Regional difference of summer heat stress of residents at cities and islands in the Seto Inland Sea

Abstract

We investigated how differences of topographical and geographical environment influence on the summer heat stress, by using the air temperature and two heat stress indices (MDI and ESI). Our meteorological observations were conducted in seven sites of inland, plain, coast, and island regions. A heat stress evaluation with air temperature exhibited a higher appearance of the heat hazard in order of inland, plain, coast, and island regions. The excess heating of atmosphere was possibly observed in more urbanized region. On the other hand, a heat stress evaluation with MDI showed a different result from the air temperature, which was a higher appearance of the severe warning hazard in order of plain, inland, coast, and island regions. The high stress in plains was thought to be due to an exposure of humid air such as a sea breeze penetration. The additional evaluation by ESI which includes solar radiation effects indicated the further different result from the above index results; an appearance of the severe warning hazard in coastal and island regions, where less clouds cover, increased compared to a use of MDI, and it increased a heatstroke risk in these regions. On the other hand, appearances of the severe warning hazard in inland regions decreased due to the insolation decrease.