PCTSMC 
color composite 
Fig. 6 Cloud screening based on color composite 
and PCTSMC methods of NOAA imagery 
in an area from Hokkaido to northeastern 
Honshu (after Utsunomiya and Katoh, 
1995), 
3.4 Surface and air temperatures 
3.4.1 Determination of surface temperature: 
Surface temperature (Ts) in each NOAA pixel was 
calculated from the relationships between XNOAA 
brightness temperature and water temperature retrieved 
from the above database. 
3.4.2 Estimation of air temperature: Air 
temperature (Ta) in each NOAA pixel was also 
computed using a statistical model based on the 
relationships between surface temperature Ts and air 
temperature derived from the above database and other 
meteorological datafiles (Fig.7, 8). 
3.4.3 Amplitude of temperature: The 
amplitudes of both surface and air temperature, dTs and 
dTa, in NOAA pixels were calculated by subtracting the 
temperatures Ts and Ta at night from each of those 
during the day, respectively. 
  
  
  
  
  
  
  
  
Fig. 7 Distribution of ground monitoring points 
in an automated meteorological data 
system for Japan. 
886 
  
Fig. 8 Distribution of estimated air temperature, 
its profile, legend and operational panel. 
4. HEAT BALANCE ANALYSIS 
4.1 Shortwave radiation 
4.1.1 Downward short-wave radiation: Down- 
ward short-wave radiation was calculated by the 
procedure suggested by Seino and Uchijima (1988) and 
statistical modeling was done from the relationships 
between TOVS and radiation data at the monitoring 
stations. Assuming the diurnal variation of solar 
radiation to be approximately sinusoidal on a cloudless 
day (Monteith, 1973), variation curves of direct and 
diffuse radiation were computed using following models. 
These parameters were computed in the following 
equation. First, solar radiation was calculated using 
parameters such as duration of sunshine, sun elevation 
and snow cover. 
[StH] = So {0.146+0.534% + 0.047G10 + 0.036 sin n 
Ae ERU (Yoshida and Shinoki, 1978) (2) 
where h: sun elevation at noon on the 15th day of each 
month, G10: index of snow cover; ratio of the number 
of days with snow cover exceeding 10 cm depth divided 
by the amount of days in any month, S0: monthly 
average duration of possible sunshine in any month 
Monthly average of direct solar radiation [SbH] was 
calculated using following equation. 
[StH] 
SoH] _ 91528 4 0.92019] . 9.0013 & - 0.0706 Gio 
[StH] So 
videns (Seino and Uchijima, 1988) (3) 
where [StH]: monthly average of global solar radiation 
[Seu], [SdH]: monthly average daily amount of direct solar and 
diffuse radiations, respectively 
ea = 4.54 exp (0.068 * Ta ).....(Seino and Uchijima,1988) (4). 
This equation for estimating vapor pressure, ea, was 
developed using data obtained in a humid climate. Ta: 
air temperature, G10: The index G10 is substituted by 
the index, GO, in the following equation, where GO is 
the ratio of the number of days with any depth of snow 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
ade. ac. be huh causé cL N 
Amm A a a