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Previous observational studies have indicated that mesoscale convective systems (MCSs) contribute the majority of precipitation over the Bay of Bengal (BoB) during the summer monsoon season, yet their initiation and propagation remain incompletely understood. To fill this knowledge gap, we conducted a comprehensive study using a combination of 20-yr satellite observations, MCS tracking, reanalysis data, and a theoretical linear model. Satellite observations reveal clear diurnal propagation signals of MCS initiation frequency and rainfall from the west coast of the BoB toward the central BoB, with the MCS rainfall propagating slightly slower than the MCS initiation frequency. Global reanalysis data indicate a strong association between the offshore-propagating MCS initiation frequency/rainfall and diurnal low-level wind perturbations, implying the potential role of gravity waves. To verify the hypothesis, we developed a 2D linear model that can be driven by realistic meteorological fields from reanalysis. The linear model realistically reproduces the characteristics of offshore-propagating diurnal wind perturbations. The wind perturbations, as well as the offshore propagation signals of MCS initiation frequency and rainfall, are associated with diurnal gravity waves emitted from the coastal regions, which in turn are caused by the diurnal land–sea thermal contrast. The ambient wind speed and vertical wind shear play crucial roles in modulating the timing, propagation, and amplitude of diurnal gravity waves. Using the linear model and satellite observations, we further show that the stronger monsoonal flows lead to faster offshore propagation of diurnal gravity waves, which subsequently control the offshore propagation signals of MCS initiation and rainfall. Significance Statement: Rainfall over the Bay of Bengal (BoB) is primarily contributed by large and organized rainfall systems in the summer monsoon season. During this season, these systems are commonly observed over the east coast of India around midnight, the western BoB in the morning, and the central BoB in the afternoon. This eastward rainfall propagation is confirmed by observations, reanalysis data, and a theoretical model to have a strong association with atmospheric diurnal gravity waves. These waves are caused by land–sea thermal contrast and can trigger rainfall systems over the offshore regions. We also found that the diurnal gravity waves, as well as their triggered rainfall systems, can be greatly modulated by the large-scale monsoonal flows. All the above findings improve our understanding of diurnal rainfall cycle over the BoB and may contribute to the future improvement of rainfall forecast over the region. [ABSTRACT FROM AUTHOR]

The South China coast (SCC) experiences frequent heavy rainfall during the warm season (May–September). Objective classification analysis on 925‐hPa geopotential height shows that the majority of warm‐season precipitation (>80%) occurs under three typical synoptic patterns: the southerly monsoon pattern (P1), the southwesterly monsoon pattern (P2), and the low‐level vortex pattern (P3). Using 20 years of satellite observations and cloud tracking, this study highlights that mesoscale convective systems (MCSs) play a pivotal role in generating precipitation under all three synoptic patterns, while the initiation and rainfall characteristics of MCSs are strongly modulated by the background synoptic circulations. The diurnal MCS precipitation under P1 and P2 is predominantly influenced by land‐sea breeze circulation, which is characterized by a morning offshore propagation and an afternoon onshore propagation. The rainfall propagation speeds, however, are strongly modulated by the prevailing low‐level monsoonal flows. Under P3, MCS precipitation initiates near the coast around midnight and then propagates offshore, merging with the widespread offshore precipitation. The analysis also shows that the majority of MCSs contributing to SCC warm‐season precipitation were locally initiated. This underscores the critical role of locally initiated MCSs in driving the SCC precipitation characteristics, as opposed to propagating MCSs. Statistical correlation analysis further indicates that the precipitation area and intensity of locally initiated MCSs are closely related to the lower‐tropospheric moisture transport and the convective available potential energy over the upstream South China Sea, and the deep‐layer wind shear (from surface to 400‐hPa) over the SCC. Plain Language Summary: The coastal region of South China (SCC) experiences frequent heavy rainfall events during the warm season, which can result in devastating damages. Our research has revealed that more than 80% of the coastal rainfall during this season occurs due to three distinct weather circulation patterns. Mesoscale convective systems (MCSs), comprising a complex of cumulonimbus clouds with contiguous precipitation over an area of greater than 100 km, substantially contribute to the total rainfall. Long‐term satellite observation and cloud tracking data have enabled us to better understand the spatial distribution, diurnal cycle, and propagation of MCS rainfall, which are largely influenced by the three typical patterns, particularly the distinct low‐level winds. Our study has also found that locally initiated MCSs produce more rainfall over the SCC than propagating MCSs, and their intensity is closely related to atmospheric moisture content, energy, and wind shear. These findings offer valuable insights into how weather patterns impact the rainfall characteristics of MCSs during the warm season, thereby providing a basis for improved forecasting of heavy rainfall events over the region. Key Points: The majority of warm‐season rainfall over the South China Coast occurs under three typical synoptic patternsThe rainfall spatiotemporal characteristics of three synoptic patterns are largely determined by mesoscale convective system (MCS) activityThe initiation, area, and rainfall intensity of MCSs are modulated by dynamical and thermodynamical environments [ABSTRACT FROM AUTHOR]

We report an ionogel with thermo-switchable conductivity and high processability based on physical self-assembly of poly(styrene-b-ethylene oxide-b-styrene) (PS-PEO-PS) in mixed ionic liquids composed of thermo-responsive 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide and polymerizable 1-(4-vinylbenzyl)-3-butylimidazolium bis(trifluoromethylsulfonyl)imide, and subsequent chemical crosslinking of the polymerizable component. [ABSTRACT FROM AUTHOR]

This study used a Weather Research and Forecasting (WRF)‐based Ensemble Kalman Filter (EnKF) system to assimilate reflectivity (Z) and radial velocity (Vr) data in precipitating and clear‐air regions from the Beijing Daxing International Airport C‐band phased‐array radar (C‐PAR) to improve the forecasts of a convective initiation (CI) case occurred on 18 June 2020. The results showed that high‐frequency assimilating the C‐PAR Vr in clear‐air region is conducive to increase the forecast lead time of CI by significantly improving the initial dynamic and thermodynamic fields, which creates a more accurate pre‐CI environment. After assimilating the C‐PAR clear‐air Vr, the CI case can be accurately predicted with a 20 min forecast lead time in the best‐case scenario. This is the first real‐case study to demonstrate the benefits of assimilating high spatiotemporal resolution PAR clear‐air radial velocity data for the CI process. Plain Language Summary: Convection initiation is the beginning stage of severe convective weather. Accurate prediction of its location and timing is very important for monitoring and early warning of severe convective weather. However, CI forecast is still a great challenge worldwide. The good news is that newly deployed phased‐array radar (PAR) with high spatiotemporal resolution can capture the much needed small‐scale information of the preconvective environment and the whole CI process. This study combines the new PAR observation and numerical weather prediction model through Ensemble Kalman Filter (EnKF), one of the most popular data assimilation techniques, to improve forecast of a CI event. With the improved data, we successfully forecast CI process mainly thanks to the PAR that help improved three‐dimensional winds, temperature, and humidity analysis, particularly in the clear‐air regions. Key Points: First real‐case assimilation of C‐band phased‐array radar clear‐air data on convection initiation using Ensemble Kalman FilterAssimilating clear‐air radial velocity plays a key role in successful forecast of convective initiation (CI)Assimilating clear‐air radial velocity has the potential to accurately forecast CI with a lead time up to 20 min [ABSTRACT FROM AUTHOR]

A programme of centrifuge model tests (100 g) was conducted to examine the vertical and lateral bearing behaviour of open caissons in clay. The dimensions of the model caisson were 0.52 m in length, 0.43 m in width and 0.28 m in height, and the soil was referred to as Malaysian kaolin clay. Soil and pore pressure cells were installed on the caisson skirt to enable detailed inspection into the soil-structure behaviour in addition to the load-displacement response. The normalised vertical penetration resistance on the model caisson during installation demonstrated satisfactory agreement with the data collected from parallel tests conducted in the field. Explicit equations were developed to quantify the soil plug coefficient, thus facilitating reliable assessment of the penetration resistance. The historical cyclic loading was found to have a significant enhancing effect on the lateral bearing behaviour of open caissons, which was demonstrated by the load-displacement response as well as the development of soil and pore pressures. After a resting period of about 14 days in prototype, the stiffness of the open caisson foundation was about four times that prior to previous lateral cyclic loading. [ABSTRACT FROM AUTHOR]