Wednesday, January 20, 2010

Overview Of The Aqua Satellite

In this post we're going to take a quick look at the main hardware components of the Aqua satellite and the people in charge of that hardware. This will be followed up with a detailed look at key components related to UAH and RSS raw data. This is being done because an understanding of the hardware is needed for a proper understanding of the data recorded by the hardware.

Atmospheric Infrared Sounder (AIRS)

The Atmospheric Infrared Sounder (AIRS), an advanced sounder containing 2378 infrared channels and four visible/near-infrared channels, aimed at obtaining highly accurate temperature profiles within the atmosphere plus a variety of additional Earth/atmosphere products. AIRS will be the highlighted instrument in the AIRS/AMSU-A/HSB triplet centered on measuring accurate temperature and humidity profiles throughout the atmosphere.

Moustafa Chahine
AIRS/AMSU/HSB Science Team Leader


Moustafa Chahine was awarded a Ph.D. in Fluid Physics from the University of California at Berkeley in 1960. He is Chief Scientist at the Jet Propulsion Laboratory (JPL), where he has been affiliated for 30 years. From 1978 to 1984, he was Manager of the Division of Earth and Space Sciences at JPL; as such, he was responsible for establishing the Division and managing the diverse activities of its 400 researchers.

For 20 years, Dr. Chahine has been directly involved in remote sensing theory and experiments. His resume reflects roles as Principal Investigator, designer and developer, and analyst in remote-sensing experiments. He developed the Physical Relaxation Method for retrieving atmospheric profiles from radiance observations. Subsequently, he formulated a multispectral approach using infrared and microwave data for remote sensing in the presence of clouds. These data analysis techniques were successfully applied in 1980 to produce the first global distribution of the Earth surface temperature using data from the HIRS/MSU sounders.

Dr. Chahine was integrally involved in the AMTS study, which laid the basis for the current AIRS spectrometer. Dr. Chahine served as a member of the NASA Earth System Sciences Committee (ESSC), which developed the program leading to EOS, and currently is Chairman of the Science Steering Group of a closely related effort, the World Meteorological Organization’s Global Energy and Water Cycle Experiment (GEWEX). Dr. Chahine is a Fellow of the American Physical Society and the British Meteorological Society. In 1969, he was awarded the NASA Medal for Exceptional Scientific Achievement and, in 1984, the NASA Outstanding Leadership Medal.

Selected Papers
Retrieval of mid-tropospheric of CO₂ directly from AIRS measurements (2009)
Application of Atmospheric Infrared Sounder (AIRS) data to climate research (2009)
Biases in total precipitable water vapor climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer (2007)
Three years of hyspersecptral data from AIRS : what have we learned. (2007)

Advanced Microwave Sounding Unit (AMSU-A)

The Advanced Microwave Sounding Unit (AMSU-A), a 15-channel microwave sounder designed primarily to obtain temperature profiles in the upper atmosphere (especially the stratosphere) and to provide a cloud-filtering capability for tropospheric temperature observations. The first AMSU was launched in May 1998 on board the National Oceanic and Atmospheric Administration's (NOAA's) NOAA 15 satellite. The EOS AMSU-A is part of a closely coupled triplet of instruments that include the AIRS and HSB.

Instrument characteristics
*) Passive multi-channel microwave radiometer measuring atmospheric temperature.
*) 15 channel microwave sounder with a frequency range of 15-90 GHz.
*) Provides atmospheric temperature measurements from the surface up to 40 km.
*) On board NOAA K/L/M as well as Aqua.

Moustafa Chahine
AIRS/AMSU/HSB Science Team Leader








Humidity Sounder for Brazil (HSB)

The Humidity Sounder for Brazil (HSB), a 4-channel microwave sounder provided by Brazil aimed at obtaining humidity profiles throughout the atmosphere. The HSB is the instrument in the AIRS/AMSU-A/HSB triplet that allows humidity measurements even under conditions of heavy cloudiness and haze. The HSB provided high quality data until February 2003.

Moustafa Chahine
AIRS/AMSU/HSB Science Team Leader








Advanced Microwave Scanning Radiometer for EOS (AMSR-E)

The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) is a twelve-channel, six-frequency, total power passive-microwave radiometer system. It measures brightness temperatures at 6.925, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz. Vertically and horizontally polarized measurements are taken at all channels. The Earth-emitted microwave radiation is collected by an offset parabolic reflector 1.6 meters in diameter that scans across the Earth along an imaginary conical surface, maintaining a constant Earth incidence angle of 55° and providing a swath width array of six feedhorns which then carry the radiation to radiometers for measurement. Calibration is accomplished with observations of cosmic background radiation and an on-board warm target. Spatial resolution of the individual measurements varies from 5.4 km at 89.0 GHz to 56 km at 6.9 GHz.

Instrument characteristics
*) Passive microwave radiometer, twelve channels, six frequencies, dual polarization, conically scanning.
*) Measures precipitation rate, cloud water, water vapor, sea surface winds, sea surface temperature, ice, snow, and soil moisture.
*) All-weather measurements of geophysical parameters supporting several global change science and monitoring efforts.
*) External cold load reflector and a warm load for calibration.
*) Offset parabolic reflector, 1.6 m in diameter, and rotating drum at 40 rpm.
*) Multiple feedhorns (6) to cover six bands from 6.9 to 89 GHz with 0.3 to 1.1 K radiometric sensitivity; vertical and horizontal polarization.

Roy Spencer
U.S. AMSR-E Science Team Leader


Dr. Spencer received his B.S. in Atmospheric Sciences from the University of Michigan in 1978 and his M.S. and Ph.D. in Meteorology from the University of Wisconsin in 1980 and 1982. He then continued at the University of Wisconsin through 1984 in the Space Science and Engineering Center as a research scientist. He joined NASA's Marshall Space Flight Center (MSFC) in 1984, where he later became Senior Scientist for Climate Studies. He resigned from NASA in 2001 and joined the Univeristy of Alabama in Huntsville as a Principal Research Scientist. Dr. Spencer has served as Pricipal Investigator on the Global Precipitation Studies with Nimbus-7 and DMSP SSM/I, and the Advanced Microwave Precipitation Radiometer High Altitude Studies of Precipitation Systems. He has been a member of several science teams: the Tropical Rainfall Measuring Mission (TRMM) Space Station Accommodations Analysis Study Team, Science Steering Group for TRMM, TOVS Pathfinder Working Group, NASA Headquarters Earth Science and Applications Advisory Subcommittee, and two National Research Council study panels.

Since 1992 Dr. Spencer has been the U.S. Team Leader for the Multichannel Imaging Microwave Radiometer (MIMR) team and the follow-on AMSR-E team. In 1994 he became the AMSR-E Science Team leader.

He received the NASA Exceptional Scientific Achievement Medal in 1991, the MSFC Center Director’s Commendation in 1989, and the American Meteorological Society’s Special Award in 1996.

Selected Papers
Satellite and Model Evidence Against Substantial Manmade Climate Change
Global Warming as a Natural Response to Cloud Changes Associated with the Pacific Decadal Oscillation (PDO)
Cloud and Radiation Budget Changes Associated with Tropical Intraseasonal Oscillations
Potential Biases in Feedback Diagnosis from Observational Data: A Simple Model Demonstration

Akira Shibata
Japanese AMSR-E Science Team Leader

Dr. Akira Shibata, co-leader of the Joint AMSR Science Team, received his B.S., M.S. and Ph.D. from Waseda University, in the Science and Engineering Department. Before moving to the Meteorological Research Institute (MRI) in 1983, he was a technical officer at the Nagasaki Marine Observatory. At MRI he worked as a research scientist. In 1996, Dr, Shibata moved to the Earth Observation Research Center as an Associate senior scientist. He also serves as the ADEOS II AMSR Science Team Leader

Moderate Resolution Imaging Spectroradiometer (MODIS)

The Moderate Resolution Imaging Spectroradiometer (MODIS), is a 36-band spectroradiometer measuring visible and infrared radiation and obtaining data that are being used to derive products ranging from vegetation, land surface cover, and ocean chlorophyll fluorescence to cloud and aerosol properties, fire occurrence, snow cover on the land, and sea ice cover on the oceans. The first MODIS instrument was launched on board the Terra satellite in December 1999, and the second was launched on Aqua in May 2002.

Instrument characteristics
*) Selected for flight on Terra (launched Dec. 1999) and Aqua.
*) Medium-resolution, multi-spectral, cross-track scanning radiometer.
*) Measures physical properties of the atmosphere, and biological and physical properties of the oceans and land.
*) 36 spectral bands—21 within 0.4-3.0 µm; 15 within 3-14.5 µm.
*) Continuous global coverage every 1 to 2 days.
*) Signal-to-noise ratios from 900 to 1300 for 1 km ocean color bands at 70° solar zenith angle.
*) NEDT's typically < 0.05 K at 300K.
8) Absolute irradiance accuracy of 5% for <3 µm and 1% for >3 µm.
*) Daylight reflection and day/night emission spectral imaging.

Michael King
MODIS Team Leader


Dr. Michael King is Senior Research Associate in the Laboratory for Atmospheric and Space Physics, University of Colorado. He served as Senior Project Scientist of NASA's Earth Observing System (EOS) from 1992 to 2008. He joined Goddard Space Flight Center in January 1978 as a physical scientist, and previously served as Project Scientist of the Earth Radiation Budget Experiment (ERBE) from 1983-1992.

His research experience includes conceiving, developing, and operating multispectral scanning radiometers from a number of aircraft platforms in field experiments ranging from arctic stratus clouds to smoke from the Kuwait oil fires and biomass burning in Brazil and southern Africa. He has lectured on global change on all seven continents.

Earlier, he developed the Cloud Absorption Radiometer for studying the absorption properties of optically thick clouds as well as the bidirectional reflectance properties of many natural surfaces, and is principal investigator of the MODIS Airborne Simulator, an imaging spectrometer that flies onboard the NASA ER-2 aircraft. This instrument has aided immeasurably in the development of atmospheric and land remote sensing algorithms for the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument.

Selected Papers
Evaluation of cirrus cloud properties derived from MODIS data using cloud properties derived from ground-based observations collected at the ARM SGP site.
Urban aerosols and their interaction with clouds and rainfall: A case study for New York and Houston.
Observed Land Impacts on Clouds, Water Vapor, and Rainfall at Continental Scales.
Remote sensing of liquid water and ice cloud optical thickness, and effective radius in the arctic: Application of airborne multispectral MAS data.

Cloud's and the Earth's Radiant Energy System (CERES)

The Cloud's and the Earth's Radiant Energy System (CERES) is a 3-channel radiometer measuring reflected solar radiation in the 0.3-5 µm wavelength band, emitted terrestrial radiation in the 8-12 µm band, and total radiation from 0.3 µm to beyond 100 µm. These data are being used to measure the Earth's total thermal radiation budget, and, in combination with MODIS data, detailed information about clouds. The first CERES instrument was launched on the Tropical Rainfall Measuring Mission (TRMM) satellite in November 1997; the second and third CERES instuments were launched on the Terra satellite in December 1999; and the fourth and fifth CERES instruments are on board the Aqua satellite.

Instrument characteristics
*) Selected for flight on TRMM, Terra, and Aqua.
*) Two broadband, scanning radiometers: One cross-track mode, one rotating azimuth plane (bi-axial scanning).
*) First instrument (cross-track scanning) is continuing ERBE, TRMM, and Terra measurements and the second (biaxially scanning) is providing angular radiance information to improve the accuracy of angular models used to derive the Earth's radiative balance.
*) Single scanner on TRMM mission (launched Nov. 1997)
*) Dual scanners on Terra (launched Dec. 1999) and Aqua, and single thereafter.

Bruce Wielicki
CERES Science Team Leader

Dr. Wielicki's research has focused on clouds and their role in the Earth's radiative energy balance for over 20 years. He currently serves as Principal-Investigator on the CERES Investigation and as a Co-Investigator on the NASA Cloudsat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) missions. Cloudsat and CALIPSO are centered on cloud studies and will fly in formation with the CERES instrument and other instruments on the Aqua platform.

Earlier, Dr. Wielicki was a Co-investigator on the Earth Radiation Budget Experiment and developed a new Maximum Likelihood Estimation (MLE) method for determination of the cloud condition in each ERBE field of view. This method enabled the development of the first estimates of cloud radiative forcing (CRF) by distinguishing individual observations as clear, partly-cloudy, mostly-cloudy, or overcast. This measurement became a standard of comparison for global climate models. The poor ability of global climate models to reproduce the ERBE cloud radiative forcing measurements was a key element in the designation of the "role of clouds and radiation" as the highest priority of the U.S. Global Change Research Program.

Dr. Wielicki was also a Principal Investigator on the First International Satellite Cloud Climatology Experiment (ISCCP) Regional Experiment (FIRE) and served as FIRE Project Scientist from 1987 to 1994. His research used Landsat satellite data to provide the first definitive validation of the accuracy of satellite derived cloud fractional coverage. More recently, he has demonstrated the surprising non-gaussian distributions of cloud optical depth present in broken boundary layer cloud fields, and has shown the large bias these distributions can cause in global climate model estimates of both solar and thermal infrared fluxes.

Throughout his career, Dr. Wielicki has pursued extensive theoretical radiative transfer studies of the effects of non-planar cloud geometry on the calculation of radiative fluxes, as well as on the retrieval of cloud properties and top of atmosphere radiative fluxes from space-based observations. Dr. Wielicki received his B.S. degree in Applied Math and Engineering Physics from the University of Wisconsin - Madison in 1974 and his Ph.D. degree in Physical Oceanography from Scripps Institution of Oceanography in 1980. He received a NASA Exceptional Scientific Achievement Award in 1992 and the Henry G. Houghton Award from the American Meteorological Society in 1995.

Selected Papers
Earth's Climate System: A 21st Century Grand Challenge
Ceres And The S'cool Project (1997)
Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment
Clouds and the Earth's Radiant Energy System (CERES): algorithm overview

References:
NASA AIRS Web Page
NASA Web Page For Dr. Moustafa Chahine
Retrieval of mid-tropospheric of CO₂ directly from AIRS measurements (2009)
Application of Atmospheric Infrared Sounder (AIRS) data to climate research (2009)
Biases in total precipitable water vapor climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer (2007)
Three years of hyspersecptral data from AIRS : what have we learned. (2007)
NASA AAMSU-A Web Page
NASA HSB Web Page
NASA AMSR-E Web Page
NASA Web Page For Dr. Roy Spencer
Dr. Spencer's Research Articles Web Page
NASA MODIS Web Page
NASA Web Page For Dr. Michael King
Evaluation of cirrus cloud properties derived from MODIS data using cloud properties derived from ground-based observations collected at the ARM SGP site.
Urban aerosols and their interaction with clouds and rainfall: A case study for New York and Houston.
Observed Land Impacts on Clouds, Water Vapor, and Rainfall at Continental Scales.
Remote sensing of liquid water and ice cloud optical thickness, and effective radius in the arctic: Application of airborne multispectral MAS data.
NASA CERES Web Page
NASA Web Page For Dr. Bruce Wielicki
Earth's Climate System: A 21st Century Grand Challenge
Ceres And The S'cool Project (1997)
Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment
Clouds and the Earth's Radiant Energy System (CERES): algorithm overview

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