Keywords : NOAA/AVHRR, SeaWiFS, MODIS, Landsat-7/ETM+, Regional Monitoring.
Abstract Hiroshima Institute of Technology (HIT) has established the ground receiving station that has capabilities to capture and process the x-band down link data from earth observation satellite. This study deals with the construction of satellite image data set used to map the environmental information using several kinds of data from NOAA/AVHRR, SEASTAR/SeaWiFS, TERRA/MODIS, Landsat-7/ETM+, SPOT-1,2/HRV and SPOT-4/HRVIR captured in HIT ground station. This satellite image data set is constructed for the purpose of environmental information mapping from the wide area to the local area scale using the different spatial and spectral resolutions such as multispectral and hyperspectral sensor data. In this paper, some preliminary results are presented to demonstrate the capability for land and sea environmental monitoring using the data set produced by the initial operation of HIT ground station.
1. Introduction
Since 1980's NOAA/AVHRR data have been widely used for monitoring of earth environment in global scale. For regional scale, AVHRR sensor still has been only one practical data source to be used to monitor land and sea environment, such as the distributions/conditions of vegetation, sea surface temperature (SST) and to monitor disaster phenomena such as forest fire or volcano eruption. On the other hand for local scale, Landsat-5/TM and SPOT/HRV have been main data sources for land cover mapping, land cover change detection, and disaster monitoring etc. Nowadays, some new sensors are going to be available in global and regional scale, i.e. SEASTAR/SeaWiFS and TERRA/MODIS. The spatial resolution of these sensors are moderate and compatible to that of AVHRR, however, the number of spectral band is significantly increased, especially for MODIS sensor. By these new sensors, the spectral information is significantly enhanced compared with that by conventional AVHRR sensor and therefore, they are highly expected to extract more plentiful and accurate environmental information in global or regional scale.
Recently Hiroshima Institute of Technology (HIT) has established the ground receiving station that has capabilities to capture and process the x-band down link data from various earth observation satellites, SeaWiFS, MODIS, Landsat-7/ETM+, and SPOT-1,2/HRV and SPOT-4/HRVIR. In this paper, we report the present status for receiving and processing of these satellite data and some preliminary results by data analysis of these satellite data to evaluate their capabilities for monitoring land and sea environment.
2. Sensor Specifications and Possible Sensor Combinations
The sensor specifications for AVHRR, SeaWiFS, MODIS and ETM+ are summarized in Table 1 to 4. As the wavelength characteristics of SeaWiFS and MODIS, it is pointed out that bandwidths are generally narrower than those of AVHRR and ETM+ as well as that number of band is much bigger. For example,
the band-1 of AVHRR corresponds to the band-6 of SeaWiFS as a wavelength region. However, the bandwidth for AVHRR is 0.1 µm, while that for SeaWiFS is 0.02 µm and five times narrower than AVHRR because the band-6 of SeaWiFS is designed to extract spectral signatures caused by absorption by chlorophyll. Therefore, the conventional vegetation index parameter like NDVI is still expected to be improved by replacing AVHRR band-1 with SeaWiFS band-6.
Table 1. Specification of NOAA-14,15/AVHRR.
| Band No. |
Wavelength Region(µm) |
Spatial Resolution |
1
2
3
4
5 |
0.58 - 0.68
0.725 - 1.1
3.55 - 3.93
or 1.58 - 1.64 (N-15 only)
10.3 - 11.3
11.5 - 12.5 |
1.1 Km
1.1 Km
1.1 Km
1.1 Km
1.1 Km |
Table 2. Specification of SEASTAR/SeaWiFS.
| Band No. |
Wavelength Region(µm) |
Spatial Resolution |
1
2
3
4
5
6
7
8 |
0.402 - 0.422
0.433 - 0.453
0.480 - 0.500
0.500 - 0.520
0.545 - 0.565
0.660 - 0.680
0.745 - 0.785
0.845 - 0.885 |
1.1 Km
1.1 Km
1.1 Km
1.1 Km
1.1 Km
1.1 Km
1.1 Km
1.1 Km |
Table 3. Specification of TERRA/MODIS.
| Band No. |
Wavelength Region(µm) |
Spatial Resolution |
1
2 |
0.620 -0.670
0.841 - 0.876 |
250 m
250 m |
3
4
5
6
7 |
0.459 - 0.479
0.545 - 0.565
1.230 -1.250
1.628 - 1.652
2.105 - 2.155 |
500 m
500 m
500 m
500 m
500 m |
8
9
10
11
12
13
14
15
16
17
18
19
26 |
0.405 -0.420
0.438 - 0.448
0.483 - 0.493
0.526 - 0.536
0.546 - 0.556
0.662 - 0.672
0.673 - 0.683
0.743 - 0.753
0.862 - 0.877
0.890 - 0.920
0.931 - 0.941
0.915 - 0.965
1.360 - 1.390 |
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km |
20
21
22
23
24
25
27
28
29
30
31
32
33
34
35
36 |
3.660 - 3.840
3.929 - 3.989
3.929 - 3.989*
4.020 - 4.080
4.433 - 4.498
4.482 - 4.549
6.535 - 6.895
7.175 - 7.475
8.400 - 8.700
9.580 - 9.880
10.780 -11.280
11.770 - 12.270
13.185 - 13.485
13.485 - 13.785
13.785 - 14.085
14.085 -14.385 |
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km
1 Km |
* Saturation level is smaller than previous band.
Table 4. Specification of Landsat-7/ETM+.
| Band No. |
Wavelength Region(µm) |
Spatial Resolution |
1
2
3
4
5
6
7
8 |
0.45 - 0.52
0.53 - 0.61
0.63 - 0.69
0.78 - 0.90
1.55 - 1.75
10.4 - 12.5
2.09 - 2.35
0.52 - 0.90 |
30 m
30 m
30 m
30 m
30 m
60 m
30 m
15 m |
Among the four sensors listed in Table-1 to 4, ETM+ is special due to its much higher resolution and narrower swath, which has been used mainly for monitoring local areas. However, as the first seven bands of MODIS almost corresponds to the wavelength regions by ETM+, there might be some possibility to use both sensor data as the complement data in spatial resolution and swath. For example, the up-scaling of land cover information using Landsat-5/TM and NOAA/AVHRR was attempted (i.e. Takeuchi and Inanaga, 2000) and proved to be effective for monitoring wide areas more accurately even if both spectral information is not compatible each other. Therefore, up-scaling using TM/ETM+ and MODIS band-1 to 7 is expected to bring more accurate monitoring capability by the combined utilization of multiple sensor data.
SeaWiFS is originally designed to extract some physical parameters for oceanic applications, like water quality and chlorophyll content using visible band information. Therefore, one of the standard ways for sensor combinations will be the combined use of visible bands from SeaWiFS with the thermal bands from AVHRR, the former brings water quality and chlorophyll content and the latter sea surface temperature (SST). In addition, due to its capability for non-saturated observation of land areas, the similar combination might be effective for land environmental monitoring. For example, NDVI by SeaWiFS might be better than that by AVHRR as described previously, or, the enhanced vegetation index (EVI) is possibly extracted from band-1/2, 6, and 8 of SeaWiFS, while it is impossible by AVHRR data. The latter approach is also possible for MODIS band-1 to 3 (Justice et al, 2000 and Huete et al, 2000). These multiple sensor combinations are expected to enable to achieve more accurate land environmental monitoring in regional scale.
