NOTES AND CORRESPONDENCE Spectral Albedo of Desert Surfaces Measured in Western andCentral China

Abstract

Spectral albedo and nadir reflectance of desert surfaces were measured with spectrometer for spectral region from 0.35 to 2.5 mm in western and central China in spring of 2001 and autumn of 2003. Desert surfaces were mainly gobi and/or sand dune around Qira in southern Taklimakan Desert, Aksu in northern Taklimakan Desert, Ejina in Badain Jaran Desert, and in Tengger Desert. The measured spectral albedos are low (0.05-0.11) at ultraviolet wavelengths but it rapidly increases to 0.2-0.3 at the wavelength about l ¼ 0:6 mm at any site. The wavelength at which the albedo reaches to the maximum is around l ¼ 1.8-2.2 mm, where the albedos range from 0.37 to 0.49 among measured sites. Nadir reflectance also basically shows a similar spectral distribution with that of the albedo, while the values are lower than albedos at any wavelength. Standard deviations of albedo and reflectance calculated from Corresponding author: Teruo Aoki, Meterological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan. E-mail: teaoki@mri-jma.go.jp ( 2005, Meteorological Society of Japan measurements for different surfaces at each site indicate that gobi surfaces around Aksu and Ejina have large variability compared with other surfaces. These datasets would be useful for the studies of climate simulation, remote sensing, radiative forcing, and so on.

Black carbon footprint of human presence in Antarctica

“…However, absorption by non-BC constituents decreases more rapidly with wavelength than does absorption by BC. Accordingly, both dust 45 and algae 39 play no significant role in the absorption at wavelengths longer than 700 nm and concentrations computed by Eq. ( 2 ) exhibit few changes over the range 700–750 nm.…”

Evaluation of MODIS-derived estimates of the albedo over the Atacama Desert using ground-based spectral measurements

“…Each site was visited once during a campaign conducted in late September 2018. Following the methodology used elsewhere [1][2][3][4] , the rotating input optics, fitted with a flat diffuser, was set up at 70 cm above the surface and 1.5 m away from the heavy-duty tripod where the spectroradiometer was installed. Although the field-of-view (FOV) of our input optics is nominally 180º, prior efforts 3 have shown that over 90% of the surface-reflected upwelling irradiance reaching the input optics corresponds to a visual angle of about 72º.…”

“…Although the correlation between MODISderived estimates and ground-based measurements remained relatively high (R= 0.94), RMBE values were slightly larger in the southernmost part of the desert (27-30° S). Both MODIS-derived data and ground-based measurements show that the albedo at some bright spots in the Atacama Desert may be high enough (up to 0.25 in visible range) for considerably boosting the performance of bifacial photovoltaic technologies (6-12%).The surface albedo is defined as the ratio of surface-reflected irradiance to incident irradiance over a given spectral interval [1][2][3][4] . The albedo varies temporally and spatially as a result of natural processes (such as vegetation growth and snowfall) and anthropogenic activities (deforestation/forestation, agriculture, wildfires, etc.).…”

“…The surface albedo is defined as the ratio of surface-reflected irradiance to incident irradiance over a given spectral interval [1][2][3][4] . The albedo varies temporally and spatially as a result of natural processes (such as vegetation growth and snowfall) and anthropogenic activities (deforestation/forestation, agriculture, wildfires, etc.).…”