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Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Qinghai-Xizang Plateau， distinguished by its vast array of lakes， exhibits marked seasonal lake ice coverage， which is highly responsive to climatic shifts.This ice coverage plays a crucial role in the dynamic interchange of fluxes between the lake surfaces and the atmosphere.Despite the significance of these ice phenomena， the limited availability of extensive， long-term observational data on plateau lake ice has led to a reliance on reanalyzed ice datasets， particularly ERA5-Land.This study aims to rigorously evaluate the effectiveness and potential enhancements of ERA5-Land's lake ice data in the distinct environment of the Qinghai-Xizang Plateau.Focusing on data collected from 2010 to 2022 for Qinghai Lake and Ngoring Lake， this research meticulously examines the ERA5-Land reanalysis data's ability to accurately capture the intrinsic characteristics of plateau lake ice.The study uncovered that ERA5-Land tends to overestimate the ice thickness by about 0.54~0.62 m and erroneously prolongs the freezing period by roughly 68 days per year for these lakes.This notable discrepancy necessitated an in-depth error analysis， which synthesized ERA5-Land data with direct observational data from Ngoring Lake， revealing that inaccuracies primarily originated from the FLake one-dimensional lake model within the ERA5-Land system.In an effort to address these inaccuracies， the study employed the MCD43A3 surface albedo product for both Qinghai Lake and Ngoring Lake over the same period.This innovative approach significantly refined the FLake model by incorporating both a multi-year average albedo and a dynamic daily average albedo.These methodological improvements led to a substantial reduction in the average bias of ice thickness， by 85% and 90% respectively， and narrowed the deviation in the modeled freezing period by about 6 and 8 days per year.The enhancements were particularly notable in lakes with longer periods of snow cover， where the dynamic albedo adjustment proved to be highly effective.This research has successfully identified the albedo parameter within the FLake model as a key source of error in ERA5-Land's lake ice characterizations and has implemented practical adjustments to rectify this.These enhancements have markedly increased the model's precision in simulating lake ice， thereby significantly improving the accuracy of ERA5-Land reanalyzed lake ice data.This advancement is particularly pertinent for the unique climatic and geographical conditions of Qinghai Lake and Ngoring Lake on the Qinghai-Xizang Plateau and offers invaluable insights for future research and practical applications in this domain.The findings of this study contribute profoundly to our understanding and modeling of lake ice phenomena in high-altitude regions and have broader implications for climatological research and environmental monitoring on the Qinghai-Xizang Plateau.

Phenological changes are of great significance to the study of climate response and ecological environment.Based on the MODIS V6 snow product and reflectivity product in the past 20 years， the snow and lake ice phenology in the Qinghai Lake Basin were obtained， and the spatial distribution characteristics of the two were analyzed.On this basis， Theil-Sen Median method and linear regression method were used to analyze the variation trend of snow phenology and lake ice phenology， as well as the correlation between them in low altitude areas.The results show that： （1） Freeze-up start， Break-up start and Exist Duration of lake ice in Qinghai Lake are in the range of 321~389 d， 425~464 d and 0~174 d， respectively.On the whole， Freeze-up start and Break-up start of lake ice were delayed， and the delay rates were 0.3 d·a-1 and 0.2 d·a-1， respectively.Exist Duration of lake ice showed a shortening trend， with a shortening rate of 0.6 d·a-1.There is a significant correlation between lake ice phenology and longitude.From east to west， Freeze-up start is postponed， Break-up start is advanced， and Exist Duration of lake ice is shortened.（2） Start of snow cover days， End of snow cover days and Snow cover days in Qinghai Lake Basin are distributed in the range of 275~404 d， 353~484 d and 3~209 d， respectively.Among them， start of snow cover days and End of snow cover days showed an early trend and a delayed trend respectively， and the change rates were 0.8 d·a-1 and 0.11 d·a-1 respectively.Snow cover days showed an increasing trend， with a growth rate of 0.6 d·a-1.Snow phenology is closely related to altitude.With the increase of altitude， start of snow cover days is advanced， End of snow cover days is delayed， and Snow cover days increases.（3） Air temperature and negative accumulated temperature in winter are important factors affecting lake ice phenology.With the increase of temperature and negative accumulated temperature in winter， Freeze-up start will be delayed， Break-up start will be advanced， and Exist Duration of lake ice will be shortened.For snow phenology， there is a significant negative correlation between Snow cover days and the temperature.The temperature decreases and Snow cover days increases.（4） There is a potential relationship between some snow cover and lake ice phenology parameters in low-altitude watersheds.There is a significant negative correlation between the beginning date of snow cover and the beginning date of lake ice freezing， and the correlation coefficient is -0.404.As the lake surface insulation layer， the increase of snow cover days will also greatly slow down the speed of lake ice melting， resulting in the delay of lake ice melting date.Therefore， there is a positive correlation between the two， and the correlation coefficient is 0.349.The change law of ecosystem in the basin revealed by this study is of positive significance to the local ecosystem， and can provide theoretical basis and technical support for the environmental monitoring of Qinghai Lake Basin.

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate changes in ice thickness, ice temperature, and ice phenology characteristics in Lake Ulansu under the influence of climate warming, the complete process of ice formation and melting of Lake Ulansu from 2015 to 2016 was simulated using the HIGHTSI model. We used the ERA5-Land and MERRA-2 reanalysis data sets for atmospheric forcing, which were combined with initial simulation data obtained from multisource satellite remote sensing images. It was found that: ① During the study period, the maximum ice thickness was up to 41. 7 cm, with freeze- up start and break- up end dates of November 21, 2015 and March 25, 2016, respectively, and an ice cover duration of 126 d. ② For Lake Ulansu, which had a shallow water depth and sufficient winter sunshine, air temperature was the main factor affecting ice thickness, followed by solar radiation, and the diurnal cycles of the two significantly affecting the thickness and temperature of the ice layer. However, when the ice was covered with snow, the influence of air temperature and solar radiation on the ice layer was significantly weakened due to the low thermal conductivity and high albedo of snow. ③ Even in the absence of field observation data, the use of meteorological data and initial simulation data derived from remote sensing could still be used to characterize the complete evolution of real snow and ice in the field accurately. This study provided the foundation for the calculation of seasonal ice cover on shallow lake ice in midlatitude arid regions and for investigations of interannual variations in lake ice formation and melting. [ABSTRACT FROM AUTHOR]

Many lakes are widely and densely distributed on the Qinghai-Tibet Plateau.Due to the high altitude， the lakes seasonally freeze with a long ice-covered period.Lake ice can significantly affect the local and regional climate and the sub-glacial aquatic ecosystem by changing the transfer process of radiation energy on and in the lakes.However， their characteristics during the ice-covered period still remain unclear.Therefore， from February 6 to 28， 2022， we conducted a systematic observation of water ice air in Qinghai Lake， the largest lake on the Qinghai-Tibet Plateau.Using field observation data， video images and the precipitation data of peripheral observation stations， the influence of different ice cover conditions on the radiation and temperature of the water-ice-atmosphere on Qinghai Lake during the ice-covered period was analyzed.Results showed that different weather processes such as snowfall， sand and gale could remarkably change the property of cover on the ice， leading to variations of ice thickness on Qinghai Lake.Furthermore， the discrepancies of solar radiation absorption and reflection of different covers result in energy equilibrium that directly dictate ice surface temperature at water-ice-atmosphere interface.Bare ice with low albedo and low absorption induced the relatively strong net solar radiation and the correspondingly large diurnal variations of ice temperature.Compared to bare ice， the high reflection of snow cover and the strong absorption of sand and dust make the ability of net short-wave radiation to penetrate ice weaker， and the diurnal variation of lake ice temperature is smaller.

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)