JPL
Near-IR
Water Spectrometer
for the ER-2, DC-8, and WB57F
Aircraft
Dr. Robert L. Herman (PI) and Dr. Randy D. May
(consultant)
The JPL Near-IR Water Spectrometer is a
new instrument for in-situ measurements of atmospheric water vapor from aircraft platforms
such as the ER-2, the DC-8, and the WB57F aircraft. It is based upon a near-IR tunable
diode laser source operating near 1.37 m m. The spectrometer
features an open-path, multipass (Herriott) cell for true in situ monitoring of H2O
concentrations with precision levels exceeding those of Lyman-a
and frost-point hygrometers. External sampling outside the aircraft boundary layer
minimizes measurement uncertainties and enables high-speed in situ sampling along
the aircraft flight track. Measurement precision is ± 0.05
ppmv in the stratosphere for a 2 s measurement integration period. The flight-ready
instrument weight is <20 lbs. Power consumption, exclusive of structural heaters,
is 7.5 Watts. Below is a photograph of the WB57 instrument shown mounted on an
underwing hatch on the right wing of the aircraft.
The WB57 aircraft is operated by NASA out of Ellington
Field in Houston, TX. It is capable of reaching altitudes of 65000 feet and carries
scientific instruments in the lower bomb bay area as well as in wing pods and in the
underwing compartments.
"Open-path, Near-Infrared Tunable Diode Laser Spectrometer for Atmospheric
Measurements of H2O", R.D. May, Journal of Geophysical Research, Vol 103,
No. D15, pp19161-19172, August 20, 1998
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