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Ernest Hilsenrath

Abstract

A hygrometer for water vapor measurements from an aircraft was developed. An aluminum oxide hygrometer mounted in an aircraft Rosemount air temperature scoop was flown on the NASA Convair 990 and on a USAF B-57 aircraft. Water vapor measurements from the Convair 990 were conducted up to 40,000 ft with penetration into the stratosphere. Good agreement was obtained with simultaneously flown remote sounders of water vapor. During transcontinental flights the hygrometer demonstrated adequate response to measure the natural variability of water vapor near the tropopause. Rapid response was demonstrated in pursuit of the jet wake of an F-104 at 35,000 ft.

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Ernest Hilsenrath

Abstract

Measurements of ozone have been performed in the mesosphere and stratosphere by means of a chemiluminescent, self-pumping parachute-sonde released from a rocket developed by Goddard Space Flight Center. Two ozone flights were performed in the arctic winter at Pt. Barrow, Alaska (71N), in January 1969, during a seasonal transition in the upper atmosphere. The change in the measured profiles was consistent with the model of a simple oxygen atmosphere in chemical equilibrium, if the supply of atomic oxygen is assumed to be constant. A diurnal measurement was performed in March 1970 at Wallops Island, Va. The ozone concentration measured below 30 km was in good agreement with data from simultaneously flown balloonsondes. The data were also in general agreement with contemporary moist-atmosphere models and other empirical data above thew altitudes. The nighttime mixing ratio between 60 and 67 km was approximately twice that measured during the day. The altitude resolution of the experiment is about 1 km, the precision 10%, and the absolute accuracy approximately 20%.

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John E. Frederick
,
Xufeng Niu
, and
Ernest Hilsenrath

Abstract

A central problem in the detection of long-term trends in upper stratospheric ozone from orbiting remote sensors involves the separation of instrument drifts from true geophysical changes. Periodic flights of a Solar Backscatter Ultraviolet radiometer (SSBUV) on the Space Shuttle will allow the detection of drifts in optically identical sensors (SBUV/2) carried on operational satellites. A detailed simulation of the SSBUV and SBUV/2 datasets defines the accuracy that can be attained by the in-orbit calibration procedure. The repeatability of the SSBUV calibration from one flight to the next is the most critical variable in the analysis. A repeatability near ±1% is essential for detection and correction of drifts in the SBUV/2 radiance measurements. The simulations show that one can infer true geophysical trends in backscattered radiance to an accuracy of approximately ±1.0% per decade when SSBUV flies approximately once per year and provides a precise calibration correction to the SBUV/2 dataset over a full decade.

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Lewis J. Allison
,
Joseph Steranka
,
G. Thomas Cherrix
, and
Ernest Hilsenrath

Mid-tropospheric circulation features under essentially clear sky conditions have been noted in the data of the 6.7 μm channel of the Nimbus 4 Temperature-Humidity Infrared Radiometer (THIR) while at the same time these features were undetected by the 11.5 μm channel of the same instrument. The characteristic response of the 6.7 μm channel to atmospheric water vapor emission is primarily from the 250-mb (10.5 km) to 500-mb (5.5 km) levels with a peak contribution at 350 mb (8 km). Dry and moist patterns seen in the 6.7 μm data on 21 February 1971 have been integrated into a 400-mb moisture analysis over the United States. This analysis provided more detailed and timely information than was conventionally available about the advection of dry air aloft prior to development of the Mississippi Tornado of February 1971. The derivation of middle to upper atmosphere flow patterns from the Nimbus 4 THIR, 6.7 μm data under cloud-free conditions has a direct application on a global scale for the GARP and World Weather Watch Programs.

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