This directory contains data from a free-falling "dropsonde" float making 
measurements of vertical-mean horizontal velocity in the Florida Current 
along 27degrees N.  This data was collected as part of the Western 
Boundary Time Series ("WBTS") project.  The WBTS project is funded by the 
National Oceanic and Atmospheric Administration and is run at the 
NOAA-Atlantic Oceanographic and Meteorological Laboratory.        

Project web page: www.aoml.noaa.gov/phod/wbts/
Florida Current web page: www.aoml.noaa.gov/phod/floridacurrent/

Florida Current dropsonde contact:
  Dr. Christopher Meinen
  NOAA-Atlantic Oceanographic and Meteorological Laboratory
  4301 Rickenbacker Cswy
  Miami, FL 33149
  Phone: 305-361-4355
  Email: Christopher.Meinen at noaa.gov

The dropsonde float is a small self-contained device, and they have 
been in use in different forms since the 1960s.  The modern dropsonde 
is typically housed in a glass tube roughly 1.5 m in length or in a 
glass sphere roughly 0.3 m in diameter.  Modern dropsondes use global 
positioning system (GPS) to monitor their location at the start and 
end of each "cast"; they determine the vertical mean horizontal 
velocity via the difference between the start and end position and 
the time interval in between.  For more information on the modern 
dropsonde, see: 

Meinen, C.S., M.O. Baringer, and R.F. Garcia, Florida Current Transport 
Variability: An Analysis of Annual and Longer-Period Signals, Deep-Sea 
Res. I, 57(7), 835-846, doi:10.1016/j.dsr.2010.04.001, 2010.

Garcia, R.F., and C.S. Meinen, Accuracy of Florida Current volume 
transport measurements at 27°N using multiple observational techniques, 
J. Atmos. Ocean. Tech., 31(5), 1169-1180, 10.1175/JTECH-D-13-00148.1, 
2014.


For the WBTS project, dropsonde casts are collected at nine stations 
during each cruise - and the same nine stations have been in use with 
regular dropsonde sections since 1991.  

This directory contains the processed and quality controlled data from 
all dropsonde sections collected as part of the WBTS project.  The 
processed data is included here is in ASCII formatted files; data are 
in one file per cruise/section.  

The file format is as follows: 
  Each row represents a single dropsonde cast.  The columns are: 

	- Deployment month
	- Deployment day
	- Deployment year
	- Site/Station number
	- Deployment hour
	- Deployment minute
	- Deployment second
	- Deployment longitude (degrees E)
	- Deployment latitude (degrees N)
	- Recovery hour
	- Recovery minute
	- Recovery second
	- Recovery longitude (degrees E)
	- Recovery latitude (degrees N)
	- Vertical-mean zonal velocity (Units: cm s^-1 / positive indicates eastward)
	- Vertical-mean meridional velocity (Units: cm s^-1 / positive indicates northward)
	- Meridional transport associated with this cast (Units: m^3 s^-1)
	- Zonal surface velocity (Units: cm s^-1 / positive indicates eastward)
	- Meridional surface velocity (Units: cm s^-1 / positive indicates northward)


All times are in GMT.  


IMPORTANT NOTES:

The dropsonde use of GPS has varied during different time periods: 

	- During 1991-1993, the GPS was a hand-held unit onboard the ship, and the 
	ending positions for each cast were determined by acoustically ranging from 
	the ship to the dropsonde when it surfaced.  Note that GPS in this time 
	period was still impacted by 'Selective Availability', which reduced the 
	position accuracy.  

	- During 1994-1999, the GPS was installed inside the dropsonde float itself,  
	allowing for direct observation of the surface position at the end of the 
	cast.  However, GPS in this time period was still impacted by 'Selective 
	Availability', which reduced the position accuracy.  

	- Since 2000, the GPS is still installed inside the dropsonde float itself,  
	allowing for direct observation of the surface position at the end of the 
	cast, and 'Selective Availability' is no longer applied to the GPS signals, 
	so position accuracy has improved.  

For more information on the GPS and dropsonde changes and accuracy, see the Garcia 
and Meinen (2014) paper cited above.