Liping Luo

The characteristics of supercooled liquid water (SLW) within icing clouds over eastern China are investigated using in situ aircraft observations and numerical simulations. Supercooled liquid water content increases from 0 to −4°C, but decreases sharply below −4°C. Abundant supercooled large droplets (SLD) were observed, with the effective diameter reaching 175 and number concentration ( N _t ) exceeding 19 cm ⁻³ . An aircraft icing rate and intensity forecast algorithm is proposed by incorporating flight conditions and SLW spectral characteristics, together with a new diagnostic relation between cloud droplet shape parameter and N _t implemented into the three‐moment NSSL scheme. Sensitivity simulations indicate that the improved scheme can reproduce well the temperature‐dependent variation of SLW content, and significantly enhance forecasted rate of icing, intensity, and icing cloud layer depth.

At midnight on September 30, 2021, a severe hailstorm swept over northeastern China, producing egg‐sized hail over Dalian Airport, causing damages to more than 40 aircrafts and imposing tremendous pressure on operational capacity of the airport. The explicit hail prediction skills of the Weather Research and Forecasting (WRF) model are investigated using different multi‐moment microphysics schemes, that is, Milbrandt–Yau (MY) and National Severe Storms Laboratory (NSSL) two‐moment, and NSSL three‐moment schemes. Simulated variables, including the radar reflectivity, maximum estimated size of hail (MESH), and cloud‐top temperature (CTT) are verified against radar, satellite, and available reports. Results indicate that the general evolution of the hailstorm system is well‐reproduced by the simulations. Additionally, substantial differences are present for the explicit hail prediction across the schemes. Specifically, the MESH values predicted by MY and NSSL two‐moment scheme are significantly overestimated, reaching approximately 60 mm. In contrast, surface hail size distribution by NSSL three‐moment scheme aligns most closely with the actual observations. Furthermore, total mass for cloud, rain, and hail within simulated hailstorms produced by two‐moment schemes are all substantially larger than that by three‐moment scheme. This indicates that the fixed shape parameters for hydrometeor in two‐moment schemes can lead to excessive hail growth microphysical processes and size sorting of particles. The findings establish valuable references for operational forecasting of severe hail events, providing a scientific basis for aviation safety early warning.

The impacts of blowing snow, a very common snow‐air interactive process over Antarctica, are investigated with a snow/ice enhanced Weather Research and Forecasting (WRF‐ice) model for the surface energy budget (SEB) and surface mass balance (SMB) modeling over the Larsen C Ice Shelf (LCIS), Antarctic Peninsula. The net effect of blowing snow on LCIS' SMB is negative, because the positive effect of enhanced precipitation, reduced surface sublimation, and blowing snow transport is more than compensated by the negative effect of blowing snow sublimation, enhanced surface melt, and runoff. In sum, blowing snow contributes to positive anomalies in LCIS' SEB and negative anomalies in SMB.

To better capture the air‐snow‐ice interaction, a snow/ice enhanced Weather Research and Forecasting (WRF‐ice) model has been developed. This study examines the performance of WRF‐ice and its blowing snow component during a strong cyclone event from October 23 to 27, 2017 over the Antarctic Peninsula, which is characterized by a synoptic cyclone crossing the northern part of the Peninsula and an embodied mesoscale cyclone over the Weddell Sea. Evolution of the cyclone is accurately reproduced in the 5‐km resolution WRF‐ice simulation, and the simulated near‐surface conditions agree well with station and satellite observations. Numerical simulations show that the process of blowing snow sublimation can be prominent within the lower atmosphere when the air is dry, and produces moistening and cooling effects. Over relatively warm and humid areas, cloud enhancement by blowing snow can lead to either colder or warmer surfaces because of competing effects of longwave and shortwave cloud radiative forcings. In particular, additional moisture from blowing snow sublimation can slightly intensify precipitation over the mountains. Surface energy budget analysis indicates that absorbed shortwave (S_a), incoming longwave (L_d), and outgoing longwave (L_u) are dominant components of surface energy budget. When increases in L_d, L_u, and sensible heat flux are combined with decreases in S_a and latent heat flux due to blowing snow effects, a negative surface net heat flux (∼0.5 W/m²) occurs during daytime. A positive domain‐total surface mass balance (∼0.43 Gt) is generated during the simulated cyclone event due to increases in precipitation, decreases in runoff, and decreases in sublimation.

The initiation and organization of a long‐duration hail‐producing mesoscale convective system (MCS) in eastern China are investigated using convection‐allowing simulations at 3‐km grid spacing with the Advanced Regional Prediction System. The lifecycle of this MCS is characterized by two stages. In the first stage, a series of convective storms are initiated along the northwest border of Jiangsu Provinces. These storms organize into a northwest southeast line as they moved southeastward, eventually organizing into an eastward moving bow‐echo structure during the second stage. Our analyses show that the storms initiate along a northwest‐southeast oriented convergence boundary set up between two low‐level mesoscale vortices, one to the northwest of Jiangsu Province and one over the East China Sea. Comparisons between the fake‐dry and control simulations show that the rearward (westward) spreading of a cold pool from another MCS proceeding the hail‐producing MCS plays a key role in generating and enhancing the vortex over Eastern China Sea. The tilting of baroclinically generated horizontal vorticity along the edge of the cold outflow creates a cyclonic and anticyclonic vortex couplet. The cyclonic vortex becomes the dominant East China Sea vortex as it is superposed onto the background cyclonic circulation. This cold outflow‐induced vortex also has strong impacts on the later organization of the hail‐producing MCS, leading to the eventual establishment of a bow‐echo structure. Finally, a three‐stage conceptual model for the initiation and organization of the long‐lasting multicellular MCS is proposed, and the understanding on the complex interactions between two MCSs will be helpful to operational forecasters.

In the late afternoon of 19 March 2014, a severe hailstorm swept through eastern central Zhejiang province, China. The storm produced golf ball‐sized hail, strong winds, and lighting, lasting approximately 1 h over the coastal city of Taizhou. The Advanced Regional Prediction System is used to simulate the hailstorm using different configurations of the Milbrandt‐Yau microphysics scheme that predict one, two, or three moments of the hydrometeor particle size distribution. Simulated fields, including accumulated precipitation and maximum estimated hail size (MESH), are verified against rain gauge observations and radar‐derived MESH, respectively. For the case of the 19 March 2014 storms, the general evolution is better predicted with multimoment microphysics schemes than with the one‐moment scheme; the three‐moment scheme produces the best forecast. Predictions from the three‐moment scheme qualitatively agree with observations in terms of size and amount of hail reaching the surface. The life cycle of the hailstorm is analyzed, using the most skillful, three‐moment forecast. Based upon the tendency of surface hail mass flux, the hailstorm life cycle can be divided into three stages: developing, mature, and dissipating. Microphysical budget analyses are used to examine microphysical processes and characteristics during these three stages. The vertical structures within the storm and their link to environmental shear conditions are discussed; together with the rapid fall of hailstones, these structures and conditions appear to dictate this pulse storm's short life span. Finally, a conceptual model for the life cycle of pulse hailstorms is proposed.