IGARSS11_VC_ppt.pdf

ASTER/TIR Vicarious Calibration
Activities in the Last 11 Years

Hideyuki Tonooka (Ibaraki Univ.)
Simon Hook (Jet Propulsion Laboratory)
Tsuneo Matsunaga, Soushi Kato (National Institute for
Environmental Studies)
Elsa Abbott, Howard Tan (Jet Propulsion Laboratory)

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

ASTER
Advanced Spaceborne Thermal Emission and Reflection Radiometer

Band Spectral Spatial
Subsystem
No. Range (μm) Resolution

1 0.52 ‐ 0.60
2 0.63 ‐ 0.69
VNIR 15m
3N 0.78 ‐ 0.86
3B 0.78 ‐ 0.86
4 1.600 ‐ 1.700
5 2.145 ‐ 2.185 Developer: Ministry of Economy, Trade & Industry
6 2.185 ‐ 2.225 (METI)
SWIR 30m
7 2.235 ‐ 2.285
8 2.295 ‐ 2.365 Platform: NASA’s Terra (Launched in Dec. 1999)
9 2.360 ‐ 2.430
10 8.125 ‐ 8.475 Total scenes: Over 2 million scenes as of Jul. 2011
11 8.475 ‐ 8.825 (day: 85%, night: 15%)
TIR 12 8.925 ‐ 9.275 90m
13 10.25 ‐ 10.95
14 10.95 ‐ 11.65
Swath width = 60km

ASTER/TIR Hardware and Calibration

• Mechanical scanning of 10 MCT detectors aligned along a
track for each of 5 spectral bands
• Full‐aperture honeycombed blackbody which can change
a temperature from 270 to 340 K
• No space viewing
• Quadratic radiometric calibration equation
– Two‐temperature basis
– Offset is determined for each Earth observation
– Gain is given on a daily basis by prediction curves determined
from periodical calibration data
– Non‐linearity is based on ground testing
• Designed accuracy of 1 K for a temperature range of 270
to 340 K


Degradation Since the Launch


Vicarious Calibration for ASTER/TIR

Its purpose is to validate at‐sensor
radiances by ground experiments
without onboard calibrator data OBC

At-sensor radiance
Response functions
Radiative transfer
Radiosonde, or
TOMS Angle Numerical forecast model
Ozone MODTRAN Pressure, Air temp., Humidity
Elevation

Surface radiant temp. Surface temp. Surface emissivity

Radiance-based Temperature-based

ASTER/TIR Vicarious Calibration Sites

• USA Automated • Japan
– Lake Tahoe (CA/NV) – Lake Kasumigaura
– Salton Sea (CA) – Lake Kussharo
– Cold Springs Reservoir (NV)
– Alkali Lake (NV)
– Railroad Valley (NV) (Blue) Water Sites (Red) Land Sites
– Lunar Lake (NV)
– Coyote Lake (CA)
– Mauna Loa (HI)


JPL’s Semi‐Automated Validation System

• Lake Tahoe (1999–), and Salton Sea (2008–)
• Skin and bulk water temperatures, and ground meteorological data
are logged and transferred to laboratory
• Atmospheric profiles (water vapor, air temp. etc.) are obtained from
NCEP’s Global Data Assimilation System (GDAS) products
Air temperature Wind Speed
& Rel. Humidity & Direction

Skin temperature Logging
System

Batteries
Bulk Water
Temperature

ASTL1A 1005201850471005230324 3m


Typical Experimental System for Land Sites

Multi‐band radiometer

radiosonde

Weather station
Single‐band radiometer

Portable blackbody

Other instruments: FTIR, thermal camera, etc.

Typical Experimental System for Water Sites

radiosonde

Single‐band radiometer

Multi‐band radiometer

Thermistor buoys
Other instruments: Weather station, Thermal Camera, etc. IGARSS 2011, July 24‐29, 2011, Vancouver, Canada

Browse Images for VC Sites

Lake Tahoe Salton Sea Railroad Valley Lake Kasumigaura Lake Kussharo
& Cold Springs Res.

Alkali Lake Lunar Lake Coyote Lake Mauna Loa
& Railroad Valley

Comparisons of brightness temperature (BT)
between OBC and VC using 287 matchup data

Typically, OBC and VC agree
within ±1 K for the water sites
and within ±1.5 K for the dry
lake sites.
ASTER/TIR onboard calibrator
has kept the expected accuracy
in the wide temperature range
(−10 to 45 C) since the launch.


BT difference between VC and OBC as a
function of time

IU: Ibaraki University
NIES: National Institute for Environmental Studies
JPL: Jet Propulsion Laboratory


BT difference between VC and OBC for each
experimental site

Straylight effect

LT: Lake Tahoe, SS: Salton Sea, CS: Cold Springs Reservoir, LK: Lake Kasumigaura,
KS: Lake Kussharo, AL: Alkali Lake, RV: Railroad Valley Playa, LL: Lunar Lake,
CL: Coyote Lake, ML: Mauna Loa

Cold Springs Reservoir (NV)

• Smallest VC site (1.6 km by 800 m)
• Not good site for vicarious calibration due to straylight
effect [1]
[1] H. Tonooka, Inflight straylight analysis for ASTER thermal infrared bands,
IEEE TGARS, Vol. 43, pp. 2752‐2762, 2005.


experimental site

Below 270 K
(Less accuracy)
Straylight effect
C


Lake Kussharo (Japan)

• Coldest VC site (below 270K)
• ASTER’s designed accuracy is 2K for this
temperature range


experimental site

Below 270 K
(Less accuracy)
Straylight effect
C

Large spatial C
variation


Mauna Loa (HI)

• Pahoehoe lava flow
• Not good for VC due to large spatial variation


function of the precipitable water vapor

BT difference seems to be almost independent of PWV, indicating that the
radiative transfer calculations were successfully made using accurate profiles

function of the OBC BT

The difference seems to be positive in the lower temperature range, and
be negative in the higher temperature range

Conclusions

• VC activities for ASTER/TIR have been continued by
the ASTER science team since March 2000.
• 287 matchup data obtained by three organizations
were analyzed
– Some results indicate large BT differences due to straylight,
low temperature, and large spatial variation effects
– No correlation between BT difference and PWV indicates
that atmospheric profiles were successfully characterized
even under humid conditions
– BT difference (VC–OBC) shows somewhat positive for low
temperatures and negative for high temperatures
– Overall, OBC has been keeping the designed accuracy (1 K
for the temperature range of 270 to 340 K)

IGARSS11_VC_ppt.pdf

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