C = C(v, t) = complex spectrumLtgt = target radianceLfo = foreoptics radianceLcr = cold reference radianceLifmtr = interferometer radiancer = instrument response (radiometric slope)φδ = phase of interferometer emissionφ= net optical and electronics phase φδ = phase of interferometer emission2πmv/vl = sampling phase (vl = laser freq.)

TES Spectral Coverage for Ozone and Its Precursors

TES Filter Bands (schematic)

700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300

2B1 1B1 1B2 2A1 2A2 2A3 2A4 1A1 1A2

N N N N

Frequency (cm-1)

Upper trop.Temperature

NO2 NO2

O3

HNO3

Water Vapor

NO

CO

Lower trop.Temperature

CH4

•• Fourier transform spectrometer Fourier transform spectrometer •• Wavelength response: 5 to 15.4 micronWavelength response: 5 to 15.4 micron•• One scan every 4 or 16 sec. (0.1 cmOne scan every 4 or 16 sec. (0.1 cm--11 or 0.025 cmor 0.025 cm--11 res.)res.)•• Four opticallyFour optically--conjugated 1x16 pixel detector arraysconjugated 1x16 pixel detector arrays•• Spatial resolution of 5 x 8 km at nadir & 2.3 km at limbSpatial resolution of 5 x 8 km at nadir & 2.3 km at limb•• Passively cooledPassively cooled•• 22--axis gimbaled pointing mirror (nadir & limb viewing)axis gimbaled pointing mirror (nadir & limb viewing)

Beer, R., T. A. Glavich, and D. M. Rider, Tropospheric emission spectrometer for the Earth Observing System's Aura satellite, Applied Optics, 40, 2356-2367, 2001.

TES on EOS-Aura

Radiometric and Frequency Calibration of EOS-Aura TES Infrared Spectra

Helen M. Worden, Reinhard Beer, Kevin W. Bowman, Brendan Fisher, Mingzhao Luo, Gregory Osterman, David Rider, Edwin Sarkissian Jet Propulsion Laboratory, Cal Tech

Denis Tremblay Raytheon Systems, ITSS

http://tes.jpl.nasa.gov

FREQ

UEN

CY

CA

LIB

RA

TIO

N

CO2 Laser 0001 - 0200 P(20) line (nominally @ 1046.8543 cm-1) Model prediction

Frequency, cm-1

1046.6 1046.7 1046.8 1046.9 1047.0 1047.1 1047.2

Rel

ativ

e am

plitu

de

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0181 cm-1

A33A-0121

ABSTRACT

TES is an infrared Fourier transform spectrometer on board the EOS-Aura spacecraft. The first on-orbit interferograms were acquired August 20, 2004. We present the methods for producing calibrated radiance spectra and show initial results for atmospheric nadir and limb spectra. We also show comparisons of TES nadir spectra to Aqua-AIRS spectra, where the AIRS data are taken on the same orbit path about 15 minutes before TES data are taken.

RA

DIO

MET

RIC

CA

LIB

RA

TIO

N

optical axis

ϕαβ

7.5 millirad

0.75millirad

pixel 0

pixel 15

TES detector array with respect to the optical axis, showing off-axis geometry

Calibration Issues & Systematic Error Sources

Time Dependence of instrument responseand offset

Ice BuildupshearOrbital variations

Scan to Scan Phase AlignmentNeeds to be more robust

Possible angle dependence

L1B Calibration Error EstimatesA)The imaginary mean is a measure of the residual radiance remaining in the imaginaryterm after complex calibration. Ideally, this should be unbiased with RMS close to the noise level. Variations from this indicate systematic calibration errors.B) Spectral averages of estimated NESR (Noise Equivalent Spectral Radiance)

(A) (B)

Rad

ianc

e (W

/cm

2 /sr/c

m-1

)

NES

R (n

W/c

m2 /s

r/cm

-1)

Frequency “compression”(δν/ν) due to off axisangles.

TES spectral response“line shape” - measuredvs. modeled.

Complex Calibration:

Signal loss due to ice build-up (1.5 days)

Ctgt = r(Ltgt + Lfo − Lcr + Lifmtreiϕδ )eiϕ ei2πmν /ν l

Ltgt =Ctgt − CCS

CBB − CCS

εBBB(TBB )

CCS = cold space complex spectrumCBB = on-board blackbody complex spectrumεBB = blackbody emissivityB(TBB) = Planck function for blackbody

Reverse scan direction

Forward scan direction

CFC11 CFC12

HNO3

O3

Rad

ianc

e (W

/ cm

2 /sr/ c

m- 1

)

CO2

Frequency (cm-1)

surface

2.3 km

4.6 km

6.9 km

7.2 km

8.5 km

10.8 km

13.1 km

15.4 km

17.7 km

20.0 km

22.3 km

25.6 km

http://tes.jpl.nasa.gov

TES-

AIR

S R

AD

IAN

CE

CO

MPA

RIS

ON

S

CO

NC

LUSI

ON

S

TES/

AIR

S R

adia

n ce

Rat

io

All Nadir Targets (1152)

TES Radiance (mW/m2/cm-1/sr)

Homogeneous Nadir Targets(190)

Zoom of middle plot

<0.5 K variability across detector array

Color indicates frequency bin, cm-1

TES Radiance (mW/m2/cm-1/sr)

Histograms of AIRS-TES brightness temperature differences (K) for 25 cm-1 frequency ranges.

___ All Nadir Targets___ Homogeneous Ocean Nadir Targets

Comparisons ofTES and AIRS observed brightness temperature where TES radiances have been convolved with the AIRS spectral response function (SRF).

NADIR OCEAN SPECTRUMwith estimated NE∆T (Noise Equivalent Delta Temperature) and known instrument spikes shown in lower the panel.

NADIR AFRICAN DESERT SPECTRUM AT NIGHT Taken over Mauritania, 19.57° N,11.07° W, 9/20/2004. TroposphericH2O and CH4 are observed in emission in the spectral region with lower surface emissivity due to silicates in the soil. Green curve shows an example of spectral emissivity for desert sandstone. (from the ASTER spectral library)

AscendingPaths(day)

DescendingPaths(night)

NADIR BRIGHTNESS TEMPERATURES(near 10 µm)for a 16-orbit Global Survey taken 9/20/2004.Colors indicate temperature in K.

LIMB spectra for 57.6° S, 128.9° E, taken 9/20/2004. Spectra clearly show features due to Nitric Acid and CFC 11,12, with distinct altitude dependence. O3, CO2and H2O spectral lines are also visible. The surface Isobscured by clouds.

TES

CA

LIB

RA

TIO

N R

ESU

LTS

Radiometric and Frequency Calibration of EOS-Aura TES Infrared Spectra A33A-0121

Initial calibration results show reasonable agreement with AIRS data.Further algorithm refinement is in progress to reduce systematic errors due to:• phase alignment of calibration and target scans• time dependence of instrument response and offset• view dependence, if detected.Beta release for TES L1B data will be in early 2005 at the Langley DAAC: http://eosweb.larc.nasa.gov/

This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with theNational Aeronautics and Space Administration