MOPITT File Spec

Table of Contents

MOPITT Level-1B Radiances
MOPITT Level-2 Geophysical Parameters
MOPITT Level-3 Daily Averaged Gridded CO
File Naming Convention
Software
Metadata
Point of Contact

MOPITT Level-1B Radiances

EOSDIS Product Code: MOP01

Data Product Overview

The MOPITT Level-1 data product consists of the geolocated, calibrated earth scene radiances, associated instrument engineering data summaries, and inflight calibration information. Data granules are one day in duration and limited to the earth scenes observed within the midnight to midnight period. Data from special calibration sequences and instrument diagnostic modes have been excluded.

Data Format

The MOPITT Level-1B product is archived using the HDF-EOS Swath structure that is described along with Application Program Interfaces (APIs) in references listed in Section 2.0. This structure has been defined to represent time ordered, multi-channel instrument data such as MOPITT. HDF-EOS is an extension to the Hierarchical Data Format (HDF) standard developed at the University of Illinois National Center for Supercomputer Applications. Readers should familarize themselves with HDF and HDF-EOS in advance of using the data.

Data Content

* NOTE -- DIMENSIONALITIES OF ARRAYS ARE DEFINED IN FORTRAN ORDER, C ORDER IS REVERSED *

DIMENSIONS

ntrack = unlimited (number of cross-tracks = Number of swaths)
nstare = 29 (29 stares per cross track swath = Number in Crosstrack)
npixels = 4 (4 pixels per stare)
nchan = 8 (8 channels of radiance measurement)
nstate = 2 (Average and difference state of correlation cell)
nengpoints = 38 (38 engineering data elements per swath)
neng = 2 (Engineering data elements are represented as an average value over a swath and a standard deviation)
ncalib = 8 (Calibration parameters for each radiance element: swath average gain, offset, noise and internal black body radiance and associated standard deviations)
nsector = 4 (Sectors A,B,C and D refer to sections of the LMC)
npchan = 2 (Two PMC channels 3 and 7)
nposition = 5 (stare positions within a packet)

GEOLOCATION FIELDS

The following are HDF VDATA variable names:

Track Count: float Number of tracks in this data set
Time: double (ntrack) (Holds time of day and date in Tai93 format for first stare in swath. Subsequent stares occur 450 milliseconds apart.)
Swath Quality: int32 (ntrack) (TBD values to flag if entire swath has valid values)

The following are HDF Scientific Data Set (SDS) variable names

Latitude: float (npixels,nstare,ntrack) (Latitude in degrees -90 to 90)
Longitude: float (npixels,nstare,ntrack) (Longitude in degrees -180 to 180)
Solar Zenith: float (npixels,nstare,ntrack) (Solar direction angles at pixel locations in degrees)
Solar Azimuth: float (npixels,nstare,ntrack) (Solar direction angles at pixel locations in degrees)
Satellite Zenith: float (npixels,nstare,ntrack) (Satellite direction angles at pixel locations in degrees)
Satellite Azimuth: float (npixels,nstare,ntrack) (Satellite direction angles at pixel locations in degrees)

DATA FIELDS

The following are HDF Scientific Data Set (SDS) variable names

MOPITT Radiances: float (nstate,nchan,npixels,nstare,ntrack) (MOPITT radiances in Watts meter^-2 Sr^-1 - swath format)

1=average state radiance
2=difference state radiance

Engineering Data: float (neng,nengpoints,ntrack) (Engineering data, one set per swath)

(in neng dimension)

1=Average over time of swath of engineering element
2=Variance of engineering element

(in nengpoints dimension)

1-4 = temperature of chopper 1 through 4 in Deg K
5-8 = temperature of filter 1,3,5,7 in Deg K
9-16 = temperature of detector 1 through 8 in Deg K
17-20 = temperature of LMC 1 through 4 in Deg K
21-24 = temperature of LMC pressure sensor 1 through 4 in Deg K
25 = cell pressure LMC 1 CO 4.7mic in kPa (20 kPa nominal)
26 = cell pressure LMC 2 CH4 2.4mic in kPa (80 kPa nominal)
27 = cell pressure LMC 3 CO 4.7mic in kPa (80 kPa nominal)
28 = cell pressure LMC 4 CO 2.3mic in kPa (80 kPa nominal)
29-30 = temperature of PMC 1 and 2 in Deg K
31 = cell pressure CO PMC 1 (High state 10 kPa) 4.7mic in kPa
32 = cell pressure CO PMC 2 (High state 5 kPa) 4.7mic in kPa
33 = cell pressure CO PMC 1 (Low state 5 kPa) 4.7mic in kPa
34 = cell pressure CO PMC 2 (Low state 2.5 kPa) 4.7mic in kPa

Calibration Data : float (ncalib,nstate,nchan,npixels,ntrack) (Calibration data for each state, channel and pixel) (AVERAGED OVER SWATH)

(in ncalib dimension)

1=gain
2=offset
3=noise equivalent radiance in Watts meter^-2 Sr^-1
4=Internal Black Body Radiance in Watts meter^-2 Sr^-1
5=variance of gain
6=variance of offset
7=variance of noise in Watts meter^-2 Sr^-1
8=variance of Internal Black Body Radiance in Watts meter^-2 Sr^-1

Sector Calibration Data: float (ncalib, nsector, nchan,npixels, ntrack)
Daily Mean Position Noise: float (nposition, nstate, nchan, npixels)
Daily Mean Noise: float (nstate, nchan, npixels)
Packet Positions : integer (nstare,ntrack) This number (ranging from 1 - 5) represents the position that stare has in the packet sent down from the spacecraft.

MOPITT Level-2 Geophysical Parameters

EOSDIS Product Code: MOP02

Data Product Overview

The MOPITT Level-2 data product consists of the geolocated, retrieved carbon monoxide profiles and total column amounts for carbon monoxide and methane. Ancillary data concerning surface properties and cloud conditions at the locations of the retrieved parameters are also included.

MOPITT geophysical parameters are derived from the Level-1B radiances in combination with ancillary data describing the global distribution of surface and atmospheric temperature and humidity. Radiance measurements in the 4.7mm CO band provide the primary information on the vertical carbon monoxide mixing ratio profile in the troposphere. Clouds have a large influence on the observed radiances and their effects must be modeled appropriately in the retrieval algorithms. Details of the approach to retrieving the geophysical parameters are presented in the Level-2 Algorithm Theoretical Basis Document referenced in Section 2.0.

Data Format

The MOPITT Level-2 product is archived using the HDF-EOS Swath structure for the Beta Delivery implementation. The Swath structure has been defined to represent time ordered, multi-channel instrument data. Where the MOPITT scenes are interrupted randomly by clouds or large variability in surface properties, much of the regularity of the original cross-track is disturbed and there will not be one-to-one correlation of retrieved parameters and radiance pixels.

HDF-EOS is an extension to the Hierarchical Data Format (HDF) standard developed at the University of Illinois National Center for Supercomputer Applications. Readers should familarize themselves with HDF and HDF-EOS in advance of using the data.

Data Content

* NOTE -- DIMENSIONALITIES OF ARRAYS ARE DEFINED IN FORTRAN ORDER, C ORDER IS REVERSED *

DIMENSIONS

ntime = unlimited (number of retrieval time/location points)
nprs = 6 (number of pressure levels in retrieved CO vertical profile)

850 hPa
700 hPa
500 hPa
350 hPa
250 hPa
150 hPa

nwavlen = 3 (number of wavelengths)

2.2 microns
2.3 microns
4.7 microns

nbound = 4 (number of boundary points to describe pixel area aggregate)
ncoord = 2 (number of coordinates for each point in pixel area aggregate)
ntwo = 2 (Number of reported elements for each retrieved parameter - i.e. for retrieved value and its error estimate)

1 = data
2 = error

GLOBAL ATTRIBUTES

MOP02_NODATA (missing_nodata): real - Value for missing data which has no data value
TIMECNT (Time Count): integer - number of times in the data set
MONTH (Month): integer - Month of observations
DAY (Day): integer - Day of observations
YEAR (Year): integer - Year of observations (4 digits)

GEOLOCATION FIELDS

TIME (ntime): double - 'Time' time in TAI format units='seconds since 12 AM 1-1-1993'
LATITUDE (ntime): real - 'Latitude' units='degrees'
LONGITUDE (ntime): real - 'Longitude' units='degrees east'

Data Fields

The following are HDF VDATA variable names:

NAME	DIMENSION	TYPE	DESCRIPTION	UNITS
Seconds in Day	ntime	real	Time of observation	seconds
Wavelengths	nwavlen	real	wavelengths associated with nwavelen variable. See the DIMENSIONS Section for a list of reported wavelengths.	microns
Pressure Grid	nprs	real	pressures associated with nprs variable. See the DIMENSIONS Section for a list of reported pressure levels.	hPa
Solar Zenith Angle	ntime	real	solar zenith angle	degrees
Satellite Zenith Angle	ntime	real	satellite zenith angle	degrees
Ancillary Surface Emissivity	ntwo,nwavlen,ntime	real	Surface Emissivitiy
Retrieval Bottom Pressure	ntwo,ntime	real	Bottom Pressure of Retrieval (surface or cloud top pressure)	hPa
Derived Effective Retrieval Bottom Temperature	ntwo,ntime	real	derived effective retrieval bottom temperature	K
Derived Effective Retrieval Bottom Emissivity	ntwo,nwavlen,ntime	real	derived effective emissivity (2.2, 2.3, 4.7 microns)
Surface Indicator	ntime	integer	0=shallow ocean water,1=land,2=shoreline,3=shallow inland water, 4=ephemeral water,5=deep inland water,6=moderate ocean, 7=deep ocean
DEM Altitude	ntime	real	digital elevation model altitude	meters
Num Pixels Aggregate	ntime	integer	number of pixels in aggregate
Aggregate Bounds	nbound,ncoord,ntime	real	Aggregate Bounds (TBD)
Cloud Description	ntime	integer (0-9)	0 = clear, only MOPITT thermal and cloudtop used 1 = clear, only MOPITT thermal used 2 = MOPITT and MODIS cloud mask agree on clear 3 = MODIS cloud mask only clear (when MOPITT determines cloudy) 4 = MOPITT overriding MODIS cloud mask over low clouds (MODIS test flags used) 5 = MODIS cloud mask only, clear over polar regions 6 - 10: reserved for cloud cleared pixels 11 = MOPITT only, cloudy (when MODIS data missing) 12 = First 2 stares in a packet discarded (obsolete for V3) 13 = MOPITT and MODIS cloud mask agree on cloudy 14 = MOPITT clear, MODIS cloudy and failed low cloud tests 15 = MODIS cloud mask only, cloudy over polar regions
CH4 Total Column Bench 1	ntwo,ntime	real	CH4 total column on Bench 1	mol/cm2
CH4 Total Column Bench 2	ntwo,ntime	real	CH4 total column on Bench 2	mol/cm2
CO Total Column	ntwo,ntime	real	CO total column	mol/cm2
CO Mixing Ratio	ntwo,nprs,ntime	real	CO mixing ratio	ppbv
Retrieval Bottom CO Mixing Ratio	ntwo,ntime	real	CO Mixing Ratio at bottom of retrieval	ppbv
CH4 Column Percent Apriori Bench 1	ntime	real	100 * (uncertainty of retrieved CH4 column from Bench 1)^2/ (A Priori variance of CH4 column)	percent
CH4 Column Percent Apriori Bench 2	ntime	real	100 * (uncertainty of retrieved CH4 column from Bench 2)^2/ (A Priori variance of CH4 column)	percent
CO Mixing Ratio Percent Apriori	nprs,ntime	real	100 * (uncertainty of retrieved CO mixing ratio)^2/ (A Priori variance of CO mixing ratio at same level)	percent
Retrieval Bottom CO Mixing Ratio Percent Apriori	ntime	real	100 * (uncertainty of retrieved CO mixing ratio)^2/ (A Priori variance of CO mixing ratio at same level)	percent
Retrieval Error Covariance Matrix	ntwo,nprs2,ntime	real	This 21 element vector is used to assemble the matrix that is needed to determine how the MOPITT levels are correlated with each other. Users are urged to read the document describing its meaning. This document includes instructions for constructing the covariance matrix.	[Parts per volume]2

Instructions for Constructing the Covariance Matrix

The covariance matix, C, is symmetric so C_i,j = C_j,i. The diagonal elements are constucted by squaring the error of the CO mixing ratio. The off-diagonal elements are arranged in a 21-element vector.

C_1,2..C_1,7,
C_2,3..C_2,7
C_3,4..C_3,7
C_4,5..C_4,7
C_5,6..C_5,7
C_6,7

MOPITT Level-3 Daily Averaged Gridded CO

EOSDIS Product Code: MOP03

Data Product Overview

The MOPITT Level-3 (L3) data product is averaged from the L2 files onto a global 1x1 degree grid.

Filters

FILTER	METHOD
LAND/WATER	Each L3 grid box is determined to be land or water. Only L2 pixels that fit into that surface type are included in the average. This prevents inhomogeneous data from being averaged together.
DAY/NIGHT	Day and Night pixels are averaged and reported separately. Night is defined when the solar zenith angle is greater than 80 degrees.
Surface Pressure	Each grid box contains the mean of profiles that have a uniform lowest level. If a pixel does not contain retrievals for all the pressure levels of that grid box, it is excluded from the average.

Data Format

The MOPITT Level-3 product is archived using the HDF-EOS Grid structure. The global grid has a 1x1 degree resolution. A fill value is inserted into the grid box where there is no data. The grid is compressed when written.

Data Content

* NOTE -- DIMENSIONALITIES OF ARRAYS ARE DEFINED IN FORTRAN ORDER, C ORDER IS REVERSED *

DIMENSIONS

nlat = 180
nlon = 360
nprs = 7 (number of pressure levels in retrieved CO vertical profile)

1000 hPa
850 hPa
700 hPa
500 hPa
350 hPa
250 hPa
150 hPa

GEOLOCATION FIELDS

LATITUDE (nlat): real - 'Latitude' units='degrees'
LONGITUDE (nlon): real - 'Longitude' units='degrees east'
PRESSURE (nprs): real - 'Pressure Grid' units='hPa'

Data Fields

The following are HDF VDATA variable names:

NAME	DIMENSION	TYPE	DESCRIPTION	UNITS
Surface Indicator	nlat,nlon	integer	LAND=1 WATER=0	unitless
Surface Pressure Day	nlat,nlon	real	Mean surface pressure during the daytime swaths	hPa
Surface Pressure Night	nlat,nlon	real	Mean surface pressure during the nighttime swaths	hPa
Surface Temperature Day	nlat,nlon	real	Mean derived effective retrieval temperature during the daytime swaths	K
Surface Temperature Night	nlat,nlon	real	Mean derived effective retrieval temperature during the nighttime swaths	K
Surface Temperature Std Dev Day	nlat,nlon	real	Standard Deviation of the mean retrieved temperatures during the daytime swaths	K
Surface Temperature Std Dev Night	nlat,nlon	real	Standard Deviation of the mean retrieved temperatures during the nighttime swaths	K
Number of Pixels Day	nlat,nlon	integer	Number of pixels which contribute to the mean for that gridbox during the daytime swaths	unitless
Number of Pixels Night	nlat,nlon	integer	Number of pixels which contribute to the mean for that gridbox during the nighttime swaths	unitless
CO Total Column Day	nlat,nlon	real	CO total column gridded and averaged over the daytime swaths	mol/cm2
CO Total Column Night	nlat,nlon	real	CO total column gridded and averaged over the nighttime swaths	mol/cm2
CO Total Column Std Dev Day	nlat,nlon	real	The Standard Deviation around the mean CO total column during the daytime swaths	mol/cm2
CO Total Column Std Dev Night	nlat,nlon	real	The Standard Deviation around the mean CO total column during the nighttime swaths	mol/cm2
CO Profiles Day	nlat,nlon,nprs	real	CO mixing ratio at the seven pressure levels for daytime swaths. Consult the Averaging Kernel Explanation Document for interpretation of the profiles	ppbv
CO Profiles Night	nlat,nlon,nprs	real	CO mixing ratio at the seven pressure levels for nighttime swaths. Consult the Averaging Kernel Explanation Document for interpretation of the profiles	ppbv
CO Profiles Std Dev Day	nlat,nlon,nprs	real	The Standard Deviation around the mean CO mixing ratio at the seven pressure levels for daytime swaths.	ppbv
CO Profiles Std Dev Night	nlat,nlon,nprs	real	The Standard Deviation around the mean CO mixing ratio at the seven pressure levels for nighttime swaths.	ppbv
Averaging Kernel Day	nlat,nlon,nprs,nprs	real	The relative contributions of CO at each different level to the reported CO mixing ratio for daytime swaths.Consult the Averaging Kernel Explanation Document for an explanation.	unitless
Averaging Kernel Night	nlat,nlon,nprs,nprs	real	The relative contributions of CO at each different level to the reported CO mixing ratio for nighttime swaths.Consult the Averaging Kernel Explanation Document for an explanation.	unitless
CO Profiles Percent Apriori Day	nlat,nlon,nprs	real	100 * (uncertainty of retrieved CO mixing ratio)^2/ (A Priori variance of CO mixing ratio at same level) for daytime swaths. Large percentages indicate that the retrievals were less constrained by the observations.	percent
CO Profiles Percent Apriori Night	nlat,nlon,nprs	real	100 * (uncertainty of retrieved CO mixing ratio)^2/ (A Priori variance of CO mixing ratio at same level) for nighttime swaths. Large percentages indicate that the retrievals were less constrained by the observations.	percent

Instructions for Unpacking the Averaging Kernel

The averaging kernel describes the relationship between the retrieved profile, the a priori profile, and the true atmospheric profile. (Consult the Averaging Kernel Explanation Document for a useful discussion.) A 7x7 averaging kernel matrix is associated with each gridbox. Each row of the matrix corresponds to a pressure level of the retrieved profile (e.g. 850hPa). Within a given row, the n-th column gives the contribution to the retrieved CO amount from the n-th pressure level of the true profile. The averaging kernel describes how information from different levels is blended together, a blending that ultimately arises from the nature of CO spectroscopy in the 4.7 micron band, together with the nadir measurement process.

File Naming Convention

ShortName	Format	Explanation	Example
MOP01	MOP01-YYYYMMDD-[THH-]L1VX.Y.Z.hdf	YYYY = year MM = Month DD = Day [THH-] = an optional field if the file is only a partial day beginning at hour HH GMT X=major Y=minor Z=config version	MOP01-19970814-L1V2.2.2.hdf
MOP01ES	MOP01ES-YYYYMMDD-L1VX.Y.Z.txt	same as MOP01	MOP01ES-19970814-L1V2.2.2.txt
MOP01QE	MOP01QE-YYYYMMDD-L1VX.Y.Z.txt	same as MOP01	MOP01QE-19970814-L1V2.2.2.txt
MOPCH	MOPCH-YYYYMMDD-L1VX.Y.Z.hdf	same as MOP01	MOPCH-19970814-L1V2.2.2.hdf
MOP02	MOP02-YYYYMMDD-L2VX.Y.Z.hdf	X=major Y=minor Z=config version - typically Z=1 implies the from launch until May 6, 2001 and Z=2 is after Aug 21, 2001	MOP02-19970814-L2V2.2.2.hdf
MOP02B	MOP02B-YYYYMMDD-L2VX.Y.Z.hdf	same as MOP02	MOP02B-19970814-L2V2.2.2.hdf
MOP02Q	MOP02Q-YYYYMMDD-L1VX.Y.Z.txt	same as MOP02	MOP02Q-19970814-L2V2.2.2.txt
MOP03	MOP03-YYYYMMDD-L3VX.Y.Z.hdf	same as MOP02	MOP03-19970814-L3V1.0.1.hdf

Software

Level 1

HDF-EOS: MOPITT data is written in HDF-EOS. You may access it with any standard HDF tools. Additional functionality may be gained by accessing the data with tools which recognize the HDF-EOS extension to HDF. An overview and additional info is provided by the NASA Langley DAAC at http://eosweb.larc.nasa.gov/HBDOCS/hdf.html.
IDL: A customized data viewer was written by the MOPITT staff (Charles Cavanaugh). It may be used to access L1 data.

Level 2

HDF-EOS: MOPITT data is written in HDF-EOS. You may access it with any standard HDF tools. Additional functionality may be gained by accessing the data with tools which recognize the HDF-EOS extension to HDF. An overview and additional info is provided by the NASA Langley DAAC at http://eosweb.larc.nasa.gov/HBDOCS/hdf.html.
IDL: A customized data viewer was written by the MOPITT staff (Yottana Khunatorn). It may be used to access L2 data.
BROWSE: Level 2 data is also displayed as a browse product. The browse product contains the data fields, stored as raster images within an HDF file.

Metadata

The list of metadata required in each product is included in the Metadata Configuration File (MCF). Sample MCFs are available for display. Note that these may not be the most recent versions, since they are updated occaisionally.

Sample metadata created by the processor can be examined in ODL format. Note that these are sample ".met" files and are specific to a version of the MCF and the algorithm which created them.

Point of Contact

Additional info may be obtained by contacting the MOPITT data manager:

Dallas Masters
National Center for Atmospheric Research (NCAR)
PO BOX 3000
Boulder CO 80307

mastersd@ucar.edu
303-497-2924

comments to mastersd@ucar.edu