Data Set Information
DATA_SET_NAME MRO MARS CLIMATE SOUNDER LEVEL 5 DDR V1.0
DATA_SET_ID MRO-M-MCS-5-DDR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION 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 MCCLEESE ET Al 2006 and the INSTRUMENT.CAT file accompanying this data set. Detailed information addressing processing of the DDR data set can be found in KLEINBOEHL 2008. 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, calibrated 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. Each table row contains one measurement, and each column contains one calibrated science, engineering or housekeeping parameter. 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). For convenience these are presented in the same table format with -9999 indicating time slots where data are not taken. Geometry information is not provided for soundings when the instrument is slewing and a value of -9999 is used in all geometry fields. 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. TBD 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, will be 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. Modified measurement selection and fixed minor bugs. Version 3: 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). Version 4: 1. 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 plance 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. Processing - Level 1 to Level 2 : Level 1 to 2 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 data (calibrated radiances and geometry) as its input and performs the following functions. 1. Selects groups of 5 contiguous limb-viewing measurements. 2. Uses radiance, roll, freeze and geometry tests to reject problem data. 3. Uses MOLA altimetry maps to assign surface altitude to measurements. 4. Outputs a data file with input needed by the profile retrieval software. Atmopheric Profile Retrieval ---------------------------- Atmopheric 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. 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 seperately. 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 [KLEINBOEHL 2008]). 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 is used to generate the geometry fields in the MCR 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. 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.
DATA_SET_RELEASE_DATE 2008-05-22T00:00:00.000Z
START_TIME 2006-09-24T04:00:00.000Z
STOP_TIME N/A (ongoing)
MISSION_NAME MARS RECONNAISSANCE ORBITER
MISSION_START_DATE 2005-08-12T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME MARS
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID MRO
INSTRUMENT_NAME MARS CLIMATE SOUNDER
INSTRUMENT_ID MCS
INSTRUMENT_TYPE INFRARED SPECTROMETER
NODE_NAME Planetary Atmospheres
ARCHIVE_STATUS IN_QUEUE
CONFIDENCE_LEVEL_NOTE Overview : Since MCS is a limb sounding instrument, the location of the measurements is slightly complex geometrically. For any given detector, the vertical resolution is defined by the appropriate weighting function (see Kleinboeul et al) and is approximately 5 km. The horizontal weighting function is controlled by the spherical atmosphere and is approxmately xxx km along the look direction (full-width half-max), centered at the tangent point. In moderately opaque (either due to aerosols or the temperature structure), this may be biased closer to the instrument than the tangent point, but since excessive opacity prevents the measurement from being used, this is a small effect. The width perpendicular to the look direction is controlled by the horizontal fields of view and is approximately 8 km [TBV]. Quality Flags ------------- The tangent point for each detector (or layer) is closer to the instrument than the one below it. This results in a shift of xxx km between the surface and a view at 80 km altitude along the line of sight. To help with this issue (and indicate the look direction) the altitude latitude and longitude are given for each pressure surface of the retrieval(columns 13, 14, and 15 in DDR part 2). While the views of the two MCS telescopes overlap, those of the individual arrays do not. This results in an effective observation region of ~100 km wide perpendicular to the line of sight. We have also included a simple location for the profile (Profile_lat and Profile_lon, columns 13 and 14 in DDR 1) for applications where the exact viewing geometry and profile shape are not relevant. These are also useful for searching for profiles in specific profiles. The timestamp on each profile (columns 2, 3, and 4 of the DDR 1 record) is the mean of the time of the limb soudnings (from the RDR dataset) used for the retrieval. The limb soundings used are always consecutive (thus at 2 second intervals), but the number may vary from 4 to 6 (the current version always uses 5 soundings). This time is used to determine the L_s and orbit number of the profile. Likewise, the Solar_lat, Solar_lon, Solar_zen, Profile_lat, Profile_lon, Profile_rad, Profile_alt and Limb_ang (columns 9, 10, 11, 13, 14, 15, 16, and 17) are the mean of the relevant RDR field for the limb soundings used in the retrieval. The latter 5 are thus the geometry for the instrument boresight tangent point (see the RDR for further description). The LTST (column 12) is derived from the averaged fields for convenience. Data Coverage and Quality : TBD Limitations : TBD Review : This archival data set was examined by a peer review panel prior to its acceptance by the Planetary Data System (PDS). The peer review was conducted in accordance with PDS procedures. Prior to creation of the final version of the archival data set, key elements of the archive were distributed for preliminary review. These included electronic versions of example PDS labels, CATALOG files, and Software Interface Specifications (SISs). These materials were distributed to PDS personnel, the experiment investigator, and others, as appropriate.
CITATION_DESCRIPTION McCleese and Schofield, MRO MARS CLIMATE SOUNDER LEVEL 4 RDR V1.0, NASA Planetary Data System, MRO-M-MCS-4-RDR-V1.0, 2006.
ABSTRACT_TEXT Unknown
PRODUCER_FULL_NAME DANIEL J. MCCLEESE
SEARCH/ACCESS DATA
  • Atmospheres Mars Archive
    		•