Monitoring the Ice Phenology of Qinghai Lake from 1980 to 2018 Using Multisource Remote Sensing Data and Google Earth Engine

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.

Impact of Meteorological Factors on Thermokarst Lake Changes in the Beilu River Basin, Qinghai-Tibet Plateau, China (2000–2016)

“…It was also inferred that the increase in the area of the single selected thermokarst lake mainly depended on the increasing thawing speed caused by high wind speed, and the thawing of ice-rich permafrost and massive ice near the selected thermokarst lake [38]. According to the literature [39], we inferred that wind speed greatly affects the freezing and thawing processes of the thermokarst lakes. The changes in wind speed make the newly appeared ice layer disappear, leading to the repeated freezing-thawing phenomena in the freezing process of the lakes.…”

Recent Ice Trends in Swiss Mountain Lakes: 20-year Analysis of MODIS Imagery

“…They reported that the FUS, FUE, BUS, BUE, CFD and ICD shifted on average by 0.73, 0.34, −1.66, −0.81, −1.91, −2.21 d/a respectively. Qi et al (2020) used AVHRR, MODIS, and Landsat data to extract the LIP of Qinghai lake (China, area of 4294 km 2 ) for the period 1980-2018. They estimated a shift of 0.16, 0.19, −0.36, and −0.42 d/a for FUS, FUE, BUS and BUE respectively, also pointing towards progressively later freeze-up and earlier break-up.…”

“…1 and Table B.8 (Appendix B). While most of the earlier works (Gou et al, 2015;Qi et al, 2019Qi et al, , 2020Yao et al, 2016) on long time-series monitoring of lake ice with MODIS concentrated on larger lakes, many lakes that freeze are actually small-or medium-sized mountain lakes, especially outside the (sub-)Arctic regions. The lakes we analyse are relatively small in area (0.78 -11.3 km 2 ), representative for this category.…”

Variation in Ice Phenology of Large Lakes over the Northern Hemisphere Based on Passive Microwave Remote Sensing Data

“…Previous studies have documented significantly earlier ice break-up dates and decreasing ice duration since the 1950s at the hemispheric scale [11,12], and in many typical regions such as in the pan-Arctic [4,[13][14][15][16] and the Tibetan Plateau [17][18][19][20][21][22]. The earlier ice break-up dates and decreasing ice durations lead to the increase in spring meltwater and runoff and, subsequently, to changes to the global hydrological cycle.…”