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MRO MARS CLIMATE SOUNDER LEVEL 5 DDR V1.0 (PDS)

NSSDCA ID: PSPA-00592

Availability: Archived at NSSDC, accessible from elsewhere

Description

This description was generated automatically using input from the Planetary Data System.

Data Set Overview

This document describes how the MRO Mars Climate Sounder (MCS) Derived Data Record (DDR) was generated, including data sources and destinations. The document is intended to provide sufficient information to enable users to understand the MCS DDR data product. The users for whom this document is intended are scientists who will analyze the data, including those associated with the Mars Reconnaissance Orbiter (MRO) Project and those in the general planetary science community. This document addresses the Mars Reconnaissance Orbiter Derived Data Record (DDR) data, and how the data are processed, formatted, labeled, and uniquely identified. This document discusses standards used in generating the product and software that may be used to access the product. The data product structure and organization is described in sufficient detail to enable a user to fully utilize the DDR data product. This data set consists of tables and supporting documentation from the final analysis of the Derived Data Record (DDR) and details how the DDR data set was derived from the Mars Reconnaissance Orbiter (MRO) Mars Climate Sounder (MCS) Reduced Data Records (RDR). The scientific goals, measurement objectives, and observational strategies for the DDR dataset are discussed in MCCLEESEETAL2007 and the INST.CAT file accompanying this data set. A mission overview and spacecraft and orbit characteristics are found in ZUREKANDSMREKAR2007 and in the INSTHOST.CAT and MISSION.CAT files. Detailed information addressing processing of the DDR data set are found in KLEINBOEHLETAL2009 and KLEINBOEHLETAL2011. MCS is an atmospheric sounder that makes one measurement every 2.048 seconds, containing science, engineering and housekeeping data, whenever the instrument is powered on. The instrument operates in a single data-taking mode and observational flexibility is provided by actuators that allow telescope boresights to be directed over a range of 270 degrees in azimuth and elevation. Each instrument packet contains one measurement. The MCS DDR contains time-ordered, atmospheric profile data for the entire MCS mission, starting with the initial instrument power-on in the MRO mapping orbit at 16:00 UT on 24th September 2006. The data are organized by UTC in monthly archive volumes, with 6 four-hour ASCII tables per day accompanied by detached headers. The MCS DDR contains all the profiles processed by the MCS science team. Gaps in the data set are only evident from discontinuities in the timing of table rows (see Data Coverage and Quality section). Fields that are not available for a specific profile contain -9999. Data Product Acquisition -----------------------The MCS software collects 192 sixteen-bit science measurements from the focal plane interface electronics every 2.048 seconds, along with associated instrument engineering and housekeeping measurements. The science and housekeeping data are organized into data packets that are transmitted to the spacecraft at the same 2.048-second spacing. The data packets are downlinked to the MRO Ground Data System (GDS) and placed into the Raw Science Data Server (RSDS). MCS software queries the data from the RSDS and assembles them into EDR data tables, each covering a 4 hour time period. The data in the EDR tables are then calibrated to produce the RDR tables. The individual records from the RDR tables observing the limb and surface are sorted and grouped, based on the geolocation of the observations. Groups of five limb viewing records are combined with pairs of on-planet views. Geophysical quantities are then retrieved from each group of RDR records. The resulting DDR records are placed into data tables. Each MCS DDR data table will be variable in size; typically 5-6 MB for each 4 hour time period; the volume of the DDR data product will be approximately 36 MB per day; 1 GB per month. Data Product Generation and Flow -------------------------------The MCS DDR data products, generated by the MCS Instrument Team at JPL, are constructed from the MRO/MCS RDR data and formatted according to the MRO/MCS DDR SIS. Meta-data derived from fields in the DDR, are used to populate the PDS label. MCS science and engineering telemetry are transferred to the MRO Project RSDS. Once transferred, the MCS software automatically processes the telemetry into Level 0 EDR data products. The MCS EDR data products are re-processed into RDR data products. The DDR data products are generated from the RDR data products and then archived locally at the MCS operation center. After an initial 6 month data validation period, the MCS team assembles the DDR data products and ancillary files into archive volumes and transfers the assembled volumes to the PDS Atmospheres Node. An archive volume consists of one month of data. Volumes are delivered approximately every 3 months. The MCS DDR archive will be made available via data releases scheduled at three month intervals as specified in the Mars Reconnaissance Orbiter Project Data Archive Generation, Validation and Transfer Plan. Data Processing Level --------------------This document uses the Committee on Data Management and Computation (CODMAC) data level numbering system to describe the processing level of the DDR data product. MCS DDR data products are considered CODMAC Level 5, equivalent to NASA level 2. The DDR data files are generated from CODMAC Level 4 or Resampled Data, which are the time-ordered instrument science data. Changes from Previous Versions -----------------------------The following section describes the changes between the various versions of the archived volumes. This archive, regardless of version number, contains the changes listed below: Version 2: 1. Improved topography calculation to get a better estimate of the Mars horizon during small rolls (up to 9 deg limb angle). 2. Optimized detector selection for temperature retrieval to achieve improved altitude resolution. 3. Modified detector selection for temperature, dust, and water ice retrieval to better accommodate calibration uncertainties (particularly in low radiances) that occur during limb staring (when the instrument is pointed at the limb with a fixed elevation angle for an extended period of time). 4. MCS Frames kernels changed to modify a fixed instrument tilt identified in off-track limb observations. The tilt of 0.431 degrees was applied about an axis in the S/C XY plane inclined at 25.8 degrees to the S/C X-Axis. The elevation rotation in the Frames kernel was changed from -0.203 degrees to -0.030 degrees to compensate for the effect of the tilt change. The overall effect of these changes is to improve limb pointing in the vertical to better than 0.02 degrees in both in and off-track observations. 5. Added a single-scattering approximation to the radiative transfer for the calculation of limb radiances (see KLEINBOEHLETAL2011). The surface contribution to the scattering term is based on observed on-planet radiances when available, otherwise it is based on a surface temperature climatology. Version 3: 1. On-planet observations within a 2 degree great circle distance of the profile location of a limb measurement are selected if available. They are used in combination with the limb measurement for a surface temperature retrieval, a near surface atmospheric temperature retrieval and the atmospheric temperature profile in the lowest 20 km. Channel B1 (31.7 microns) is used to determine the surface temperature. Depending on the atmospheric opacity and viewing angle, either A1 (16.5 microns) or A1 and A2 (15.9 microns) are used for the atmospheric temperature retrievals. These are nadir-like views and the corresponding weighting functions are broader than the ones for limb views and have ~10 km vertical resolution. The algorithm meshes the two types of weighting functions. An overview on results obtained with this version is given in MCCLEESEETAL2010. 2. The radiance residual criteria for profile acceptance were slightly modified to be partly based on the absolute radiance and not just the NER. This avoided rejecting otherwise good profiles on the day side equatorial regions (where the warm atmosphere and surface create large radiances). These profiles will have somewhat larger uncertainties associated with them, reflecting the quality of the radiance fit. 3. Finally, the opacity criteria were tuned so the algorithm would better recognize when the limb path is too opaque for temperature sounding. Version 4: 1. The retrieval code was modified to execute a retrieval with climatological surface pressure in case at the end of a retrieval that included pressure as a retrieved quantity the criteria for a successful retrieval were not met. This leads to a significant improvement in retrieval coverage compared to previous versions. The climatological pressure is based on Viking Lander 1, adjusted for elevation. In Level 2 data files, profiles with retrieved pressure are marked with pqual=0, while profiles with climatological pressure are marked with pqual=9. Intercomparisons of this version with other datasets are found in SHIRLEYETAL2015 and HINSONETAL2014. 2. The representation of the polar CO2-ice cap was improved. It is now based on a circular, pole-centered fit to day/night temperature differences in the MCS B1 channel. 3. The selection of detectors for temperature retrieval has been optimized to be more conservative in the presence of large aerosol opacities. In addition, on-planet radiance measurements in channel A3 (15.4 microns) are now used for atmospheric temperature retrievals in high aerosol conditions. This extends the vertical range of temperature profile retrievals to lower altitudes by adding information comparable to a T15 temperature. On-planet radiance measurements in channels A2 and A3 can now also be included in the atmospheric temperature retrieval over CO2-ice if sufficient atmospheric opacity is present, extending the vertical range to lower altitudes. 4. The vertical coverage of aerosol profile retrievals has been extended. In addition, the climatological surface temperatures during the 2007 dust storm was adjusted to be more representative of conditions during a global dust storm. This yields a significantly better retrieval coverage during dust storm conditions.

Processing - Level 1 (RDR) to Level 2 (DDR)

RDR to DDR data processing can be divided into three phases. 1. Pre-processing. 2. Atmospheric profile retrieval. 3. Post-processing. Pre-Processing ------------- Pre-processing takes the MCS level 1 (RDR) data (calibrated radiances and geometry) as its input and performs the following functions: 1. Selects groups of 5 contiguous limb viewing measurements. 2. Selects groups of up to 2 contiguous on-planet measurements. 3. Uses radiance, roll, freeze and geometry tests to reject problem data. 4. Uses MOLA altimetry maps to assign surface altitude to measurements. 5. Outputs a data file with input needed by the profile retrieval software. Atmospheric Profile Retrieval --------------------------- Atmospheric profile retrieval is the most complex element of the MCS level 1 to level 2 processing suite. Its primary functions are to: 1. Read and average groups of 5-limb measurements with geometry as well as accompanying on-planet measurements when available. 2. Select average radiance measurements used for profile retrievals. 3. Retrieve profiles of temperature, dust and water ice as a function of pressure from radiances using a modified Chahine method. 4. Output results of profile retrieval in a form suitable for the post-processing software. Post-Processing --------------- Post-processing applies quality control to the retrieved profiles and outputs level 2 products suitable for input to the PDS. Its chief functions are to: 1. Read relevant data output by the Profile Retrieval software. 2. Select good profile retrievals based on radiance residual criteria for the pressure, temperature, dust, and water ice retrievals considered separately. 3. Calculate parameters needed for Level 2 data set. 4. Output formatted level 2 data for each good profile set. All three phases of level 1 to level 2 data processing are described in more detail below (see [KLEINBOEHLETAL2009]).

Data

The MCS DDR is represented by a single PDS labeled table. Each table is accompanied by a full PDS detached label with the same name except for suffix *.LBL. The PDS label completely describes the format and contents of the table. The naming convention for the tables and detached headers follow the time-organization of the data itself and use the following naming convention: yyyymmddhh_DDR.TAB; where: yyyy = year in which the data was acquired mm = month of the year in which the data was acquired dd = day of the month in which the data was acquired hh = hour of the day in which the data was acquired Note that the hour is UT (to within the nearest second) at the start of the coverage of the data contained in the file. There are six possible values for hour. The first data after powering on in September 2006 are: - 2006092416_DDR.LBL: The PDS label that describes the DDR data - 2006092416_DDR.TAB: The actual DDR data formatted into a PDS TABLE object

Ancillary Data

Ancillary data are used to generate the geometry fields in the MCS DDR product. This data comes from the navigation team and is assumed to be the best available. The following SPICE NAIF Kernels are used: 1. Sclk to Scet kernel (sclk) 2. Leap Seconds kernel (lsk) 3. Frame reference kernel (fk) 4. Planetary constants kernel (pck) 5. Spacecraft ephemeris kernel (spk) 6. Pointing kernel (ck)

Coordinate System

All positions and vectors in the MCS DDR product files are specified in Areocentric spherical coordinates. All coordinates follow the MRO mission convention and use north latitude and east longitude.

Software

The MCS DDR products are formatted as columnar ASCII data; and as such, they can be read and manipulated by standard, public-domain software. For this reason, no special utilities are provided. The MCS DDR products are standard PDS-labeled tables that can be viewed with NASAView, an application developed by the PDS and available for a variety of computer platforms from the PDS web site.

Archive Format

The individual archives were delivered to the PDS Atmospheres node as gzipped tar files via ftp. Once validated they are available online with the archive volume structure.

These data are available on-line from the Planetary Data System (PDS) at:

http://atmos.nmsu.edu/PDS/data/ in subdirectories MROM_2XXX.

Alternate Names

  • MRO-M-MCS-5-DDR-V1.0

Discipline

  • Planetary Science: Atmospheres

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Daniel J. McCleeseData ProviderNASA Jet Propulsion Laboratorydaniel.j.mccleese@jpl.nasa.gov
Dr. Daniel J. McCleeseGeneral ContactNASA Jet Propulsion Laboratorydaniel.j.mccleese@jpl.nasa.gov
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