scholarly journals An analysis of Polar Ozone and Aerosol Measurement (POAM) II Arctic polar stratospheric cloud observations, 1993-1996

1999 ◽  
Vol 104 (D20) ◽  
pp. 24341-24357 ◽  
Author(s):  
Michael D. Fromm ◽  
Richard M. Bevilacqua ◽  
John Hornstein ◽  
Eric Shettle ◽  
Karl Hoppel ◽  
...  
Keyword(s):  
Aerosol Measurement ◽  
Polar Stratospheric Cloud ◽  
Polar Ozone

scholarly journals Aerosol optical depth measurements by airborne sun photometer in SOLVE II: Comparisons to SAGE III, POAM III and airborne spectrometer measurements

2005 ◽  
Vol 5 (5) ◽  
pp. 1311-1339 ◽  
Author(s):  
P. Russell ◽  
J. Livingston ◽  
B. Schmid ◽  
J. Eilers ◽  
R. Kolyer ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Stratospheric Aerosol ◽  
Line Of Sight ◽  
Aerosol Measurement ◽  
Validation Experiment ◽  
Satellite Sensors ◽  
Beam Transmission ◽  
Relative Differences ◽  
Polar Ozone

Abstract. The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) measured solar- beam transmission on the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). This paper presents AATS-14 results for multiwavelength aerosol optical depth (AOD), including comparisons to results from two satellite sensors and another DC-8 instrument, namely the Stratospheric Aerosol and Gas Experiment III (SAGE III), the Polar Ozone and Aerosol Measurement III (POAM III) and the Direct-beam Irradiance Airborne Spectrometer (DIAS). AATS-14 provides aerosol results at 13 wavelengths λ spanning the range of SAGE III and POAM III aerosol wavelengths. Because most AATS measurements were made at solar zenith angles (SZA) near 90°, retrieved AODs are strongly affected by uncertainties in the relative optical airmass of the aerosols and other constituents along the line of sight (LOS) between instrument and sun. To reduce dependence of the AATS-satellite comparisons on airmass, we perform the comparisons in LOS transmission and LOS optical thickness (OT) as well as in vertical OT (i.e., optical depth, OD). We also use a new airmass algorithm that validates the algorithm we previously used to within 2% for SZA<90°, and in addition provides results for SZA≥90°. For 6 DC-8 flights, 19 January-2 February 2003, AATS and DIAS results for LOS aerosol OT at λ=400nm agree to ≤12% of the AATS value. Mean and root-mean-square (RMS) differences, (DIAS-AATS)/AATS, are -2.3% and 7.7%, respectively. For DC-8 altitudes, AATS-satellite comparisons are possible only for λ>440nm, because of signal depletion for shorter λ on the satellite full-limb LOS. For the 4 AATS-SAGE and 4 AATS-POAM near-coincidences conducted 19-31 January 2003, AATS-satellite AOD differences were ≤0.0041 for all λ>440nm. RMS differences were ≤0.0022 for SAGE-AATS and ≤0.0026 for POAM-AATS. RMS relative differences in AOD ([SAGE-AATS]/AATS) were ≤33% for λ<~755nm, but grew to 59% for 1020nm and 66% at 1545nm. For λ>~755nm, AATS-POAM differences were less than AATS-SAGE differences, and RMS relative differences in AOD ([AATS-POAM]/AATS) were ≤31% for all λ between 440 and 1020nm. Unexplained differences that remain are associated with transmission differences, rather than differences in gas subtraction or conversion from LOS to vertical quantities. The very small stratospheric AOD values that occurred during SOLVE II added to the challenge of the comparisons, but do not explain all the differences.

scholarly journals The Lagrangian chemistry and transport model ATLAS: simulation and validation of stratospheric chemistry and ozone loss in the winter 1999/2000

2010 ◽  
Vol 3 (2) ◽  
pp. 769-817
Author(s):  
I. Wohltmann ◽  
R. Lehmann ◽  
M. Rex
Keyword(s):  
Transport Model ◽  
Active Species ◽  
The Arctic ◽  
Time Step ◽  
Stratospheric Chemistry ◽  
Polar Stratospheric Cloud ◽  
Efficient Code ◽  
Stratospheric Clouds ◽  
Code Parallelization ◽  
Polar Ozone

Abstract. ATLAS is a new global Lagrangian Chemistry and Transport Model (CTM), which includes a stratospheric chemistry scheme with 46 active species, 171 reactions, heterogeneous chemistry on polar stratospheric clouds and a Lagrangian denitrification module. Lagrangian (trajectory-based) models have several important advantages over conventional Eulerian models, including the absence of spurious numerical diffusion, efficient code parallelization and no limitation of the largest time step by the Courant-Friedrichs-Lewy criterion. This work describes and validates the stratospheric chemistry scheme of the model. Stratospheric chemistry is simulated with ATLAS for the Arctic winter 1999/2000, with a focus on polar ozone depletion and denitrification. The simulations are used to validate the chemistry module in comparison with measurements of the SOLVE/THESEO 2000 campaign. A Lagrangian denitrification module, which is based on the simulation of the nucleation, sedimentation and growth of a large number of polar stratospheric cloud particles, is used to model the substantial denitrification that occured in this winter.

The Polar Ozone and Aerosol Measurement instrument

1996 ◽  
Vol 101 (D9) ◽  
pp. 14479-14487 ◽  
Author(s):  
W. Glaccum ◽  
R. L. Lucke ◽  
R. M. Bevilacqua ◽  
E. P. Shettle ◽  
J. S. Hornstein ◽  
...  
Keyword(s):  
Measurement Instrument ◽  
Aerosol Measurement ◽  
Polar Ozone

scholarly journals Comparison of Polar Ozone and Aerosol Measurement (POAM) II and Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol measurements from 1994 to 1996

2000 ◽  
Vol 105 (D3) ◽  
pp. 3929-3942 ◽  
Author(s):  
C. E. Randall ◽  
R. M. Bevilacqua ◽  
J. D. Lumpe ◽  
K. W. Hoppel ◽  
D. W. Rusch ◽  
...  
Keyword(s):  
Stratospheric Aerosol ◽  
Aerosol Measurement ◽  
Polar Ozone

scholarly journals Polar Ozone and Aerosol Measurement (POAM) II stratospheric NO2, 1993-1996

1998 ◽  
Vol 103 (D21) ◽  
pp. 28361-28371 ◽  
Author(s):  
C. E. Randall ◽  
D. W. Rusch ◽  
R. M. Bevilacqua ◽  
K. W. Hoppel ◽  
J. D. Lumpe
Keyword(s):  
Aerosol Measurement ◽  
Polar Ozone

scholarly journals Nitric acid trihydrate (NAT) formation at low NAT supersaturations

2004 ◽  
Vol 4 (6) ◽  
pp. 8579-8607 ◽  
Author(s):  
C. Voigt ◽  
H. Schlager ◽  
B. P. Luo ◽  
A. Dörnbrack ◽  
A. Roiger ◽  
...  
Keyword(s):  
Nitric Acid ◽  
High Altitude ◽  
Equilibrium Temperature ◽  
In Situ Measurements ◽  
The Arctic ◽  
Ozone Loss ◽  
Polar Stratospheric Cloud ◽  
Research Aircraft ◽  
Polar Ozone

Abstract. A polar stratospheric cloud (PSC) was observed on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10−4 cm−3) of nitric acid (HNO3) containing particles – probably NAT – with diameters up to 6 µm were measured at altitudes between 18 and 20 km. These particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures T>TNAT−3.5 K, just slightly below the NAT equilibrium temperature TNAT. This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤11) constrains current NAT nucleation theories. In particular, NAT formation on ice can for certain be excluded. Conversely, we suggest that meteoritic particles may be favorable candidates for triggering nucleation of NAT at the observed low number densities.

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