...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Monthly Weather Review >Diurnal Patterns of Rainfall in Northwestern South America. Part Ⅲ: Diurnal Gravity Waves and Nocturnal Convection Offshore
【24h】

Diurnal Patterns of Rainfall in Northwestern South America. Part Ⅲ: Diurnal Gravity Waves and Nocturnal Convection Offshore

机译：南美西北部地区的降雨日变化规律。第三部分：近海日重力波与夜间对流

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Afternoon/evening near-coastal convection over land is easily understood as a response to solar heating of the land, turbulent transfer of heat and moisture to the boundary layer, and lifting of air by vigorous sea-breeze fronts. Subtler processes apparently underlie the late night and morning convection that is prevalent over coastal waters throughout the Tropics. Sensitivity tests using the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), and further diagnoses of the control run described in Part Ⅱ, are used to explore these processes. Prior studies have speculated that "land-breeze" circulations, analogous but opposite to the sea breeze, drive offshore convection at night. However, nighttime radiative cooling of land and the associated thermal breezes are much weaker than the corresponding daytime processes, especially under humid tropical skies. Analysis of model mean soundings reveals that modest (fractions of a degree Celsius) temperature changes near the 800-hPa level change the sign of the buoyancy of low-level air, from negative (inhibited) to positive (conveeting) after about midnight in the coastal zone. These diurnal temperature changes are seen to be signatures of a diurnal gravity wave with a propagation speed of ～15 m s~(-1), similar to the speed of motion of the diurnal seaward sweep of convection seen in satellite data as well as in the model. This wave radiates from the diurnally oscillating heat source of the daytime mixed layer, raised up into the stratified layers of the atmosphere by elevated terrain. A surprising finding is that the model mean rainfall field is almost the same in a simulation without diurnally varying solar radiation.
机译：午后/傍晚在陆地上的近岸对流很容易理解为对土地的太阳加热，热量和水分向边界层的湍流传递以及剧烈的海风前沿抬高空气的反应。在整个热带地区的沿海水域中，深夜对流和暗流对流显然是深夜的基础。使用第五代宾夕法尼亚州立大学NCAR中尺度模型（MM5）进行的敏感性测试以及对第二部分中描述的控制运行的进一步诊断被用于探索这些过程。先前的研究推测，类似于海风但与海风相反的“陆风”环流会在夜间推动近海对流。但是，夜间的陆地辐射冷却和相关的微风比相应的白天过程弱得多，尤其是在潮湿的热带天空下。对模型平均测深的分析表明，大约800hPa左右的温和温度（几分之一摄氏度）温度变化会改变低空空气的浮力，从午夜大约在午夜后从负（抑制）变为正（对流）。沿海地区。这些昼夜温度变化被认为是日重力流的特征，传播速度为〜15 ms〜（-1），类似于卫星数据和卫星数据中对流的日对海扫掠运动的速度。模型。该波从白天混合层的昼夜振荡热源辐射出来，通过升高的地形上升到大气的分层层中。令人惊讶的发现是，模型的平均降雨量在模拟中几乎相同，而没有太阳辐射的日变化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号