Available Solar Energy and Weather Forecasting on Mars Surface

Introduction

The design of both photovoltaic and photothermal systems operating on Mars requires detailed information on the solar radiation flux incident on the surface of the planet as a function of latitude, longitude, time of day and year. The atmospheric (vertical) optical depth τ is an indicator of solar radiation attenuation in the atmosphere. One can concisely define the optical depth as follows. Let us assume that the sun is at zenith and denote by I ₀ and I _ground the direct solar irradiance at the top of the atmosphere and at ground level, respectively. Then, usage of τ allows to write the Beer’s law as ${I_{ground}/I_{0}=e^{-\tau}}_{-}$ Suspended dust absorbs solar radiation and emits (and absorbs) longer-wavelength radiation. Mars may be considered ”clear” when the dust content in the atmosphere is low, but when local or global storms occur the optical depth increases and the direct beam solar radiation decreases drastically.