The martian dust chronicle: Eight years of reconstructed climatology from spacecraft observations

摘要

We have reconstructed the climatology of airborne dust from Martian years (MY) 24 to 31 using multiple datasetsudof retrieved or estimated column optical depth. The datasets are based on observations of the Martian atmosphereudfrom March 1999 to July 2013 by different orbiting instruments: the Thermal Emission Spectrometer (TES)udon board Mars Global Surveyor, the Thermal Emission Imaging System (THEMIS) on board Mars Odyssey,udand the Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO). The procedure we haveudadopted consists in gridding the available retrievals of column dust optical depth (CDOD) from TES and THEMISudnadir observations, as well as the estimates of this quantity from MCS limb observations. Our gridding methodudcalculates weighted averages on a regular but likely incomplete spatial grid, using an iterative procedure withudweights in space, time, and retrieval uncertainty. The derived product consists of daily synoptic gridded maps ofudCDOD at a resolution of 6 degree longitude x 3 degree latitude for MY 24-26, and 6 degree longitude x 5 degreeudlatitude for MY 27-31.udWe have statistically analyzed the gridded maps to present an overview of the dust climatology on Marsudover eight years, specifically in relation to its intraseasonal and interannual variability.udFinally, we have produced complete daily maps of CDOD by spatially interpolating the available incompleteudgridded maps using a kriging method. These complete maps are used as dust scenarios in the Mars ClimateudDatabase (MCD) version 5, and should be useful for many other applications.udThe maps for the eight available Martian years are publicly available and distributed with open access, underudCreative Commons Attribution-ShareAlike 3.0 Unported License. The current version and future updatesudcan be downloaded from the MCD website at the Laboratoire de Meteorologie Dynamique: http://wwwmars.udlmd.jussieu.fr/mars/dust_climatology/