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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
product), which will provide more information of vegetation for
BJ-1 microsatellite data applications(Chen Zhengchao 2006).
In the past ten years, various medium resolution sensors have
been launched. Several land products derived from these
sensors, or will be soon available to the user community at both
regional and global scales. Table 1.(Marie Weiss 2007).For
almost 25 years, the Earth surface has been monitored at
medium to coarse resolution (not better than 1 km 2 * 1 pixels)
thanks to the series of NOAA/AVHRR sensors. More recently,
new sensors have been launched with improved spectral (e.g.
SEAWIFS/VEGETATION/MODIS/MERIS) or directional (e.g.
POLDER/MISR) sampling, and higher spatial resolution e.g.
MERIS/MODIS).
Reference
Project
Sensor
LAI
URL
Knyazikhin et al.(l998)
NASA/MODIS
MODIS
2000-now
http://cliveg.bu.edu/modismisr/laifpar/laifpar.html
Roujean and Lacaze
CNES/POLDER
POLDE
1996-1997
http://polder.cnes.fr/
(2002)
R
2003
Chen et al. (2002)
AVHRR
1993-2002
Bacour et al. (2006)
ESA/MERIS
MERIS
2002-now
http://www.brockmann-consult.de/beam/plugins.html
Baret et al. (2007)
FP5/CYCLOPES
VGT
1998-2003
http://postel.mediasfrance.org/
Plummer et al. (2006)
ESA/GLOBCAR
VGT
1998-2003
http://geofront.vgt.vito.be/geosuccess/
BON
ATSR
MERIS
1998-2003
http://geofront.vgt.vito.be/geosuccess/
ATSR
1998-2003
MERIS
1998-2003
VGT
1998-2003
The eight-day composites of the LAI/Fapar products
(MOD15A2) version 4 pertaining to study sites were
downloaded from the LP-DAAC Internet site. The MODIS
LAI/Fapar product is produced at the 1-km spatial resolution
daily(MOD15Al) and composited over an eight-day period,
where the selected value in a compositing period is that with
the highest corresponding Fapar. The products are projected on
the integerized sinusoidal and sinusoidal 1 Oo grid, respectively.
CYCLOPES products derived from VEGETATION sensors are
available freely at the following web site:
http://postel.mediasfrance.org/. The period 1998-2003 is
currently available. Products are organized by tiles of 10°zenith
and 10°azimuth. For effective use in such large-scale models,
regional and global LAI must be available over a period of time.
Field measurements of LAI, however, are cumbersome, time
consuming, and impossible to obtain at the global scale. But
satellite remote sensing is the most effective means of
estimating LAI global fields on a regular basis(Pandya 2006).
In this paper, the main object is to study on the method of the
leaf area index inversion for producing BJ-1 LAI product.
Based on the field measured data and computer simulation
model simulated data, we can estimated the LAI of Beijing-1
images. Then according to the Beijing-1 LAI estimation, the
second object of this paper is to generate of high spatial and
high temporal resolution LAI product. A method is proposed to
get high spatial and temporal resolution LAI product by fusing
the time-series MODIS LAI product(l km, 8-day product)and
Beijing-1 LAI images.
2 MATERIAL AND METHOD
This section describes: 1) spectral and structure datasets of
vegetations; 2) satellite data used in the study; 3) the generation
of of Beijing-1 LAI maps; and 4) remote sensing data analysis
and generation of LAI maps.
2.1 Material
imaging are 16 March, 06; 14 May, 06 and 17 June, 06
respectively. In order to get the time serial LAI variation,
MODIS products (MOD15A2 and MOD12Q1) are used. Next
we will introduce these data in detail.
Description
Site: Beijing
Field experiment Sites
Shun Yi, Beijing,China
Location
Luan Cheng, Heibei
Date of BJ-1 acquisition
province, China
16 March, 06
14 May, 06
Date of MODIS LAI
17 June, 06
1 Jan 06- 31 Dec,06
8-day product
MODIS Tile number
H26V4, H26V5,
MODIS Land cover product
H27V5, H27V5.
MOD 120,2004
BJ-1 multi-spectral image has green, red, NIR bands
(spatial resolution: 32m).
Tabled LAI Sites and details of satellite data/product
acquisition used in the study.
2.1.1. spectral and structure datasets of vegetations
1) Field Sites and Experimental Measured data:
In the “Spectral Database System of Typical Objects in China”
supported by 863 program, we have collected spectrums of
typical objects and their corresponding parameters for about 20
years. In the database, there are more than 20,000 of the
spectral data about vegetation, such as winter wheat, maize,
rice, cotton and rapeseed, and also their corresponding growth
structure parameters, the land use and land cover type in the
experimental sites, crop phenology and farming methods(Wang
Jindi 2004).
(a) Winter wheat data: winter wheat spectrum data and their
parameters, LAI, LAD and so on in Shun Yi, Beijing in China
in 2001,2003 and 2004;
(B) Maize data: maize spectrum data and their parameters LAI,
LAD and so on in Luancheng, Heibei province in China in
Table.l lists the all data used in this study. The field
experiment sites are Shun Yi, Beijing,China and Luan Cheng,
Heibei province, China. And the dates of Beijing-1 images