Atypically Intense and Delayed Response of the Martian Ionosphere to the Regional Dust Storm of 2016: A Study Using MAVEN Observations and Models

Abstract

Based on their spatial and temporal extent, Martian dust storms are classified into three types viz. local, regional, and global dust storms. Being of relatively low dust opacity and limited spatial extent, local dust storms are the ones that occur most commonly. Regional dust storms, formed by the coalescence of the local storms, have a larger spatial and temporal coverage and have a higher dust opacity. Sometimes these storms grow globally, engulfing the planet for several months. Such events are known as global dust storms or planet-encircling dust events. Even though dust storms are lower atmospheric events, their impact on the atmosphere extends well up into the thermosphere. The dust particles loaded into the atmosphere absorbs solar radiation and result in excessive heating. The lower atmosphere thus heats and expands, pushing the thermosphere above it upward. The expansion of the neutral atmosphere subsequently gets reflected in the ionospheric features. The M2 peak, where the Martian electron density profile shows maximum density, is known to form at fixed neutral pressure