Search

Lake surface water temperature (LSWT) has significantly increased over China and even globally in recent decades due to climate change. However, the responses of LSWTs to climate warming in various climatic regions remain unclear due to the limited lake observations. Satellite-observed LSWT data from the Moderate Resolution Imaging Spectroradiometer (MODIS) dataset were extended using the air2water model. This research aimed to investigate summer LSWT trends across various climatic zones in China, shedding light on the complex interplay between surface air temperatures and LSWT from 1950 to 2020. The results demonstrate robust model performance, with high Nash–Sutcliffe efficiency coefficients, affirming its capability to simulate LSWT variability. Regional disparities in LSWT patterns are identified, revealing notable warming trends in dryland lakes, particularly in central Inner Mongolia. Notably, the study unveils a substantial increase in the intensity and duration of lake heatwaves, especially in semi-arid regions. Dryland lake heatwaves emerge as dominant contributors to intensified LSWT warming, showcasing stronger and longer-lasting events than humid regions. The research highlights a positive feedback loop between lake warming and heatwaves, further amplifying dryland LSWT warming. These findings underscore the vulnerability of dryland lakes to climate change and signal the potential ramifications of increased greenhouse gas concentrations. [ABSTRACT FROM AUTHOR]

This paper reviews the three-pattern decomposition of global atmospheric circulation (3P-DGAC) developed in recent years, including the decomposition model and the dynamical equations of global horizontal, meridional, and zonal circulations. Compared with the traditional two-dimensional (2D) circulation decomposition method, the 3P-DGAC can effectively decompose the actual vertical vorticity into two components that are caused by the horizontal circulation and convergent/divergent movement (associated with the meridional and zonal circulations). It also decomposes the vertical velocity into the components of the meridional vertical circulation and the zonal vertical circulation, thus providing a new method to study the dynamical influences of convergent/divergent motions on the evolution of actual vertical vorticity and an accurate description of local vertical circulations. The 3P-DGAC is a three-dimensional (3D) circulation decomposition method based on the main characteristics of the actual atmospheric movements. The horizontal, meridional, and zonal circulations after the 3P-DGAC are the global generalization of Rossby waves in the middle-high latitudes and Hadley and Walker circulations in low latitudes. Therefore, the three-pattern decomposition model and its dynamical equations provide novel theoretical tools for studying complex interactions between middle-high and low latitude circulations as well as the physical mechanisms of the abnormal evolution of large-scale atmospheric circulations under the background of global warming. [ABSTRACT FROM AUTHOR]

China was hit by extreme precipitation in July and August of 2021 along with significant monthly variation. The positive precipitation anomalies observed in July were mainly located in eastern China, but these anomalies shifted to the middle and lower reaches of the Yangtze River (MLYR) in August. In this study, we investigated the July and August precipitation anomaly dynamics based on the three-pattern decomposition of global atmospheric circulation (3P-DGAC) method. The results showed that the mid-latitude zonal circulation played a dominant role in July 2021, causing anomalous positive relative vorticity advection over the center of the positive precipitation anomalies, thus providing strong convective activity for the anomalous precipitation. Nevertheless, the August anomalies could be better explained from a climate perspective. The anomalous relative vorticity distribution patterns recorded in August were often accompanied by extreme precipitation in the MLYR, and the negative relative vorticity anomalies identified in Northeast Asia also played a crucial role. In conclusion, the mechanisms of precipitation anomalies in July and August 2021 were almost completely disparate. In this study, we emphasized the role of the mid-latitude zonal circulation in extreme precipitation events, and suggested that the impact of mid-latitude zonal circulation will be further accentuated under global warming. • China was hit by extreme precipitation event in July and August of 2021. • A new method of global atmospheric circulation was used to study dynamic mechanism. • The mid-latitude zonal circulation played a vital role in this extreme event. [ABSTRACT FROM AUTHOR]

Lake surface water temperature (LSWT) is sensitive to climate change. Previous studies have found that LSWT warming is occurring on a global scale and is expected to continue in the future. Recently, new global LSWT data products have been generated using satellite remote sensing, which provides an inimitable opportunity to study the LSWT response to global warming. Based on the satellite observations, we found that the warming rate of global lakes is uneven, with apparent regional differences. Indeed, comparing the LSWT warming in different climate zones (from arid to humid), the lakes in drylands experienced more significant warming (0.28 °C decade−1) than those in semi-humid and humid regions (0.19 °C decade−1) during previous decades (1995–2016). By further quantifying the impact factors, it showed that the LSWT warming is attributed to air temperature (74.4%), evaporation (4.1%), wind (9.9%), cloudiness (4.3%), net shortwave (3.1%), and net longwave (4.0%) over the lake surface. Air temperature is the main driving force for the warming of most global lakes, so the first estimate quantification of future LSWT trends can be determined from air temperature projections. By the end of the 21st century, the summer air temperature would warm up to 1.0 °C (SSP1-2.6) and 6.3 °C (SSP5-8.5) over lakes, with a more significant warming trend over the dryland lakes. Combined with their higher warming sensitivity, the excess summer LSWT warming in drylands is expected to continue, which is of great significance because of their high relevance in these water-limited regions. [ABSTRACT FROM AUTHOR]