Mesoscale system description

Mesoscale weather refers to a weather phenomenon with a horizontal scale of tens to hundreds of kilometers and a time scale of several hours to dozens of hours. According to its nature, it can be divided into mesoscale convective weather and mesoscale stable weather. Among them, mesoscale convective weather includes thunderstorm, short-term heavy precipitation, hail, thunderstorm gale, tornado and downburst, which is a mesoscale weather system formed by the interaction of various physical conditions under a certain large-scale circulation background. The subjective analysis of mesoscale convective weather is to analyze the mesoscale convective system and its environmental conditions by using various high-altitude and ground observation data, radar, satellite and other remote sensing detection data, as well as numerical analysis and forecasting products.

There are many kinds of mesoscale systems, and table 1 is the result of comprehensive classification according to the pressure, flow field, weather characteristics and movement of mesoscale systems with reference to the classification results of different authors.

Table 1 Classification of mesoscale systems by pressure field Mesoscale high pressure (thunderstorm high pressure) Mesoscale low pressure (front mesoscale low pressure, wake low pressure, etc. ), according to the shear line of flow field, convergence line and convergence center, divergence center, mesoscale cyclone, mesoscale anticyclone, according to weather conditions, severe storm weather (manifold), multicell storm, supercell, large area thunderstorm group, squall line, MCS, etc. Mesoscale systems that cause convective mesoscale rain belts, rain masses, MCC, gravity waves and other non-convective rain belts such as gale, hail and thunderstorm to move to the right according to their motion properties are consistent with the average wind lag: they are often related to topography.