Data Visualization

Large amounts of data were collected from several co-located aerosol sensors on the GLOBE Pacific survey missions. Data visualization and analysis software techniques were used to present data taken from various sensors over one flight in co-registered image formats. LinkWinds developed by Jet Propulsion Laboratory (JPL) was used to display measured aerosol backscatter coefficients and related meteorological variables in time-altitude cross-section plots with a false color display (256 color palette). Examples of these plots follow. (Note the time scale labels provided on the images should have 24 subracted after 00 UTC.)

Japan to Hawaii (Flight 14)

Flight 14 began late on 3 June 1990 in Tokyo, Japan, and ended early on 4 June 1990 in Honolulu, Hawaii. The flight track was nearly straight and level, with a cruising altitude of 8.3 km. During the first two hours of the flight, the DC8 experienced 30-40 meters/second westerly tailwinds associated with a midlatitude jet. As the aircraft headed southward toward Hawaii, the westerlies gradually decreased in strength to less than 10 meters/second during the second half of the flight. For much of the flight, a large cirrus plume was observed overhead and to the north of the track. Flightlevel windshifts indicative of the penetration of a pair of shortwave troughs were encountered during the third and fourth hours of the flight, followed by slowly veering winds suggestive of a midtropospheric ridge. During traversal of the shortwave troughs, some convective development up to 7 km deep was noted along the flight track. Later in the flight, a subtropical environment prevailed, with only a few scattered shallow cumulus accompanied by patches of cirrus aloft.

The European Center for Medium-Range Weather Forcasting (ECMWF) model provided global fields of several meteorological parameters every 12 hours on a 2 degree by 14 level 3-D grid. ECMWF wind fields were used to transport selected meteorological variables from the ECMWF grid cell to the location, altitude and time of each pixel within the range of the GLOBE pulsed lidars above and below the DC-8 aircraft. The transported quantities were interpolated in altitude and converted as needed to the metorological variables required.

Relative Humidity (NASA MSFC)

The ECMWF model output provided the cross-section of relative humidity (RH) for Flight 14. Based on flight level observations, the RH field shows good consistency with the scenario presented above. Much of the flight track was characterized by a substantial upper tropospheric moist layer, with RH high enough to suggest widespread cirrus. There is a hint of plumes of moist air ascending in the vicinity of the shortwave troughs, although the ECMWF data do not reveal as much detail as the actual flight level data.

Log aerosol backscatter mixing ratio at 1.06 um ( NASA GSFC )

The Goddard Space Flight Center (GSFC) lidar operated in a vertical downward viewing mode during Flight 14. The field of log aerosol backscatter mixing ratio ( B ) for the flight is shown. (Aerosol backscatter mixing ratio ( B ) at a particular altitude is defined as aerosol backscatter coefficient divided by air density at that altitude, generally analogous to the water vapor mixing ratio commonly used in meteorology. Values of B tend to be conserved in atmospheric transport processes but altered in processes that involve aerosol generation, removal and physical or chemical modification. Consequently, uniformity of B values is suggestive of common sources or source processes .) Values of log B above the boundary layer were generally high, often around -7. By 03 UTC, the midtropospheric backscatter decreased, and the GSFC data indicate the presence of an interface between high and low backscatter that tilted southward and eastward with height. However, in this case, the lower tropospheric backscatter field remains quite agitated, with some eastward-leaning 5 km deep plumes of enhanced backscatter arising from the boundary layer in the vicinity of Midway Island. In the false-color representation given, these plumes resemble smoke from a windblown forest fire. As in the other flights, values of log B in the 1-2 km deep boundary layer are around -6.

Log aerosol backscatter mixing ratio at 9.25 um ( JPL )

The Jet Propulsion Laboratory (JPL) lidar operated in both vertical upward (zenith) and downward (nadir) positions for this flight to provide 9.25 um log aerosol backscatter mixing ratio data. The zenith data reveal backscatter from a cirrus layer (yellow regions) above the aircraft which eventually approaches flight level at around 01:30 UTC. The nadir B data clearly show strong backscatter from marine boundary layer cloud (red regions) and aerosols (yellow regions) in the first 1.5 kms above the surface. Aerosol layers in the troposphere (2-6km) provide moderate backscatter values around -8 (green). The plumes of backscatter seen in the 1.06 um image around 03:45 UTC are also evident at the 9.25 um wavelength.

Log ratio of aerosol backscatter mixing ratio at several wavelengths (NASA MSFC)

Ratio plots of lidar aerosol backscatter mixing ratio (B) measured at two wavelengths can reveal the following features:

Large ratio values indicate small submicrometer particles are mostly responsible for the backscatter.
Small ratio values indicate large, micrometer-sized particles.
Ratios increase as the wavelength difference increases.

The histogtram of the log of the ratio of the 1.06 and 9.25 um aerosol backscatter data shows:

a peak around 0.5 which mostly comes from an aerosol regime containing moderately large particles encountered around 03:45 UTC.
a second peak in the ratio around 1.5 arising from a dominance of small particles in the aerosol plume seen after 02:00 UTC.

The ratio of the 0.53 and 1.06 um aerosol backscatter data shows:

over the period 03:00 to 04:20 UTC the presence (red) of very small particles in the mid-tropospheric region. (Log ratio > 1.7)

Responsible Official: Dr. James E. Arnold (jim.arnold@msfc.nasa.gov)
Page Curator: Paul J. Meyer (paul.meyer@msfc.nasa.gov)

Last Updated: May 15, 1995