Abstract
Lake ice, one of the most direct lake physical characteristics affected by climate change, can reflect small-scale environmental changes caused by the atmosphere and hydrology, as well as large-scale climate changes such as global warming. This study uses National Oceanic and Atmospheric Administration, Advanced Very High Resolution Radiometer (NOAA AVHRR), MOD09GQ surface reflectance products, and Landsat surface reflectance Tier 1 products, which comprehensively used RS and GIS technology to study lake ice phenology (LIP) and changes in Qinghai Lake. Over the past 38 years, freeze-up start and freeze-up end dates were gradually delayed by a rate of 0.16 d/a and 0.19 d/a, respectively, with a total delay by 6.08 d and 7.22 d. The dates of break-up start and break-up end showed advancing trends by −0.36 d/a and −0.42 d/a, respectively, which shifted them earlier by 13.68 d and 15.96 d. Overall, ice coverage duration, freeze duration, and complete freeze duration showed decreasing trends of −0.58 d/a, −0.60 d/a, and −0.52 d/a, respectively, and overall decreased by 22.04 d, 22.81 d, and 9.76 d between 1980 and 2018. The spatial pattern in the freeze–thaw of Qinghai Lake can be divided into two areas; the west of the lake area has similar spatial patterns of freezing and ablation, while, in the east of the lake area, freezing and ablation patterns are opposite. Climate factors were closely related to LIP, especially the accumulated freezing degree-day (AFDD) from October to April of the following year. Furthermore, freeze-up start time was more sensitive to changes in wind speed and precipitation.
Highlights
Lakes, as an important component of the terrestrial hydrosphere, are the bonds connecting the cryosphere, atmosphere, hydrosphere, and biosphere of the earth’s surface system
According to the results from the same period of extraction based on the AVHRR and MODIS data, we introduced the mean absolute error (MAE) and relative error (RE) to compare and in the same year
According to the results from the same period of extraction based on the AVHRR and MODIS data, we introduced the mean absolute error (MAE) and relative error (RE) to compare and analyze these results [39], as shown in Table 3 and Figure 5
Summary
As an important component of the terrestrial hydrosphere, are the bonds connecting the cryosphere, atmosphere, hydrosphere, and biosphere of the earth’s surface system. Lake periodic formation and decay of ice cover and the changes in its timing as a result of seasonal and interannual variations in climate are called lake ice phenology (LIP) [1]. The LIP is strongly influenced by variations in the air temperature, while consistent long-term records of lake ice change provide a sensitive climate change indicator [3,4,5]. Studies have shown that lake ecosystems with periodic temperatures below 0 ◦C in the northern hemisphere are very sensitive to climate change [6]. The duration of lake ice cover on most lakes in the northern hemisphere showed a rapid shortening trend from 2002 to 2015, and similar changes were more obvious and widespread in lakes at higher latitudes [9]. When a large air mass passes over the Laurentian Great Lakes in North America in winter, the warmer water surface and the lakeshore results in the formation of lake effect snow systems that can result in significant snowfall events [16]
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