2005年7月北极地区大气环流特征的数值研究

利用一个极地中尺度数值模式(Polar MM5)对北极地区大气环流进行了2005年7月17-19日48 h的中尺度数值模拟研究。数值分析表明,2005年7月19日500 hPa高度上,北冰洋上空北极点以东由一个冷低压控制,在极点以西则是一个暖性高压系统,在地面图上对应的则是一个气旋性环流和反气旋性环流;整个极区呈现出高(反气旋)-低(气旋)-低(气旋)-高(反气旋)的波动分布型态。选择了5个北极地区探空站与相应温度场和风场的数值模拟结果进行了对比;气象变量统计分析和垂直分布表明了数值模式很好地再现了观测大气特征,表现为小的模式偏差和较高的相关系数。在Barrow站2 m处空气温度,感热通量和潜热通量具有明显的日变化特征,PolarMM5还有效地反映出此处极地逆温层和下降风的垂直结构特征。

Numerical study of atmospheric circulation over Arctic region at July of 2005

The 48 h mesoscale model simulations from July 17 to 19,2005 of the atmospheric circulation around Arctic region with the polar MM5 are presented.The numerical analyses indicate there was a cold,low pressure around the east of the Pole and a warm high pressure at the west of the Pole over the Arctic.At the map of surface,the corresponding systems were a cyclone and an anticyclone circulation.There was a fluctuation mode of high(cyclone)-low(anticyclone)-low(anticyclone)-high(cyclone) over the entire Arctic region.Five upper-air observations from the Arctic are used to verify the simulated atmospheric state for the variables of temperature and wind.The model is found to reproduce the observed atmospheric state based on statistic and vertical analyses.This is evident as smaller model biases and larger correlation coefficients for the variables of temperature and wind.Moreover,the mesoscale model reflects there were evident diurnal cycle for the temperature at height of 2 m,sensible heat and latent heat fluxes at station Barrow;and the inversed temperature and Katabatic vertical structures at Barrow was simulated by the model,effectively.