NASA Contractor Report 172437 IqASA-CR-172437 19840023777 Empirical Studies of Upper Atmospheric Species John Nicholson, Mike Pitts and Dave Young Systems and Applied Sciences Corporation 17 Research Drive Hampton, VA 23666 Contract NASI-17089 July i0, 1984 L[EEA".,00PY i_,. _;, , .,,".., '"-'_'t 1984 LAf:_GL_' RESF3_RCH CENT£f% L!_RARY, NASA HAMP_'[Pfj,YlRGINIA. NASA " NationalAeronauticsand SpaceAdministration LangleyResearchCenter Hampton,Vir.ainia23665 I ._.1,_1 ,._t ".n.....-q:::-_2""27 LI_..................i=: _H31 --i ."...."-'o.-,'Or............................_'1_":3// i:.;: --'9_uS"_AC"r""---" :Jr_i...,i_H..,:_21"iLU / i !TT!=" -_=''"i ":........... TLCF Fi "-'-": R....... _=" 5'-"PI-_T"- _ ............... ..................:....,:...,:_i"'; ,_':-_ k_ili_ _" I.LIH._.:Ji l-_J_" _'E_ : *........._: :'...'_ _ "_'-'_-r.--.',,_.,,_-,i_,_'-.,.'=.--'_"i. ........._.,..s""_"_-.._"._'_-'-_. ........_._ _. 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[id._.F._LCdt'-'_r:aJ._.i UI i.i"aVi=Jl_L O'Ii.L;iii.'_'_" _TILI i...l_I I__1%s i ik ' K- -" TABLE OF CONTENTS Page 1 - INTRODUCTION .................................. 1 2 - SPIN-SCAN OZONE IMAGING EXPERIMENT ............ 2 3 - OZONE-TEMPERATURE RELATIONSHIP ................ i0 3.1 Satellite Data ........................... ii 3.2 Theoretical Model Data ................... 13 4 - DATA SETS OF OTHER ATMOSPHERIC SPECIES ........ 18 4.1 Limb Infrared Monitor of the Stratosphere (LIMS) ................................... 18 4.2 Stratospheric and Mesospheric Sounder (SAMS) ................................... 19 5 - PIONEER VENUS ORBITER ...................... ... 20 5.1 Updating of the Venus Orbiter Atmospheric Drag (OAD) Model ......... ................. 21 5.2 Comparison of OAD with other Models ...... 22 5.3 Inclusion of other Models into the OAD Model .................................... 24 5.4 New Theoretical Models ................... 25 1 - INTRODUCTION This document is the final report for contract NASI-17089 for the time period beginning July 23, 1982 and ending May 7, 1984. During this period, Systems and Applied Sciences Corporation developed for the National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) some of the computer programs for processing and analyzing atmospheric data from experiments aboard Earth and Venus orbiting spacecraft. The experiments were the Spin-Scan Ozone Imaging (SOI) Experiment on the Dynamics Explorer Spacecraft (DE-I), the Backscatter Ultraviolet (BUV) and Selective Chopper Radiometer (SCR) Experiments on Nimbus 4, the Solar Backscatter Ultraviolet (SBUV), the Stratospheric and Mesospheric Sounder (SAMS) and the Limb Infrared Monitor of the Stratosphere (LIMS) Experiments on Nimbus 7, and the Orbiter Atmospheric Drag (OAD) Experiment on the Pioneer Venus Orbiter Spacecraft. The computer programs were then used to perform collaborating studies with LaRC scientists for the determination of the distribution in the Earth's atmosphere of total columnar ozone (total ozone) from SOI, ozone mixing ratio (ozone) and temperature from BUV and SBUV, and SCR and SAMS respectively, nitric acid (HN03), nitrogen dioxide (NO2) and water (H20) mixing ratios from LIMS, methane (CH4) and nitrous oxide (N20) mixing ratios from SAMS, and the Venus atmospheric densities from OAD. 1 2 - SPIN-SCAN OZONE IMAGING EXPERIMENT Data reduction, validation, and analysis of total column ozone (total ozone) data from the Dynamics Explorer I (DE-I) Spin-Scan Ozone Imaging (SOI) Experiment is in progress. This experiment measures total ozone using the backscattered ultraviolet (BUV) technique similar to that used on Nimbus 4 and 7. Measurements of backscattered sunlight are made at 317.5 nm and 360.0 nm using the Spin-Scan Imaging Instrumentation on DE- I. The spin of the DE-I spacecraft, coupled with a laterally scanning mirror enables a global-scale image of the total ozone field to be produced in twelve minutes or less dependent upon the size of the image. Additionally, the DE-I satellite is in a highly eccentric polar orbit. This not only allows continuous global-scale total ozone images for hours at a time while the satellite is near apogee (~23,000 km), but also permits high resolution (~3 km) images of the total ozone field while near perigee. Some of the SOI data for October, 1981 has been processed. Data-blocking and modeling software developed for prior empirical modeling studies has been modified for use in validating and analyzing these data. In addition, new software has been refined for producing synoptic ' pseudo-color images of the total ozone field. These images are an important, qualitative tool for the study of short- term total ozone variations and can be animated to produce films of the evolving total ozone field. Since these images are 2 synoptic, they can be compared directly with synoptic meteorological data in order to demonstrate the relation between the total ozone distribution and atmospheric dynamics near the tropopause. During this contract, the emphasis of the SOI data analysis has been: I) comparing SOI data with the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus 7 spacecraft and ground-based Dobson data to assure the accuracy of the SOI data; 2) comparing synoptic SOI images with asynoptic TOMS data in order to study short-term variations in the total ozone field; and 3) studying the correlation between SOI total ozone and upper tropospheric synoptic data in order to establish the meteorological applications for this data set. Approximately 2800 SOI radiance data images measured during the time period September 29 to November 14, 1981 have been catalogued, copied, and archived on magnetic tape. From this data base more than 750 total ozone images have been produced. The total ozone data have also been catalogued and archived on magnetic tape at NASA Langley Research Center. The software for reading, displaying, and blocking both the radiance data tapes and the total ozone data tapes has been refined and is currently operational. The blocking routines, which group and average the data onto a 2° latitude by 2° longitude grid, are used in order to more practically handle the large amount of data. Once the data are blocked, reblocking (either into a coarser grid or using running means) and displaying the data is vastly simplified and less expensive. 3 The total ozone data reduction and co-location programs have been incorporated into the NASA-Langley computer system. Included with these programs are the tables of theoretical 317.5 nm and 360.0 nm albedos, slant path, and terrain height necessary for the calculation of total ozone. One of the principal goals of this research has been the validation of the SOI total ozone measurements. Prior to this work, validation had consisted solely of comparisons of 15th order-15th degree spherical harmonic models of the SOI total ozone data with ground-based Dobson measurements from the time period September 29 - October 3, 1981. The comparison between the two data sets was excellent, with a standard deviation of less than 3% for all weather conditions excluding rain. Comparisons have now been performed between SOI and TOMS. The TOMS data is particularly advantageous for use in validating SOI total ozone measurements. First of all, both SOI and TOMS use backscattered ultraviolet techniques for measuring total ozone and can thus be directly compared. In addition, global TOMS total ozone data are available for October, 1981 so that same-day comparisons can be made. However, since the TOMS experiment produces global images by piecing together data from many orbits, only a portion of each TOMS image will contain concurrently measured SOI data. Thus, although TOMS represents the best available data set for validating SOI, care has been taken concerning time differences when direct comparisons have been made. Software has been developed to perform this comparison. Programs have been designed to: I) read the TOMS data tapes and block the data into 2° latitude by 2° longitude cells; 2) reblock the SOI data using running means; and 3) reblock, correlate, and plot the two data sets. The reblocking software has been used to study the quality of the SOI data. It has been demonstrated that hourly averaged, 6° x 6° running means of the SOI total ozone values reveal data comparable to the 2° x 2° TOMS data. All comparisons have been performed using this degree of smoothing. The correlation and plotting routines were used to search for biases between the two data sets. This study has led to the detection of the following trends: i. A constant bias in ozone of 8% assumed due to the different values of the ozone absorption coefficient used by SOI and TOMS in the ozone retrieval algorithm.