ISSN 1006-9895

CN 11-1768/O4

Seasonal differences in the trend transition characteristics of the surface sensible heat on the central and eastern Tibetan Plateau
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    Abstract:

    In this paper, the Piecewise Linear Fitting Model (PLFIM) was used to analyze the seasonal differences of the Surface Sensible Heat (SSH) trend evolution characteristics at 70 meteorological stations on the Central and Eastern Tibetan Plateau (CETP) during1982-2018, and the key meteorological factors influencing the changes of the SSH in different seasons were quantitatively evaluated using the analysis of variance method. Results show that: (1) the seasonal average SSH fluxes in the CETP have a trend transition feature in all four seasons, as a whole, the trend transition time of autumn and winter is earlier (1999), and spring and summer is later (2000); regionally speaking, the turning time is earliest in Zone II (Eastern part of TP), followed by Zone IV (Southeastern part of TP) and Zone I (Northern part of TP), and the turning time is latest in Zone III (Southwestern part of TP). Before the trend transition time, the weakening of the SSH is most prominent in summer, followed by spring and autumn, and weakest in winter; after the trend transition time, the enhancement of the SSH is strongest in winter, and the enhancement trend is similar in other seasons. In winter and spring, the key areas for the trend transition of the SSH are in the eastern and southern of TP, respectively, while in summer and autumn, the key areas are mainly in Zone II and III. (2) Before the trend transition time, the decrease of the surface wind speed has an important contribution to the decreasing trend of the SSH in four seasons, but the interannual variation of the SSH in winter is dominated by the change of ground-air temperature difference; in spring and autumn are affected by both the variations of ground-air temperature difference and surface wind speed; and in summer is dominated by the surface wind speed. After the trend transition time, the increases of the surface wind speed and surface-air temperature difference in autumn and winter jointly lead to the trend turning of the SSH, but the interannual variation of the SSH is dominated by the variation of ground-air temperature difference; the increase of ground-air temperature difference in spring is the main cause of the trend turning of the SSH, and the ground-air temperature difference also plays a dominant role in the influence of the interannual variation of the SSH; the significant increase of surface wind speed in summer leads to the trend turning of the SSH, but the interannual variation of the SSH is affected by both the ground-air temperature difference and the surface wind speed.

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History
  • Received:February 04,2021
  • Revised:May 13,2021
  • Adopted:May 25,2021
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