MODIS-based Daily Lake Ice Extent and Coverage Dataset for Tibetan Plateau
datasetposted on 12.06.2019, 00:00 by Y. (Yubao) Qiu, Pengfei Xie, M. (Matti) Leppäranta, X. (Xingxing) Wang, Juha Lemmetyinen, H. (Hui) Lin, L. (Lijuan) Shi
The Tibetan Plateau houses numerous lakes, the phenology and duration of lake ice in this region are sensitive to regional and global climate change, and as such are used as key indicators in climate change research, particularly in environment change comparison studies for the Earth three poles. However, due to its harsh natural environment and sparse population, there is a lack of conventional in situ measurement on lake ice phenology. The Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Snow Index (NDSI) data, which can be traced back 20 years with a 500m resolution, was used to monitor lake ice for filling the observation gaps. Daily lake ice extent and coverage under clear sky conditions was examined by employing the conventional SNOWMAP algorithm, and those under cloud cover conditions were re-determined using the temporal and spatial continuity of lake surface conditions through a series of steps. Through time series analysis of every single lake with size greater than 3 km2, 308 lakes within the Tibetan Plateau were identified as the effective records of lake ice extent and coverage to form the Daily Lake Ice Extent and Coverage dataset, including 216 lakes that can be further retrieved with four determinable lake ice parameters: Freeze-up Start (FUS), Freeze-up End (FUE), Break-up Start (BUS), and Break-up End (BUE), and 92 lakes with two parameters, FUS and BUE. The data set contains 5,834 raster files, one vector file and 308 Excel files. The raster file is named Daily Lake Ice Extent. The vector file contains such information as the series number, name, location, surface area and classification number of the processed lake. The names of the excel files correspond to lake numbers. Each excel file contains six columns with the daily lake ice coverage information of its corresponding lake from July 2002 to June 2018. The attributes of each column are: succession, date, lake water coverage, lake ice coverage, cloud coverage, lake water coverage and lake ice coverage after cloud processing. Users can first use the vector file to determine the number, location and classification number of a given lake, and then obtain the corresponding daily lake ice coverage data for a given year from the Excel file to use for the monitoring of lake-ice freeze-thaw and research on climate change.