Winter nocturnal air temperature distribution for a mesoscale plain of a snow-covered region: Field meteorological observations and numerical simulations

Tomotsugu Yazaki, Hirokazu Fukushima, Tomoyoshi Hirota, Yukiyoshi Iwata, Atsushi Wajima, Ayumi Yokota

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Winter air temperatures strongly affect crop overwintering and cold resource usage. To clarify how winter air temperature distributions are formed in a mesoscale plain, field observations and simulations were conducted for the Tokachi region in Japan. Results elucidating the winter climate within the plain revealed that the winter mean air temperature at each site was correlated closely with the mean daily minimum air temperature. The daily minimum air temperature was not correlated with altitude, suggesting that local variation of the daily minimum temperature influences the temperature distribution. Observations at different distances from the upwind mountains revealed that nocturnal air temperatures were higher for stronger winds closer to the mountain foot. Low temperatures associated with wind speed suggest that radiative cooling strongly affects the temperature distribution. Wind and temperature conditions in the boundary layer influence the degree of drop in nocturnal air temperature and its distribution. The wind speed and direction, respectively, affect the extent and direction of the high-temperature zone from the northwest mountain foot. Simulations with a spatial resolution of 2 km reproduced the observed temperatures, but the error exceeded 5°C at sites having complex terrain under moderate or strong wind conditions. A higher-resolution model of 0.5 km showed that simulated temperatures approach the observed temperatures in association with a local wind system of down-valley drainage flow. In conclusion, the synoptic background, wind strength and direction over the plain, and microscale valleys affect boundary layer mixing and, thereby, determine the winter air temperature distribution.

Original languageEnglish
Pages (from-to)519-533
Number of pages15
JournalJournal of Applied Meteorology and Climatology
Volume56
Issue number2
DOIs
Publication statusPublished - Jan 1 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Fingerprint Dive into the research topics of 'Winter nocturnal air temperature distribution for a mesoscale plain of a snow-covered region: Field meteorological observations and numerical simulations'. Together they form a unique fingerprint.

Cite this