.

[5]  Richard Swinbank,et al.  A Stratosphere-Troposphere Data Assimilation System , 1994 .

[6]  Yuk L. Yung,et al.  The Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment: Deployment on the ATLAS Space Shuttle Missions , 1996 .

[7]  W. Randel,et al.  Climatology of Arctic and Antarctic Polar Vortices Using Elliptical Diagnostics , 1999 .

[8]  M. Santee,et al.  Polar vortex dynamics during spring and fall diagnosed using trace gas observations from the Atmospheric Trace Molecule Spectroscopy instrument , 1999 .

[9]  G. Muscari,et al.  Millimeter wave spectroscopic measurements over the South Pole. 5. Morphology and evolution of HNO3 vertical distribution, 1993 versus 1995 , 2000 .

[10]  John C. Gille,et al.  The Limb Infrared Monitor of the Stratosphere: Experiment Description, Performance, and Results , 1984 .

[11]  J. Knox.  On converting potential temperature to altitude in the middle atmosphere , 1998 .

[12]  Michael R. Gunson,et al.  Polar stratospheric descent of NO y and CO and Arctic denitrification during winter 1992-1993 , 1999 .

[13]  Alyn Lambert,et al.  Stratospheric and mesospheric observations with ISAMS , 1994 .

[14]  M. Santee,et al.  Intercomparison of stratospheric HNO3 measurements over Antarctica: Ground‐based millimeter‐wave versus UARS/MLS Version 5 retrievals , 2002 .

[15]  S. Bühler.  Microwave Limb Sounding , 2002 .

[16]  S. Solomon,et al.  Ozone destruction through heterogeneous chemistry following the eruption of El Chichón , 1989 .

[17]  Kenneth P. Bowman,et al.  Large-scale isentropic mixing properties of the Antarctic polar vortex from analyzed winds , 1993 .

[18]  J. Russell,et al.  Space‐time patterns of trends in stratospheric constituents derived from UARS measurements , 1999 .

[19]  L. Froidevaux,et al.  MLS observations of ClO and HNO3 in the 1996–97 Arctic Polar Vortex , 1997 .

[20]  J. Russell,et al.  An assessment of southern hemisphere stratospheric NOx enhancements due to transport from the upper atmosphere , 2000 .

[21]  M. McCormick,et al.  Balloon profiles of stratospheric NO2 and HNO3 for testing the heterogeneous hydrolysis of N2O5 on sulfate aerosols , 1994 .

[22]  R. D. Zafra,et al.  On the formation of HNO3 in the Antarctic mid to upper stratosphere in winter , 2001 .

[23]  E. Mahieu,et al.  Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment Version 3 data retrievals. , 2002, Applied optics.

[24]  H. L. Miller,et al.  On the relationship between stratospheric aerosols and nitrogen dioxide , 1993 .

[25]  Jerry Lumpe,et al.  Polar Ozone and Aerosol Measurement III measurements of water vapor in the upper troposphere and lowermost stratosphere , 2002 .

[26]  C. Randall,et al.  Polar Ozone and Aerosol Measurement (POAM) II stratospheric NO2, 1993–1996 , 1998 .

[27]  D. Andrews.  Some comparisons between the middle atmosphere dynamics of the Southern and Northern Hemispheres , 1989 .

[28]  L. Froidevaux,et al.  Microwave Limb Sounder measurement of stratospheric SO2 from the Mt. Pinatubo volcano , 1993 .

[29]  A. O'Neill,et al.  The Seasonal Evolution of the Extra-Tropical Stratosphere in the Southern and Northern Hemispheres: Systematic Changes in Potential Vorticity and the Non-Conservative Effects of Radiation , 1990 .

[30]  Jerry Lumpe,et al.  Validation of POAM III aerosols: Comparison to SAGE II and HALOE , 2001 .

[31]  M. Patrick McCormick,et al.  The poleward dispersal of Mount Pinatubo volcanic aerosol , 1993 .

[32]  John C. Gille,et al.  Comparison of correlative data with HNO3 version 7 from the CLAES instrument deployed on the NASA Upper Atmosphere Research Satellite , 1996 .

[33]  Gail P. Anderson,et al.  Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) Earth limb spectral measurements, calibration, and atmospheric O3, HNO3, CFC‐12, and CFC‐11 profile retrieval , 1997 .

[34]  G. Manney,et al.  Interhemispheric comparison of the development of the stratospheric polar vortex during fall: A 3‐dimensional perspective for 1991–1992 , 1993 .

[35]  S. Pawson,et al.  Persistence of the lower stratospheric polar vortices , 1999 .

[36]  Wesley A. Traub,et al.  Validation of CFC‐12 measurements from the Improved Limb Atmospheric Spectrometer (ILAS) with the version 6.0 retrieval algorithm , 2002 .

[37]  D. Allen,et al.  Missing chemistry of reactive nitrogen in the upper stratospheric polar winter , 1995 .

[38]  S. Pawson,et al.  The cold winters of the middle 1990s in the northern lower stratosphere , 1999 .

[39]  S. Massie,et al.  Observations of Antarctic polar stratospheric clouds by POAM II: 1994–1996 , 1997 .

[40]  James M. Russell,et al.  Hemispheric asymmetries in water vapor and inferences about transport in the lower stratosphere , 1997 .

[41]  Mark R. Schoeberl,et al.  The structure of the polar vortex , 1992 .

[42]  M. Santee,et al.  Onset, extent, and duration of dehydration in the southern hemisphere polar vortex , 2001 .

[43]  D. Weisenstein,et al.  Post‐Mount Pinatubo eruption ground‐based infrared stratospheric column measurements of HNO3, NO, and NO2 and their comparison with model calculations , 2003 .

[44]  A. Tuck,et al.  A comparison of the longitudinal distributions of polar stratospheric clouds and temperatures for the 1987 Antarctic spring , 1989 .

[45]  H. Oelhaf,et al.  Remote sensing of vertical profiles of atmospheric trace constituents with MlPAS limb-emission spectrometers. , 1996, Applied Optics.

[46]  Santee,et al.  Quantifying denitrification and its effect on ozone recovery , 2000, Science.

[47]  K. Jucks,et al.  A comparison of Arctic HNO3 profiles measured by the Improved Limb Atmospheric Spectrometer and balloon‐borne sensors , 2000 .

[48]  G. Brasseur,et al.  Mount Pinatubo Aerosols, Chlorofluorocarbons, and Ozone Depletion , 1992, Science.

[49]  Eric P. Shettle,et al.  POAM III measurements of dehydration in the Antarctic lower stratosphere , 2000 .

[50]  M. Mills,et al.  A 2D microphysical model of the polar stratospheric CN layer , 1999 .

[51]  L. Froidevaux,et al.  Six years of UARS Microwave Limb Sounder HNO3 observations: Seasonal, interhemispheric, and interannual variations in the lower stratosphere , 1999 .

[52]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[53]  M. Santee,et al.  Trajectory Hunting: A Case Study of Rapid Chlorine Activation in December 1992 as Seen by UARS , 2000 .

[54]  C. B. Farmer,et al.  Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987 , 1989 .

[55]  G. Siebes,et al.  The Upper Atmosphere Research Satellite microwave limb sounder instrument , 1993 .

[56]  Dong L. Wu,et al.  The UARS Microwave Limb Sounder version 5 data set: Theory, characterization, and validation , 2003 .

[57]  C. Rinsland,et al.  The effect of the Mt. Pinatubo aerosol on the HNO3 column over Mauna Loa, Hawaii , 1994 .

[58]  Paul Newman,et al.  Meteorology of the polar vortex: Spring 1997 , 1997 .

[59]  L. Froidevaux,et al.  Interhemispheric Differences in Polar Stratospheric HNO3, H2O, CIO, and O3 , 1995, Science.

[60]  P. Hamill,et al.  A stratospheric aerosol climatology from SAGE II and CLAES measurements: 2. Results and comparisons, 1984–1999 , 2003 .

[61]  A. O'Neill,et al.  On the motion of air through the stratospheric polar vortex , 1994 .

[62]  G. Muscari,et al.  On the cryogenic removal of NOy from the Antarctic polar stratosphere , 2003 .

[63]  R. McKenzie,et al.  Impact of Pinatubo aerosols in the partitioning between NO and HNO , 1994 .

[64]  Stanley C. Solomon,et al.  Stratospheric ozone depletion: A review of concepts and history , 1999 .

[65]  V. L. Orkin,et al.  Scientific Assessment of Ozone Depletion: 2010 , 2003 .

[66]  M. Pitts,et al.  Polar stratospheric cloud climatology based on Stratospheric Aerosol Measurement II observations from 1978 to 1989 , 1994 .

[67]  A. J. Miller,et al.  Interannual variability of the North Polar Vortex in the lower stratosphere during the UARS Mission , 1996 .

[68]  Eric P. Shettle,et al.  An analysis of Polar Ozone and Aerosol Measurement (POAM) II Arctic polar stratospheric cloud observations, 1993–1996 , 1999 .

[69]  Richard R. Lay,et al.  The UARS and EOS Microwave Limb Sounder (MLS) Experiments. , 1999 .

[70]  R. Garcia,et al.  On the atmospheric photochemistry of nitric acid , 1986 .

[71]  L. Froidevaux,et al.  Trajectory hunting as an effective technique to validate multiplatform measurements: Analysis of the MLS, HALOE, SAGE‐II, ILAS, and POAM‐II data in October–November 1996 , 2002 .

[72]  Martin Riese,et al.  CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere - CRISTA , 1999, Optical Remote Sensing of the Atmosphere.

[73]  Susanne Crewell,et al.  Millimeter wave spectroscopic measurements over the South Pole: 3. The behavior of stratospheric nitric acid through polar fall, winter, and spring , 1997 .

[74]  Ellis E. Remsberg,et al.  The Area of the Stratospheric Polar Vortex as a Diagnostic for Tracer Transport on an Isentropic Surface , 1986 .

[75]  A. Lambert,et al.  Global atmospheric chemistry from satellites: results from UARS/ISAMS , 1995 .

[76]  D. Murtagh,et al.  An overview of the Odin atmospheric mission , 2002 .

[77]  H. Pumphrey,et al.  The impact of the mixing properties within the Antarctic stratospheric vortex on ozone loss in spring , 2001 .

[78]  J. Russell,et al.  Two‐dimensional model calculations of nitric oxide transport in the middle atmosphere and comparison with Halogen Occultation Experiment data , 1997 .

[79]  E. Mahieu,et al.  Heterogeneous conversion of N2O5 to HNO3 in the post‐Mount Pinatubo eruption stratosphere , 1994 .

[80]  P. Good,et al.  High‐latitude stratospheric NO2 and HNO3 over Fairbanks (65°N) 1992–1994 , 1998 .

[81]  J. H. Shaw,et al.  Measurements of odd nitrogen compounds in the stratosphere by the ATMOS experiment on Spacelab 3 , 1988 .