Data Set Information
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| DATA_SET_NAME |
VL1/VL2 MARS LCS DERIVED ATMOSPHERIC OPTICAL DEPTH V1.0
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| DATA_SET_ID |
VL1/VL2-M-LCS-5-ATMOS-OPTICAL-DEPTH-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : Viking Lander camera images of the Sun were used to compute total normal atmospheric optical depth at the two landing sites over a period of about 900 Mars days. The data set contains 1044 measurements of optical depth and associated error estimates. The optical depths were derived from Sun diode images, which were obtained by the Lander cameras at a wavelength of 0.67 micrometers. Note that no images of Phobos were used in deriving this data set. Studies of diurnal, seasonal, and annual variations in optical depth, surface-based observations of great dust storms, and analyses of the contributions of ice haze and dust particles to the observed optical depth, have been carried out using these data. See COLBURN_ETAL_1989, POLLACK_ETAL_1977, and POLLACK_ETAL_1977 for further information on the derivation and interpretation of this data set. This data set is composed of the following fields (listed as the field name followed by a description): SC_ID Spacecraft id CAMERA_ID Viking Lander camera id EARTH_DAY The fractional 1976 day number (Universal Time) SOL_LON Areocentric longitude of the Sun (Ls) VIKING_YEAR Viking mission year, starting at 1 when the Viking spacecraft reached Mars, and incremented at Ls : 0 every martian year MARTIAN_DAY The martian solar day (sol), starting at day 0 when each Lander touched down LOCAL_HOUR Local hour (Earth hour), beginning at midnight (hr 0) LOCAL_MINUTE Local minute (Earth minutes) OPACITY Atmospheric optical depth OPACITY_FLAG Opacity limitation flag, identifying upper and lower bound estimates ERR_DIGITIZE The uncertainty in optical depth due to digitization error in the brightness signal ERR_DEVIATE The uncertainty in optical depth due to the deviation in the multiple measurements averaged to determine the observed solar intensity at the surface ERR_VIGNET The uncertainty in optical depth due to brightness loss in the Lander cameras resulting from vignetting ERR_INTEN_0 The uncertainty in optical depth due to uncertainty in the determination of the observed solar intensity at the surface ERR_TOTAL The total uncertainty in optical depth, taken as the root mean square of the relevant errors (ERR_DEVIATE, ERR_VIGNET, and ERR_INTEN_0). ERR_DIGITIZE is excluded as it is implicit in ERR_DEVIATE. Processing Level Id : 5 Software Flag : Y Processing Start Time : UNK Processing Stop Time : UNK Native Start Time : 99.7 AREOCENTRIC SOL LON, EARTH YR 1976 Native Stop Time : 234.7 AREOCENTRIC SOL LON, EARTH YR 1979 Parameters : Data Set Parameter 'OPTICAL DEPTH' ---------------------------------- Optical depth is a dimensionless number that expresses the amount of radiation that is absorbed or scattered over a given path length through an atmosphere. Given an optical depth of 1, the amount of radiation reaching the surface is 1/e times the amount incident at the top of the atmosphere. Data Set Parameter Name : OPTICAL DEPTH Data Set Parameter Unit : N/A Sampling Parameter Name : TIME Sampling Parameter Unit : MINUTE Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : 1.000000 Noise Level : N/A Source Instrument Parameters : N/A Measurement Information : N/A Processing : Processing History ------------------ Source Data Set ID : VIKING LANDER SUN DIODE IMAGES Software : UNK Product Data Set ID : VL1/VL2-M-LCS-5-ATMOS-OPTICAL-DEPTH-V1.0
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| DATA_SET_RELEASE_DATE |
1989-11-01T00:00:00.000Z
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| START_TIME |
1976-01-01T12:00:00.000Z
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| STOP_TIME |
1979-01-01T12:00:00.000Z
|
| MISSION_NAME |
VIKING
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| MISSION_START_DATE |
1975-08-20T12:00:00.000Z
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| MISSION_STOP_DATE |
1983-02-01T12:00:00.000Z
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| TARGET_NAME |
MARS
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
VL1
VL2
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| INSTRUMENT_NAME |
CAMERA 1
CAMERA 2
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| INSTRUMENT_ID |
CAM1
CAM2
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| INSTRUMENT_TYPE |
CAMERA
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| NODE_NAME |
Planetary Atmospheres
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Overview : An error analysis of the derivation technique indicates errors on the order of 0.02 to 0.03 can be ascribed to the optical depth measurements contained in this data set. See COLBURN_ETAL_1989 for a full discussion of the error analysis, derivation, and interpretation of this data set. The data set contains the following fields documenting the ERR_DIGITIZE The uncertainty in optical depth due to digitization error in the brightness signal ERR_DEVIATE The uncertainty in optical depth due to the deviation in the multiple measurements averaged to determine the observed solar intensity at the surface ERR_VIGNET The uncertainty in optical depth due to brightness loss in the Lander cameras resulting from vignetting ERR_INTEN_0 The uncertainty in optical depth due to uncertainty in the determination of the observed solar intensity at the surface ERR_TOTAL The total uncertainty in optical depth, taken as the root mean square of the relevant errors (ERR_DEVIATE, ERR_VIGNET, and ERR_INTEN_0). ERR_DIGITIZE is excluded as it is implicit in ERR_DEVIATE.
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| CITATION_DESCRIPTION |
Citation TBD
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| ABSTRACT_TEXT |
Viking Lander camera images of the Sun were used to compute total normal atmospheric optical depth at the two landing sites over a period of about 900 Mars days. The data set contains 1044 measurements of optical depth and associated error estimates. The optical depths were derived from Sun diode images, which were obtained by the Lander cameras at a wavelength of 0.67 micrometers. Note that no images of Phobos were used in deriving this data set. Studies of diurnal, seasonal, and annual variations in optical depth, surface-based observations of great dust storms, and analyses of the contributions of ice haze and dust particles to the observed optical depth, have been carried out using these data. See COLBURN_ETAL_1989, POLLACK_ETAL_1977, and POLLACK_ETAL_1977 for further information on the derivation and interpretation of this data set.
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| PRODUCER_FULL_NAME |
DAVID S. COLBURN
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| SEARCH/ACCESS DATA |
Atmospheres Online Archives
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