CoRP Cal/Val Symposium July 13, 2005

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MODIS Thermal Band Radiance Cal/Val Chris Moeller Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin with contributions from Jack Xiong, MODIS Characterization Support Team (MCST), GSFC Dave Tobin, Cooperative Institute for Meteorological Satellite Studies Simon Hook, Jet Propulsion Laboratory (JPL, NASA) CoRP Cal/Val Symposium July 13, 2005

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Transcript of CoRP Cal/Val Symposium July 13, 2005

Page 1: CoRP Cal/Val Symposium July 13, 2005

MODIS Thermal Band Radiance Cal/Val

Chris MoellerCooperative Institute for Meteorological Satellite Studies,

University of Wisconsin

with contributions from Jack Xiong, MODIS Characterization Support Team (MCST), GSFC Dave Tobin, Cooperative Institute for Meteorological Satellite Studies

Simon Hook, Jet Propulsion Laboratory (JPL, NASA)

CoRP Cal/Val SymposiumJuly 13, 2005

Page 2: CoRP Cal/Val Symposium July 13, 2005

Outline

• Brief MODIS background

• Cal/Val procedure

• MODIS L1B validation findings

• Contributions to Uncertainty

• Summary

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Instrument Background

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• 2-sided Paddle Wheel Scan Mirror– (10km by 2330 km swath per 1.478 sec)– Day data rate: 10.6 Mbps, night data rate:

3.3 Mbps (100% duty cycle, 50% day and 50% night)

• 3 Nadir Spatial Resolutions– 250m (1-2), 500m (3-7), and 1km (8-36)

• 4 Focal Plane Assemblies (FPAs)– VIS, NIR, SMIR, and LWIR

• 36 Spectral Bands (490 detectors)– Reflective solar bands (1-19, and 26),

thermal emissive bands (20-25, 27-36)• On-Board Calibrators (OBCs):

– Solar diffuser (SD)– SD stability monitor (SDSM)– Blackbody (BB)– Spectro-radiometric calibration assembly

(SRCA)– Space view (SV)

• Science Applications– Land, oceans, and atmosphere– Nearly 40 science products generated and

distributed

Terra (EOS-AM):Launched on 12/18/99First light on 02/24/00

PFM

Aqua (EOS-PM):Launched on 05/04/02 First light 06/24/02

FM1

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MODIS TEB Calibration Using Blackbody

2EV 0 1 EV 2 EV SV EV SM

EV

1L a b dn a dn RVS RVS L

RVS

/21 BB BB BB SV BB SM BB BB cav cav 0 2 BB BBb RVS L RVS RVS L RVS 1 L a a dn dn

Radiance (TOA), LEV

Calibration coefficient, b1, from BB

RVS: Response Versus Scan-angle

: EmissivityL: Spectral band averaged radiancedn: Digital count with background corrected

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MODIS IR Spectral Bands, MAS FWHM

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Why are high altitude aircraft useful for Cal/Val work?

• Direct observation of integrated upwelling radiance, closely simulating on-orbit sensors.

• Uncertainty dominated by airborne instruments• Mobile laboratory. Aircraft meets the satellite at

a chosen time/place.• Covers several thousand km2 in 10 minutes (lots

of samples).

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Cloud Physics Lidar (CPL)

Scanning High ResolutionInterferometer Sounder (SHIS)

Dual RC-10 Camera

Video Imaging System (VIS)

MODIS Airborne Simulator (MAS)

NPOESS Atmospheric Sounder Testbed (NAST-I)

• MAS - 50 channel VIS/IR spectrometer, 50 m res., 36 km swath• SHIS - Scanning M/LWIR 0.5 cm-1 interferometer, 2 km res, 32 km swath• CPL – micropulse dual polarization lidar, 15 m res, nadir only• NAST-I – Scanning MWIR/LWIR interferometer, 2km res, 40 km swath • RC-10 - b/w and false color IR photo, 1-5 m res., 15 x 15 km coverage• VIS video imaging system - color video CCD camera; continuous

TX-2002 ER-2 Payload

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MODIS Emissive Band Cal/Val from theER-2 Platform

MODIS Footprint

36 km

MAS, SHISon ER-2

20 km

705 km

MODIS on Terra

1. Collect MODIS and ER-2 co-incident data

2. Transfer SHIS calibration to MAS

3. Co-locate MODIS FOV on MAS

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Terra MODIS

2000

WISC-T2000SAFARI-2000

2001

TX-2001 CLAMS

2002Aqua MODIS

TX-2002

2003 2004 2005

THORpex-2003 Tahoe-2004

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MAS and SHIS data sets collected on the NASA ER-2 aircraft have been key for directly assessing Terra and Aqua MODIS L1B accuracy.

MODIS spec. given by box

Along Track Profile

TerraMODIS11 um

04/01/01

Terra MODIS

Detector averaged

11 124 wvCO2

CO2

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The Lake Tahoe 2004 field activity evaluated Terra MODIS radiometric performance.

April 9, 20040544 UTC

Buoy Sites

MAS_SHIS Simulated MODIS BT (K)

MO

DIS

Obs

erve

d B

T (

K)

MODIS Band Number

MA

S_SH

IS -

MO

DIS

(K

)

Terra MODIS

Vertical bars represent radiometric accuracy spec.Wavelength (um)

Pred

icte

d –

Mea

sure

d B

righ

tnes

s T

empe

ratu

re (

K)

SHIS

SHIS April 9, 2004 - Night Run 09

-5

-4

-3

-2

-1

0

1

2

3

4

5

8 9 10 11 12 13

Pred

icte

d - M

easu

red

BT (K

)

tr1

tr2

tr3

tr4

average SHIS

Detector averaged

11 124 wvCO2

CO23.7um 3.9um

11um 12um

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MODIS Band Number

MO

DIS

Res

idua

l (K

) Aqua MODIS

Nov. 21, 20021941 UTC

Aqua

Nov 21, 2002MAS

B45 (11 um)

Detector averaged

Detector dependent(window bands)

TX-2002 Experiment Assess Aqua MODIS

Cal/Val Detector dependent(atmospheric bands)

11 124 wv

CO2

CO2

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Uncertainties

• SHIS calibration uncertainty

• Altitude correction

• Geolocation error (spatial mismatch)

• Temporal mismatch

• Sunglint influence

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Blackbody Geometry AERI, NAST, S-HIS, GIFTS

BLACKBODYCAVITY

HEATER

CAVITY SUPPORT(THERMAL ISOLATOR)

HANDLE

ELECTRICALCONNECTOR

CASE

THERMALINSULATION

THERMISTORS(2 SENSE, 1 CONTROL)

2.70 IN.APERTURE

Figure n-n. AERI BLACKBODY

THERMISTOR(APEX)

Aperture DiametersAERI: 2.7”S-HIS: 1.6”NAST: 1.0”

SHIS Accuracy

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SHIS Expected PerformanceTABB = 227K, THBB = 310K

SW

MW

LW

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ER-2Level MODIS B30, 9.6um (Ozone)

MODIS B33, 13.3um (CO2)MODIS B35, 13.9um (CO2)MODIS B36, 14.2um (CO2)MAS B43, 9.6um (Ozone)MAS B48, 13.2um (CO2)MAS B49, 13.8um (CO2)MAS B50, 14.3um (CO2)

Normalized Weighting Function

Atm

osph

eric

Pre

ssur

e (m

b)

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Influence of Altitude Difference between MODIS and MAS

Atmospheric absorption above the ER-2 altitude (20 km) is important for O3 and CO2 sensitive bands. O3

CO2

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Spatial Uncertainty

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Temporal Uncertainty

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Sun Glint:magnifies spatial and temporal uncertainty

in 4um region

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What Are We Learning?

• Cal/Val of MODIS L1B is viable, even necessary, from high altitude aircraft.

• MODIS meets spec in almost all bands.• Detector striping is corroborated by Cal/Val. • MODIS radiometric biases can be cautiously

applied to L2 products, e.g. CO2 cloud heights.

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Back-up Slides

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The MODIS spatial weighting function was measured in the scan and track directions during prelaunch testing using a 0.1 x 10 FOV slit stepped across the MODIS focal planes. Idealized smearing was added to the scan direction measurements to simulate the effect of the scan mirror motion.

TRACKSCAN

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APRIL 01, 2001

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November 21, 2002

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April 9, 2004