1. CURRENT STATUS OF ADEOS SCIENCE PROGRAM
Haruhisa Shimoda
ADEOS Program Scientist
Earth Observation Research and application Center, Japan Space Exploration Agency
Unfortunately, ADEOS has stopped its operation on 30, June, 1997. However,
about 8 to 9 months of data from ADEOS already exist, and it is possible to
achieve main goals of ADEOS science program except annual variation and long
term trend analyses. Here, current status of ADEOS science program of JAXA
will be described.
1.1 Development of Algorithms
(1) Algorithms for Standard Products
Standard products are those products routinely prepared by the EOC. Under
the ADEOS Science Program, algorithms for Level 2 and higher products among
standard products are developed and validated. The standard products
subject to algorithm development are as follows.
- Chlorophyll-a, Pigment concentration (OCTS)
- SST (OCTS)
- Vegetation index (OCTS)
All the algorithms are implemented in the EOC processing facility, and the
validation efforts are continued. Now, version 2 algorithm is used for
Chlorophyll-a and SST, and version 3 algorithm will be adopted from this
October. If there exists better algorithms, the new algorithm will be
implemented next year after comparison with the existing algorithm.
(2) Algorithms for ADEOS AO Sensors
The EORC conducts experimental algorithm development for AO sensors in
regard to the following items.
- Total ozone; SO2 (TOMS)
- Particle size distribution/refractive index of aerosols (POLDER)
TOMS algorithm is already implemented to the EORC system, and it is under
evaluation process.
(3) Higher Level ADEOS Datasets
The planned higher level data sets using ADEOS data and the timing of
preparation are listed below.
a. Carbon cycle
- Land cover data set OCTS 97
b. Energy cycle
- SST OCTS, IMG 97
- Air-sea interaction OCTS, NSCAT, IMG 98
- Sea surface aerosols OCTS, POLDER 97/98
c. Stratospheric ozone depletion
- Total ozone TOMS/IMG, ILAS 97
- Three dimensional ozone distribution
ILAS/IMG, TOMS 98
d. Digital Elevation Model retrieval
- DEM AVNIR (in some areas) 97
1.2 CAL/VAL of Sensors and Products
(1) Basic CAL/VAL
Calibrations of sensors can be divided into following 3 categories. They
are 1) ground based calibration, 2) on-board calibration and 3) vicarious
calibration. Ground based calibrations are conducted using data from ground
test before launch. These calibration data are the base of ground processing
system, but they cannot correspond to the changes of sensor performance
after launch.
On-board calibrations are done based on the data from on-board calibration
source. However, any sufficient on-board calibration source has not been
established except TOMS case.
Vicarious calibrations are conducted based on the data collected from the
ground measurements at the time of satellite overpass. This method still
has some ambiguities for the accuracy of ground measurements and radiative
transfer codes.
Anyway, all the types of calibrations have been tried for ADEOS case.
Validations are done by the comparison between satellite-derived products
and in-situ measurements. The accuracy and credibility of validations
mainly depend on the accuracy and quantity of in-situ measurements.
The CAL/VAL of JAXA sensors are being conducted with the aid of aircraft
under-flights, vicarious calibrations, and in-situ data obtained from many
sources, i.e. existing database, PI activities, joint research efforts,
field campaigns, etc. Calibration coefficients from AVIRIS underflights for
OCTS and AVNIR and calibration coefficients from vicarious calibration for
OCTS will be established until the end of October.
(2) Field Campaigns
The JAXA is expected to conduct the following field campaigns, etc., mainly
to support CAL/VAL activities. These field campaigns include the in-situ
observation by airplane and radiosonde, etc.
1) Independent Field Campaign by JAXA
Two under-flights using AVIRIS on board NASA ER-2 with the help of NASA/JPL
was conducted over California area. The first one was done on October 1996
over desert area, i.e. Edwards Air Force Base and Ivanpah Playa, for AVNIR
calibration. The second flight was done on May 1997 off the coast of
California for OCTS calibration.
2) Joint Field Campaign
Two joint field campaigns were held. The first one was held over Alaska for
atmosphere and cryosphere on April to May 1997. For atmospheric campaign,
many field measurements were made such that two large balloon flights with
several sensors on board, many ozone sonde flights, laser heterodyne
measurements from ground, etc. For cryosphere, lake ice measurements and
radiation measurements were conducted over Barrow area.
The second campaign was done for oceanic studies off the Sanriku coast area
from April to June 1997. Around eight research vessels attended this
campaign.
1.3 Better Understanding of Global Environmental Phenomena Using ADEOS Data
The prospective research fields using the datasets described above are as
follows.
(1) Atmosphere
- Understanding of ozone destruction mechanism of Antarctic ozone hole
- Understanding of ozone depletion dynamics over Arctic area in 1997 Spring
- Observation of 3 dimensional global ozone distribution, especially the
distribution of tropospheric ozone
- Observation of vertical profile of temperature and water vapor,
especially over the ocean and upper troposphere
- Observation of global distribution of green house gases
- Observation of global aerosol distribution
- Observation of global clouds including cirrus clouds
- Understanding of earth radiation
(2) Ocean
- High accuracy and high frequency observation of global sea surface wind
vector
- Detailed description of sea surface wind fluctuation and understanding of
physical process
- Observation of global phyto-plankton distribution and understanding of
its dynamics
- Observation of sea water flux in coastal zone
- Observation of global ocean primary production and understanding of its
dynamics
- Understanding of air sea interaction, especially energy flux
(3) Land and Cryosphere
- Generation of land cover and vegetation global map
- Observation of global land albedo
- High accuracy observation of sea ice dynamics
- High frequency observation of continental snow cover
1.4 ADEOS Symposium/Workshop
The next ADEOS symposium/workshop will be held from 26 to 30 January, 1998 at
Sendai Japan. In the plenary sessions, ADEOS sensor characteristics and
several scientific results (invited papers) will be presented.
Earth Observation Research Center