Abstract
Land surface albedo (LSA) is an important parameter that affects surface–air interactions and controls the surface radiation energy budget. The spatial and temporal variation characteristics of LSA reflect land surface changes and further influence the local climate. Ganzhou District, which belongs to the middle of the Hexi Corridor, is a typical irrigated agricultural and desert area in Northwest China. The study of the interaction of LSA and the land surface is of great significance for understanding the land surface energy budget and for ground measurements. In this study, high spatial and temporal resolution GF-1 wide field view (WFV) data were used to explore the spatial and temporal variation characteristics of LSA in Ganzhou District. First, the surface albedo of Ganzhou District was estimated by the GF-1 WFV. Then, the estimated results were verified by the surface measured data, and the temporal and spatial variation characteristics of surface albedo from 2014 to 2018 were analyzed. The interaction between albedo and precipitation or temperature was analyzed based on precipitation and temperature data. The results show that the estimation of surface albedo based on GF-1 WFV data was of high accuracy, which can meet the accuracy requirements of spatial and temporal variation characteristic analysis of albedo. There are obvious geographic differences in the spatial distribution of surface albedo in Ganzhou, with the overall distribution characteristics being high in the north and low in the middle. The interannual variation in annual average surface albedo in Ganzhou shows a trend of slow fluctuations and gradual increases. The variation in annual albedo is characterized by “double peaks and a single valley”, with the peaks occurring from December to February at the end and beginning of the year, and the valley occurring from June to August. Surface albedo was negatively correlated with precipitation and temperature in most areas of Ganzhou.
Highlights
All available clear sky GF-1 wide field view (WFV) data and ground measurement data were paired for albedo estimation accuracy validation
The results show that the negative correlation between surface albedo and temperature became stronger and the positive correlation became weaker after removing the effect of precipitation
The GF-1 satellite is the first satellite of the China high-resolution Earth observation system, which breaks through key technologies, such as high spatial resolution and multispectral and wide coverage combined with optical remote sensing
Summary
Shortwave land surface albedo, which is defined as the ratio of the reflected solar radiation at the land surface to the total incoming solar radiation over the entire solar spectrum and represents the reflection ability of the surface to solar radiation [1], is an important parameter in land surface processes and climate simulation studies. Accurate estimation of surface albedo is essential in considering the surface energy budget. Field albedo is obtained from measured radiation flux data at surface flux sites, and albedo is calculated from the ratio of downward shortwave radiation flux to upward shortwave radiation flux [2]. Due to the complexity and diversity of underlying
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