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  • Author or Editor: J. R. Drummond x
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J. R. Drummond
,
D. Turner
, and
A. Ashton

Abstract

The determination of the horizontal attitude of a balloon-borne, infrared, limb-scanning radiometer is discussed. In particular, the relationship between scan-angle, as measured by the instrument, and the tangent height of the ray path through the atmosphere is considered. The instrument is unusual in that it scans in two opposite directions. This property is used to derive the scan angle from the same radiance profiles, which are used to determine the constituent profiles, subject only to the assumptions that the attitude is steady, the stratosphere is locally horizontally homogeneous, and the instrumental optical alignment is correct.

The results of this determination for the first flight of the Toronto Balloon Radiometer are compared to previous methods of determining the instrumental scan angle and are found to agree to the accuracy with which the comparisons are made. Techniques by which the accuracy and resolution of the two-sided attitude determination could be improved are discussed.

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J. T. Pisano
,
J. W. Drummond
, and
D. R. Hastie

Abstract

A new lightweight NO2 instrument that can be flown from a tethered balloon to give vertical NO2 profiles is described. The detection principle is the chemiluminescent reaction between NO2 and a solution of luminol. The instrument is integrated with a radiosonde to also give temperature, humidity, and pressure data. Tests show the instrument is linear from 2.8 to 75 ppbv but nonlinear below 2.8 ppbv. A calibration curve is determined. The sensitivity varies directly with pressure and it has a −3.5% per degree temperature dependence. Data from trial flights as part of the PACIFIC'93 field study show NO2 data from the surface to 900 m.

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G. J. Nott
,
T. J. Duck
,
J. G. Doyle
,
M. E. W. Coffin,
,
C. Perro
,
C. P. Thackray
,
J. R. Drummond
,
P. F. Fogal
,
E. McCullough
, and
R. J. Sica

Abstract

A Rayleigh–Mie–Raman lidar has been installed and is operating in the Polar Environment Atmospheric Research Laboratory at Eureka in the High Arctic (79°59′N, 85°56′W) as part of the Canadian Network for the Detection of Atmospheric Change. The lidar operates in both the visible and ultraviolet and measures aerosol backscatter and extinction coefficients, depolarization ratio, tropospheric temperature, and water vapor mixing ratio. Variable field of view, aperture, and filtering allow fine-tuning of the instrument for different atmospheric conditions. Because of the remote location, operations are carried out via a satellite link. The instrument is introduced along with the measurement techniques utilized and interference filter specifications. The temperature dependence of the water vapor signal depends on the filter specifications, and this is discussed in terms of minimizing the uncertainty of the water vapor mixing ratio product. Finally, an example measurement is presented to illustrate the potential of this instrument for studying the Arctic atmosphere.

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M. N. Deeter
,
G. L. Francis
,
D. P. Edwards
,
J. C. Gille
,
E. McKernan
, and
James R. Drummond

Abstract

Optical bandpass filters in the Measurements of Pollution in the Troposphere (MOPITT) satellite remote sensing instrument selectivity limit the throughput radiance to absorptive spectral bands associated with the satellite-observed trace gases CO and CH4. Precise specification of the spectral characteristics of these filters is required to optimize retrieval accuracy. The effects and potential causes of spectral shifts in the optical bandpass filter profiles are described. Specifically, a shift in the assumed bandpass profile produces a relative bias between the calibrated satellite radiances and the corresponding values calculated by an instrument-specific forward radiative transfer model. Conversely, it is shown that the observed bias (as identified and quantified using operational MOPITT satellite radiance data) can be used to determine the relative spectral shift between the nominal (prelaunch) filter profiles and the true operational (in orbit) profiles. Revising both the radiance calibration algorithm and the forward radiative transfer model to account for the revised filter profiles effectively eliminates the radiance biases.

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