The interdecadal change of the summer (July–August) rainfall over North China (SRNC) is of great concern to the climate research community. Based on the sliding correlation and interdecadal difference analysis, the interdecadal change of SRNC was studied. Results show a significantly wetter period of SRNC since the mid-2000s, which was associated with strengthening negative relationship between SRNC and PDO. PDO affected the SRNC through the jet stream in the upper-level and the East Asia–Pacific (EAP) teleconnection pattern. In the negative phase of the PDO since the mid-2000s, the contractive upper-level jet stream in the west of North China resulted in the abnormal updraft over the southern region of North China. Meanwhile, the positive phase of the EAP teleconnection pattern brought warm and wet southeast flow entering North China from its eastern boundary, both bringing more rainfall in North China. The abnormal water vapor transport from the western Pacific was very different from that accompanying the East Asian summer monsoon.

The impact on the Gulf Stream and Kuroshio from Arctic sea ice loss is investigated using the Community Climate System Model version 4 (CCSM4) model for their important roles during climate change. Results show that the Gulf Stream (Kuroshio) weakens (strengthens) in response to Arctic sea ice loss via ocean (atmosphere) adjustments. More precisely, the Kuroshio acceleration is mainly due to the anomalous wind stress over the North Pacific, while the ocean gyre adjustments in the Atlantic are responsible for the weakened Gulf Stream. As positive buoyancy fluxes induced by Arctic sea ice loss trigger a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), the Gulf Stream decelerates evidently and the current speed decreases by about 5–8 cm/s in the upper ocean. Resulting from less advection and horizontal diffusion in the temperature budget, less poleward warm water leads to narrow sea surface cooling sandwiched between strong warming in the subpolar and subtropical Atlantic. Furthermore, colder surface decreases the upward heat flux (mainly latent heat flux) along the Gulf Stream Extension (GE) path, which leads to a warming hole in the atmosphere.

With global warming, extreme high temperatures become more frequent and are an important factor affecting aircrafts’ takeoff performance. Using Community Earth System Model version 1 (CESM1) and Boeing Performance Software (BPS), the influence of increasing temperature on aircrafts’ maximum takeoff weight (MTOW) and takeoff distance is evaluated quantitatively in this study. The results show that the distribution of summer daily maximum temperature shifts obviously to higher temperature at all the chosen airports and the variation in temperature is larger at four airports (Jinan, Shanghai, Lhasa, and Urumqi) during 2071−2080 under the RCP8.5 scenario than that in the historical run (1991−2000). The warming air leads to the MTOW reducing and takeoff distance increasing. Taking the Boeing 737–800 aircraft as an illustration, the number of weight-restriction days increases significantly across the airports, which can influence airlines’ economic benefit and flight operations in the future. It is also found that the takeoff distance does not change linearly with temperature, but shows a stronger increase with higher temperature. The takeoff distance increases about 6.2% on average during 2071−2080 compared to 1991−2000 for the low-altitude airports, calling for an additional 113−222 m takeoff distance in future summers.

The jet stream is a primary factor contributing to turbulence, especially for upper-level aircraft. This study utilized pilot reports and ERA5 data from 2023 to investigate the relationship between upper-level turbulence and the East Asian westerly jet (EAJ). The results indicate that approximately 45.9% of upper-level aircraft turbulence occurs within the jet stream, with the lowest proportion in August and the highest in January. Additionally, the strongest vertical wind shear (VMS) is found concentrated in the lower part of the jet stream core, particularly in the South–Down part of the jet stream, where upper-level aircraft turbulence occurs most frequently (27.1%). The most turbulent area is located between 30–40° N and 110–120° E, with the main air routes experiencing turbulence being the Henan sections of G212 and B208. From a seasonal perspective, there is less frequent occurrence of upper-level aircraft turbulence in summer and autumn but more in winter and spring. The EAJ volume increases with the strengthening of the jet core wind speed, with the jet core regions being most distinct at altitudes of 200~300 hPa. Meanwhile, the jet stream intensity index peaks at 70.6 m/s in January and reaches its lowest value of 7.1 m/s in August. The jet stream axis shifts southward in winter and northward in summer, reaching the southernmost position in December at 32.2° N and the northernmost position in August at 43.5° N. Furthermore, the VMS at turbulence points within the jet stream is higher than that at the turbulence points outside the jet stream, and the Richardson number (RI) is lower. Moreover, the temporal distribution of upper-level aircraft turbulence is primarily determined by the location and intensity of the jet stream, of which the jet stream intensity index provides guidance and thus serves as a reliable indicator.

The southwest vortex (SWV), a low-pressure system bringing severe rainfall in southwest China, is one of the most important synoptic systems in China. Using both the National Centers for Environmental Prediction Final (NCEP-FNL) operational global analysis dataset and the Weather Research and Forecasting (WRF) model simulation, a sophisticated SWV with dual-core structure (DCSWV) over the Sichuan Basin in 2010 was studied. The DCSWV system consisted of two cores, one near Leshan City (named “C1”) and another near Langzhong City (named “C2”). The high-resolution WRF model reproduced the life cycle of the DCSWV well. The diagnostic analysis of the vorticity budget indicated that the stretching and tilting terms played important roles in the development stage of “C1”, while the stretching and vertical advection of vorticity were the major contributors to the formation and development stage of “C2”, which implied the importance of moisture convergence and ascending motion. Sensitivity experiments showed that the DCSWV was closely associated with the release in latent heat as well as the effect of topography. The great release in latent heat provided significantly positive feedback to the DCSWV system, which was decisive to the formation and development stages of “C2”. The topography of the Tibetan Plateau and the Yun-Gui Plateau affected the location and duration of the DCSWV.