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A fast response chemiluminescent ozone sensor was mounted in a National Center for Atmospheric Research Queen Air aircraft instrumented for air motion, temperature, and humidity measurements. The vertical flux of ozone was then obtained... more
A fast response chemiluminescent ozone sensor was mounted in a National Center for Atmospheric Research Queen Air aircraft instrumented for air motion, temperature, and humidity measurements. The vertical flux of ozone was then obtained by the eddy correlation technique for several flights in the day‐time atmospheric boundary layer over eastern Colorado. Because of the range and mobility of the aircraft, this technique can be utilized for a wide variety of situations. For example, a flight leg over an interstate highway shows large negative fluctuations in O3 due to vehicular emission of NO that are well correlated with positive temperature and vertical velocity fluctuations. On one flight the significant terms in the mean ozone concentration budget (and also, for comparison, the sensible heat and humidity budgets) were evaluated from the airplane measurements. For this flight, which occurred under clear skies over range and cropland about 100 km northeast of Denver, the time rate of change of ozone density in the lower half of the boundary layer was about 2.4 ng m−3 s−1. This was several times larger than the contributions by horizontal advection and the divergence of the vertical eddy flux of ozone. Thus, most of the observed increase in ozone concentration must have been the result of internal photochemical production of ozone. This may be the first well‐documented example where the rate of O3 increase with time is shown to be balanced by photochemical production of O3. The deposition velocity of ozone for this case was about 0.47 cm s−1.
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Research Interests: Environmental Science, Convection, Air pollution, Multidisciplinary, Atmospheric sciences, and 15 moreAtmospheric Boundary Layer, Ozone, Layered Structure, Marine Environment, Geophysical, Moisture Content, Pacific ocean, Flow Velocity, Boundary Layer, Eastern Pacific Ocean, Mixed layer, Long Distance, Troposphere, Vertical mixing, and Mixing Process
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... Steven T. Siems ... levels through the mixed layer or variance measurements from a minimum of two levels to solve for the surface and entrainment fluxes using the top–down—bottom–up (TD–BU) gradient or variance relations,... more
... Steven T. Siems ... levels through the mixed layer or variance measurements from a minimum of two levels to solve for the surface and entrainment fluxes using the top–down—bottom–up (TD–BU) gradient or variance relations, respectively, first proposed by Wyngaard and Brost ...
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Page 1. JOURNAL OF GEOPHYSICAL RESEARCH, VOL 103, NO. D13. PAGES 16,411-16,432, JULY 20, 1998 Bidirectional mixing in an ACE 1 marine boundary layer overlain by a second turbulent layer Lynn M. Russell.1,2 Donald H. Lertschow, 2 Krista K.... more
Page 1. JOURNAL OF GEOPHYSICAL RESEARCH, VOL 103, NO. D13. PAGES 16,411-16,432, JULY 20, 1998 Bidirectional mixing in an ACE 1 marine boundary layer overlain by a second turbulent layer Lynn M. Russell.1,2 Donald H. Lertschow, 2 Krista K. Laursen. 2 Pani В. ...
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Aircraft have had a long history of use for meteorological research. Indeed, the history of aircraft closely parallels the history of meteorology. This is not surprising, since flying requires accurate weather information and, conversely,... more
Aircraft have had a long history of use for meteorological research. Indeed, the history of aircraft closely parallels the history of meteorology. This is not surprising, since flying requires accurate weather information and, conversely, aircraft provide a convenient and unique platform for collecting meteorological information. Thirty years ago, before the widespread use of pressurized aircraft, a large fraction of aircraft flight time was within the boundary layer. Even now, commercial jet aircraft must at least pass through the boundary layer on takeoff and landing. Thus, the structure of the boundary layer is still very relevant to the needs of aviation. At the same time, developments in aviation technology have led to improved tools for observing the boundary layer from aircraft.
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Throughout this research effort we have analyzed data collected from the Southern Great Plains 1997 (SGP) experiment to evaluate terms in the budget of water vapor in the atmospheric boundary layer (ABL). The analysis is centered on using... more
Throughout this research effort we have analyzed data collected from the Southern Great Plains 1997 (SGP) experiment to evaluate terms in the budget of water vapor in the atmospheric boundary layer (ABL). The analysis is centered on using data obtained from the Lidar Atmospheric Sensing Experiment (LASE) downward-looking differential absorption lidar (DIAL) that was flown on the NASA-P3 aircraft. The DIAL is able to measure vertical profiles of water vapor, as well as aerosol backscatter, throughout the ABL. Initial work on using the DIAL is summarized in the attached meeting preprint, which discusses results from a segment of the 12 July 1997 flight. Additional analysis has been carried out using both the DIAL data and in situ measurements to obtain more complete and detailed estimates of terms in the ABL water vapor budget. This includes data from the Canadian National Research Council Twin Otter aircraft, as well as from a spectrum of surface-based instruments. This work is expected to lead to a refereed article planned for submission to the Journal.
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Research Interests: Geography and Subtropics
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Airplane measurements of the stably stratified boundary layer obtained during the Severe Environ- mental Storms and Mesoscale Experiment (SESAME) over rolling terrain in south-central Oklahoma indicate that considerable horizontal... more
Airplane measurements of the stably stratified boundary layer obtained during the Severe Environ- mental Storms and Mesoscale Experiment (SESAME) over rolling terrain in south-central Oklahoma indicate that considerable horizontal variability exists in the flow on scales of several kilometers. Much of this wave-like structure appears to be tied to the terrain. The criteria for existence of stationary gravity waves indicate that these waves can exist under the observed conditions. The spectrum of terrain variations also supports the existence of these waves. Observed spectra of the vertical velocity have two peaks: one at wavelengths of several kilometers, which is due to waves and the other at wavelengths of about 100 m, which is due to turbulence. The variance at several kilometers wavelength increases somewhat with height at least up to about 800 m, but the variance contributed by turbulence decreases rapidly with height.
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The goal of the Atlantic Stratocumulus Transition Experiment (ASTEX) held in the North Atlantic during June 1992 was to determine the physical reasons for the transition from stratocumulus to broken clouds. Some possible reasons for this... more
The goal of the Atlantic Stratocumulus Transition Experiment (ASTEX) held in the North Atlantic during June 1992 was to determine the physical reasons for the transition from stratocumulus to broken clouds. Some possible reasons for this transition were such things as cloud top entrainment instability and the decoupling effects of drizzle. As part of this experiment, the Environmental Technology Laboratory`s cloud sensing Doppler radar and three-channel microwave radiometer were deployed in the island of Porto Santo in the Madeira Islands of Portugal along with a carbon dioxide Doppler lider. Drizzle properties in stratus were examined using a log-normal droplet distribution model that related the model`s three parameters to the first three Doppler spectral moments of the cloud radar. With these moments, we are then able to compute the drizzle droplet concentration, modal radius, liquid water, and liquid water flux as a function of height.
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Intercomparison flights were flown in the spring of 2001 between the NASA-Wallops P-3B and NCAR C-130Q aircraft. These research aircraft were participating in overlapping Tropospheric missions, the Global Tropospheric Experiment's... more
Intercomparison flights were flown in the spring of 2001 between the NASA-Wallops P-3B and NCAR C-130Q aircraft. These research aircraft were participating in overlapping Tropospheric missions, the Global Tropospheric Experiment's (GTE) Transport and Chemical Evolution in the Pacific (TRACE-P) and Aerosol Characterization Experiment's ACE-ASIA mission, respectively. Both aircraft were equipped with similar air-motion measurement systems and in situ meteorology sensors designed to measure the eddy-correlation fluxes of momentum, heat, and water vapor. This paper presents the results of the informal intercomparison flights performed over the Sea of Japan. Data from intercomparison flight legs flown at several different altitudes within the atmospheric boundary layer in a "pacer aircraft" scenario have been analyzed. The variances and spectra of the three-dimensional winds, temperature, and humidity are presented along with the cospectra of the vertical velocities and...
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ABSTRACT Summary This chapter contains sections titled: Introduction Historical Aircraft State Variables Static Air Pressure Static Air Temperature Water Vapor Measurements Three-Dimensional Wind Vector Small-Scale Turbulence Flux... more
ABSTRACT Summary This chapter contains sections titled: Introduction Historical Aircraft State Variables Static Air Pressure Static Air Temperature Water Vapor Measurements Three-Dimensional Wind Vector Small-Scale Turbulence Flux Measurements