Simulating observed boundary layer clouds on Mars

Abstract

[1] A microphysical model for Mars dust and ice clouds has been applied in combination with a model of the planetary boundary layer (PBL) for the interpretation of measurements by the LIDAR instrument on the Phoenix Mars mission. The model simulates nighttime clouds and fall streaks within the PBL that are similar in structure to the LIDAR observations. The observed regular daily pattern of water ice cloud formation and precipitation at the top of the PBL is interpreted as a diurnal process in the local water cycle in which precipitation of large ice crystals (30 -50 mm effective radius) results in downward transport of water vapor within the PBL. This is followed by strong vertical mixing during daytime, and this cycle is repeated every sol to confine water vapor within the PBL. Citation: Daerden, F.,

The Modern Near-Surface Martian Climate: A Review of In-situ Meteorological Data from Viking to Curiosity

“…As part of the MET instrument, Phoenix also included a light detection and ranging (LIDAR) system to probe the vertical structure of the atmospheric boundary layer using pulsed laser light with wavelength of 532 nm backscattered from dust and ice particles from ∼200 m to ∼20 km above the ground (Whiteway et al 2008). The optical extinction coefficient derived from the LIDAR signal can then be related to the ice-water content (IWC) profile to resolve the internal structure of water-ice clouds (Whiteway et al 2009;Daerden et al 2010;Dickinson et al 2010;Moores et al 2011). In addition, Phoenix's Thermal and Electrical Conductivity Probe (TECP) was used to measure subsurface and near-surface temperature, conductivity, permittivity and humidity (Hecht et al 2008;Zent et al 2009).…”

MGS TES observations of the water vapor above the seasonal and perennial ice caps during northern spring and summer

“…Numerical modeling of the water vapor diurnal behavior (Zent et al, 1993;Pathak et al, 2008), and recent observations by Phoenix Lander Tamppari et al, 2010;Whiteway et al, 2009;Daerden et al, 2010) and orbiting instruments on Mars Express (e.g. Tschimmel et al, 2008) indicate that large proportion of the atmospheric water vapor may be confined to a near-surface layer from 100 m to 1-2 km thick in the afternoon (at the time of TES nadir observations analyzed here) and that cloud formation and precipitation at night may keep water vapor confined to heights below 4-6 km above the surface.…”

Studying methane and other trace species in the Mars atmosphere using a SOIR instrument

“…In general the vertical mixing of an emitted tracer occurs very rapidly throughout the planetary boundary layer (PBL) on Mars. The PBL height is typically of the order of 5 km and the strong daytime mixing redistributes dust and vapours uniformly throughout the PBL over a few hours (Whiteway et al, 2009;Daerden et al, 2010). Once the tracer reaches the PBL top, global circulation takes over.…”