Summary of Terra and Aqua MODIS Summary of Terra and Aqua MODIS Long-term PerformanceLong-term Performance

Jack Xiong1, Brian Wenny2, Sri Madhaven2, Amit Angal3,

William Barnes4, and Vincent Salomonson5

1. NASA /GSFC; 2. Sigma Space Corp; 3. SSAI; 4. UMBC; 5. U. of Utah

Other Contributors: Members of MCST

IGARSS 2011, July 24-29, 2011, Vancouver, Canada

EOS

• MODIS– Terra and Aqua

• On-orbit Operation and Calibration Activities

• On-orbit Performance– Instrument, Focal Plane Assembly (FPA)

– On-board Calibrators (OBC)

– Radiometric, Spectral, Spatial, and Geometric

• Summary

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Outline

Aqua

Terra Terra: over 11 years of successful operationAqua: over 9 years of successful operation

MODIS observations:

36 spectral bands: 0.41 to

14.5 m (VIS to LWIR)

3 spatial resolutions: 0.25,

0.5, and 1 km

Nearly 40 data products for

land, ocean, and atmospheric

applications

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Terra and Aqua MODIS

• Terra MODIS– A-side: launch to Oct 30, 2000– B-side: Oct 30, 2000 to June 15, 2001– A-side: July 02, 2001 to Sept 17, 2002– A-side electronics & B-side formatter: Sept 17, 2002 to

present– BB temperatures set at 290K– Cold FPA controlled at 83K

• Aqua MODIS – B-side: launch to present– BB temperatures set at 285K– Cold FPA controlled at 83K

On-orbit Operation and Calibration Activities

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No changes to instrument operational configurations in recent years

On-orbit Calibration Activities

SDSM

Scan Mirror

SolarDiffuser

SRCA

Blackbody

SpaceView

SD/SDSM:Weekly to tri-

weekly

SRCA:Radiometric:

monthlySpatial: bi-

monthlySpectral: quarterly

Moon: monthly (nighttime orbits)0-20o spacecraft roll maneuvers55o phase angle

BB: quarterly WUCDSpacecraft maneuvers:

Yaw (SD BRF, VF)Roll (Moon)Pitch (only applied to

Terra) Page 5

On-orbit Calibration Activities

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SD / SDSM

MOONBB

WUCDSRCA RAD

SRCA SPEC

SRCA SPAT

Terra 325 103 76 135 48 63

Aqua 216 83 39 107 27 45

Frequencies to operate on-board calibrators are gradually reduced for both Terra and Aqua MODIS as a result of their extended missions

Spacecraft Maneuvers:Yaw (SD BRF, VF), Roll (Moon), Pitch (only applied to Terra)

Ground Calibration Targets:Dome C and Desert Sites

As of June 30, 2011

• Temperatures (Instrument and FPA)

• On-board Calibrators (BB and SD)

• Radiometric

• Spectral

• Spatial

• Geometric

Performance

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Instrument Temperatures

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3.5 K increase over 11 years 2.0 K increase over 9 years

T-MODIS A-MODIS

Similar trends for warm FPA, scan cavity, and mirror temperatures

VIS, NIR

T-MODIS A-MODIS

VIS, NIR

Cold FPA Temperatures

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T-MODIS A-MODISSMIR, LWIR SMIR, LWIR

Short-term: granule averaged

Extremely stable

Short-term: granule averaged

Less stable (recent loss of cooler margin)

Blackbody Temperatures (nominal operation)

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B-Side

Short-term: granule averaged Short-term: granule averaged

< 30 mK increase over 11 yr

T-MODIS A-MODIS

Extremely stable

Aqua MODIS BB performance is extremely stable (long- and short-term)

Solar Diffuser (SD) Degradation

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Larger degradation at shorter ; More SD degradation in Terra MODIS

Increased SD degradation due to SD door fixed at “open” position

SD degradation as a function of wavelength

T-MODIS A-MODIS

SD degradation (mission-long trend)

Gradually reduced SD calibration frequency as mission continues

On-orbit Changes in RSB (VIS, NIR, and SWIR) Responses

Page 12Wavelength, angle of incidence (AOI), and mirror side dependent

On-orbit Changes in TEB (MWIR and LWIR) Responses

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Excluding changes due to use of different operational configurations, changes in TEB responses are relatively small (compared to RSB); PV bands (20-25 and 27-30) are more stable than PC bands (31-36)

Detector Characterization

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• 36 spectral bands: 490 individual detectors– Terra MODIS

– 45 noisy detectors (30 from pre-launch; 35 at launch)

– No inoperable detectors

– Aqua MODIS

– 6 noisy detectors (2 from pre-launch; 3 at launch)

– 15 inoperable detectors (13 in band 6 and most since pre-launch and/or at launch)

– There are no new noisy and inoperable detectors in recent years

On-orbit Changes in Spectral Band CW and BW

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Aqua MODIS on-orbit changes in both CW and BW are less than 0.5 nm for most VIS/NIR spectral bands

Terra MODIS VIS and NIR spectral bands

Changes in center wavelength (CW) are less than 0.5 nm for most VIS/NIR

Changes in bandwidth (BW) are less than 1.0 nm for most VIS/NIR

On-orbit Changes in Band-to-Band Registration (BBR)

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Large BBR offsets in A-MODIS between cold FPA and warm FPA band pairs

(a known problem since pre-launch); offsets remain stable

Terra MODIS along-scan BBR

Terra MODIS along-track BBR

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Robert Wolfe et al. T-MODIS track RMS: 43/42m (C5/C6); scan RMS: 44/42m (C5/C6)A-MODIS track RMS: 47/45m (C5/C6); scan RMS: 53/51m (C5/C6); and small N/S hemispherical differences

Terra MODIS Geolocation Results

• Both instruments continue to operate normally

– Stable instrument and warm FPA temperatures

– CFPA temperatures stably controlled at 83K for Terra MODIS; small and slow increase (up to 0.30K) for Aqua MODIS CFPA temperatures

• All on-board calibrators continue to provide key design functions

– BB temperatures remain extremely stable for both Terra and Aqua MODIS, short- and long-term

– Terra MODIS SD degradation is much larger than Aqua MODIS

• Radiometric

– Changes in responses are tracked and corrected in L1B calibration; other effect could exist due to large changes in VIS responses

• Spectral and Spatial

– Stable performance for both Terra and Aqua

– No change to large BBR offsets in Aqua MODIS for band pairs between CFPA and WFPA (a known problem since pre-launch)

Summary

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• Large changes in VIS spectral band/detector response

• Large SD degradation at short wavelengths, especially in Terra MODIS

• Aqua MODIS CFPA temperature stability (decrease of cooler margin)

• Calibration consistency between Terra and Aqua MODIS (scene dependent differences: offsets and trends)

• MODIS lessons and experience for future missions

Challenges

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EOS

MODIS Specifications and Applications

– 20 reflective solar bands (RSB: bands 1-19, and 26) from 0.41 - 2.2m– 16 thermal emissive bands (TEB: bands 20-25, 27-36) from 3.5 - 14.4m Page 20