Observational Study of Diurnal Temperature Range In the Chichibu Basin and the Kofu Basin

  • Momoko NEGISHI, 2016: Observational Study of Diurnal Temperature Range In the Chichibu Basin and the Kofu Basin .


The temperature in the basin tends to be hotter and colder than the plain. It is known that diurnal temperature range is large in the basin. The relationship between the basin topography and the temperature difference is based on the theory of Topographic Amplitude Factor (TAF). The theory of TAF is explained based on the volumetric effect that the smaller volumes are easier to warm when giving the same amount of heat to substances of the same density. In comparison with the basin and the plain, it is easier for the atmosphere in the basin to warm when the same amount of solar radiation is added. Thus, the volumetric ratio between the plain and the basin correspond ration of diurnal temperature range between the plain and the basin. It is the theory of TAF. The theory of TAF has been investigated in large basins. Therefore, in this study, we investigated whether TAF is established even in a small scale basin by observation. The observation is made on the Chichibu Basin in Saitama Prefecture and the Kofu Basin in Yamanashi Prefecture. The observation data of September - December 2016 and the observation data of weather observation data of the Japan Meteorological Agency from January 2014 to December 2016 was used. Analysis result of observational data and analysis result of Meteorological Agency data in this study are different. The results of using the former data show that there is no big difference in the temperature change and the diurnal temperature range for all basins and the relation of TAF. On the other hand, the results using the Meteorological Agency data showed that there was a tendency for the smaller Chichibu Basin to have a somewhat larger diurnal temperature difference than the Kofu basin, mainly because of the nighttime temperature difference. The difference in the results for these two types of data are considered to be one of the causes due to the difference in nighttime cooling which caused by the difference in the observation point. The results indicate that approximately TAF is true even in small basins. However, temperature difference occurred due to the difference in nighttime cooling, and it became clear that it was slightly out of relation with TAF

Keywords: Topographic Amplitude Factor (TAF), Diurnal Temperature Range, Small scale basin, Observation, Nocturnal cooling