The navigation and positioning subsystem offers important position information for an autonomous underwater vehicle (AUV) system. It plays a crucial role during the underwater exploration and operations of AUV. Many scholars research underwater navigation and positioning. Various improved methods and systems were presented. However, as the diversity of the ocean environment, the random drift of the gyroscope, error accumulation, the variety of tasks, and other negative factors, the navigation and positioning results are uncertain and incredible. The accuracy, stability, and robustness are not guaranteed, which cannot meet the increasing application requirement. Therefore, we put forward a SINS/DVL/USBL integrated navigation and positioning IoT system with multiple resource fusion and a federated Kalman filter. In this method, we first present an improved SINS/DVL combined subsystem with a filtering gain compensation strategy. So we can enhance the accuracy and stability of the navigation and position system. Secondly, we proposed a USBL positioning subsystem with the Kalman filtering acoustic signals to improve USBL positioning performance. Lastly, we present a federated Kalman filter to fuse the positioning information from the SINS/DVL combined positioning subsystem and the USBL positioning subsystem. Through the three methods, we can enhance the positioning accuracy and robustness. Comprehensive simulation results indicated the feasibility and effectiveness of the proposed SINS/DVL/USBL integrated navigation and positioning system, which provides critical reference for other positioning method, and it also offers crucial position information for AUV to achieve high accuracy and efficiency tasks.

This study analyzes the spatial and temporal distribution characteristics of the in situ aircraft observations in the middle and higher troposphere in 2019. These aircraft observations are mainly distributed in China, and relatively evenly recorded between 0000 and 1500 UTC in time and 6 and 10 km in height. Based on the 3395 stronger clear-air turbulence (CAT) events and 4038 weaker CAT events selected from the observations in the study region (15°–55°N, 70°–140°E), the performances of 24 CAT diagnostics calculated from the ERA5 data are evaluated. Results show that the diagnostics connected with vertical wind shear (i.e., version 1 of the North Carolina State University index, negative Richardson number, variant 3 and variant 1 of Ellrod’s turbulence index) have the best performances. However, the performances vary greatly from season to season, and overall performances are the best in winter and worst in summer. The annual and seasonal best thresholds for these diagnostics are also listed in this study.

On 13 November 2019, seven commercial aircraft of China Eastern Airlines encountered nine severe-or-greater clear-air turbulence (CAT) events over central and eastern China within 12 h (0000–1200 UTC). These events mainly occurred at altitudes between 6.0 and 6.7 km. A high-resolution nested numerical simulation is carried out using the Weather Research and Forecasting (WRF) Model to investigate the generation mechanism of these CAT events, with a horizontal resolution of 1 km over the inner domain. In addition, seven CAT diagnostics with outstanding performances are employed for the mechanism analysis. The WRF Model can reasonably reproduce both synoptic-scale systems (Siberian high and upper-level jet stream) and local vertical structures (temperature, dewpoint temperature, and wind field). The simulation indicates that an upper-level front–jet system with a remarkable meridional temperature gradient intensifies over central and eastern China, with the maximum wind speed increasing from 59.0 to 67.3 m s⁻¹. The intensification of the front–jet system induces the tropopause folding, and nine localized CAT events occur in the region with large vertical wind shear (VWS) (1.55 × 10⁻²–2.53 × 10⁻² s⁻¹) and small Richardson numbers (Ri) (0.42–0.85) below the cyclonic side of the jet stream. Diagnostic analysis reveals that Kelvin–Helmholtz instability plays an important role in CAT generation, while convective and inertial instability is not directly associated with CAT generation in this study. A typical flight case with continuous CAT events also suggests that large VWS (greater than 1.3 × 10⁻² s⁻¹) accompanied with small Ri (less than 1) favors CAT generation in a front–jet system environment. Significance Statement: A high-resolution nested numerical simulation is carried out using the Weather Research and Forecasting (WRF) Model to investigate the generation mechanism of nine severe-or-greater clear-air turbulence (CAT) events over central and eastern China. Intensification of a front–jet system induces tropopause folding, and nine CAT events occur in the region with large vertical wind shear (greater than 1.55 × 10⁻² s⁻¹) and small Richardson numbers (less than 0.85) below the cyclonic side of the jet stream. Kelvin–Helmholtz instability plays an important role in the CAT generation, rather than convective and inertial instability.

East Antarctica has experienced significant positive temperature anomalies during winter 2018, with Zhongshan (ZS) station recording its highest winter average temperature since 2008 and fourth highest since its establishment in 1989. This study employs observational data and ERA5 reanalysis to diagnose the phenomenon, revealing that temperature anomalies at 300 hPa are mainly driven by advection and adiabatic processes, which is the second highest recorded from 2000 to 2020. However, diabatic process are significantly important at 700 hPa, being the third highest during the period. The reduction in sea ice, combined with enhanced sinking motion and increased sea‐air temperature difference, together contributes to the variations of diabatic heating. The increased precipitation, exceeding the historical average by 100% along the southwestern shore of Prydz Bay, further induces localized warming. The increased atmospheric pressure associated with the negative Southern Annular Mode phase is the primary cause influencing the advection, adiabatic, and diabatic processes.

During the 2018 Southern Hemisphere winter, a pronounced surface air temperature positive anomaly occurred over East Antarctica, with Zhongshan Station recording its highest winter‐mean air temperature since 2007. Combining in situ observations, satellite remote sensing, and reanalysis data sets, this study diagnoses the temperature anomalies across representative isobaric surfaces (975, 500, and 300 hPa). Results indicate that this phenomenon originates from the disturbances of zonal wave, which in turn triggers anomalous regional sea‐ice‐atmosphere coupling processes. Specifically, this disturbance excited a persistent high‐pressure ridge or blocking high over the South Indian Ocean, and then directed poleward heat and moisture transport, dominating lower‐tropospheric temperature anomalies. Moreover, anomalous offshore winds induced by the pressure anomaly, combined with warm‐moist air mass intrusion, accelerated thermodynamic‐dynamic sea ice retreat, thereby enhancing upward sensible and latent heat fluxes from the ocean. In the mid‐to‐upper troposphere, anomalous subsidence driven by pressure perturbations caused warming primarily through vertical warm advection and adiabatic heating, with secondary contributions from horizontal advection. This study reveals a cross‐sphere coupled dynamic‐thermodynamic mechanism linking upper‐level zonal wave anomalies to Antarctic surface temperature extremes.