Prospects for Precision Measurement o f C02 Column from Space

I William S. Heaps & S. Randolph Kawa NASA 6oddard Space Flight Center

The Team:

John F. Burris and Emily L Wilson

Elena Gcorgieva and Marty Miodek

fran NASA Wdard Spocc Fight Center

frcm Science System ond Applicoiions. Inc.

Instrument Pesign

Model f o r the CO, channel Overlap of Fringes and CO, Lines

1 0

0 4 i 02

0 0

8315 6320 6325 6330 6335

r R ~ o u ~ N c f (em-I) I FUSED snm FP ETALON ,191 CM THICK REFLECTIM - FINESSE=10

SENSITIVITY=1565

Comparison of Overlap at Two Temperature: ,010

1

https://ntrs.nasa.gov/search.jsp?R=20050180633 2018-05-28T06:38:48+00:00Z

The flight hardened version bround testing results with the fiber-coualed Sun Tracker

Sensitivity Estimates using birect Sun

CO, Ratio change per airmass = (1.1 - 1.0)/(2.0 - 6.0) = -.025 1/10 second CO, Ratio Noise = +/- .00025 so SNR - 1OO:l Since 1 airmass - 370 ppm Sensitivity - 3.7 ppm in 1/10 sec

0, Ratio change per airmass = (6 - 4)/(4.5 - 1.5) = .666

1/10 second 0, Ratio Noise = +/- .004 so SNR - 165:l Since 1 airmass - 1013 mB Sensitivity - 6.1 mB in 1/10 set

2

Effects of Atmospheric Scattering

Diurnal Variation of C02 a t boddard in May 2004

- 2 U." -W." - - - l b Y q n Y."

3% f 0 t 2 I 4 5 8 7

Dy o( W r L

Effects of Atmospheric Scattering

CONFSUTK)N OF sc*m mi TO m2 uo 02 D

I

3

c ATMOSPHERIC SCATTERING ALTERS THE

OPTICAL PATH

FPICC rack and instrument shown installed in DC-8 cabin

Results from PAVE Campaign Results from PAVE Campaign

4

Results from PAVE Campaign

02-07 PM c02 iy 02 mnos M SEC A= I b 1 ' < . . . . . . 7 - . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . , . . . , , . . . a r

Results from PAVE Campaign 62-07 P A K C M h 02 CORREIATIOA M SEe A%

Results from PAVE Campaign m-07 PAVE C02 k 01 MTK) M SEC A W

I 4 _'

baling with Atmospheric Scattering

I S E THE 6LIM

6LINT IS REFLECTION OF SUNLIGHT OFF THE SURFACE OF WATER-ADVANTAM IS THAT YOU KNOW THE PATH LEN6TH FOR GLINT.

GLINT CAN BE AS MUCH AS 1,OOO.OOO TIMES BRIGHTER THAN REFLECTION OFF GROUND

5

GLINT PROVIOES A KNOWN PATH I

SUMMARY & STATUS

*SMALL. INEXPENSIVE. PREUSE SYSTEM HAS POTENTIAL FOR GROUND BASED, A I C F T . : OR SATELUTE USE.

aFVTVRE WORK HIGHLY DESIRABLE AIMED AT VER;6P/IN6 T E C H W E S F Q L E E € A n T SCATTER, STABILIZIW DESI6N. AND D(TENDIN6 TECHNIQJE TO OTHER SMALL MOLECULES

@ SUMMARY & STATUS *INSTRUMENT FOR SIMULTANEOUS MEASUREMENT OF C02 AND OXY6EN DEMONSTRATED I N FIELD WITH VERY HIGH INTRINSIC PRECISION.

-PATH LENGTH UNCERTAINTY DUE TO ATMOSPHERIC SCATTERIN6 INTRODUCES SERIOUS PROBLEMS I N DATA INTERPRETATION FOR OMCES OF THIS TYPE

.USIN6 THE GLINT HAS BEEN PROPOSED TO AMELIORATE SCATTERING PROBLEMS BUT THIS APPROACH IS UNTESTED

We gratefully acknowledge the support of NASA's

Earth Science Technology Off ice.

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Prospects for Precision Measurement of COZ Column from Space

William S. Heaps, S. Randolph Kawa, John F. Burris and Emily L Wilson, NASA Goddard Space Flight Center, Elena

Georgieva and Marty Miodek, Science Systems and Applications, Inc.

ABSTRACT

In order to address the problem of sources and sinks of C02 measurements are needed on a global scale. Clearly a satellite is a promising approach to meeting this requirement. Unfortunately, most methods for making a C02 measurement from space involve the whole column. Since sources and sinks at the surface represent a small perturbation to the total column one is faced with the need to measure the column with a precision better than 1%. No species has ever been measured from space at this level.

We have developed over the last 3 years a small instrument based upon a Fabry-Perot interferometer that is very sensitive to atmospheric C02 and has a high signal to noise ratio. We have tested this instrument in a ground based configuration and from aircraft platforms simulating operation from a satellite.

We wil l present results from these tests and discuss ways that this promising new instrument could be used to improve our understanding of the global carbon budget.