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Oceanography/Meteorology
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Estimating Atmospheric Turbidity from SPOT and GMS-5 Data
Figure 2. The contours of AOD (x 0.1) estimated from SPOT data on 31 Aug, 1994.
2.AOD retrieved from GMS-5 data
The GMS-5 visible data, 01Z 27 June, 1998, was used to retrieve AOD . The reference AOD is obtained by Ce-318 sumphotometer ground measurements during the images observation. Good result of AOD retrieved from GMS-5 visible band (550 ~900 mm) in Chung-Li area is 0.230 when compared with the ground measurement, 0.225. The retrieved AOD of whole image is illuminated in figure 3. At also showed that a reasonable distribution of AOD around Taiwan area which the AOD near cities area are larger than oceanic or mountain area.
Figure 3. the distribution of AOD estimated from GMS-5 data on 01Z 27 Jun, 1998.
3. The relationship between AOD and S.S.
The sunphotometer observation is located on the National Central University, Chung-Li, Taiwan to observe AOD, and the S.S. data is provided from the Environmental Protection Agency (EPA) of Taiwan measured at EPA Chung-Li station. The relationship between these two ground observations is showed in figure 4. It seems no correlation can be found between these two measurements from the figure 4. It may be caused by the sunphotometer observation mode. The measurement of sunphotometer includes the total column AOD of atmosphere, but the measurement of S.S. may be just near ground surface. So, when the boundary of ground layer is increased , the measurements of S.S. on the ground will be decreased. But the total quantity of S.S. in the atmosphere does not change. So, the thickness variation of boundary layer and ground observation range should be considered further to find the relationship between AOD and S.S. Also, it needs long-term data for advanced analysis.
Figure 4. The relationship between AOD and S.S.
Discussions
The results of applying SPOT and GMS-5 data to estimate the local AOD shows high practical. Once the relationship between AOD and S.S. is established, the satellite observation can be applied to monitor the air pollution efficiently. So, to construct the relationship between AOD and S.S. is most important thing for monitoring air pollution satellite observation in the future research.
Reference
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Retrieval over Land from AVHRR Data-Application for Atmospheric Correction. IEEE Trans. on Geoscience and Remote Sensing, Vol. 30, NO. 2 pp. 212-222.
- Liu G.R, T.H. Lin, and A.J. Chen, 1997: An Improved Method to Determine Aerosol Optical Depth from SPOT Data. COAA '97-First International Ocean-Atmosphere Conference, 19-19 Oct 1997, Washington, D.C., USA.
- Liu C.H, A.J. Chen, and g.R. Liu, 1996: An Image-based Retrieval Algorithm of aerosol Characteristics and Surface Reflectance for Satellite Images. INT. J. Remote Sensing, Vol. 17, No. 17, 3477-3500.
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