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Wind speed is an important parameter reflecting the climate and environmental conditions on the Earth's surface. It is also a pivotal factor influencing wind energy, a renewable and clean energy source. The mechanisms exerting influence on the surface wind speed over China, which have been mentioned in previous studies, include the temperature difference between the high and low latitudes of China, surface drag force, and climatic factors such as the Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO), and El Niño-Southern Oscillation (ENSO). The Indian Ocean Dipole (IOD), which has attracted increasing attention during the past two decades, is an important climatic factor that exerts a significant influence on the climate and environment in the areas surrounding the Indian Ocean and globally. However, to date, it has not been reported whether the IOD is a climatic factor that significantly affects surface wind speed in China. Coastal South China is one of the most economically developed areas in China, and wind energy is becoming an important energy source in this area. An investigation of the relationship between the IOD and wind speed variations in coastal South China and their connecting mechanisms would contribute substantially to the understanding of the controlling mechanisms of climatic and environmental variations in coastal South China as well as to the planning of sustainable development in this area. Based on observations of surface wind speed in coastal South China, reanalysis data from the National Center of Environment Prediction (NCEP) and the National Center of Atmospheric Research (NCAR), research on the IOD over the last two decades, the effects of IOD activities on surface wind speed in coastal South China, and the controlling mechanisms were investigated using statistical analyses and atmospheric circulation variations. The results indicate that, regardless of the temporal or spatial scale, variations in the surface wind speed in coastal South China show significant positive correlations with the dipole mode index (DMI), which is a proxy for IOD activity. An increase in the DMI index (indicating a strengthening of IOD activity) corresponds to a decrease in the surface wind speed in coastal South China, and vice versa. This suggests that, in addition to the factors suggested in previous studies, which include the temperature difference between high and low latitudes, AO, PDO, and ENSO, IOD activity is also one of the most important factors affecting surface wind speed variation in coastal South China. The influence of IOD activity was weaker than that of the temperature difference between high and low latitudes. However, it played a more important role in the surface wind speed variation in this region than the AO, PDO, and ENSO. Strengthening of the IOD activity would enhance two anti-cyclones in the northwest Pacific and Bengal Bay, east of the Indian subcontinent, and, in turn, contribute to the reduction of surface wind speed variation in coastal South China. More serious global warming and increasing greenhouse gas emissions will further strengthen IOD activity in the future. Consequently, a greater decline in surface wind speed is expected in coastal South China, necessitating attention to sustainable wind energy use in this region.

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The Aeolian foredunes in the southern coast of China are records of paleoenvironmental changes for marine monsoon region. Intensive studies have been conducted to decipher their formation and paleoenvironmental implications in which chronology played a key role. However, robust dating results are still limited due to the scarcity of organic materials for radiocarbon and the limited application of quartz optically stimulated luminescence (OSL). Here, we collected 11 OSL samples and 140 grainsize samples from the Changle section with a thickness of 7 m from a coastal foredune in Fujian Province. The dating results indicated that the section spanned a time period from 0.32±0.04 ka (depth of 700 cm) to 0.18±0.02 ka (depth of 80 cm), after removal of age outliers. According to the OSL ages and sedimentary structural characteristics, the section could be divided into two stages, i.e. the stable accumulation period with an age range of 0.32–0.18 ka from the depth of 700 cm to 80 cm, and the activation period above the depth of 60 cm, at which the dune erosion was retained. The foredune development due to increased transport of dune sediment at the top part of the section was the result of recent human activities. Inside the foredunes, normal cross-bedding was generated by seasonal changes in wind direction. Seasonal changes in the wind direction were the primary cause for various sedimentary bedding within the dunes. [ABSTRACT FROM AUTHOR]

A series of convection‐permitting numerical experiments using the Weather Research and Forecasting Model with different model configurations are performed to investigate physical mechanisms governing convection initiation (CI) at the coast of South China (SC) during a warm‐sector heavy rainfall event occurred before the South China Sea (SCS) monsoon onset. The simulation results are more sensitive to initial state from the different reanalysis products than the microphysics schemes, horizontal resolutions, initialization time, and lateral boundary conditions with the variation examined. It is found that the speeds of easterly to southeasterly winds in the boundary layer (BL) over northern SCS determine the strength of horizontal convergence of the warm and moist airflows arriving at the coast. The mid‐tropospheric divergence over the west coastal areas of SC and its southwest upstream impact vertical motion of the mid‐to‐lower tropospheric southwesterly airflows when approaching the coast. Differences in such features of upstream airflows in the experiments lead to distinct temporal evolutions of BL dynamic lifting and temperature stratification in the mid‐to‐lower levels at the CI location, thus the level of free convection and convective available potential energy. The modeling evidence presented shows that the synoptic dynamic and thermodynamic characteristics of the upstream airflows in BL and mid‐to‐lower troposphere, with local modulation by the coastal mountains, play important roles in determining the time and location of CI, and the distribution and amount of rainfall. Studies on more cases are needed to gain more general and robust conclusions about physical mechanism governing the warm‐sector coastal CI. Key Points: The synoptic air flows have significant impacts on the time of coastal convection initiation (CI)The speed of the marine boundary layer easterly airflows from northern South China Sea plays a key role in determining the CI timeThe mid‐troposphere divergence belt over the CI region and its southwest upstream plays a relatively secondary role [ABSTRACT FROM AUTHOR]

The interdecadal changes in the diurnal cycle of summertime rainfall over coastal South China (CSC) were analyzed for the period of 1884–2018. The results revealed that rainfall intensity has increased with the decrease of occurrence frequency during both pre‐ and mid‐summer in the past 135 years. During the most recent 40 years, occurrence frequency and intensity of nocturnal rainfall, especially extreme rainfall, have substantially increased over CSC, whereas those of daytime extreme rainfall have decreased. Different increasing rates of near‐surface temperature over land and sea are the main contributors to the distinct trends of daytime and nocturnal extreme rainfall. During daytime, a higher increasing rate of near‐surface temperature over sea results in a smaller temperature gradient along the coast, leading to a less convective atmosphere. This negates the effect of increased air‐temperature over CSC in both pre‐ and mid‐summer. In contrast, during nighttime, a higher increasing rate of near‐surface temperature over sea results in a greater temperature gradient along the coast, leading to stronger low‐level offshore winds and more convective layers over coastal waters. During pre‐summer, the stronger nocturnal low‐level offshore winds meets the warm and moist monsoonal flows, substantially enhancing nocturnal extreme rainfall along the coast. In mid‐summer, more vigorous upward motions over coastal waters of CSC enhance convective activities during nighttime, which also lead to an intensification of nocturnal rainfall. The most significant increase and intensification of extreme rainfall is observed in western CSC during pre‐summer, where the land‐sea difference of near‐surface temperature is the greatest over CSC. Key Points: Diurnal cycle of rainfall over coastal South China during summertime from 1884 to 2018 were analyzedDifferent from the 135‐year trend, daytime and nocturnal rainfall, especially extreme rainfall, exhibits distinct trends during 1979–2018Different rates of near‐surface temperature over land and sea contribute to the distinct trends of daytime and nocturnal extreme rainfall [ABSTRACT FROM AUTHOR]

Abstract: The sediments in Lake Huguang Maar in coastal South China were previously thought to originate mainly from wind-blown dust transported from North China, such that the lake sediments recorded the varying strength of the Asian winter monsoon. An alternative explanation was that the local pyroclastic rocks supplied the lake sediments, but the actual contributions from the different sources remained unclear. Geochemical analyses including 87Sr/86Sr and 143Nd/144Nd and trace elements support the local pyroclastic rock as the dominant source: <22% of the total Sr in the lake sediments and ∼17% of the Nd arises from the distant source. Nb/Ta and Zr/Hf for the lake sediments are identical to those for the local rock but differ from the ratios for the wind-blown dust, and chondrite-normalized rare earth element patterns for the lake sediments are similar to those for the local rock and soil, but differ from those for the distant source. The sediments in Lake Huguang Maar are probably input into the lake through runoff and thus controlled by the hydrology of the lake. Wind-blown dust transported by the Asian winter monsoon from arid North China is only a minor contribution to the sediments. [Copyright &y& Elsevier]