Climatologies of the Martian Atmospheric Dust Optical Depth

Introduction

We provide a multiannual climatology of airborne dust from Martian year 24 to 32 using observations of the Martian atmosphere from April 1999 to June 2015 made by the Thermal Emission Spectrometer (TES) aboard Mars Global Surveyor, the Thermal Emission Imaging System (THEMIS) aboard Mars Odyssey, and the Mars Climate Sounder (MCS) aboard Mars Reconnaissance Orbiter (MRO).

Our methodology works by gridding the available retrievals of column dust optical depth (CDOD) from TES and THEMIS nadir observations, as well as the estimates of this quantity from MCS limb observations. The resulting (irregularly) gridded maps were validated with independent observations of CDOD by PanCam cameras and Mini-TES spectrometers aboard the Mars Exploration Rovers "Spirit" and "Opportunity", by the Surface Stereo Imager aboard the Phoenix lander, and by the Compact Reconnaissance Imaging Spectrometer for Mars aboard MRO.

Finally, regular maps of CDOD are produced by spatially interpolating the irregularly gridded maps using a kriging method. These latter maps are used as dust scenarios in the Mars Climate Database (MCD) version 5, and are useful in many modelling applications.

The two data sets (irregularly gridded maps and regularly kriged maps) for the nine available Martian years are publicly available and can be downloaded below (version 2.0).

The detailed description of the methodology and data sets can be found in the following scientific article:
Montabone, L., Forget, F., Millour, E., Wilson, R.J., Lewis, S.R., Cantor, B., Kass, D., Kleinböhl, A., Lemmon, M.T., Smith, M.D., Wolff, M.J., Eight-year Climatology of Dust Optical Depth on Mars, Icarus (2015), doi: http://dx.doi.org/10.1016/j.icarus.2014.12.034 [Access the article]

If you have no subscription to the journal Icarus and cannot access the article, please send an email to the contact below.

Data sets

Observation-only incomplete-coverage maps: Daily irregularly gridded maps of 9.3 μm absorption column dust optical depth for several Martian years (MY). Resolution: 6° longitude x 3° latitude for MY24, 25, 26; 6° longitude x 5° latitude for the other Martian years. Data files are available in NetCDF format (74 MB for MY24, 25, 26; 45 MB for the other years; 485 MB for the complete tar file including all years). Plotted maps for the first 8 years (MY24-31) are available as animated GIF (47 MB; each frame represents a sol-of-year with 8 maps, one for each available Martian year).

MY24 MY25 MY26 MY27 MY28 MY29 MY30 MY31 Animation New! MY32 All MYs (tar file)

Complete-coverage reconstructed maps (for Mars Climate Modeling): Daily dust scenarios (regularly kriged maps of 9.3 μm absorption column dust optical depth) for several Martian years (MY). Resolution: 3° longitude x 3° latitude. Data files are available in NetCDF format (56 MB for single year file; 497 MB for the complete tar file including all years). Plotted maps for the first 8 years (MY24-31) are available as animated GIF (43 MB; each frame represents a sol-of-year with 8 maps, one for each available Martian year).

MY24 MY25 MY26 MY27 MY28 MY29 MY30 MY31 Animation New! MY32 All MYs (tar file)

N.B.1 To get the extinction optical depth, you can multiply the absorption optical depth by 1.3. Equivalent visible column optical depths can be obtained by multiplying the 9.3 μm absorption column dust optical depth by 2.6. See detailed discussion in Montabone et al., Icarus, 2015, Section 2.3.4

N.B.2 The data files include both the column dust optical depth normalized to the 610 Pa reference level and the column dust optical depth normalized to the gridded surface pressure value (surface pressure is gridded from the Mars Climate Database). If you require a local column optical depth, you could either interpolate the provided variable normalized to the gridded MCD surface pressure, or multiply the provided variable normalized to 610 Pa by "surface pressure (Pa)/610", where "surface pressure" is the local surface pressure of your choice.

Figures: (Left) Zonal means of the daily irregularly gridded maps of 9.3 μm absorption column dust optical depth normalized to the reference 610 Pa pressure level for the different Martian Years. (Right) Zonal means of the daily regularly kriged maps of 9.3 μm absorption column dust optical depth normalized to the reference 610 Pa pressure level for the different Martian Years.

Contact

Please, send questions and feedback to Luca Montabone (lmontabone [at] spacescience.org). Feedback from users are extremely important for us, as they will be taken into account in future versions of the data sets.

Although we do not require any formal registration to download the data sets, we would highly appreciate if you tell us who you are if you download the files, by sending an informal email to the contact email address above, including at least your name, affiliation (if applicable), and planned use of the data sets. This would help us a lot to assess the impact of our work, and would make sure that we will keep you updated about possible errors, warnings, and future versions. We will not use your contact details for anything else than just keeping you updated about the data sets when needed. Even if you do not want to be updated, please consider sending us an email to tell us who you are, and make explicit that you do not want to be contacted further.

Copyright and disclaimer

Data included in the NetCDF files above are publicly available with open access, under Creative Commons Attribution-ShareAlike 3.0 Unported License (i.e. you are free to copy, redistribute, and modify the material for scientific as well as commercial purposes, as far as you give appropriate credit, indicate if changes were made, and distribute your contributions with the same license as the original).

These data are made publicly available on the condition that we provide no warranties regarding the reliability, validity or accuracy of the data, and we bear no responsibility for any use made of such data.

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