Factors Affecting the Inland and Orographic Enhancement of Sea-Effect Snowfall in the Hokuriku Region of Japan
Factors Affecting the Inland and Orographic Enhancement of Sea-Effect Snowfall in the Hokuriku Region of Japan
复制标题
DOI：
10.1175/mwr-d-19-0007.1
复制
发表时间：
2019-08
影响因子：
3.2
通讯作者：
Peter;-G.;Veals;-W.;James W. Steenburgh
中科院分区：
文献类型：
--
作者：
Peter;-G.;Veals;-W.;James W. Steenburgh
北陆地区沿着日本本州岛西海岸的降雪量异常大，从12月到2月，在海平面附近超过500厘米，在高海拔地区超过1300厘米，其中大部分是由海洋效应系统产生的。虽然降雪的气候增强很大，但个别风暴中的低地-高地降雪分布变化很大，这对天气预报和气候预测提出了挑战。利用C波段监视雷达、ERA 5再分析和地面降水观测的数据，我们研究了2007年12月至2016年2月北陆地区9个冬季（12月至2月）海洋效应期间内陆和地形增强的影响因素。由于三维地形的影响，降水的分布和强度对流向有很强的依赖性。对于一个给定的流动方向，较高的边界层风速和海引起的CAPE值有利于较高的降水率，最大位移更远的内陆和更高的海拔，和一个更大的比例高地到低地降水。这些特征也可以用无因次的山高H^来很好地表示，而H^1具有相反的效果。然而，即使在高增强时期，降水率下降，因为一个移动内陆从第一个主要的山脉障碍，即使在高地形。这些结果突出了海洋效应和地形过程之间的相互作用如何调节复杂和强大的地形区域的降水分布和强度。
The Hokuriku region along the west coast of the Japanese island of Honshu receives exceptionally heavy snowfall accumulations, exceeding 500 cm from December to February near sea level and 1300 cm at high elevation sites, much of which is produced by sea-effect systems. Though the climatological enhancement of snowfall is large, the lowland–upland snowfall distribution within individual storms is highly variable, presenting a challenge for weather forecasting and climate projections. Utilizing data from a C-band surveillance radar, the ERA5 reanalysis, and surface precipitation observations, we examine factors affecting the inland and orographic enhancement during sea-effect periods in the Hokuriku region during nine winters (December–February) from December 2007 to February 2016. The distribution and intensity of precipitation exhibits strong dependence on flow direction due to three-dimensional terrain effects. For a given flow direction, higher values of boundary layer wind speed and sea-induced CAPE favor higher precipitation rates, a maximum displaced farther inland and higher in elevation, and a larger ratio of upland to lowland precipitation. These characteristics are also well represented by the nondimensional mountain height H^, with H^1 having the opposite effect. Nevertheless, even in high enhancement periods, precipitation rates decline as one moves inland from the first major mountain barrier, even over high terrain. These results highlight how the interplay between sea-effect and orographic processes modulates the distribution and intensity of precipitation in an area of complex and formidable topography.