Mesoscale convective systems (MCSs) are organized thunderstorm clusters in mid-latitude and tropical regions that can produce extreme precipitation threatening human safety and property. Under global warming, extreme precipitation is expected to increase in intensity and frequency over most regions, primarily due to increased moisture availability and convective available potential energy (CAPE). However, using a recently developed 4 km, hourly MCS-tracking dataset (Feng, 2024), we find that extreme precipitation produced by MCS over the central US shows decreasing trends during the warm seasons (April–September) of 2004–2021.Extreme hourly MCS precipitation events are defined using the 95th percentile threshold (63 mm h-1). Over the study period, the number, mean rain rate, and total rainfall of extreme precipitation events all exhibit decreasing trends, with the decline in mean rain rate being statistically significant. Similar patterns are observed using the 90th (54.38 mm h-1) and 98th (73.63 mm h-1) percentiles, indicating robustness across thresholds.To examine concurrent environmental changes, we extract sounding data from ERA5 and calculate thermodynamic and kinematic parameters. The results show that, despite increasing trends in instability (e.g., CAPE and lifting index) and downdraft CAPE (DCAPE), the decreasing MCS precipitation is associated with low-level drying and weakening of low-level vertical wind shear. Low-level relative humidity is found to decrease significantly, accompanied by rising lifted condensation level (LCL), indicating that the low-level atmosphere has become drier despite a slight (but not significant) increase in precipitable water. This suggests that warming has outpaced moistening. Meanwhile, both 0-1 km and 0-3 km vertical wind shear show consistent weakening trends.Together, low-level drying and reduced vertical wind shear are likely to suppress organized MCSs capable of producing extreme precipitation under global warming. In addition, whether the overall extreme precipitation budget is compensated by isolated deep convection remains an open question for future research.

Abstract Ya'an is located in the transition zone between the eastern Tibetan Plateau and the Sichuan Basin (SB), featuring a distinct trumpet‐shaped terrain. This complex topography provides unique thermodynamic and dynamic conditions for convective initiation (CI), with highly intricate mechanisms. Based on radar observations, National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analysis and forecast data, and high‐resolution simulations using the Weather Research and Forecasting (WRF) model, this study investigates the terrain‐related triggering mechanisms of a heavy rainfall event that occurred on the southwestern slope of Ya'an on 19 July 2024. Results indicate that convection was initiated over the southwestern slope between 19:00 and 20:00 BJT, with the initiation process jointly modulated by local thermal and dynamic effects. In the daytime, the northwestern slope exhibited a pronounced “heat‐pump” effect due to solar short‐wave radiative heating, enhancing the upslope flow. In the evening, downslope winds developed at the foot of the northwestern slope and extended toward the central SB. This thermally‐forced downslope flow acted to strengthen the dynamical blocking effect of the northwestern slope for the low‐level southeasterly flow from the southeastern SB, which was thus forced to turn leftward, forming barrier‐jet‐like northeasterly winds. In consequence, the upslope lifting on the southwestern slope was enhanced, thereby triggering the convection of the heavy rainfall event. This study elucidates the key mechanisms governing nocturnal CI in this complex terrain region, highlighting the importance of coupling between orographic thermal and dynamical processes.

Accurate prediction of rainfall in regions of complex terrain is very challenging. While the parameterization of small-scale turbulent orographic form drag (TOFD) has been found to be critical in kilometer-scale numerical models, the parameterization of mesoscale orographic gravity wave drag (OGWD) is often thought to be unimportant. Using 3-km resolution Weather Research and Forecasting (WRF) simulations, this work studies the impact of OGWD parameterization for a heavy rainfall event in April 2023 and a 13-day rainy episode in July 2023 in the Sichuan Basin (SCB), Southwest China. Results show that the simulated heavy rainfall is much stronger and is located too far east when ignoring the subgrid orographic drag in the model. The parameterization of OGWD exerts a much more notable influence on the heavy rainfall than that of TOFD. OGWD decreases the moisture transport by decelerating the low-level winds, thereby alleviating the overestimation of the rainfall intensity. The decelerated airflow is evidently blocked by the mountains in northeastern SCB, leading to a greater blocking high. The mesoscale cyclonic vortex that produces the heavy rainfall is forced to move southwestward, which decreases the eastward location biases of the simulated rainfall. The forecast skills (in terms of mean bias, root-mean-square error, pattern correlation coefficient and equitable threat score) are thus improved for the heavy rainfall event. The model also shows a better skill for the 13-day rainy episode in July 2023 when using OGWD parameterization. The findings highlight the importance of OGWD parameterization for the prediction of orographic precipitation in kilometer-scale models.

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.

Mesoscale convective systems (MCSs) experience complex changes in intensity as they move from land to the ocean. Predicting the offshore evolution of these systems poses a significant forecasting challenge. Using radar observations and ERA5 reanalysis data from the warm seasons of 2016–2018, this study investigates the characteristics and environmental controlling factors of land-to-sea (LS) MCSs over the Yangtze-Huai River Basin (YHRB). These systems are classified into offshore-intensifying and offshore-weakening types, accounting for approximately 40% and 60% of the total cases, respectively. Spatiotemporally, intensifying MCSs predominantly occur in spring (April–May; 56%) at lower latitudes, whereas weakening MCSs peak in summer (June–July; 45%) at higher latitudes. Composite analysis reveals that intensifying MCSs occur in environments with weaker thermodynamic instability but stronger dynamic forcing. Specifically, most unstable convective available potential energy (MUCAPE) is ~43% lower with reduced total column water (TCW), yet they are characterized by enhanced upper- and lower-level jets and greater vertical wind shear (VWS). A critical factor facilitating intensification is the cooler marine atmospheric boundary layer (MABL), which promotes enhanced isentropic lifting and lowers the lifting condensation level (LCL) via increased relative humidity. Crucially, offshore intensity evolution is governed by environmental change rather than absolute coastal conditions. Weakening MCSs originate in thermodynamically and dynamically superior environments over land but undergo considerable deterioration in thermodynamic and moisture conditions (MUCAPE drops ~47%, TCW decreases) upon moving offshore. Conversely, intensifying MCSs experience modest MUCAPE reduction (~26%) but benefit from significant enhancement of dynamic conditions (low-level VWS strengthening) and moisture enhancement (TCW increases in 60% of cases) during transit, enabling their intensification over the ocean despite lower absolute instability at the coast. These findings provide crucial insights into how coastal environments alter storm intensity, and offer practical insights to improve offshore weather forecasting.

The Yunnan-Guizhou Plateau (YGP) represents the steepest and most sophisticated terrain in China, as well as being highly susceptible to extreme meteorological disasters. The eastern YGP has a high incidence of regional extremely persistent heavy precipitation (REPHP). Hourly gridded precipitation data from May to July during 2019-2023 were used to define and study REPHP in eastern YGP. It was found that the REPHP events in the eastern YGP were mainly concentrated near the southern boundary and western mountainous areas. Two distinct high-incidence areas (HIAs) of REPHP were identified: the Plain-Hills HIA, situated on the southeastern windward slopes near the Nanling Mountains, and the Plateau-Mountain HIA, located on the western windward slopes near the Laowang Mountains. They mainly occurred from May to July, but especially in June. Influenced by local characteristics, the peaking time of diurnal variations differed between HIAs. ERA5 reanalysis data were used to investigate the synoptic patterns and their impacts in HIAs. The synoptic patterns in both HIAs were accompanied by the Western Pacific Subtropical High (WPSH). When the WPSH was located near 112°E, 16°N and there were southwest low-level jets (LLJs), shear line at 850 hPa and upslope wind would lead to REPHP over the Plain-Hills HIA. If WPSH extended to Beibu Gulf, the Plateau-Mountain HIA was controlled by the updraft generated by South Asia high (SAH), the trough at 500 hPa, shear line at 700 hPa and southerly LLJs. The Plain-Hills HIA features a more favorable convective environment than the Plateau-Mountain HIA, with higher most unstable convective available potential energy MUCAPE, stronger 0–3 km vertical wind shear, and higher precipitable water. Consequently, REPHP events in the Plain-Hills HIA typically exhibit a longer duration, stronger intensity and larger spatial extent.

There have been significant wet biases in the simulation of precipitation over the Tibetan Plateau (TP) for a long time. One of the important reasons is that current numerical models cannot accurately describe the influence of small-scale orography. In the orographic gravity wave drag (OGWD) parameterization used to describe small-scale orographic effects, this study develops a high-precision calculation method of sub-grid mountain sharpness that varies with geographical areas to revise and optimize the current constant mountain sharpness parameter (results in a constant drag coefficient at the surface). Batch numerical experiments on precipitation over the TP are carried out using the Yin-He Global Spectral Model. The results show that the newly calculated drag coefficient of revised OGWD scheme improves the simulation of precipitation and atmospheric circulation over the TP. The new mountain sharpness overall increases the OGWD over the TP on the westerly circulation. According to the vertical vorticity equation, changes in OGWD enhance the positive vorticity over the southern TP. Compared to the original scheme, the revised OGWD experiment exhibits a cyclonic circulation difference over the southern TP, which weakens the flow of water vapor into the TP. The water vapor budget of the main precipitation area over the western TP decreases by about 12.66%, thus reducing precipitation and wet biases over the western TP.

In the morning of 12 November 2022, severe aircraft icing occurred over Anhui Province, Eastern China during weather modification operations. In-situ airborne measurements revealed the presence of a substantial concentration of supercooled droplets with effective diameter exceeding 45 mu m, and liquid water content (LWC) above 1.2 g m-3 during the icing event. Given the importance of microphysical parameterization (MP) scheme for icing conditions, simulations using different multi-moment MP schemes, i.e., WDM6, NSSL, Milbrandt-Yau (MY) schemes, are conducted at 1-km grid spacing for the case. Comparisons against satellite observations indicate that the general evolution of the frontal system and surface precipitation are well reproduced by the simulations. However, all simulations underpredict upper-level clouds with cloud-top temperature below 240 K over the northeastern part of the front. Besides, WDM6 scheme produces ice cloud-top area (CTA) closest to satellite observations but only produces approximately half of the observed CTA for supercooled cloud tops. The Milbrandt-Yau scheme shows superior performance in simulating the cloud top features during the icing event. Examinations of explicit supercooled cloud water (SCW) prediction skills indicate that WDM6 generates excessive total number concentration (Nt) of small SCW, with Nt reaching up to 1011 m-3 and effective diameter (ED) below 20 mu m. In contrast, the NSSL scheme produces significantly larger SCW particles but substantially lower Nt at approximately 107 m-3 and ED of above 200 mu m. Notably, the particle size distribution of SCW predicted by MY scheme is more realistic compared with in-situ aircraft measurements.

The China Meteorological Administration Global Forecast System (CMA-GFS) v4.0 model was upgraded to a higher resolution of 0.125 degrees in May 2023. To be compatible with its fine resolution, the parameterization scheme of orographic gravity wave drag (OGWD) in CAM-GFS is revised herein by accounting for the nonhydrostatic effect (NHE) on the wave momentum flux of subgrid-scale orographic gravity waves. The performance of the revised OGWD scheme is then evaluated for the 10 d medium-range forecast in December 2023. Results show that the revised OGWD scheme can better capture the large-scale circulation in the Northern Hemisphere (NH), particularly in the high latitudes. The easterly (westerly) wind biases in the NH polar stratosphere (troposphere) are decreased. The underestimation of East Asia subtropical jet is also alleviated. Quantitative evaluation shows that the revised OGWD scheme reduces both the mean bias and root mean square error of 500 hPa geopotential height in the NH after the 6th forecast day, reaching 11.59 % and 5.06 %, respectively, by day 10. The decrease of easterly biases in the polar stratosphere is owing to the weakening of stratospheric zonal OGWD by the NHE. For the decrease of westerly biases in the NH polar troposphere, it is due to the fact that the enhanced stratospheric winds suppress the upward propagation of Rossby waves into the stratosphere, resulting in greater convergence of Eliassen-Palm flux in the mid-upper troposphere.

Abstract Bow echoes, identifiable by their bow-like shape on radar, are often associated with specific convective processes. The T-initiation Mesoscale Convective System (MCS) exemplifies this phenomenon, appearing as a quasi-linear bow echo with downstream nascent leading convection (LC), forming a 'T' shape on radar. The LC presents challenges for operational forecasts and can lead to severe weather conditions when they merge with parent bow echoes. Focusing on a T-initiation MCS over the Bohai Sea in China, this study investigates the physical mechanisms governing LC initiation. Utilizing the WRF-ARW model, backward trajectory tracking within a Lagrangian framework and vertical momentum budget analysis are employed to explore the dynamic factors driving the uplift of air parcels within the LC cells. Results reveal that a mid-level mesoscale anticyclonic vortex associated with the bow echo’s upper-level outflow modulated the wind field, resulting in stronger vertical wind shear between 2.5–5 km AGL downstream of the bow-echo. Interactions between this enhanced shear and pre-existing vertical motion led to low perturbation pressures at midlevels, which resulted in a nonhydrostatic vertical perturbation pressure gradient force that aided parcel ascent, contributing to the initiation of new LC cells. Thus, this study helps elucidate the self-organizing and sustaining processes of bow echoes by potentially identifying a novel initiation mechanism for LC cells in a T-initiation MCS.

Mesoscale convective systems (MCSs) over the Tibetan Plateau (TP) can significantly impact local environments and further affect surrounding regions when moving out of the TP. However, the characteristics of MCSs with different movement paths and their subseasonal variations remain unclear. Based on half-hourly GPM satellite data from 23 warm seasons (2001–23), this study reveals that the dominant movement paths of MCSs generated over TP are the southeast (SE), northeast (NE), and southwest (SW) paths, accounting for approximately 50%, 30%, and 15% of the total MCSs, respectively. For MCSs dissipating locally (LT-MCSs), eastward-moving MCSs travel faster and exhibit stronger maximum precipitation, while for moving-out MCSs (MT-MCSs), the SW path exhibits the highest strengths in terms of various properties. MCSs generated over the southern (eastern) part of TP tend to move out of TP along the south (east) path, while those in the center TP quickly dissipate. Notably, maximum precipitation increases with the distance away from the TP for MT-MCSs with the SE and SW paths but decreases for the NE path. Regarding subseasonal variations, the occurrences of both MT-MCSs and LT-MCSs increase from May to July and then decrease, and the ratio of MT-MCSs to total MCSs during midsummer (i.e., July and August) is lower than that during other months. Meanwhile, the number of eastward-moving MT-MCSs decreases during midsummer, accompanied by the westward shift of the high value centers of maximum precipitation, which can be attributed to the subseasonal variations of circulation and water vapor transport.

Hail forecasting using numerical models remains a challenge due to the uncertainties and deficiencies in microphysics schemes. In this study, we assessed the hail simulation performance of the two-moment Milbrandt-Yau (MY2) microphysics scheme within the Weather Research and Forecast (WRF) model by simulating three heavy rainfall events in Meiyu systems in which hail was rarely observed, rather than focusing on hail cases as done in previous research. Simulation results showed that the MY2 scheme produced noticeable hail in these rainstorms. Further analysis revealed that the overprediction of hail was caused by the imperfect graupel-to-hail conversion parameterization method adopted in the MY2 scheme. By incorporating the graupel spongy wet growth process, the modified scheme significantly mitigated the hail overforecasting. Moreover, the modified MY2 scheme kept the ability to simulate hail in real hail cases, demonstrating its ability to differentiate between heavy rainfall and hail events - a distinction the original scheme lacked. By comparing simulations of both rainstorms and hailstorms, it is concluded that the upward transport of large raindrops near the 0 degrees C level is critical for the graupel-to-hail conversion.

This study examines the genesis of atmospheric bores near sunset and their role in initiating and maintaining late‐afternoon mesoscale convective systems (MCSs) over the Southern North China Plain. A key finding is that 20% of documented bore occur during the sunset period. These bores form in the local environment preconditioned by the convective outflows from late afternoon MCSs, or by sea breezes that peak at this time. These bores aid in initiating and maintaining afternoon convection, subsequently favoring the development of nocturnal MCSs and associated bores. While bore research often concentrates on their impact on nocturnal MCSs, this study highlights that accurately predicting the diurnal cycle of MCSs requires properly representing bores. Thus, it helps address the long‐standing challenge of simulating the diurnal cycle of convective rainfall in weather and climate models.

Subgrid-scale orographic gravity wave drag (OGWD) significantly influences atmospheric circulation and weather systems. However, Current OGWD schemes, based on the "dry air" assumption, struggle to meet high-precision simulation demands. This study uses the moist OGWD scheme that incorporates moisture effects in gravity wave surface stress and vertical propagation of waves to simulate the global summer circulation in 2023 and three recent heavy rainfall events in China. In this scheme, moist buoyancy frequency varies with moisture: it decreases with abundant moisture and increases with less moisture, compared to the original scheme. Results show that buoyancy frequency differences alter low-level blocking height and drag, directly affecting gravity wave surface stress. During the vertical propagation of gravity waves, reduced tropospheric buoyancy frequency increases wave amplitudes and reduces Richardson number in moist scheme, which enhances tropospheric wave breaking and reduces waves propagation to the stratosphere. This increases tropospheric OGWD and decreases stratospheric OGWD, improving positive biases of troposphere westerly winds and negative biases of stratosphere easterly winds in Northern Hemisphere (NH) mid-high latitude, as well as the bias in the stratospheric jet near the Antarctic. The moist OGWD scheme also improves simulations of three recent heavy rainfall cases. In the Henan extreme rainfall, moist buoyancy frequency decreases due to abundant water vapor. Increased tropospheric OGWD weaken circulation and moisture transport to western and northern mountainous areas, intensifying rainfall and improving underestimation. The moist OGWD scheme partially addresses the limitations of "dry air" assumption, improving atmospheric circulation and heavy rainfall simulations.

In spring, eastern Himalayas (EH) receives the largest amount of rainfall in South Asia. However, the characteristics and formation mechanisms of spring precipitation, especially heavy precipitation (HP), in this region remain poorly understood. Based on 10-yr IMERG precipitation and the clustering approach of the self-organizing map, two types of HP are revealed with the rainfall center located at the northern coast of the Bay of Bengal (BOB) and the Gangetic Plain near the foot of EH, respectively. Despite low occurrence frequency, HP contributes importantly to the total rainfall, especially after the onset of South Asian summer monsoon. The coastal HP and inland HP are of opposite diurnal cycles, which peak in the early afternoon and midnight, respectively. Composite analyses are conducted for the synoptic circulation patterns using ERA5 reanalysis. The occurrence of HP is promoted by the moisture transport and uplifting of southwesterly boundary layer jet (BLJ) associated with an anomalous lower-tropospheric cyclonic circulation over BOB, which is dynamically induced by the excessive surface sensible heating (SH) over the Indian subcontinent. When the surface SH is enhanced in northwestern-central India, BLJ terminates near the northern coast of BOB, resulting in coastal-type HP. By contrast, when the enhanced surface SH mainly occurs in northwestern India, BLJ penetrates further northward to the foot of EH and thus produces inland HP. In the latter case, the interaction between BLJ and EH topography helps increase the water vapor convergence and dynamical lifting, leading to heavier precipitation than the former.

The impacts of the anthropogenic heat (AH) effect on the evolution of a merger‐formation bow echo over the Guangdong‐Hong Kong‐Macao Greater Bay Area are documented. The utilization of radar data assimilation greatly improves the simulated results comparing against observations, strengthening the robustness of analyses in this work. The simulation with AH effect produces the most accurate results compared to observations, exhibiting approximately 62% larger spatial extent of heavy rainfall (>30 mm) and twice the area of strong winds (>10.8 m s −1 ) compared to the non‐AH simulation. Additionally, the top 1% rain rates and surface winds from the AH‐included simulation are about 25% stronger and 23% greater, respectively, relative to the non‐AH counterpart. On the one hand, higher AH flux tends to enhance the values of convective available potential energy and vertical wind shear within urban areas on average, providing favorable thermodynamic environmental conditions for convective development. On the other hand, greater AH effect triggers stronger convective cell, leading to a more intense merged system. This cell plays a crucial role in the merger process and the formation of bow echo, but it does not persist sufficiently in the non‐AH simulation. A third sensitivity simulation, excluding the urban land cover, produces results comparable to those of the non‐AH simulation. This study quantifies the relative contribution of the AH effect to the evolution of convective systems and the associated weather‐related hazards over the Greater Bay Area, underscoring the significant impacts of AH forcing on the regional flow patterns and the corresponding convection dynamics.

Summer precipitation over the Tibetan Plateau (TP) significantly affects the regional and global climate. In this paper, the orographic gravity wave drag (OGWD) parameterization is revised by incorporating the moisture effect of saturated air into the Weather Research and Forecasting model. Seasonal simulations are performed for the summer rainfall over the TP during 2003–2023 employing the original and modified OGWD schemes. The results indicate that the rainfall and thus the wet biases over the southeastern TP are reduced when the moist OGWD scheme is employed. The moisture effect first enhances the lower-tropospheric OGWD over the Indian Peninsula, thereby weakening the low-level winds. The decrease in the horizontal wind speed leads to a reduction of the surface gravity wave momentum flux and thus the OGWD, which in turn strengthens the low-level flow. The latter process initiates intensification of the monsoon circulation over the Bay of Bengal (BOB). During mid-to-late summer, the monsoon circulation is continuously intensified through the circulation–precipitation interaction. The enhanced cyclonic circulation over the BOB induces an easterly flow to the south of the TP, which is opposed to the climatological southwesterly monsoon circulation. Therefore, the water vapor transport toward the TP is decreased.

The Northeast China cold vortex (NECV) is a major weather system producing heavy rainfall in northern China, yet the influence of complex terrain, especially orographic gravity waves (OGWs), on such heavy rainfall remains poorly understood. This study investigates the impact of OGW drag (OGWD) parameterization on an NECV heavy rainfall event over the southern Yanshan Mountains on 6 July 2011, using the Weather Research and Forecasting Model at 3-km resolution. Results show that the OGWD parameterization can weaken the NECV circulation and diminish the orographic lifting and moisture transport over the southern slope of the Yanshan Mountains given the decelerated upslope flow. Therefore, the overestimation of the heavy rainfall intensity in the absence of OGWD parameterization was alleviated significantly, indicating the importance of OGWD parameterization even in high-resolution numerical models. However, the parameterization of OGWD introduced weak but widespread spurious rainfall ahead of the Taihang Mountains, as it decelerated the northwesterly downslope winds on the southeastern slope of the Taihang Mountains which enhanced the upslope moisture transport. This spurious rainfall was mitigated significantly when using a revised OGWD scheme accounting for the nonhydrostatic effect (NHE) on the surface momentum flux of vertically propagating OGWs. The NHE more notably attenuated the OGWD over the Taihang Mountains than over the Yanshan Mountains, which strengthened the NECV northwesterly flow downgliding the Taihang Mountains and inhibited the moisture transport.

The cold pole and westerly wind biases associated with an overly strong polar vortex are typical systematic biases in climate models, indicating the insufficient stratospheric wave drag. To investigate the effects of orographic gravity wave drag (OGWD) on the stratospheric atmospheric circulation, two sets of experiments are performed by the middle‐atmosphere version of Beijing Climate Center Atmospheric General Circulation Model, employing different OGWD parameterization schemes with and without the second‐order Wentzel‐Kramers‐Brillouin (WKB) corrections to the surface wave momentum flux (SWMF) caused by wind profile shear and curvature. In the simulation with the WKB‐corrected OGWD scheme, the cold pole bias is reduced up to 2°C, and the associated westerly wind bias diminishes up to 4 m s −1 , particularly during the austral winter. Changes in the SWMF can further affect the vertical transport of orographic gravity waves. The enhanced SWMF in the modified scheme transports more wave momentum flux upward. Consequently, more wave momentum flux is transported into the upper stratosphere, enhancing the wave breaking there. The OGWD‐induced meridional circulation is strengthened over Antarctic, contributing to the alleviation of the cold pole and westerly wind biases. In addition, the upward propagation of planetary Rossby waves in the mid‐high latitudes of the Southern Hemisphere is enhanced, which contributes to the reduction of the westerly wind biases of the polar vortex as well. Overall, the WKB‐corrected scheme is effective to alleviating the delayed breakdown of the polar vortex in Antarctica.