Engineering topics

Vanek, M. D.

Publications and source records attributed to Vanek, M. D..

6 records

NASA NTRS1999

Far Infrared Measurements of Cirrus

Improved techniques for remote sensing of cirrus are needed to obtain global data for assessing the effect of cirrus in climate change models. Model calculations show that the far infrared/sub-millimeter spectral region is well suited for retrieving cirrus Ice Water Path and particle size parameters. Especially useful cirrus information is obtained at frequencies below 60 cm-1 where single particle scattering dominates over thermal emission for ice particles larger than about 50 m. Earth radiance spectra have been obtained for a range of cloud conditions using an aircraft-based Fourier transform spectrometer. The Far InfraRed Sensor for Cirrus (FIRSC) is a Martin-Puplett interferometer which incorporates a polarizer for the beamsplitter and can be operated in either intensity or linear polarization measurement mode. Two detector channels span 10 to 140 cm-1 with a spectral resolution of 0.1 cm-1; achieving a Noise Equivalent Temperature of approximately 1K at 30 cm-1 in a 4 sec scan. Examples are shown of measured and modeled Earth radiance for a range of cloud conditions from 1998 and 1999 flights.

Nolt, I. G.↗

NASA NTRS1991

Tunable far infrared studies of molecular parameters in support of stratospheric measurements

Lab studies were made in support of far infrared spectroscopy of the stratosphere using the Tunable Far InfraRed (TuFIR) method of ultrahigh resolution spectroscopy and, more recently, spectroscopic and retrieval calculations performed in support of satellite-based atmospheric measurement programs: the Global Ozone Monitoring Experiment (GOME), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY).

Chance, Kelly V.↗

NASA NTRS1991

Balloon borne optical disk mass storage system

An on-board data recording system for balloon-borne interferometer using a vacuum operable, ruggedized WORM optical drive is presented. This system, as presently under development, provides 320 Mbytes of data storage (or approximately 11 hrs at the 64 kbits/sec telemetry rate of the experiment). It has the capability of recording the unmodified telemetry bit system as transmitted or doing some preprocessing of the data onboard. The system is compact and requires less than 28 watts of battery power to operate.

Vanek, M. D.↗

NASA NTRS1991

Pressure broadening of the 2.5 THz H(Cl-35) rotational line by N2 and O2

The pressure broadening coefficients of the 2.5 THz rotation line of H(Cl-35) by N2 and O2, for application to the analysis of far infrared spectra obtained in the stratosphere, are reported. The broadening coefficients were measured in absorption at 296 and 201 L using a tunable far infrared spectrometer. Results show that at room temperature the N2 pressure broadening coefficient is 0.0669 +/-0.0021/cm/atm (2sigma), with a temperature coefficient B of 0.58 +/-0.02.

Park, K.↗

NASA NTRS1991

Pressure broadening of the 118.455/cm rotational lines of OH by H2, He, N2, and O2

Tunable far-infrared spectroscopy was used to measure pressure broadening of the 118.455/cm rotational lines of OH by H2, He, N2, and O2. Broadening coefficients of H2 and He were measured for the temperature range of 296 to 80 K, and N2 and O2 broadening coefficients were measured for the 296-210 K temperature range.

Chance, K. V.↗

NASA NTRS1987

Air- and oxygen-broadening coefficients for the O2 rotational line at 60.46/cm

Using an NBS laser-based tunable far-infrared spectrometer, the air- and oxygen-broadening coefficients were measured for the J = 10 - 10, N = 11 - 9 O2 rotational transition at 60.46/cm (1.812 THz). The air-broadening coefficient is 5.04 + or - 0.38 x 10 to the -7th/cm/Pa (0.0511 + or - 0.0039/cm/atm) (HWHM) at 245 + or - 6 K; the oxygen-broadening coefficient is 4.92 + or - 0.47 x 10 to the -7th/cm/Pa (0.0499 + or - 0.0048/cm/atm) (HWHM) at 259 + or -2 K. These direct experimental measurements of the air-broadening coefficient should improve the accuracy of retrieval calculations for far-infrared stratospheric balloon experiments which use O2 rotational lines to calibrate the viewing geometry.

Jennings, D. A.↗