CCSD1Z00000100000052CCSD1R00000300000032 DELIMITER=EOF; TYPE=CCSD1F000001; CCSD1C00000400000013 ADI=NURSSU07; CCSD1R00000300000032 DELIMITER=EOF; TYPE=CCSD1D000002; SUSIM WHOLE DATA SET DESCRIPTION Version 2.8, 05 December 1996 Linton Floyd and Ed Esfandiari Author's note: The descriptions of the level 2 and 3 data sets and the algorithms used to create them are found in separate SFDU metafiles. WHOLE DATA SET for SUSIM (data versions 15, 16, 17, 18, and 19) DATA_SET_NAME: SUSIM_Level2_Data and SUSIM_Level3_Data DATA_SOURCE: Satellite/Instrument = UARS/SUSIM UARS = Upper Atmosphere Research Satellite SUSIM = Solar Ultraviolet Spectral Irradiance Monitor SCIENTIFIC_CONTACT: Dr. Guenter Brueckner Code 7660, Naval Research Laboratory Washington, DC, 20375 PHONE: (202) 767-3287 FAX: (202) 767-5636 SPAN: SUSIM::BRUECKNER Internet: brueckner@susim.nrl.navy.mil SOURCE_CHARACTERISTICS: The UARS orbits the earth at an approximate height of 585 km and inclination of about 57 degrees. Its attitude is maintained such that the bottom of the spacecraft always faces the earth (aka airplane mode). Precession of the inclination by 5 degrees per day requires that on average every 36 days the UARS yaw angle attitude is moved 180 degrees in order to ensure that one side of the satellite is always facing the sun. SUSIM is an absolutely calibrated solar ultraviolet dual dispersion, dual spectrometer instrument. It is mounted on the UARS Solar Stellar Pointing Platform (SSPP) which normally tracks the sun for at least 35 minutes throughout each of the approximately 16 90-minute orbits per day. When illuminated by the sun, SUSIM measures the solar ultraviolet spectral irradiance in the 110 to 410 nm range. To calibrate the instrument during its long flight, it carries four deuterium lamps that are periodically scanned. Additional calibration capability is provided by SUSIM's ability to substitute different elements for each position in the optical path, namely, entrance filter, entrance slit, primary grating, secondary grating, exit slit, exit filter, and detector. SUSIM measurements are taken using pairs of slits which yield 0.15 (narrow), 1.1 (mid) or 5 (wide) nm spectral bandpass, using one of eight optical channels (defined by the available primary and secondary grating pairs) with one of six entrance filters (2 Quartz, 4 MgF2), one of seven exit filters (1 MgF2, 2 Corning, 2 7% neutral density, 2 15% neutral density) and one of seven detectors (3 RbTe diodes, 2 bialkali diodes, 1 RbTe photoncounter, 1 bialkali photoncounter). There are also four deuterium lamps, each of which can be used with the eight different optical channels. Solar irradiance data are acquired either in scanning mode, during which the solar irradiance is measured over a range of wavelengths, or in dwelling mode where the received irradiance is measured continuously at one selected wavelength. INVESTIGATION_OBJECTIVES: The primary scientific goal of the SUSIM experiment was to measure the solar ultraviolet spectral irradiance with an absolute accuracy of 6% and to determine changes in this radiation over the duration of the expected many years duration of the UARS mission with a long term precision of better than 2%. In addition, SUSIM was intended to collect solar data to facilitate an understanding of the solar processes that generate irradiance variations through analysis of the data in conjunction with an extensive suite of independent ground-based solar activity observations. As well, the SUSIM instrument was designed to acquire important quantitative data that will increase our understanding of the progression of optical responsivity degradation in ultraviolet optical components during extended space operation and continuing solar observations. INSTRUMENT_ATTRIBUTES: SUSIM comprises two separate, identical dual dispersion solar ultraviolet spectrometers, each having four separate optical paths by virtue of a turret of four gratings when selected, any one of which diffracts radiation from the entrance slit to a second grating and thence to the exit slit. Solar irradiances are measured with any of the four channels in the "upper" of two spectrometers (called the solar spectrometer). The four channels in the "lower" spectrometer (aka the reference spectrometer) are retained in a relatively pristine condition as a control on the amount of responsivity degradation caused by UV exposure. Wavelengths are selected by changing the orientation of the gratings with respect to the remainder of the optical path using the wavelength scan drive. A single wavelength scanning mechanism is used to move the arms connected to the grating mounts for both spectrometers. Two redundant linear drive screws driven by two stepper motors provide wavelength scanning with a resolution of 50 steps/nanometer over the range 110 to 410 nm. A readout device (aka the linear encoder) is attached directly to the grating arms to provide wavelength readings that are relatively free of backlash. Wavelength scanning consists of repeated wavelength scan drive moves and stops. At each stop, a specified number of measurements (aka signals) are acquired each representing a raw solar irradiance measurement at grating positions (and thus wavelength) measured by a linear encoder. Different spectral regions of the solar irradiance between 110 to 410 nm are measured by SUSIM's upper spectrometer using different combinations of optical elements. Typically, the shortest wavelengths, from 110 to 260 nm, are scanned using a MgF2 entrance filter whereas the longer wavelengths, from 240 to 410 nm are scanned using a synthetic quartz entrance filter. With wide (5 nm resolution) or mid (1.1 nm resolution) slits, a p-type diode (RbTe photocathode) and an n-type diode (bialkali photocathode) are used at the shorter and longer wavelength regions, respectively. Photoncounters are typically used with narrow (0.15 nm) slits. Since the solar flux increases by over 5 orders of magnitude in the wavelength region scanned by SUSIM, neutral density exit filters (which transmit either 7% or 15% of the incident radiation) may be used at the longer wavelengths to ensure that the signal levels remain within the detectors' ranges. SUSIM also carries two calibrated current generators that are used to measure the offsets and gains of its five diodes when they are not collecting solar data. Approximately once every 36 days, one (lamp #3) of SUSIM's four on-board deuterium lamps is used to sequentially irradiate the currently operating optical channel of the solar spectrometer as well as, for comparison, selected optical channels of the reference spectrometer. This activity provides a calibration of the solar spectrometer with the (independently calibrated) deuterium lamp light source and allows, as a check of this calibration, a comparison of the solar and reference spectrometers. During the measurements with the deuterium lamp, a Corning exit filter is used to eliminate second order radiation. Another part of the lamp calibration process is separate measurement of the transmittances (responsivities) of the filters and comparative measurements of the gratings that have been used during the past month of solar observations. These data allow changes in the calibration of the solar spectrometer to be traced to specific optical elements. Every three months, calibration of SUSIM with a deuterium lamp is repeated with an additional deuterium lamp (lamp #1). Every six months, a third deuterium lamp (lamp #2) is also scanned coincident with solar scans taken with the reference channel. Every year a fourth (lamp #4) is added. These additional lamp scans provide not only additional verification of the instrument responsivity changes as well as a way of degradation of the lamps themselves. The responsivity of the instrument (and especially its standard channel) is also tracked through solar scans of what is called the reference channel which consists of a different optical paths for both upper (235-410 nm) and lower (110-265 nm) wavelengths. The reference channel shares the upper spectrometer with the standard (working) channel except these have different entrance filters, primary grating, and detectors. The six monthly lamp #2 scans track the much smaller responsivity changes in the reference channel thus providing a calibration correction suitable for deriving solar irradiance on the day of the reference scan. By comparison of this with the output of the working channel, a calibration of the working channel is found. In this way, SUSIM's responsivity changes are quantitatively determined throughout the UARS mission. The SUSIM flight computer contains a number of databases. Among the most important of these are the Instrument Operations Program (IOP), the set table and the sequence table. The IOP contains the instructions used to initiate most SUSIM operations. It is written in a SUSIM instrument specific high level language which has the dual purpose of making SUSIM operations simpler while allowing operations changes in a controlled and less error prone manner. A SUSIM "set" is a parameterized complete specification of a scan including optical path, data gathering frequencies, and wavelength intervals. A SUSIM "sequence" is a list of sets to be done as a group. All of these databases change on an irregular time frame as is required by the SUSIM operations team. Thus, a particular set, sequence, or IOP index may mean one thing on one day and quite another on some later day. Despite this, all of information required to interpret the data scientifically is contained elsewhere in the output level 2 and level 3 data records. Further, among the sets, we can make some general statements about their meaning: SET USE 1-2 Daily mid resolution (1.1 nm) scans 4-5 Daily low resolution (5 nm) scans 7-9 Weekly high resolution (0.15 nm) scans 11-15 Daily high resolution scans of solar spectral features 16-20 Similar mid resolution scans of solar spectral features; now used for more occultation dwells and scans 22-23 Scans used during SUSIM offset maneuver where the SSPP is pointed at preselected positions away from the sun 24-42 Lamp calibration scans of various specific types 43-60 Solar occultation dwells and miniscans 61-64 Special scans including those of the reference channel and those specifically designed to measure scattered light among others. The software index is a two digit hexadecimal number that each second identifies what activity the SUSIM is engaged in. Below is a list of available software indicies that may appear in the level 2 data: S/I Meaning 21 Operate D2 Lamp 41 Instruction Processor of the IOP Interpreter 42 Dwell Processor of the IOP Interpreter 44 Scan Processor of the IOP Interpreter 45 Configuration Processor of the IOP Interpreter 46 Active Calibration Processor of the IOP Interpreter 47 Passive Calibration Processor of the IOP Interpreter FF Completion of the above Operations MEASURED_PARAMETERS: The primary goal of the SUSIM is to measure the UV solar irradiance from 115 nm to 410 nm over the lifetime of the UARS mission. The most important problem associated with obtaining these measurements is UV induced instrument responsivity degradation and its estimation. Thus, in addition to the solar measurements, SUSIM carries deuterium lamps that are periodically scanned to maintain instrument responsivity calibration. Measurements include: 1) daily 1.1nm and 5 nm solar scan measurements over the entire 110 nm to 410 nm spectrum; 2) Daily high resolution, 0.15nm, measurements are made over selected wavelength ranges, 118-125nm, 129-135nm, 153-157nm, 275-288nm, and 391-400nm; and 3) Weekly high resolution spectra over the entire wavelength range; 4) Weekly molocular oxygen (4) and ozone (5) occultation miniscans and dwells; 5) weekly scanning offset maneuvers where the pointing of sun is scanned in alpha and then beta. Each file contains data collected in one 24 hour period. The actual temporal resolution of the data depends on how the data have been collected, which can be determined from information which is included in the data files. For example, sun viewing may be limited due to the presence of the South Atlantic Anomaly (SAA), distributing the scans of the complete spectrum over longer time periods. The duration of the various low, mid and high resolution spectral scans will also depend on the wavelength increment of the scans and the time spent collecting data at each wavelength. Typically, a low resolutions (5 nm) scan of the entire solar spectrum from 110 to 410 nm will take 15 to 20 minutes, whereas a high resolution (0.15 nm) scan will extend over 60 minutes. Files may contain data collected using either the sun or the deuterium sources. Some solar data may also be collected while the line-of-sight from SUSIM to the sun passes through the earth's atmosphere. For this reason, certain spacecraft parameters are also included in the data files. DATA_SET_QUALITY: A. PI_DQ The PI Data Quality value is determined as follows. A data quality value of 4.0 is currently given to level 3BS products. This indicates that optical calibration for that data was determined using interpolation between reference calibration days. A data quality value of 2.0 is currently given to level 3AS products. This indicates that extrapolation from a reference calibration or monthly lamp was used to determine the optical calibration coefficients. A data quality of 0.0 indicates that there is no usable data in this file. B. UARS_DQ UARS Data Quality is set to 0.4 if better than 98% of data is valid. It is set to 0.3 if between 76% to 98% of data is valid and is set to 0.2 if between 50% to 76% of data is valid. Finally, UARS Data Quality is set to 0.1 If less than 50% of data is valid. PI_DQ and UARS_DQ flags are located in the catalog entry on the CDHF and in the metafile on the GSFC DAAC. Generally speaking, reviews of the level 2 and level 3 irradiances including comparisons with data generated by other instruments indicate a 5% absolute accuracy and a 1-2% relative accuracy from day 81 to day 895 for most wavelengths. For all of the days before this period (UARS days 30-80) the size of the relative errors approachs the absolute errors because the instrument responsivity was changing rapidly and consequently, was not completely characterized. There are also larger uncertainties in absolute irradiance at both ends of the SUSIM UV spectrum. For wavelengths shortward of about 130nm the continuum between the various emission lines can have errors of 20% or larger. This is due to a lack of true signal and to uncertainties in the stray light correction. The peak of the mid resolution Lyman alpha emission line is believed to be uncertain to about 10%. Above about 395 nm there remain unresolved problems in the SUSIM optical calibration and modeling of stray light and field of view corrections that increase both relative and absolute error estimates. DATA_PROCESSING_OVERVIEW: The principal purpose of the SUSIM Production Processing Software is to convert SUSIM's Level 0 raw telemetry, and observatory engineering and orbit/attitude data into Level 2 and Level 3AS/3BS solar ultraviolet irradiances as a collected during a given 24-hour period function of wavelength and time and produce several solar indices. In version 6 of the SUSIM reduction software, there are four processing streams named: PRODUCTION, SSPPGET, SUBSET, and LOG. Of these, only SSPPGET and PRODUCTION job steps are relevant to the purpose stated above. The SSPPGET job stream uses level 0 spacecraft file to create a level 1 output file containing alpha and beta sun pointing errors and associated OBC times for use by the PRODUCTION job stream. The SUBSET job stream generates level 1 data suitable for analysis of the data occulted by the earth's atmosphere. The log job stream generates a summary of SUSIM activities for each day. Only the PRODUCTION job stream generates level 2 and 3 output files. It consists of two phases containing a total of five job steps. The first three programs SUS1, SUS2, and SUS3 comprise phase 1 of the PRODUCTION job stream. The first job step, SUS1, converts the Level 0 data to as many as 15 Level 1 files mostly containing engineering data. It also generates another catalog file (RAW_ACTIVITY) which contains most of the necessary raw data from level 0 science (SUSIMA), ENGINEERING and OBC files that will be used in later job steps to produce the science data products. The second job step, SUS2, converts the RAW_ACTIVITY file to another Level 1 data file and also a scratch file (DET_IOP_PROFILE) for input to the next job step. SUS2 incorporates gain, temperature, nonlinearity, and dark signal corrections. The third job step of the PRODUCTION job stream, SUS3, converts the scratch file from SUS2 to additional Level 1 data files and scratch files that are used by this job step only. Time dependent field of view corrections and signal data reduction (where the many signals collected at a given wavelength are reduced to a single value), and wavelength assignment are done in SUS3. Phase 2 of the PRODUCTION job stream comprises the SUS4 and SUS5 job steps. It uses the SOLAR_SCANS file from phase 1 processing to generate three level 2 SFDU labeled files, namely, IOP_SCANS, IOP_SCANS_PARAM, and IOP_SCANS_MID, through conversion to one level 1 cataloged data file (SOLAR_SCANS). Stray light, degradation, another wavelength, and 1 AU corrections are performed by SUS4. SUS5 converts two level 2 cataloged data files IOP_SCANS_MID and IOP_SCANS_PARAM to level 3AS or 3BS data. The mid resolution irradiances are placed through 0.25 nm grid interpolation and reconvolution onto the 1 nm level 3 grid. Mean Solar Distance (MSD) at the average time of mid resolution scans, the seven solar indices, H I Lyman alpha, O I, C II, C IV, Al Edge, Mg II, and Ca II Index, and average time of grid data (Grid Data Avg. Time) in seconds are also computed in this job step. SOFTWARE AND DATA VERSION DESCRIPTIONS The differences among the softwre versions is displayed in the table below. data software ADI optical calibration algorithm version version level2 level3 WDS file version differences ------- -------- -------------------- ------------------- ----------- 14 5.0-5.04 SU05 SU06 SU07 9 numerous 15 6.0 SU05 SU08 SU07 17 FOV 16 6.0 SU05 SU08 SU07 19 none 17 6.1 SU05 SU08 SU07 28 stray light indices quadratic extrp. spline interp. MSD 18 6.2 SU05 SU08 SU07 40 FOV stray light gridding 19 6.3 SU05 SU08 SU07 66 degradation (responsivity) FOV stray light (hi res only) The SUSIM production software version 6.3 is changed from version 6.2 in the following ways: 1. Degradation: The method of interpolating the responsivity between calibration days has been updated to use "abscissa" and "fitting" functions. Previously, responsivities for each optical element were linearly interpolated based on an abscissa which represented the cumulative number of days that the spectrometer observed the sun or lamps. In version 6.3, each optical element is interpolated over an abscissa which is read from the ABSCISSA cataloged file. Further, optionally, the functional dependence upon the abscissa can optionally be a log function having one specified parameter instead of a linear interpolation (with no specified parameter). For V19, we use an abscissa function for the M1 and Q1 filters and the UG4 grating. A logarithmic fitting function is used wherever an entrance filter is part of the optical path. 2. Field-of-View: The version 6.3 software has separate corrections for MM and WW slits. The interpolation between calibrations is done using the UG4 abscissa described above. Additionally, we have improved calibration values for wavelengths greater than 381nm and for days prior to UARS day 200. Another set of calibration values are supplied for day 1800. 3. Stray Light: The stray light algorithm has been updated for the high resolution scans (we call this version "gcorr"). The V19 stray light correction differs from that of V18 in the following ways: a. The values of all stray light parameters for the high-resolution sets have been recalculated. In the case of sets 7 and 8, it was found necessary to make the stray light parameters vary with wavelength. b. The anomalous stray light for high res set 9 in the 400 nm region has been completely reanalyzed and improved. The SUSIM production software version 6.2 is changed from version 6.1 in the following ways: 1. Field of View: The FOV code in V6.2 is exactly the same as in V6.1 except that slit dependency for narrow, mid, and wide slits is allowed. In addition, flat, rather than linear, extrapolation is used to extrapolate the multiplicative factors. 2. Stray Light: Version 6.2 software corrects a sorting problem found in the previous versions for scans taken from high to low wavelengths. This improves the stray light correction for these scans. 3. Gridding: In version 6.2 software, the hard coded 0.25 nm used for grid interpolation value is read from a runstream parameter so it can have any value. However, 0.25 nm is still used. The SUSIM production software version 6.1 is changed from version 6.0 in the following ways: 1. Quadratic Extrapolation: The code can optionally extrapolate responsivity calibrations through fitting a quadratic function for each wavelength through the previous three calibration days rather than a linear function through the last two. 2. Stray Light: The "hg" stray light model now used improves the characterization of the stray light by modeling it as a linear combination of a Lorentzian and a constant. The amount of correction was increased resulting in lower reported irradiance values in the short wavelength continuum, i.e. 115nm to 160nm. 3. Indices: Version 6.1 incorporates, as a safety feature, a second wavelength shift by fitting a three point parabola through a feature and using the minimum or maximum. This is done for all indices except for OI which uses either Lyman Alpha or CII. If the parabola fit fails, no index is calculated. 4. Spline Interpolation: Version 6.1 has, as an option, the ability to produce a L3CS file by gridding level 2 mid resolution data directly to level 3 1 nm bins using spline interpolation. The L3CS file will be generated only when a L3BS file (using linear interpolation) is produced and an additional L3CS is requested by setting a runstream parameter. This option, however, will not be used until the necessary UCSS code change to handle this new data level is made available at CDHF. 5. MSD: Version 6.1 software uses the average time at which mid resolution scans were taken to compute the Mean Solar Distance instead of using 12:00 noon GMT as was done in previous software versions. The data version 17 responsivities (to the extent that they exist) were improved over that found for version 16 in that data from a monthly reference channel and a newly introduced mission reference channel were also used to calibrate the working channel. The responsivities for data version 18 are further improved due to better wavelength registration of the calibration scans and better modeling of the degradation for days before UARS day 190. The principal difference between production code versions 5.0 and 6.0 is in the field of view correction algorithm. The version 5.X software applied the field of view correction immediately before the stray light correction. It used a time independent linear correction for alpha angle offsets extracted from the level 0 OBC file. The version 6.0 software applies the field of view correction before the signals for a given wavelength are averaged. It also incorporates mission day dependency as the optical responsivity dependence on the field of view has been observed to grow during the UARS mission. The correction is separately quadratic in both alpha and beta angle offsets. The SSPPGET program of the production software retrieves these offsets from the SPACECRAFT level 0 file instead of the OBC file because there the offsets are reported 16 times more often. The optical responsivity calibration files used to produce data versions 15 and 16 differ from the previous version in that the degradation of the reference channel calibration lamp is applied. This results in better estimates of the irradiance on later mission days. Several other subtle changes to the optical calibrations were made which eliminate induced artifacts in the data. Please note that the only difference between versions 15 and 16 data is due to these optical calibrations. Examination of version 15 data indicated the need for more optical calibration adjustments to further improve the estimated irradiance. SUSIM PRODUCTION JOB-STREAM SCHEMATIC, VERSIONS 6.1-6.3 Level 0 files: ENG SMA OBC | | | +-----------+------------+ | SUS1 | | - segregate useful data | L1 raw_activity_prof | SUS2 | encoder to wavelength assignment - | - gain nonlinearity (photon counters only) - | - temperature darks - | | * det_iop_profile L1 sspp_data (for FOV) |__________________| | SUS3 | +----------------+-------------------+--+-------------------+ | | | | L1 dwell_prof L1 det_cal_prof * iop_scans_prof * d2_b4_moves | | | | | - field of view | moves - | | - moves | - moves | | | * solar_b4_wavecor | | | | +-------------------+ | - wavelength | | | | L1 solar_scans_nofov L1 solar_scans L1 d2_scans_prof (V6.3 only) | SUS4 | - scattered light | - irrad./degrad. | - wavelength | - 1 AU adjustment | * adj_solar_scans | +---------------------+-------------+-----+------------------+ | | | | L1 phase2_fid_lines L2 iop_scans_param L2 iop_scans_mid L2 iop_scans | | | +---------------------+-------------------+ | SUS5 | - .25nm grid | - reconvolution | - grid/bin to 1nm | - indices | L3 grid_indices_profile SUS1 + SUS2 + SUS3 = PHASE 1 processing (level 1 outputs) SUS4 + SUS5 = PHASE 2 processing (one level 1 + level 2 and 3 outputs) PHASE 1 and PHASE 2 have their own SUSIM_STAT user status files * : scratch file L1: catalog level 1 data L2: catalog level 2 data (contain SFDU header) L3: catalog level 3 data RAW_ACTIVITY_PROF : file containing activity records for all data with S/I not equal to 41H. Consists mostly of raw level0 data. DET_IOP_PROFILE : scratch file containing all iop_activity records DWELL_PROF : contains dwell data stripped from DET_IOP_PROF. DET_CAL_PROF : contains uncorrected detector calib. data stripped from DET_IOP_PROF D2_SCANS_PROF : contains d2 scans stripped from DET_IOP_PROF. It has moves correction. IOP_SCANS_PROF : scratch file containing remaining of DET_IOP_PROF SOLAR_B4_WAVECOR : same as IOP_SCANS_PROF but corrected for moves SOLAR_SCANS : catalog file containing reduced data (signals averaged for each wavelength) after wavelength correction. SOLAR_SCANS_NOFOV : same as SOLAR_SCANS except no FOV correction is applied ADJ_SOLAR_SCANS : irradiance scratch file resulted from applying FOV, stray light, irradiance, degradation, wavelength, and one AU adjustments to SOLAR_SCANS IOP_SCANS_PARAM : contains parameter data extracted from ADJ_SOLAR_SCANS plus a SFDU header. It is used for calculating CIV index. IOP_SCANS_MID : contains only mid res. scans extracted from ADJ_SOLAR_SCANS file plus a SFDU header. It is used for calculating Lyman Alpha, OI, CII, Al Edge, MgII, and CaII indices. IOP_SCANS : same as ADJ_SOLAR_SCANS plus a SFDU header GRID_INDICES_ : final mid scans irradiances and indices for use by the PROFILE outside world. NOTE: SUS1, SUS2, SUS3 software produce level 1 data (engineering) SUS4 software produces one level 1 (engineering) plus level 2 data (science) SUS5 software produces level 3 data (science, for the outside world) Full listing of SUS1 to SUS5 outputs: SUS1: CMD_PROF.DAT (catalog) CURRENT_PROF.DAT (catalog) DARK_DATA.DAT (catalog) DBASE_PROF.DAT (catalog) DBASE_SCR_PROF.DAT (scratch) DBASE_UPDATE_PROF.DAT (catalog) DUMP_PROF.DAT (catalog, may contain no data) EXCEPT_PROF.DAT (catalog) OBC_RPT1.DAT (scratch) OBC_RPT2.DAT (scratch) OBSERVE_PROFILE.DAT (catalog) PROG_PROF.DAT (catalog) PROG_UPDATE_PROF.DAT (catalog) RAW_ACTIVITY_PROF.DAT (catalog) SUN_SAT_DIST.DAT (catalog) TEMP_PROF.DAT (catalog) UVEXPOS_PROF.DAT (catalog) VOLT_PROF.DAT (catalog) SUS2: ACTIVITY_PROF.DAT (scratch) DARKS_ALL.DAT (catalog) SUS3: D2_B4_MOVES.DAT (scratch) D2_SCANS_PROF.DAT;1 (catalog) DET_CAL_PROF.DAT (catalog) DWELL_PROF.DAT (catalog) FIDUCIAL_LINES.DAT (catalog) IOP_SCANS_PROF.DAT (scratch) SOLAR_B4_MOVES.DAT (scratch) SOLAR_B4_WAVECOR.DAT (scratch) SOLAR_SCANS.DAT (catalog) SOLAR_SCANS_NOFOV.DAT (catalog) SUSIM_STAT.DAT (user status created by sus1 and updated by sus1, sus2, and sus3) SUS4: ADJSOLAR_B4_WAVECOR.DAT (scratch) ADJ_SOLAR_SCANS.DAT (scratch) IOP_SCANS.DAT (catalog) IOP_SCANS_MID.DAT (catalog) IOP_SCANS_PARAM.DAT (catalog) PHASE2_FID_LINES.DAT (catalog) SUS5: GRID_INDICES_PROFILE.DAT (catalog) SUSIM_STAT.DAT (user status created by sus4 and updated by sus4 and sus5) DATA_USAGE: The three level 2 files of SUSIM data contain all of the solar UV data gathered at various times during one 24 hour period. The data are the products of solar spectral scans, provided in the form of solar irradiances, ordered sequentially with the time that they were measured and tabulated at the actual wavelength at which the data were collected. The data in the IOP_SCANS file are scans of the UV solar irradiance collected with narrow, mid or high spectral resolution, using a variety of instrument configurations and covering a variety of different wavelength intervals. The data in MID_SOLAR are simply a subset of the data in the IOP_SCANS file, containing only those scans collected with the mid-resolution (1.1 nm) configuration. In the IOP_SCANS_PARAM file are short scans over a few (10 or so) selected wavelength intervals of special significance for either atmospheric or solar investigations, for example the H I Lyman a line at 121.6 nm, the Mg II h & k lines at 280 nm and the Ca II H & K lines near 393 nm. The data described above can be used to estimate the absolute level of the solar irradiance on a given day. It may also be used to do time dependent studies of the measured irradiance in broad wavelength intervals or in the given solar indices. DATA_ORGANIZATION: The three level 2 SFDU labelled SUSIM data files each have the same format. They consist of one SFDU header record followed by many data records, terminated by an EOF record. The structure and fields of the data records within each of the three types of files are identical. FILE_CLASS_RELATIONSHIP: Each of the three level 2 files of SUSIM data have the same structure and format. There is only one level 3 formatted file which has the same data as is found in the IOP_SCANS_MID except that additional corrections have been made as outlined above. The files and their corresponding ADI's are: At level 2: IOP_SCANS NURS1I00SU05 IOP_SCANS_MID NURS1I00SU05 IOP_SCANS_PARAM NURS1I00SU05 At level 3: GRID_PROFILE NURS1I00SU08 LIT_REFERENCES: 1) Brueckner, G.E. et al., "The Solar Ultraviolet Spectral Irradiance Monitor Experiment Onboard the Upper Atmosphere Research Satellite (UARS)", JGR, v98, pp. 10965-10711, 1993. 2) Brueckner, G.E. et al., "Solar ultraviolet spectral- irradiance observations from the SUSIM-UARS experiment", Metrologia, v32, pp. 661-665, 1995/1996. 3) Woods, T.N. et al., "Validation of the UARS solar ultraviolet irradiances: Comparison with the ATLAS 1 and 2 measurements", JGR, v101, D6, pp. 9541-9569, 1996. 4) Floyd, L.E. et al., "Maintaining calibration during the long term space flight of the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM)", SPIE Proceedings, v2831, pp. 36-47, 1996. 5) UARS CDHF Software System (UCSS) Programmer's Guide to Production Software Support Services, Computer Sciences Corporation, CSC/SD-86/6704/UD6, NASA GSFC Contract NAS 5-31000, February 1993.