2004
THE CORRELATION BETWEEN NDVI VALUE AND SURFACE TEMPERATURE
MEASURED BY ASTER
K. Takemata* *, Y. Kawata®, N. Naoe“
? Div. of Practical Engineering Education, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501,
Japan - takemata@neptune.kanazawa-it.ac.jp
® Dept. of Media Informatics, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501,
| Japan - kawata@infor.kanazawa-it.ac.jp
€ Dept. of Electrical and Computer Engineering ,Kanazawa Technical College, Kanazawa, Ishikawa 921-8601,
Japan - naoe@kanazawa-tc.ac.jp
Commission VII, WG VII/4
KEY WORDS: Atmospheric correction, Land cover, Vegetation, Temperature, Correlation
ABSTRACT:
The thermal environment in urban areas is characterized by the heat island phenomenon. To estimate the thermal conditions of land
surfaces by satellite, it is necessary to find the relationship between the surface temperature and land cover type. The most widely
used vegetation index for ecological application is the Normalized Difference Vegetation Index (NDVI). We studied the correlation
between NDVI values and the surface temperature in our study area. NDVI uses radiance values or apparent reflectance values of
the red and the near-infrared spectral bands. These reflectance values are influenced by the atmospheric aerosols. In order to
caleulate accurate NDVI values (aerosol-free NDVI), we first estimated the surface reflectance at visible bands by using our
atmosphere-ground surface system based on the aerosol observation data. At the test site, we measured the aerosol optical thickness
of visible bands using a sky radiometer, and we measured the air temperature and humidity by using a thermometer-hygrometer with
a data logger. In this paper, we show the variations of aerosol optical thickness in the spring and summer and demonstrate the
oc
correlation between the surface temperatures of ASTER level 2B products and our observed screen temperatures.
1. INTRODUCTION optical thickness in the spring and summer and demonstrate the
correlation between the ASTER surface temperatures (ASTER
The thermal environment in urban areas is characterized by the level 2B products) and our observed screen temperatures.
heat island phenomenon. In the summer, the temperature of
urban areas rises in comparison with the surrounding rural areas. | | |
To estimate the thermal condition of land surfaces by satellite, |
it is necessary to find the relationship between the surface pet
temperature and land cover type.
ASTER spectral bands are separated into three sub-systems:
visible and near-infrared radiometer (VNIR) bands, short-wave
infrared radiometer (SWIR) bands, and thermal infrared
radiometer (TIR) bands. VNIR has 3 spectral bands with a
spatial resolution of 15 m, SWIR has 6 spectral bands with a
spatial resolution of 30 m, and TIR has 5 spectral bands with a
spatial resolution of 90 m.
e
Ishikawa
The most widely used vegetation index for ecological
application is the Normalized Difference Vegetation Index 4 m
(NDVI), which uses radiance values or apparent reflectance
: deus 100E 140E 160E
values of the red and the near-infrared spectral bands. These 0 120E ;
reflectance values are influenced by atmospheric aerosols. In Figure 1. Map of study area
order to calculate accurate NDVI values (aerosol-free NDVI),
the atmospheric effects must first be removed from the 2, ANALYTIC FLOW
reflectance values (Karnieli et al., 2001).
The analytic flow is shown in Figure 2. ASTER product 1B
The purpose of this research is to investigate the conditions of data were used to analyze land cover. We used ASTER level
the heat island phenomenon in a Japanese city. F igure 1 shows 2B products to measure surface temperatures.
our study area. In this paper, we show the variations in aerosol
* Corresponding author.
