Title:  INDOEX: Ship Ron Brown Meteorology Water Vapor Profiles (Welton)

Contact:

Lidar Data Contact:

Judd Welton
NASA/Goddard Space Flight Center
Code 912
Greenbelt, MD 20771

Phone: (301) 614-5492
Fax: (301) 614-6279

welton@virl.gsfc.nasa.gov

OCAG PI:
Piotr Flatau
pflatau@atol.ucsd.edu

Dataset Description:

These files contain lidar data from the R/V Ronald H. Brown. The data was collected by the Ocean Color 
and Aerosol Characterization Group (OCAG) during the INDOEX-99 cruise.  All data files contain MPL 
results from Feb 25 to Mar 15 1999.

File Format:

bl_hts.txt
tab delim text file containing aerosol heights in the boundary layer

cloud_hts.txt
tab delim text file containing cloud layer heights above 5 km

aop.txt
tab delim text file containing column aerosol optical properties of the boundary layer 

Special Notations/Conventions/Abbreviations

TOAL: top of uppermost aerosol layer in km
AOD: aerosol optical depth 523 nm
BER: backscatter-extinction ratio (1/sr) 523 nm
S Ratio: extinction-backscatter ratio (sr) 523 nm
asl: above sealevel

"Date" given in  month/day/year 

"Time" given in UTC (average times as noted in file)

"Day of Year" given in decimal day-of-year
(DOY 32.5 = noon UTC of Feb 1)

"Latitude" and "Longitude" given in decimal form


Brief Overview of Measurements:

A micro-pulse lidar system (MPL) was operated onboard the NOAA R/V Ronald H. Brown during INDOEX 99. 
The MPL transmits rapid pulses of low energy laser light at 523 nm and is able to profile the vertical 
structure of aerosols and clouds using the time-of-flight from pulse transmission to reception of the 
returned signal. The MPL ran continuously from Feb 22 to Mar 15 1999, except during periods of routine 
maintainence and/or mid-day periods when the sun was directly overhead (on average, 2-3 hours off-time 
per day).

Automated procedures have been developed which provide time series information on aerosol heights in 
the boundary layer. I have made available the following data: the top of the uppermost aerosol layer 
(maximum top of boundary layer), and an estimate of the top of the marine boundary layer. The marine 
boundary layer top is an untested data product as yet, but appears to be working within a few 100m 
error. I have also included a file of cloud layer heights above 5km from visual inspection of each 
day's signal returns. If anyone is interested in more in-depth studies of a specific cirrus event 
please contact me.

Automated procedures provide time series information on the following column averaged parameters: 
aerosol optical depth (523 nm) of the boundary layer, and the aerosol extinction-backscatter ratio 
(sr) of the boundary layer. The boundary layer is defined as sealevel to the top of the uppermost 
aerosol layer. 

Height resolved profiles of aerosol extinction and optical depth in the boundary layer can be generated 
for specific time periods. If interested in aerosol profiles at specifics times please contact me.

--- Judd

References:

 Instrument and Data Processing References:
 MPL instrument: Spinhirne et al., Rev. Laser Eng., 23, 112-118, 1995.
 Basic Data Processing: Welton et al., Tellus B, in press (2000)

 GSFC Website:
http://virl.gsfc.nasa.gov/mpl-net/mpl-indoex.htm