Survival of Snow in the Melting Layer: Relative Humidity Influence
Survival of Snow in the Melting Layer: Relative Humidity Influence
复制标题
雪在融化层中的生存：相对湿度的影响
DOI：
10.1175/jas-d-20-0353.1
复制
发表时间：
2021
影响因子：
3.1
通讯作者：
C. Schmitt
中科院分区：
文献类型：
--
作者：
Heymsfield;A. Bansemer;A. Theis;C. Schmitt
这项研究量化了多远的雪可以落入融化层（ML）之前，所有的雪已经融化，通过检查结合在拉格朗日螺旋下降从上面通过ML和下降和上升到ML，以及在过去的50年中，NOAA表面观测报告的广泛数据库飞机测量的现场观测。机载数据包含有关粒子相态（固体、混合或液体）、粒子群大小分布和形状、沿着温度、相对湿度和垂直速度的信息。广泛的温度和环境相对湿度范围用于机载和地面数据。结果表明，0°C的冰球温度，连同空气温度和压力（海拔），是很好的一阶预测的最高温度雪花可以生存在融化层完全融化之前。粒子的大小也很重要，就像粒子是<$球还是冰雹一样。如果相对湿度太低，颗粒将在落入熔融层时完全升华。从飞机测量和地面观测中可以观察到温度为+7 ° C的雪。雪丸甚至可以在更高的温度下存活。建立关系以代表主要发现。
This study quantifies how far snow can fall into the melting layer (ML) before all snow has melted by examining a combination of in situ observations from aircraft measurements in Lagrangian spiral descents from above through the ML and descents and ascents into the ML, as well as an extensive database of NOAA surface observer reports during the past 50 years. The airborne data contain information on the particle phase (solid, mixed, or liquid), population size distributions and shapes, along with temperature, relative humidity, and vertical velocity. A wide range of temperatures and ambient relative humidities are used for both the airborne and ground-based data. It is shown that an ice-bulb temperature of 0°C, together with the air temperature and pressure (altitude), are good first-order predictors of the highest temperature snowflakes can survive in the melting layer before completely melting. Particle size is also important, as is whether the particles are graupel or hail. If the relative humidity is too low, the particles will sublimate completely as they fall into the melting layer. Snow as warm as +7°C is observed from aircraft measurements and surface observations. Snow pellets survive to even warmer temperatures. Relationships are developed to represent the primary findings.