Computer resources have been developed for the analysis and reduction of MAPS experimental data from the OSTA-1 payload. The MAPS Research Project is concerned with the measurement of the global distribution of mid-tropospheric carbon monoxide. The measurement technique for the MAPS instrument is based on non-dispersive gas filter radiometer operating in the nadir viewing mode. The MAPS experiment has two passive remote sensing instruments, the prototype instrument which is used to measure tropospheric air pollution from aircraft platforms and the third generation (OSTA) instrument which is used to measure carbon monoxide in the mid and upper troposphere from space platforms. Extensive effort was also expended in support of the MAPS/OSTA-3 shuttle flight. Specific capabilities and resources developed are discussed

Gormsen, Barbara B.

Tiwari, S. N.

English

NASA Technical Reports Server

DEPARTMENT OF MECHANICAL E N G I N E E R I N G  AND MECHANICS ~?3/ 77 
SCHOOL OF ENGINEERING 
OLD DOMINION UNIVERSITY 
NORFOLK, V I R G I N I A  
COMPUTERIZED DATA REDUCTION TECHNIQUES FOR 
NADIR V I E W I N G  REMOTE SENSORS 
BY 
Barbara B. Gormsen 
P r i n c i p a l  I n v e s t i g a t o r :  S. N. T i w a r i  
F i n a l  Report  
For  t h e  p e r i o d  February 15, 1984 - A p r i l  1, 1985 
Prepared f o r  t h e  
N a t i o n a l  Aeronaut ics  and Space A d m i n i s t r a t i o n  
Langley Research Center 
Hampton, V i r g i n i a  23665 
Under 
Research Grant NAG-1-456 
H. Andrew W a l l i o ,  Technical  M o n i t o r  
ASD-Chemi s t r y  and Dynamics Branch 
( b A S A - C B - 1 8 1 2 5 6 )  C C B E U T E R I Z I C  E A T A  ~ a 7 - 2 e 2 9 6  
tikDUCIIC15 T E C P l l C U E S  ECIi  L A f I E  V I E Y X H G  
1 APE- 1985 ( C l d  Doatinion U c i v , )  13 ]F Unclas 
A v a i l :  bills EC A O Z / P l I  A 6 1  CSCL 09B G 3 / 6 1  0093179  
c 3 € f 1 0 T E  SENSORS €inal ReFort, 15 Eeh. 1984 - 
A p r i l  1985 
https://ntrs.nasa.gov/search.jsp?R=19870018863 2020-03-20T10:22:18+00:00Z
DEPARTMENT OF MECHANICAL ENGINEERING AND MECHANICS 
SCHOOL OF E N G I N E E R I N G  
OLD D O M I N I O N  UNIVERSITY 
NORFOLK, V I R G I N I A  
COMPUTERIZED DATA REDUCTION TECHNIQUES FOR 
N A D I R  V I E W I N G  REMOTE SENSORS 
BY 
Barbara B. Gormsen 
P r i n c i p a l  I n v e s t i g a t o r :  S. N.  T i w a r i  
F i n a l  Report  
For t h e  per iod February 15 ,  1984 - A p r i l  1, 1985 
Prepared f o r  t h e  
Nat iona l  Aeronaut ics  and Space Adminis t ra t  ion  
Langley Research Center  
Hampton, V i r g i n i a  23665 
Under 
Research Grant NAG-1-456 
H. Andrew Wall io ,  Technical  Monitor 
ASD-Chemistry and Dynamics Branch 
Submitted by t h e  
Old Dominion Un ive r s i ty  Research Foundation 
P.O. Box 6369 
Norfolk,  V i r g i n i a  23508 
A p r i l  1985 
FOREWORD 
This  r e p o r t  d e s c r i b e s  t h e  work completed on t h e  research  p r o j e c t  
"Experimental  S t u d i e s  of Computerized Data Reduction Techniques for  Nadir 
Viewing Remote Sensors." 
s e a r c h  Center  (Atmospheric Sciences Divis ion - Chemistry and Dynamics 
Branch) through r e s e a r c h  grant  NAG-1-456. 
H. Andrew Wall io ,  of t h e  Atmospheric Sciences D i v i s i o n ,  Mail Stop 401A, 
Phone: (804) 865-2576. 
The work w a s  supported by t h e  NASA Langley Re- 
This  gran t  was monitored by M r  
ii 
TABLE OF CONTENTS 
FOREWORD ............................................................ 
SUMMARY ............................................................. 
1 . INTRODUCTION .................................................... 
2 . OSTA-1 DATA ANALYSIS ............................................ 
2.1 Instrument Characterization ................................ 
2.2 Atmospheric Modeling ....................................... 
2.3 Coefficient Generation ..................................... 
2.4 Data Inversion ............................................. 
2.5 Cloud Filtering ............................................ 
2.6 Data Display ............................................... 
3 . CORRELATIVE MEASUREMENTS PROGRAM ................................ 
4 . OSTA-3 DATA ..................................................... 
5 . 3RROR STUDIES ................................................... 
6 . CONCLUSIONS ..................................................... 
ii 
4 
4 
5 
5 
6 
9 
iii 
COMPUTERIZED DATA REDUCTION TECHNIQUES 
FOR NADIR VIEWING REMOTE SENSORS 
BY 
* 
Barbara B.  Gormsen 
** 
P r i n c i p a l  I n v e s t i g a t o r :  S. N .  T i w a r i  
SUMMARY 
Computer r e s o u r c e s  have been developed f o r  t h e  a n a l y s i s  and r e d u c t i o n  
of MAPS exper imenta l  d a t a  from t h e  OSTA-1 payload. 
also expended i n  suppor t  of t h e  MAPSIOSTA-3 s h u t t l e  f l i g h t .  
c a p a b i l i t i e s  and r e s o u r c e s  developed a r e  d i scussed .  
Extens ive  e f f o r t  w a s  
S p e c i f i c  
~ * 
Numerical Analys t ,  Old Dominion Un ive r s i ty  Research Foundat ion,  
P.O. Box 6369, Norfo lk ,  V i r g i n i a  23508 
** 
Eminent P r o f e s s o r ,  Department of Mechanical Engineer ing  and 
Mechanics, Old Dominion Un ive r s i ty ,  Norfo lk ,  V i r g i n i a  23508 
1. INTRODUCTION 
The MAPS Research Project is concerned with the measurement of the 
global distribution of mid-tropospheric carbon monoxide. The measurement 
technique for the MAPS instrument is based on non-dispersive gas filter 
radiometer operating in the nadir viewing mode. The MAPS experiment has 
two passive remote sensing instruments 
is used to measure tropospheric air pollution from aircraft platforms and 
the third generation (OSTA) instrument which is used to measure carbon 
monoxide in the mid and upper troposphere from space platforms. 
the prototype instrument which 
The major objectives of this study were as follows: 
I. To provide programming analysis for the reduction and analysis 
of the data obtained from the OSTA-1 shuttle flight. To 
develop a color display software for the OSTA-1 reduced data. 
To assemble, integrate develop and adapt a new LSI 11/23 
computer system for the MAPS correlative measurement program. 
11. 
111. To provide programming analysis for the OSTA-3 spacecraft 
and correlative measurements data. 
IV. To provide an error analysis of the carbon monoxide retrieval 
procedure. 
The works completed on these objectives are presented separately in the 
following sections. 
2. OSTA-1 DATA ANALYSIS 
The MAPS experiment flew as part of the OSTA-1 payload aboard the 
second flight of the Space Shuttle (STS-2) during November 1981. 
2 
This experiment was the first attempt to measure a pollutant gas in the 
troposphere from an orbiting platform. 
altitude and 38.1" inclination was achieved. 
the MAPS experiment operated approximately 42 hours. 
approximately 32 hours of nadir viewing data, with the remaining 10 hours of 
time devoted to periods of instrument warm-up and calibration or to periods 
when the spacecraft was not in Earth viewing altitude. 
nadir viewing data provided coverage of the troposphere between 38"N and 
35"s latitude. 
data along the flight track. 
a major accomplishment and accounts for approximately 80% of the study 
work effort. 
A nearly circular orbit of 139 N.M. 
During the 56 hour mission, 
The experiment acquired 
The 32 hours of 
This represents approximately 1 million kilometers of 
The reduction and analysis of this data was 
The data reduction and analysis process was comprised of six major 
steps: 
(1) Instrument characterization 
(2) Atmospheric modeling 
( 3 )  Coefficient generation 
( 4 )  Data inversion 
(5) Cloud filtering 
( 6 )  Data display 
These are discussed briefly in the following subsections. 
2 . 1  Instrument Characterization 
The equations to convert instrument voltage signals into radiance 
measurements and instrument temperatures were obtained from personnel 
responsible for instrument characterization studies. These equations 
were incorporated into the program used to compute CO mixing ratios. 
3 
Because of various problems associated with instrument thermal instability, 
it was necessary to modify these equations numerous times and then reprocess 
the OSTA-1 data for new CO mixing ratios. 
2.2 Atmospheric Modeling 
To define the meteorological conditions from 45" south to 45" north, six 
latitudinal averaged models were developed. 
by the MAPS radiative transfer program to compute the predicted atmospheric. 
radiation for the three channels as a function of solar zenith angles for 
night and day and surface emissivities for land and water. 
These models were processed 
Additional analysis led to the development of nine atmospheric models 
based on constant lapse rates and on varying tropopause heights and surface 
temperatures. These nine models were also processed with two solar zenith 
angles and two surface emissivities and were used in the final data analysis. 
Additional atmospheric models were developed for error studies. A 
total of 74 atmospheric models were processed with the M A P S  radiative 
transfer program. 
2 . 3  Coefficient Generation 
The predicted atmospheric radiation from the atmospheric models was 
then used in a regression analysis technique to generate the coefficient 
sets for the data inversion program. The data inversion program selects 
the coefficient set to be used in the calculation of CO on the basis of 
signal function weighted temperature, terrain type and a day or night 
condition. 
A coefficient study was conducted to improve the accuracy of the CO 
retrieval technique. In this error study, those radiance values for CO 
concentrations outside the solution set were excluded in the regression 
technique. Four combinations were considered in the study and 118 coef- 
ficient sets were generated. 
The coefficient sets based on six CO concentrations ranging from 22 
to 137.5 ppbv gave an accuracy improvement in GO retrieval of two to four 
percent and were used for the final data inversion. 
2.4 Data Inversion 
The program used to compute inferred CO was modified several times 
because of changes in radiance equations, coefficient selection methods, 
temperature equations, terrain type selection, and etc. The OSTA-1 data 
was processed for radiance values and inferred CO numerous times. These 
results were then plotted, compared and analyzed. 
2.5 Cloud Filtering 
An interactive cloud filtering program was developed to generate a 
data set with the cioud contaminated data removed. The data was processed 
in time blocks ranging from one second of data up to 30 minutes of data. 
The data was filtered by a maximum and/or minimum range and/or a statis- 
tical filtering method. With the statistical filter, each data point was 
differenced to the mean of the T-I preceding data points. If the difference 
was less than Q times the standard variance.of the preceding TI points the 
data was considered cloud free and retained in the data set. The time 
interval, maximum value, minimum value, and u were specified interactively. 
The filtered data was then graphically displayed and the decision was 
made to either refilter with different criteria or accept as cloud free data. 
This filtering process was applied to the OSTA-1 data and the results 
plotted for comparison to the MAPS photography. 
data was refiltered to remove additional cloud contaminated data. 
After this comparison, the 
2 . 6  Data Display 
Several graphics programs were developed to display the OSTA-1 data 
during the analysis phase. Numerous plots of CO mixing ratios, voltages, 
radiance values, blackbody temperatures, etc. were generated for MAPS 
scientist and engineers. 
A system of color graphics programs were developed to display the 
OSTA-1 reduced data. A file containing the data as 30 second averages 
and a file of the data summed as 5" x 5" latitude/longitude boxes were 
generated for graphic display on the color graphics system. 
3. CORRELATIVE MEASUREMENTS PROGRAM 
The MAPS OSTA instrument was also an experiment on the OSTA-3 payload 
which flew on the Space Shuttle (Mission 41-G) in October 1984. In support 
of this flight, grant personnel participated in conducting a correlative 
measurements program using the prototype instrument on an aircraft platform. 
The existing data system for the prototype instrument was a PCM system 
which wrote the data to a 7-track tape. In June 1984, the MAPS project 
purchased a LSI  11/23  computer system with a 9-track tape recorder as a 
replacement for the PCM system. 
The first phase in the development of the new inflight data system was 
the generation of the RSX 1 1 M  4.1 operating system and the modification of 
the system t o  meet the special needs of the MAPS instrumen'tation. The next 
phase was the installation of an RSX-LIB software package which was used 
to interface the computer with the A/D boards. 
errors found in the software package, it was modified to meet the specific 
After correcting the 
needs of the MAPS data system. 
of computer software for data collection, storage and display. 
diagnostics were performed for system verification. 
The next phase consisted of the development 
Extensive 
Data comparisons 
were also made between the PCM system and LSI 11/23 system. Additional 
computer programs were developed for the post-flight display and verification 
of inflight data. 
Both the PCM and the LSI 11/23 data systems, working independently, 
were used in the correlative measurements program, with the PCM system 
being designated as the primary data system. 
correlative measurements program was Homestead Air Force Base in Florida. 
Two computer facilities with 7-track tape drives, Cape Canaveral Computer 
Center at KSC and the N O M  Hurricane Tracking Center in Miami, were 
The staging point for the 
contacted and arrangements were made for the post-processing of the PCM 
&.i-- A -  L ~ ~ P S .  Software used at the LaRC computer center was E d i f i e d  for 
use at the KSC complex. By working directly with NOAA personnel, new 
software was developed to post-process the PCM data on an HP 2117F 
computer at their facility. 
Responsibilities as an active participant in the correlative 
measurements program included functioning as flight coordinator and 
crew member in aircraft under flights, traveling to KSC and NOAA to 
post-process the PCM inflight data tapes, post-processing the LSI 11/23 
inflight data tapes, and verifying that the data collected on the two 
systems was in agreement with inflight panel readings. 
4. OSTA-3 DATA 
A s  p rev ious ly  s t a t e d ,  t h e  MAPS experiment f lew on the  Space S h u t t l e  
i n  October 1984. Based on information gained from t h e  OSTA-1 f l i g h t ,  
several e l e c t r o n i c  mod i f i ca t ions  were made t o  t h e  s p a c e c r a f t  ins t rument .  
Because of t h e s e  in s t rumen t  changes,  so f tware  mod i f i ca t ions  were r e q u i r e d  
i n  t h e  t ape  decoding program and i n  the  g raph ic s  s t r i p c h a r t  program. 
A f t e r  t h e  s p a c e c r a f t ,  t h e  OSTA-3 d a t a  t ape  w a s  p rocessed  t o  gene ra t e  
computer l i s t i n g s  of  c a l i b r a t i o n  d a t a  and NOS compatiable  d a t a  t apes .  
The NOS compatiable  d a t a  t a p e s  were then processed  t o  produce a s t r i p -  
c h a r t  of t e n  ins t rument  v a r i a b l e s .  
The a i r c r a f t  PCM f l i g h t  d a t a  tapes w e r e  p rocessed  t o  g e n e r a t e  
computer l i s t i n g s  of t h e  d a t a ,  NOS compatiable d a t a  tapes and s t r i p -  
c h a r t s  of t h e  d a t a .  
complete computer l i s t i n g s  of t he  da t a .  
The L S I  1 1 / 2 3  da t a  t a p e s  w e r e  processed t o  gene ra t e  
5. ERROR STUDIES 
S t u d i e s  were conducted t o  determine t h e  sou rces  of e r r o r  i n  t h e  
procedure used t o  i n f e r  carbon monoxide mixing r a t i o s .  These s t u d i e s  
i n c l u d e  an a n a l y s i s  of e r r o r s  due t o  ins t rument  n o i s e ,  e r r o r s  from 
ins t rument  c h a r a c t e r i z a t i o n  equa t ions ,  a tmospheric  model l ing e r r o r s  
from t h e  equa t ions  used t o  compute t h e o r e t i c a l  r ad iance  v a l u e s ,  r eg res -  
s i o n  e r r o r s  i n  t h e  i n v e r s i o n  method, and e r r o r s  i n  t h e  assumptions used 
i n  t h e  r e t r i e v a l  p rocess .  The r e s u l t s  of t h e s e  s t u d i e s  are d i scussed  i n  
a paper  t h a t  i s  t o  be  submi t ted  f o r  j o u r n a l  p u b l i c a t i o n .  
I 
6 .  CONCLUSIONS 
The following specific tasks were completed during the present study: 
1. 
2 .  
3 .  
4 .  
5 .  
Development of software systems for the reduction and analyses 
of OSTA-1 spacecraft data, 
development of colorgraphic systems for the display of OSTA-1 
reduced data sets, 
development of a new LSI 11/23 computer system for the MAPS 
correlative measurement program, 
participation in the MAPS aircraft correlative measurements 
program in support of the OSTA-3 shutlle flight, and 
preliminary examination of the OSTA-3 spacecraft and correlative 
measurements data. 
Further work, however, is needed to review other available software 
systems, make essential modifications, and develop new methods for the 
reduction and analysis of MAPS data. 


Computerized data reduction techniques for nadir viewing remote sensors

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server