TITLE:
Effects of Land Surface Temperature on the Frequency of Convective Precipitation in the Tokyo Area
AUTHORS:
Yohei Shiraki, Yoshinori Shigeta
KEYWORDS:
Remote Sensing; Geographic Information System; Heat Island; Land Surface Temperature; Convective Precipitation
JOURNAL NAME:
Journal of Geographic Information System,
Vol.5 No.3,
June
19,
2013
ABSTRACT:
This study
uses statistical evaluation by correlation analysis to examine the effects of thermal
environment on the frequency of convective precipitation in the Greater Tokyo Area
between 12:00 and 18:00 on summer days from 1997 to 2006. To extract the frequency
of convective precipitation we used Automated Meteorological Data Acquisition System
radar data to obtain detailed rainfall distribution maps, and to extract the urban
thermal environment we used surface temperature data from a National Oceanic and
Atmospheric Administration weather satellite. Results were a coefficient of determination
of 0.01, indicating no clear relation between surface temperature and convective
rain frequency in the study area. Examining the convective rain frequency distribution
map in conjunction with an elevation map of the area indicates that higher elevation
is a better predictor of increased frequency of convective rainfall than is surface
temperature. Because this indicates that orographic precipitation has a large influence
in the study area, we used an elevation map to exclude hilly and mountainous regions,
regions bordering flat areas (under the assumption that wind could easily move orographic
precipitation to such areas), and regions containing marine areas. Doing so resulted
in a coefficient of determination of 0.38, a clear signal that differences in the
thermal environment in the Greater Tokyo Area have an effect on the frequency of
convective precipitation. We next focused on metropolitan Tokyo, the most developed part of the region and
the part experiencing the most frequent occurrences of convective precipitation,
and we performed correlation analysis considering parameters related to buildings.
Results indicate that orographic precipitation has a strong influence in metropolitan
Tokyo as well, so
we excluded those areas that were excluded from the Greater Tokyo Area analysis
and again performed correlation analysis. However, we found no clear relation of
convective precipitation frequency with surface temperature or building parameters.