Environmental Engineering Reference
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are essential for more reliable climate change detection and analysis (NSC
2004
;
Cao et al.
2008
; Hao and Qu
2008
). Although satellite remote sensing has become
the primary approach for Earth observation, each spaceborne sensor has limited life
cycle; integration of remote-sensing measurements from multiple missions is
necessary for constructing consistent long-term Climate Data Records. Differences
in spectral responses and spatial specifications of sensors from different missions,
as well as variations in calibration and retrieval algorithms, make it challenging to
generate long-term consistent CDRs, especially the Fundamental Climate Data
Records (FCDRs), i.e., calibrated radiance at top of atmosphere (TOA), which
are fundamental for producing Thematic Climate Data Records (TCDRs) with
consistent algorithms.
As global temperature change has been the focus of climate change study, it is
important to integrate long-term remote-sensing measurements of thermal emissive
channels and construct thermal emissive Climate Data Records. Major milestone
for operational observation of surface temperature is the launch of the satellite
TIROS-N in 1978, with the Advanced Very High Resolution Radiometer
(AVHRR). From then on, AVHRR has become the primary sensor onboard the
NOAA polar-orbiting satellites. AVHRR is a radiometer with four to six channels
and daily global coverage at the spatial resolution of 1.1 km (AVHRR/1 had four
channels, AVHRR/2 had five channels, and the latest version of AVHRR, i.e.,
AVHRR/3, has six channels). AVHRR data have been collected and archived
continuously and have become of the most important datasets for global change
study. From 1999, the National Aeronautics and Space Administration (NASA)
launched EOS series of satellites for global observation. The Moderate Resolution
Imaging Spectroradiometer (MODIS) is a key instrument aboard the Terra and
Aqua satellites of NASA EOS mission. Terra MODIS and Aqua MODIS can cover
the entire Earth's surface every 1-2 days, acquiring data in 36 spectral bands
ranging in wavelength from 0.4 to 14.4
m (Salomonson et al.
2006
). MODIS
provides the capability to improve our understanding of global dynamics and
processes occurring on the land, ocean, and atmosphere (Justice et al.
1998
;
Salomonson et al.
2006
). MODIS satellite data products have been widely used
for global and regional applications for environment monitoring, natural hazards
detection, weather forecasting, and climate change study (Salomonson et al.
2006
).
AVHRR and MODIS have been the primary sensors for global surface tempera-
ture observation. In near future, the Visible Infrared Imager Radiometer Suite
(VIIRS) of the NPP/JPSS mission will be the next-generation operational sensor
replacing AVHRR and MODIS. Inter-sensor comparison and analysis has to be
conducted to construct Climate Data Records across multiple Earth observation
missions. Figure
5.1
illustrates the temporal coverage of AVHRR and MODIS.
Figure
5.2
illustrates the spectral response functions of the 11- and 12-
μ
m channels
of AVHRR onboard some NOAA satellites and MODIS onboard the Aqua satellite.
For each band, although the central wavelengths are similar among different
AVHRR versions, differences in spectral response are significant. So, even data
products from different versions of AVHRR cannot be simply put together to
construct long-term CDRs. The bias and error bound of data products from these
sensors has to be identified. MODIS and VIIRS have spectral bands close to
μ
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