Mars analysis correction data assimilation: a multi-annual reanalysis of atmospheric observations for the red planet
L. MontaboneS. R. LewisL. J. SteeleP. L. ReadTao RuanM. D. SmithD. M. KassA. KleinböhlJ. T. SchofieldJ. H. ShirleyD. J. McCleese
1
Citation
0
Reference
20
Related Paper
Citation Trend
Abstract:
Ever-increasing numbers of atmospheric observations from orbiting spacecraft, and increasingly sophisticated numerical atmospheric models, have recently permitted data assimilation techniques to be applied to planets beyond the Earth. Mars is the first extra-terrestrial planet for which reanalyses of the atmospheric state are now available.
The Thermal Emission Spectrometer (TES) on board NASA’s Mars Global Surveyor (MGS) has produced an extensive atmospheric data set during its scientific mapping phase between 1999 and 2004. Nadir thermal profiles for the atmosphere below about 40 km altitude, and total dust and water ice opacities, have been retrieved from TES spectra, covering almost three complete Martian seasonal cycles (each seasonal cycle on Mars corresponds to 668.6 mean solar days, and the Martian mean solar day is about 24 hours and 40 minutes). Note that dust on Mars plays a key role in the weather and climate, mainly through its strong absorption of short wave radiation with a short radiative relaxation timescale of 1-2 days. Assimilating dust opacities correctly is, therefore, particularly important for atmospheric data assimilation on the Red Planet.
TES retrieved observations have been analysed by assimilation into a Mars general circulation model (MGCM), making use of a sequential procedure known as the Analysis Correction scheme, a form of successive corrections method which has proved simple and robust under Martian conditions, even during the less-than-ideal MGS aerobraking period. The MGCM used at the University of Oxford and at The Open University consists of a spectral dynamical solver and a tracer transport scheme developed in the UK. Its package of state-of-the-art physical parameterization routines is shared with the LMD-MarsGCM, developed by the Laboratoire de Meteorologie Dynamique in Paris (France).
One limitation of TES is that relatively few limb profiles are available, compared to nadir soundings. Our MGS/TES reanalysis, therefore, does not include observations of temperature above about 40 km altitude, nor 3D information on dust opacity (the vertical distribution of dust opacity is prescribed assuming a well mixed dust layer with a rapid transition to a clear upper atmosphere at a height which depends on latitude and season.
In September 2006 NASA’s Mars Reconnaissance Orbiter (MRO) started its mapping phase. The Mars Climate Sounder (MCS) on board MRO is a radiometer with eight mid- and far-infrared
channels and one visible channel, which takes measurements in limb and off-nadir geometries. Retrieved vertical profiles of temperature, dust and water ice opacities from MCS observations can now be assimilated using the same scheme we used for TES, with the advantage of the extension in altitude (thermal profiles can extend to above 80 km altitude, although errors become larger at greater altitudes), the increased vertical resolution (~ 5km compared to > 10km for TES nadir retrievals), and the direct information on the vertical distribution of dust and water ice.
Overall, the application of our data assimilation scheme to retrieved observations from TES and MCS spans almost six complete Martian seasonal cycles. This represents a multi-annual climatology for Mars, which has the advantage of being a complete, dynamically-balanced, four-dimensional best-fit to observations for all the atmospheric variables, including those for which no direct measurements are available (e.g. wind and surface pressure) and with regions of no observations filled-in in a physically-consistent way.
The reanalysis represents, therefore, a unique opportunity to study the inter-annual variability of the Martian weather and climate with respect to all its components, such as the dust cycle, the water cycle, the CO2 cycle, the atmospheric tides and other prominent waves, such as high latitude baroclinic waves.
In this contribution we present the first results of a complete assimilation of both datasets, using a consistent model and data assimilation scheme, and highlight the challenges of combining TES and MCS data assimilation to produce a multi-annual climatology. Particular attention will be devoted to the inter-annual variability of the atmospheric thermal field in response to dust storm activity. We will also provide an insight into the dynamics, looking in particular at the high latitude winds, waves and polar vortices.
Our data assimilation products are freely available to the community for both science- and engineering-oriented purposes. The British Atmospheric Data Centre (BADC, http://badc.nerc.ac.uk) hosts our datasets, which, for the time being, are limited to the MGS/TES reanalysis. People may contact the corresponding author in order to register their interest and be updated about the status of the project. New versions of the MGS/TES reanalysis as well as the MRO/MCS reanalysis will be made available through the BADC in future.
Interested people can download the current TES reanalysis dataset by registering at the BADC and searching for the MACDA (“Mars Analysis Correction Data Assimilation”) project. The direct link to the project is provided by the following URL: http://badc.nerc.ac.uk/view/badc.nerc.ac.uk__ATOM__DE_095e8da2-cf02-11e0-8b7a-00e081470265Keywords:
Atmosphere of Mars
Cite
Wind products from geostationary satellites have been generated for over 20 years and are now used in numerical weather prediction systems. However, geostationary satellites are of limited utility poleward of the midlatitudes. This study demonstrates the feasibility of deriving high latitude tropospheric wind information from polar-orbiting satellites. The methodology employed is based on the algorithms currently used with geostationary satellites, modified for use with the Moderate-Resolution Imaging Spectroradiometer (MODIS) infrared window and water vapor bands. These bands provide wind information throughout the troposphere in both clear and cloudy conditions. The project presents some unique challenges, including the irregularity of temporal sampling, varying viewing geometries, and uncertainties in wind vector height assignment as a result of low atmospheric water vapor amounts and thin clouds. A 30-day case study dataset has been produced and is being used in model impact studies. Preliminary results are encouraging: when the MODIS winds are assimilated in the European Centre for Medium Range Weather Forecasts (ECMWF) system and the NASA Data Assimilation Office system, forecasts of the geopotential height for the Arctic, the Northern Hemisphere extratropics, and the Antarctic are improved significantly.
Geopotential height
Middle latitudes
Moderate-resolution imaging spectroradiometer
Geopotential
Cite
Citations (92)
This study explores the sensitivity of planetary boundary layer height and related atmospheric dynamics to the assimilation of cloud-cleared AIRS (Atmospheric Infrared Sounder) radiances in the Goddard Earth Observing System (GEOS, version 5) data assimilation and forecast system during the boreal fall 2014 season using observing system experiments (OSEs). Examined here are comparisons between the current, operational approach of assimilating AIRS clear-sky radiances against the assimilation of cloud-cleared radiances (CCR). In polar regions, assimilation of AIRS CCRs is particularly beneficial because of the sparsity of conventional observations and the prevalence of extended low-level stratus cloud cover, which limit the ingestion of clear-sky data. Assimilation of hyperspectral infrared information from AIRS over the Arctic region slightly modifies the lower midtropospheric temperature structure, which in turn contributes to adjustments in geopotential height, affecting the baroclinic instability properties over the entire hemisphere and explaining the overall improvement in global forecast skill. In addition, it is shown that the assimilation of CCRs benefits the representation of convectively-driven small-scale cyclones at high latitudes in the same way as previously noted for tropical cyclones. Specifically, assimilation of CCRs create a temperature dipole over the top of meteorologically active and strongly convective systems such as polar, arctic, and antarctic lows, which helps constrain the analyzed representation of their scale and vertical structure.
Atmospheric Infrared Sounder
Extratropical cyclone
Cite
Citations (0)
Our Global Circulation Model (GCM) simulates the atmospheric environment of Mars. It is developped at LMD (Laboratoire de Meteorologie Dynamique, Paris, France) in close collaboration with several teams in Europe (LATMOS, France, University of Oxford, The Open University, the Instituto de Astrofisica de Andalucia), and with the support of ESA (European Space Agency) and CNES (French Space Agency). GCM outputs are compiled to build a Mars Climate Database, a freely available tool useful for the scientific and engineering communities. The Mars Climate Database (MCD) has over the years been distributed to more than 350 teams around the world. The latest series of reference simulations have been compiled in version 5.3 of the MCD which was released in 2017.
To summarize, MCD v5.3 provides:
- Climatologies over a series of synthetic dust scenarios: standard (climatology) year, cold (ie: low dust), warm (ie: dusty atmosphere) and dust storm, all topped by various cases of Extreme UV solar inputs (low, mean or maximum). These scenarios have been derived from home-made, instrument-derived (TES, THEMIS, MCS, MERs), dust climatology of the last 8 Martian years. The MCD also provides simulation outputs (MY24-33) representative of these actual years.
- Mean values and statistics of main meteorological variables (atmospheric temperature, density, pressure and winds), as well as surface pressure and temperature, CO2 ice cover, thermal and solar radiative fluxes, dust column opacity and mixing ratio, [H20] vapor and ice columns, concentrations of many species: [CO], [O2], [O], [N2], [H2], [O3], ...
- A high resolution mode which combines high resolution (32 pixel/degree) MOLA topography records and Viking Lander 1 pressure records with raw lower resolution GCM results to yield, within the restriction of the procedure, high resolution values of atmospheric variables.
- The possibility to reconstruct realistic conditions by combining the provided climatology with additional large scale and small scale perturbations schemes.
At EGU, we will report on the latest improvements in the Mars Climate Database, with comparisons with available measurements from orbit (e.g.: TES, MCS, TGO) and landers (Viking, Phoenix, Curiosity).
Atmosphere of Mars
Cite
Citations (14)
Mars landing
Atmosphere of Mars
Orbiter
Cite
Citations (19)
Large‐scale carbon sources and sinks can be estimated by combining atmospheric CO 2 concentration data with atmospheric transport inverse modeling. This approach has been limited by sparse spatiotemporal tropospheric sampling. CO 2 estimates from space using observations on recently launched satellites (Atmospheric Infrared Sounder (AIRS)), or platforms to be launched (Infrared Atmospheric Sounding Interferometer (IASI), Orbiting Carbon Observatory (OCO)) have the potential to fill some of these gaps. Here we assess the realism of initial AIRS‐based mid‐to‐upper troposphere CO 2 estimates from European Centre for Medium‐Range Weather Forecasts by comparing them with simulations of two transport models (TM3 and Laboratoire Meteorologie Dynamique Zoom (LMDZ)) forced with one data‐based set of surface fluxes. The simulations agree closer with one another than with the retrievals. Nevertheless, there is good overall agreement between all estimates of seasonal cycles and north‐south gradients within the latitudinal band extending from 30°S to 30°N, but not outside this region. At smaller spatial scales, there is a contrast in the satellite‐based retrievals above continents versus above oceans that is absent in the model predictions. Hovmoeller diagrams indicate that in the models, high Northern Hemisphere winter CO 2 concentrations propagate toward the tropical upper troposphere via Northern Hemisphere high latitudes, while in retrievals, elevated winter CO 2 appears instantaneously throughout the Northern Hemisphere. This raises questions about lower‐to‐upper troposphere transport pathways. Prerequisites for use of retrievals to provide an improved constraint on surface fluxes are therefore further improvements in retrievals and better understanding/validation of lower‐to‐upper troposphere transport and its modeling. This calls for more independent upper troposphere transport tracer data like SF 6 and CO 2 .
Atmospheric Infrared Sounder
Atmospheric sounding
Atmospheric models
Cite
Citations (51)
An accurate representation of spatial and temporal variability of the Upper Troposphere Lower Stratosphere (UTLS) ozone is essential for understanding both the tropospheric ozone budget and ozone s contribution to radiative forcing. The complex, dynamically driven structure of trace gas fields in the UTLS presents a challenge to data-based and modelling studies. Small features are not fully resolved in data from limb-sounding instruments such as the Microwave Limb Sounder on EOS-Aura (the EOS-MLS), but are captured in assimilation of those data as vertical structure is added from the assimilated meteorology. This will be demonstrated using a multi-year assimilation of EOS-MLS observations in the Goddard Earth Observing System, Version 5 (GEOS-5) data assimilation system. The results demonstrate the realism of the seasonal and year to year variability of laminar structures in the mid-latitudinal ozone field between years 2005-2007, for which independent validation data are available from the HIRDLS instrument. The analysis is done in the context of the underlying large scale dynamics. The lifetimes of most research instruments are too short for them to be used throughout the duration of long-term (at least 3 decades) reanalyses. For example, the EOS-MLS instrument has operated since mid-2004 until present. By contrast, Solar Backscatter Ultra Violet (SBUV) measurements provide continuous data since late 1978, but their vertical resolution is insufficient to represent the profile shape in the UTLS. Assimilation of these SBUV/2 observations in the GEOS-5 data assimilation system has hitherto not captured a realistic ozone structure in the UTLS, even though transport studies using GEOS-5 wind fields do show such structures. We show that careful construction of the background error covariance structure in GEOS-5 can lead to more realistic UTLS ozone fields when assimilating SBUV/2 observations. The reasoning behind this will be discussed, emphasizing the need to retain the sharp gradient of ozone concentrations across the tropopause. We analyze the UTLS ozone distributions in multi-year SBUV/2 assimilation experiments, comparing the results against the independent HIRDLSdataset and, for a longer period, with the MLS assimilation and discuss the consequences for tropospheric ozone and radiative forcing.
Microwave Limb Sounder
Trace gas
Cite
Citations (0)
The concept of cloud radiative forcing (CRF) has been widely employed in studying the effects of clouds on the earth's radiation budget and climate. CRF denotes, in principle, the net influence of cloud alone on the radiation budget of a system. In practice, however, observational determination of CRF is fraught with uncertainties due to factors other than cloud that induce changes in atmospheric background conditions. The most notable variables include aerosol, water vapor, and the data sampling scheme. The impact of these factors on the derivation of CRF and cloud absorption is investigated here by means of modeling and analysis of multiple datasets. Improved estimation of CRF is attempted at the top of the atmosphere (TOA) and at the surface from spatially and temporally collocated ground and satellite measurements for broadband shortwave fluxes. Satellite data employed include pixel measurements from ERBE (1988-90), ScaRaB (1994-95), and CERES (1998), as well as surface data acquired across the Canadian radiation network, the ARM Central Facility site in Oklahoma, the US/NOAA SURFRAD networks, and the world BSRN (WMO) networks. It is found that surface CRF is much more susceptible to the variability in background conditions than TOA CRF. Selection of overly clear sky conditions often leads to significant overestimation of surface CRF, but TOA CRF remains intact or only slightly affected. As a result, the ratio of CRF at the surface and TOA is prone to overestimation. With careful treatments of these effects, the CRF ratio turns out to vary mostly between 0.9 and 1.1, implying approximately the same magnitude of atmospheric absorption under clear-sky and cloudy-sky conditions.
Albedo (alchemy)
Cite
Citations (1)
We have reconstructed the climatology of airborne dust from Martian years (MY) 24 to 31 using multiple datasets
of retrieved or estimated column optical depth. The datasets are based on observations of the Martian atmosphere
from March 1999 to July 2013 by different orbiting instruments: the Thermal Emission Spectrometer (TES)
on board Mars Global Surveyor, the Thermal Emission Imaging System (THEMIS) on board Mars Odyssey,
and the Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO). The procedure we have
adopted consists in 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. Our gridding method
calculates weighted averages on a regular but likely incomplete spatial grid, using an iterative procedure with
weights in space, time, and retrieval uncertainty. The derived product consists of daily synoptic gridded maps of
CDOD at a resolution of 6 degree longitude x 3 degree latitude for MY 24-26, and 6 degree longitude x 5 degree
latitude for MY 27-31.
We have statistically analyzed the gridded maps to present an overview of the dust climatology on Mars
over eight years, specifically in relation to its intraseasonal and interannual variability.
Finally, we have produced complete daily maps of CDOD by spatially interpolating the available incomplete
gridded maps using a kriging method. These complete maps are used as dust scenarios in the Mars Climate
Database (MCD) version 5, and should be useful for many other applications.
The maps for the eight available Martian years are publicly available and distributed with open access, under
Creative Commons Attribution-ShareAlike 3.0 Unported License. The current version and future updates
can be downloaded from the MCD website at the Laboratoire de Meteorologie Dynamique: http://wwwmars.
lmd.jussieu.fr/mars/dust_climatology/
Longitude
Orbiter
Atmosphere of Mars
Nadir
Cite
Citations (0)
A four-dimensional variational data assimilation system for stratospheric trace gas observations has been extended and evaluated to draw full advantage from stratospheric remote sounding data and upper troposphere lower stratosphere (UTLS) in-situ aircraft measurements. The UTLS is the transition layer between the tratosphere and the troposphere and is marked by strong spatial and temporal variability of dynamic structures and distribution of trace gases. Aircraft measurements, highly resolving the UTLS filamental structures, are of most interest for local studies. Although, the satellite instruments are delivering an unprecedented wealth of observations of a number of stratospheric trace gases with global coverage, they are scattered and have a limited resolution in space or time. Combining these
measurements and applying advanced data assimilation techniques to compare benefits from satellite and air borne data, and to analyse the chemical composition of the tropopause and lower stratosphere, was the issue of this work. For this purpose, a model grid refinement and full revision of the chemical mechanism were performed.
The resolution of the horizontal grid points was increased from about 240 km to 150 km, resulting in
23 042 grid points per model level. The vertical resolution was increased with twelve additional layers, especially in the UTLS region. Hence, the vertical separation between grid levels is now less than 1 km below 22 km altitude. The chemistry module was extended and revised to better represent chemical processes in the UTLS region. All reaction rates were updated according to the recommendations of the NASA's Jet Propulsion Laboratory. In total, a number of 197 photolysis, gas phase, and heterogeneous reactions of 51 stratospheric trace gases is considered by the chemistry module now. The meteorological fields are computed online by the global forecast model GME of German Weather Service. A comprehensive set of case studies has been
conducted in order to test and evaluate the extended system. Retrievals of various stratospheric trace gases derived from measurements of the Earth Observing
System Microwave Limb Sounder, as well as retrievals of aircraft measurements have been assimilated. The analyses show a perfect performance with respect to the assimilated ozone observations. For assimilation of water observations in UTLS additional preconditioning issue is desirable. Comparison with independent observations from satellite instruments and radiosondes demonstrates
a very good performance of the extended assimilation system.
Trace gas
Tropopause
Atmospheric sounding
Atmospheric chemistry
Cite
Citations (0)
High latitude weather forecasts, on scales ranging from mesoscale to synoptic, present difficulties due, in part, to the sparsity of conventional observations. In addition, the prevalence of extended low-level stratus cloud cover limits the use of infrared data, which are operationally assimilated only in areas unaffected by clouds. Use of cloud-cleared AIRS (Atmospheric Infrared Sounder) radiances (AIRS CCR), allows the assimilation of infrared information in cloudy regions, permitting data ingestion in regions usually undersampled. This study explores the sensitivity of planetary boundary layer height and related atmospheric dynamics to the assimilation of these data in the Goddard Earth Observing System (GEOS, version 5) data assimilation and forecast system during the boreal fall 2014 season using observing system experiments (OSEs). Examined here are comparisons between the current, operational approach of assimilating AIRS clear-sky radiances against the assimilation of CCR. Assimilation of hyperspectral infrared information from AIRS over the Arctic region slightly modifies the lower midtropospheric temperature structure, which in turn contributes to adjustments in geopotential height, affecting the baroclinic instability properties over the entire hemisphere and explaining the overall improvement in global forecast skill.
Atmospheric Infrared Sounder
Geopotential height
Cloud top
Cite
Citations (0)