Abstract
The life cycle of mesoscale convective systems (MCSs) in eastern China is yet to be fully understood, mainly due to the lack of observations of high spatio-temporal resolution and objective methods. Here, we quantitatively analyze the properties of warm-season (from April to September of 2016) MCSs during their lifetimes using the Himawari-8 geostationary satellite, combined with ground-based radars and gauge measurements. Generally, the occurrence of satellite derived MCSs has a noon peak over the land and an early morning peak over the ocean, which is several hours earlier than the precipitation peak. The developing and dissipative stages are significantly longer as total durations of MCSs increase. Aided by three-dimensional radar mosaics, we find the fraction of convective cores over northern China is much lower when compared with those in central United States, indicating that the precipitation produced by broad stratiform clouds may be more important for northern China. When there exists a large amount of stratiform precipitation, it releases a large amount of latent heat and promotes the large-scale circulations, which favors the maintenance of MCSs. These findings provide quantitative results about the life cycle of warm-season MCSs in eastern China based on multiple data sources and large numbers of samples.
Highlights
Mesoscale convective systems (MCSs) are one of the most impactful weather phenomena on Earth
Remote Sens. 2020, 12, 2307 clouds as detected from Advanced Himawari Imager (AHI)/HW8 over northwestern China, which is largely due to large sensor zenith angles of AHI [38], this study focused on the temporal evolutions of MCSs over eastern China (100–136◦E, 18–54◦N, bounded by blue lines in Figure 1a) from the perspective of AHI/HW8 and gauge measurements
Certain cloud systems tracked by geostationary satellite data may not be associated with deep convective clouds that produce measurable precipitation reaching ground, because the Infrared-only tracking method may artificially pick up segments of persistent non-precipitating upper-level clouds [2]
Summary
Mesoscale convective systems (MCSs) are one of the most impactful weather phenomena on Earth. MCSs are defined as convective systems with contiguous precipitation over 100 km in at least one direction [1,2]. MCSs contribute significantly to warm-season precipitation, both in the tropics and mid-latitude regions [3,4]. The intensity and explicit structures of MCSs are affected by a variety of factors, including low-level jet streams [5,6,7], topography [8,9] and large-scale circulation [10,11]. The MCSs in the mid-latitude regions tend to occur most frequently in front of the troughs in the prevailing westerlies [13]. Low-level jet streams tend to enhance MCS formation and continuation at the downstream region, due to the increase in atmospheric instability and the advection of warm and moist air masses [14]
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