Abstract
By studying the evolution of the color index (CI) during twilight at high latitudes, polar stratospheric clouds (PSCs) can be detected and characterized. In this work, this method has been applied to the measurements obtained by a visible ground-based spectrometer and PSCs have been studied over the Belgrano II Antarctic station for years 2018 and 2019. The methodology applied has been validated by full spherical radiative transfer simulations, which confirm that PSCs can be detected and their altitude estimated with this instrumentation. Moreover, our investigation shows that this method is useful even in presence of optically thin tropospheric clouds or aerosols. PSCs observed in this work have been classified by altitude. Our results are in good agreement with the stratospheric temperature evolution obtained by the global meteorological model ECMWF (European Centre for Medium Range Weather Forecasts) and with satellite PSCs observations from CALIPSO (Cloud-Aerosol-Lidar and Infrared Pathfinder Satellite Observations). To investigate the presence and long-term evolution of PSCs, the methodology used in this work could also be applied to foreseen and/or historical observations obtained with ground-based spectrometers such e. g. those dedicated to Differential Optical Absorption Spectroscopy (DOAS) for trace gas observation in Arctic and Antarctic sites.
Highlights
Polar Stratospheric Clouds (PSCs) are often observed in the Arctic and Antarctic skies mostly during winter and spring
Based on the work of Sarkissian et al 1991 [32], we have studied the evolution of a normalized color index (CI) during twilight to detect and characterize PSCs over the Belgrano II Antarctic station, during 2018 and 2019
We have shown that using a spectral range half-shorter than previous works, we are still able to detect PSCs and estimate their altitude
Summary
Polar Stratospheric Clouds (PSCs) are often observed in the Arctic and Antarctic skies mostly during winter and spring. Using a pseudo-spherical single scattering radiative transfer model (RTM), they simulated different PSC scenarios based in four parameters: cloud altitude, geometrical and optical thickness, and scattering wavelength (λ) dependence (considering this dependence through a parameter: λ-α ; with 0 < α < 3). Similar methods have been applied to the detection of PSCs from ground-based spectroscopic observations in different works [35,36,37], all of them performed at Arctic latitudes and using simple single scattering models.
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