In August 2018, a remarkable polynya was observed off the north coast of Greenland, a perennial ice zone where thick sea ice cover persists. In order to investigate the formation process of this polynya, satellite observations, a coupled iceocean model, ocean profiling data, and atmosphere reanalysis data were applied. We found that the thinnest sea ice cover in August since 1978(mean value of 1.1 m, compared to the average value of 2.8 m during 1978-2017) and the modest southerly wind caused by a positive North Atlantic Oscillation(mean value of 0.82, compared to the climatological value of-0.02) were responsible for the formation and maintenance of this polynya. The opening mechanism of this polynya differs from the one formed in February 2018 in the same area caused by persistent anomalously high wind. Sea ice drift patterns have become more responsive to the atmospheric forcing due to thinning of sea ice cover in this region. 相似文献
It has been over a hundred years since the birth of research on Chinese geosciences history, which was accompanied by the continuous progress of Chinese geosciences. For hundreds of years, it has grown out of nothing to brilliant performance by several generations of Chinese geologists committing their hearts and minds with the spirit of exert and strive without stop to promote the process of China's industrialization and to produce the significant impact on serving the society. The study of Chinese geosciences history reflects objectively and historically the history of geosciences in China, which has recorded, analyzed and evaluated the dynamic process sitting in the background and clue of the history of Chinese geosciences development. The study of the history of geological science has roughly experienced two stages in China. The first stage is the study of individual researchers. It spanned approximately 70 years from the early 20th century to the end of the 1970s. The research contents were mainly based on the evolution of geological organizations, the development and utilization of individual mineral species, the history of deposit discovery and the research of geological characters. The main representatives are Zhang Hongzhao, Ding Wenjiang, Weng Wenhao and Li Siguang, Ye Liangfu, Huang Jiqing, Yang Zhongjian, Xie Jiarong, Gao Zhenxi, Wang Bingzhang and etc. The most prominent feature of this period is the accumulation of a very valuable document for the study of the history of China's geological history and lays a foundation for the exchange of geological science between China and foreign countries. The second stage is organized group study. It took around 60 years from the 1920s to 1980s. It includes the history of Chinese geology, the history of geological organizations, the history of geological disciplines, the history of geological education, the history of geological philosophy, the history of Chinese and foreign geological science communication, the history of geologists and etc. The most chief feature of this stage is the birth of academic research institute―the establishment of the Commission on the History of Geology of the Geological Society of China. 相似文献
Carbon dioxide (CO2) is an important greenhouse gas that influences regional climate through disturbing the earth’s energy balance. The CO2 concentrations are usually prescribed homogenously in most climate models and the spatiotemporal variations of CO2 are neglected. To address this issue, a regional climate model (RegCM4) is modified to investigate the non-homogeneous distribution of CO2 and its effects on regional longwave radiation flux and temperature in East Asia. One-year simulation is performed with prescribed surface CO2 fluxes that include fossil fuel emission, biomass burning, air–sea exchange, and terrestrial biosphere flux. Two numerical experiments (one using constant prescribed CO2 concentrations in the radiation scheme and the other using the simulated CO2 concentrations that are spatially non-homogeneous) are conducted to assess the impact of non-homogeneous CO2 on the regional longwave radiation flux and temperature. Comparison of CO2 concentrations from the model with the observations from the GLOBALVIEW-CO2 network suggests that the model can well capture the spatiotemporal patterns of CO2 concentrations. Generally, high CO2 mixing ratios appear in the heavily industrialized eastern China in cold seasons, which probably relates to intensive human activities. The accommodation of non-homogeneous CO2 concentrations in the radiative transfer scheme leads to an annual mean change of–0.12 W m–2 in total sky surface upward longwave flux in East Asia. The experiment with non-homogeneous CO2 tends to yield a warmer lower troposphere. Surface temperature exhibits a maximum difference in summertime, ranging from–4.18 K to 3.88 K, when compared to its homogeneous counterpart. Our results indicate that the spatial and temporal distributions of CO2 have a considerable impact on regional longwave radiation flux and temperature, and should be taken into account in future climate modeling. 相似文献
We conduct several experiments using a fully-coupled climate model to understand the role of Tibetan Plateau (TP) surface heating in the climate variations over West Asia, South Europe, North Africa, and the North Atlantic during summer. Emphasis has been placed on the physical processes and responsible mechanisms that involve the shift of the Hadley cell and the important features of rotational and divergent response of the atmosphere to the TP heating. The relative importance of the TP to the Asian continent is also analyzed. A heating of the TP surface leads to local increases in tropospheric temperature and the thickness of the air column due to the so-called air pumping effect. In the upper troposphere, the South Asian high intensifies and extends westward. To the west of TP, especially in West Asia, South Europe, North Africa, and the North Atlantic, distinguished Rossby wave responses to the TP heating occur with anomalous high pressure and uniform warming in the entire troposphere. Correspondingly, descending motions intensify and precipitation decreases. However, the tropical Sahel rainfall increases because of a northward shift of the Atlantic intertropical convergence zone and the anomalous westerlies due to the weakening of the southeastern portion of the Atlantic subtropical high. These effects of the TP heating explain a remarkable portion of the effects by the Asian continent heating. In addition, the impacts of different magnitudes of TP surface heating are also discussed.