Night-Time Study

Strategy for Studying Nocturnal Aerosol Optical Depth Using Artificial Lights

Night-Time Study

In this concept study, we develop a strategy for the monitoring of night-time aerosol particle optical properties over land using artificial lights on the earth's surface. We demonstrate the possibility of detecting significant aerosol events and deriving variations in aerosol optical depth using the operational linescan system (OLS) on defense meteorological satellite program (DMSP) platforms. Since the OLS instruments have no onboard calibration, only a qualitative study of the potential to estimate aerosol and cloud properties using city lights at night is shown in this paper. The technique is demonstrated using China and India as test regions. With the launch of the visible/infrared imager/radiometer suite (VIIRS) instrument on the national polar-orbiting operational environmental satellite system (NPOESS) in the coming decade, fully quantitative retrieval of night-time aerosol particle optical properties from space observations using such methods will become possible. Such work will benefit aerosol forecasting, safety of navigation, aerosol data assimilation, and climate studies.

Night-Time Study Using VIIRS

Night-Time Study

A great need exists for reliable nighttime aerosol products at high spatial and temporal resolution. In this concept demonstration study, using Visible/Infrared Impager/Radiometer Suite (VIIRS) Day/Night Band (DNB) observations on the Suomi National Polar-orbiting Partnership (NPP) satellite, a new method is proposed for retrieving nighttime aerosol optical depth (τ) using the contrast between regions with and without artificial surface lights. Evaluation of the retrieved τ values against daytime AERONET data from before and after the overpass of the VIIRS satellite over the Cape Verde, Grand Forks, and Alta Floresta AERONET stations yields a coefficient of determination (τ2) of 0.71. This study suggests that the VIIRS DNB has the potential to provide useful nighttime aerosol detection and property retrievals.