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Snowmelt Onset Time of High Mountain Asia over the Past Four Decades

A dataset of snowmelt onset time of High Mountain Asia over the past four decades is currently published at the National Tibetan Plateau Data Center (http://data.tpdc.ac.cn) and is freely available. Results related to the dataset are published in the paper entitled “Change of snow and ice melting time in High Mountain Asia” in Chinese Science Bulletin by Dr. XIONG Chuan (Southwest Jiaotong University), Prof. SHI Jiancheng (the Institute of Remote Sensing and Digital Earth of the Chinese Academy of Sciences) and other collaborators.

This dataset is the initial time of ice and snow melting in the high Asia region retrieved by using the satellite microwave radiometer and scatterometer observations from 1979 to 2018. The passive microwave remote sensing data are SMMR on satellite (1979-1987) and SSM / i-ssmis radiometer on DMSP (1988 present). The active microwave remote sensing data is the QuikSCAT satellite scatterometer (2000-2009).

High Asia is very sensitive to climate change, and is a hot area of global change research. The changes of temperature and precipitation will be reflected in the freezing and thawing time of ice and snow. Satellite microwave remote sensing can provide continuous monitoring ability of ice and snow surface state in time and space. When a small part of ice and snow begins to melt, micro liquid water will also be reflected in active and passive microwave remote sensing signals. In the microwave band, the dielectric constant of ice and liquid water is very different, so it provides a basic theory for the microwave remote sensing monitoring of ice and snow melting. In the case of passive microwave, when ice and snow begin to melt and liquid water appears, its absorption and emissivity increase rapidly, so its emissivity, brightness temperature and backscatter coefficient will also change rapidly.

The analysis of the time-series average snowmelt time shows that most of the regions in high Asia have an earlier trend, but only the Karakorum Mountains and some parts of the West Karakorum Mountains remain relatively stable or even have a certain delayed trend. By analyzing the relationship between elevation and the rate of change in melt time, it is found that the rate of change is positively correlated with the elevation, i.e., the negative rate of change is basically at the lower elevation. This suggests that the lower elevations are more susceptible to the effects of climate change and have an earlier onset of snowmelt, while the higher elevations have a more stable or even slightly delayed melting time. The data can support researches on climate change in high Asia and its impact on the high Asian cryosphere, and provide a better understanding of the temporal and spatial trends and characteristics of environmental change in the high Asia.

Snowmelt onset time of High Mountain Asia in 2000

This study was supported by the Second Tibetan Plateau Scientific Expedition and Research program (2019QZKK0206) and the National Natural Science Foundation of China (41871266), and other projects.

Link to data and articles:

https://data.tpdc.ac.cn/en/data/01be1b50-d9b6-4189-8aa0-9e005514b6d1/

Citations:

1. Xiong, C., Shi, J., Cui, Y., & Peng, B. (2017). Snowmelt Pattern Over High-Mountain Asia Detected From Active and Passive Microwave Remote Sensing. IEEE Geoscience and Remote Sensing Letters, 14, 1096–1100. doi: 10.1109/LGRS.2017.2698448( View Details | Bibtex)

2. Xiong, C., Yao, R.Z., Shi, J.C., Lei, Y.H., Pan, J.M. (2019). Change of snow and ice melting time in High Mountain Asia. Chinese Science Bulletin, 64(27), 2885-2893. (in Chinese)( View Details | Bibtex)