Remote sensing-based bathymetry retrieval of supraglacial lakes on polar ice sheets using images from small optical satellite PlanetScope and ICESat-2 laser altimetry data
During the melt season,supraglacial lakes are widely distributed across polar ice sheets,storing large amounts of surface meltwater.When some of these supraglacial lakes rupture at the bottom,the released meltwater infiltrates ice sheets,affecting their movement and stability.Therefore,accurate bathymetry retrieval of supraglacial lakes and estimating the volume of supraglacial lakes are significant for understanding the hydrological processes of polar ice sheets.However,field measurement of supraglacial lake depth is difficult,costly,and small-scale.Meanwhile,the bathymetry models derived from optical satellite images with low to medium spatial resolutions are insufficiently accurate.Given these,this study conducted the bathymetry retrieval of supraglacial lakes based on eight-band remote sensing images from the small-size optical satellite PlanetScope SuperDove(spatial resolution:3 m)and ICESat-2 laser altimetry data.First,the ICESat-2 laser altimetry point clouds data for the lake surface and bottom were separated and modeled using adaptive kernel density estimation to derive lake depth observations.Second,Optimal Band Ratio Analysis(OBRA)was used to examine the correlations between various bands of PlanetScope images(and combinations thereof)and ICESat-2 bathymetry data,leading to the development of four kinds of empirical formulas for the bathymetry retrieval of supraglacial lakes:quadratic,exponential,power,and logarithmic functions.Then,four supraglacial lakes covered by concurrent PlanetScope and ICESat-2 data were selected to test the retrieval accuracy.The results indicate that the Green Ⅰ band of PlanetScope is the most favorable for the bathymetry retrieval,demonstrating the strongest correlation with the ICESat-2 derived depths(R2=0.94)and the highest inversion accuracy(RMSE=1.0 m,RRMSE=0.15).The study reveals that integrating active and passive satellite data has great potential for analyzing hydrological processes in polar ice sheets.
万方数据
维普
