EOSS #204: NOAA LASP Flight - MARCH 7th, 2015 Recap

EOSS204 was the second EOSS flight for the NOAA/LASP Tropopause Temperature Profiler which is designed to use an optical fiber to make in-situ measurements of temperature near the tropopause.  The idea is to lower a length of optical fiber from the balloon payload and interrogate it by sending laser pulses down the fiber and determine temperature from the Raman scattering within the fiber.  The first time this was tried on EOSS199, the fiber broke after about 50 meters of fiber were reeled out.  The fiber that time was 200 microns in diameter with no protective coating.  This time the glass fiber was the same 200 microns in diameter, except there was a protective coating that increased the diameter to 800 microns.

Another change was that the 20 gram End of Fiber (EOF) dongle was initially housed in a blue foam “garage” on the bottom of the payload to constrain EOF motion on pre-deployment and initial ascent.  The EOF did not start being reeled out until after the payload is above 1000 m AGL to avoid any boundary layer turbulence.  The acceleration rate on the fiber reel was reduced from what was used in EOSS199 to reduce dynamic load.  These changes all helped avoid a repeat of the earlier flight and this time the 200 m of fiber were reeled out so that temperature profile data could be recovered over that 200 m length during ascent of the EOSS204 balloon.

At the ground station, observers could visually see the EOF being reeled out at about 8,000 feet MSL and within about 5 minutes the entire 200 m of fiber was deployed and remained deployed until the balloon was at about 70,000 feet when the EOF was reeled back in.  The balloon continued upward to burst slightly below 98,000 feet.  Then the payload (with the EOF reeled in and held in the blue foam “garage” on the bottom of the payload) descended back to earth under parachute and was recovered undamaged.  The flight profile and the ascent rates listed for every 30 seconds before, during and after the flight ate shown in the first figure below.  Note that the start time and end time of the data record are given along with the time and height of the burst.

Please see charts and graphs in the attached gallery.