Winter nocturnal air temperature distribution for a mesoscale plain of a snow-covered region -field meteorological observations and numerical simulations-
Winter nocturnal air temperature distribution for a mesoscale plain of a snow-covered region -field meteorological observations and numerical simulations-
复制标题
雪区中尺度平原冬季夜间气温分布-野外气象观测与数值模拟-
DOI：
10.1175/jamc-d-16-0133.1
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发表时间：
2017
影响因子：
3
通讯作者：
A.
中科院分区：
文献类型：
--
作者：
Yazaki;T. Fukushima;H. Hirota;T. Iwata;Y. Wajima,A. Yokota;A.
冬季气温对作物越冬和冷资源利用影响较大。为了阐明中尺度平原冬季气温分布是如何形成的，对日本的德胜地区进行了实地观测和模拟。结果表明，各站点冬季平均气温与平均日最低气温密切相关。日最低气温与海拔高度不相关，表明日最低气温的局部变化影响了气温分布。在离逆风山脉不同距离的观测显示，靠近山脚的地方风越强，夜间气温越高。与风速相关的低温表明辐射冷却强烈影响温度分布。边界层的风和温度条件影响夜间气温下降的程度及其分布。风速和风向分别从西北山脚影响高温区的范围和方向。空间分辨率为2 km的模拟再现了观测温度，但在地形复杂的站点，在中等或强风条件下，误差超过5°C。一个0.5 km的高分辨率模式表明，模拟温度与观测温度接近，与当地的山谷下游排水风系统有关。综上所述，天气背景、平原风力强度和风向以及微尺度山谷影响边界层混合，从而决定冬季气温分布。
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.