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Analysis of fluorescent particle tracer data

Description: Four fluorescent particle tracer experiments were conducted during the July 1979 ASCOT experiment in the Anderson Creek Valley of northern California. The purpose of the experiment was to examine the transport and elongation of a plume traveling in the Anderson Creek nocturnal drainage flow and investigate the interaction of the Anderson Creek and Putah Creek flow fields. Sequential samples of tracer material at three downwind locations in Anderson Creek gave effective transport velocities of 1 to 2 m/s and showed an approximately linear relationship between plume elongation and travel distance. Integrated samples taken in both the Anderson Creek and Putah Creek air sheds indicated considerable interaction between the two flow fields.
Date: January 1, 1980
Creator: Clements, W.E.
Partner: UNT Libraries Government Documents Department

Comparison of experimental nights during the ASCOT 1980 Geysers field study using radon-222

Description: This study was designed to help classify drainage flow nights by looking at the behavior of radon 222 at the outflow of the Anderson Creek/Putah Creek airshed. The data will also be used to investigate stability, mixing depth, and transition characteristics of the drainage flow out of the basis. (PSB)
Date: January 1, 1981
Creator: Clements, W.E.
Partner: UNT Libraries Government Documents Department

Some physical concepts in complex terrain meteorology derived from the US Department of Energy's ASCOT program

Description: Since 1978 the United States Department of Energy's Atmospheric Studies in Complex Terrain program has conducted research fundamental to a better understanding of atmospheric transport and diffusion in complex topographies. Expertise in atmospheric physics theory, computer modeling, laboratory modeling, and field experimentation have been integrated into a balanced program. The initial emphases of the research were on nocturnal drainage winds, the effect terrain has on them, and their interactions with external flows. Highlights of some physical concepts of nocturnal drainage winds, derived mainly from the results of the field experiments, are presented. 21 references, 11 figures.
Date: March 24, 1984
Creator: Clements, W.E.
Partner: UNT Libraries Government Documents Department

Summary of the setting, air quality problems, and meteorological activities in the oil shale region

Description: This document discusses air quality problems that may arise in the valleys of the Uinta mountains and the Roan Ridge in the oil shale area in western Colorado and eastern Utah. A meteorological field expedition that was undertaken in August 1980 by LASL and PNL is described. (DLC)
Date: January 1, 1981
Creator: Barr, S. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

The cross-valley structure of the nocturnal along-valley wind in Brush Creek, Colorado

Description: The purpose of the study was to investigate the nocturnal katabatic wind in the valley and its morning breakup. One of the instruments, a doppler lidar operated by the National Oceanic and Atmospheric Administration's Wave Propagation Laboratory (NOAA/WPL), made detailed measurements of the along-valley component of the nocturnal katabatic wind in the valley. We have used this data to examine the cross-valley structure of this wind.
Date: January 1, 1987
Creator: Clements, W.E. & Hoard, D.E.
Partner: UNT Libraries Government Documents Department

Mean physical properties of the nocturnal along-valley wind in Brush Creek, Colorado

Description: Some physical properties of the nocturnal katabatic wind in Brush Creek, Colorado, have been examined for four nights when the ridgetop wind had an upvalley component. The maximum wind speed u/sub m/ in the katabatic jet increases linearly with the surface inversion strength SIS. Furthermore, the depth and the mass flux decreases linearly with increasing ridgetop wind speed. These relationships suggests that a ridgetop wind speed of 10 to 15 m/s may completely cut off the katabatic wind.
Date: January 1, 1987
Creator: Clements, W.E. & Archuleta, J.A.
Partner: UNT Libraries Government Documents Department

Determining depths of drainage winds

Description: A study was made to determine the depth of the drainage driven flows initiated by nocturnal surface cooling. Three methods used to determine the depth of the drainage layer from vertical profiles of meteorological data wwere evaluated. These are a shift in wind direction, the top of the surface based inversion, and the velocity minimum above the surfac layer jet. For relatively simple slope sites good agreement was found among all three methods of depth determination. In Brush Creek, a well defined valley, all three methods also indicated the same depth of drainage flow. When there was no clear wind direction shift at this site, the depths determined from the velocity minimum and the surface inversion were in agreement. At the somewhat more complicated Corral Gulch site, measurements were made in a shallow gulch imbedded in an extensive sloping terrain feature. There we found good agreement between the shift in wind direction and the velocity minimum, but the top of the drainage layer as determined from the surface inversion was always greater. In the outflow of the Anderson Creek basin, an area where possible flow divergence existed due to the deterioration of confining terrain, there was more variation in the results of the three methods. Results of an analysis of vertical profiles which were amenable to the application of all three methods are discussed.
Date: January 1, 1983
Creator: Wolfsberg, D.G. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Near-surface temperature field in a basin during nocturnal drainage flow

Description: An empirical analysis of data from 27 surface meteorological stations in a complex basin indicates that the near-surface nighttime temperature patterns can be approximated. A critical pressure or elevation exists each night. Stations above this elevation show an increase in temperature during the night while those below it show a decrease. Cooling rates increase with decreasing elevation in the basin. A possible explanation of this behavior is that we are observing the combined effects of local radiative cooling and advective warming due to entrainment of external air. At sites above the critical elevation the advective effects are dominant and below it radiative effects begin to have the stronger influence. The lower a site is in the basin, the less influence advection has; consequently the observed cooling rates are greater.
Date: January 1, 1983
Creator: Kyle, T.G. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Some observations of a subsynoptic scale disturbance

Description: A subsynoptic scale disturbance in the lower troposphere passed through the Georgia-South Carolina area during a field experiment in which supplementary meteorological data were available at the Savannah River Laboratory. Consistencies were noted in the fields of wind, temperature, and cloudiness, which aided in the documentation of the feature. This event is suggested as a useful case study for the application of mesoscale dynamical models.
Date: July 1, 1978
Creator: Barr, S.; Clements, W.E. & Archuleta, J.
Partner: UNT Libraries Government Documents Department

Effective transport velocity and plume elongation in nocturnal valley wind fields

Description: Using three atmospheric tracers the effective transport velocity and plume elongation produced by nocturnal drainage wind in three different valleys were investigated. Tracer was released in each valley in a well defined drainage wind field and sequentially sampled at downvalley locations. The effective transport velocity (V-eff) was determined from the elapsed time from the start of the release to the time when the plume concentration reached 10% of its peak value and the distance from the release site. The plume elongation factor was determined from the ratio of the width (time) of the plume at 10% of its peak value to the duration of the release. This method was chosen as an objective analysis scheme. Mean measured winds (V) were computed from surface wind instruments along the drainage flow path with values weighted by the estimated time the plume was in the wind field best represented by a measurement. The values used were from the start of release to the time of arrival at the sampler in question. V is compred to V-eff to see how reasonable an estimate of plume transport in valleys can be made from a few surface measurements in the valley. The simple tracer technique used in the studies has proven to be a good one in accomplishing the stated objective of investigating effective transport velocity and plume elongation in nocturnal valley drainage winds.
Date: January 1, 1980
Creator: Clements, W.E.; Barr, S. & Fowler, M.M.
Partner: UNT Libraries Government Documents Department

The ASCOT 1988 valley/tributary interaction study

Description: This paper describes a regular oscillation observed in nighttime valley air flows under relatively light upper level wind conditions. The period of these oscillations is about 20 minutes with at least one harmonic at about 10 minutes. These oscillations are important to pollutant dispersion in valley flows at night. The strong coherence of tributary flow and main valley oscillations and the fact that tributary oscillations lead valley oscillation indicate the importance of tributaries as major contributors to the cold air flow in valleys. 13 refs., 12 figs.
Date: January 1, 1990
Creator: Porch, W.M. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Nocturnal drainage wind characteristics in two converging air sheds

Description: During the short experimental period in the Grants Basin of Northeastern New Mexico a survey was conducted on the complex meteorology of this area. Emphasis was placed on the nocturnal drainage flow because of the potential hazards to the populated areas of Milan and Grants from the effluents of the uranium mining and milling operation in this area. This investigation has shown that the nocturnal drainage flow patterns agree with the winds predicted on the basis of the complex terrain of the area. Because of the surface cooling at night (over 25/sup 0/C during summer and about 20/sup 0/C during winter), air from elevated surrounding areas flows to the low lying regions consequently setting up a nocturnal drainage flow. This regime exists over 60% of the time during summer months and over 65% of the time during winter months with a depth generally less than 200 m. In the San Mateo air shed the drainage flow is east northeast, and in the Ambrosia Lake air shed it is from northwest. The confluence of these two air flows contributes mainly to the drainage flow through the channel formed by La Ja Mesa and Mesa Montanosa. The analysis of data collected by the recording Flats Station confirms the prediction that although the area south of the channel region broadens considerably causing a reduction in flow speed, contributions from the southside of La Jara Mesa and Mesa Montanosa partly compensate for this reduction. The position of this recording station is 15 to 20 km from the populated towns of Milan and Grants. A drainage flow speed of approximately 2.2 m s/sup -1/ and the duration of over 11 hours as recorded by this station indicates that air from the San Mateo and Ambrosia Lake regions may be transported southwards to these population centers ...
Date: January 1, 1980
Creator: Gedayloo, T.; Clements, W.E.; Barr, S. & Archuleta, J.A.
Partner: UNT Libraries Government Documents Department

Comparison of atmospheric temperature structure at the wall and in the middle of a valley

Description: Previously reported results indicate that measurements of temperatures near ground level on hillsides and valley walls serve as a reasonable approximation to the ambient nocturnal lapse rates. At Anderson Creek Valley in the Geysers area of California temperatures on the valley wall were compared with temperature profiles in the middle of the valley. An ensemble of temperature measurements including vertical soundings and surface based measurements from fixed stations and a mobile unit were analyzed. Although intercalibration was not rigorously conducted between the various systems, each system was calibrated independently and sufficient agreement exists when sensors were co-located to support confidence in the measurements. Surface measurements at various altitudes in Anderson Creek Valley were as much as 10/sup 0/C cooler than the temperature in mid-valley at the same altitude. The departures were smallest in the early evening and grew during the night. The cold air was quite shallow and if care were taken to make ground-based measurements on promontaries or towers, the gross stability could be characterized by surface temperature observations up the side of the valley. A more promising analysis of the data is to interpret the thermal gradients from the valley wall to the center in terms of the driving force they provide to the drainage flow. The circulations theorem of Bjerknes provides the link between the stable temperature gradients on sloping ground and the velocity field through pressure-density solenoids. By applying the theorem and accounting for frictional drag effects at the surface, a drainage domain about 100 m in depth with a speed of 4 m s/sup -1/ at TVR is estimated. Measured with profiles at that location show quite good agreement in a sublayer although larger scale driving forces account for a complex structure of wind speed and direction above the 100 to 200 m layer. (JGB)
Date: January 1, 1980
Creator: Barr, S.; Clements, W.E. & Wilson, S.K.
Partner: UNT Libraries Government Documents Department

Summertime nocturnal drainage flow in the San Mateo and Ambrosia lake air sheds of the grants basin. [Data used for determination of /sup 222/Rn transport from local uranium operations]

Description: An initial study of some fundamental meteorological properties of two major air sheds in the Grants Basin of northwestern New Mexico was conducted from May 18 to September 19, 1978. Three mechanical weather stations were used in conjunction with a few vertical wind soundings to develop a data set for the summer regime. Data collected between May 18 and July 30 is analyzed to investigate nocturnal drainage flows, daytime flows, and channeling of synoptic wind. Drainage wind averaging 2.5 m s/sup -1/ was found to exist in a surface layer not greater than 200 m deep on 60% of the nights investigated. This frequently occurring drainage flow is characterized by a strong decoupling from the upper level winds. Daytime winds, on the other hand, are representative of the synoptic flow patterns suggesting a rather rapid coupling after sunrise.
Date: January 1, 1979
Creator: Gedayloo, T.; Barr, S.; Clements, W.E. & Wilson, S.K.
Partner: UNT Libraries Government Documents Department

Developing public awareness for climate change: Support from international research programs

Description: Developing regional and local public awareness and interest in global climate change has been mandated as an important step for increasing the ability for setting policy and managing the response to climate change. Research programs frequently have resources that could help reach regional or national goals for increasing the capacity for responding to climate change. To obtain these resources and target recipients appropriately, research investigators need clear statements of national and regional strategies or priorities as a guide. One such program, the Atmospheric Radiation Measurement (ARM) Program, has a requirement to develop local or regional education enrichment programs at their observational sites in the central US, the tropical western Pacific (TWP), and on the north slope of alaska. ARM's scientific goals will result in a flow of technical data and as well as technical expertise that can assist with regional needs to increase the technical resources needed to address climate change issues. Details of the ARM education program in the Pacific will be presented.
Date: December 31, 1998
Creator: Barnes, F.J. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Some atmospheric tracer experiments in complex terrain at LASL: experimental design and data. [Fluorescent particle tracer study]

Description: Two series of atmospheric tracer experiments were conducted in complex terrain situations in and around the Los Alamos Scientific Laboratory. Fluorescent particle tracers were used to investigate nighttime drainage flow in Los Alamos Canyon and daytime flow across the local canyon-mesa complex. This report describes the details of these experiments and presents a summary of the data collected. A subsequent report will discuss the analysis of these data.
Date: March 1, 1978
Creator: Archuleta, J.; Barr, S.; Clements, W.E.; Gedayloo, T. & Wilson, S.K.
Partner: UNT Libraries Government Documents Department

Northern Arizona Basin Study (NABS), 1989

Description: An experiment was conducted to better understand a frequent layer of northwest winds found in the Northern Arizona region. This layer has been observed most often in winter near the surface at Page, Arizona, and often opposes larger scale upper level west winds. The results of this experiment improved both the temporal and the down-valley spatial resolution of the flow structure in this region during winter. 11 refs., 9 figs.
Date: January 1, 1989
Creator: Porch, W.M.; Clements, W.E. & Grant, T.A.
Partner: UNT Libraries Government Documents Department

Drainage flow over complex terrain

Description: Model calculations even carried in order to simulate tracer release experiments at the Geysers Area. Comparisons with the experimental data provide a test of current ability to model pollutant transport. The calculations were carried out with a windfield code (ATMOS1) and an advection-diffusion code (ATMOS2). The resulting concentrations permit prediction of tracer particle collections at the measurement stations. Comparison of the observations and predictions of sequential and integrated counts shows generally good agreement, but with discrepancies in some instances. The method appears to be a useful one for pollutant transport predictions and for parametric studies.
Date: January 1, 1981
Creator: Davis, C.G.; Bunker, S.S.; King, D.S.; Mutschlecner, J.P.; Barr, S. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

The ARM program in the Tropical Western Pacific

Description: The Department of Energy`s Atmospheric Radiation Measurement (ARM) Program was created in 1989 as part of the US Global Change Research Program to improve the treatment of atmospheric radiative and cloud processes in computer models used to predict climate change. The overall goal of the ARM program is to develop and test parameterizations of important atmospheric processes, particularly cloud and radiative processes, for use in atmospheric models. This goal is being achieved through a combination of field measurements and modeling studies. Three primary locales were chosen for extensive field measurement facilities. These are the Southern Great Plains of the United States, the Tropical Western Pacific, and the North Slope of Alaska and Adjacent Arctic Ocean. This paper describes the ARM program in the Tropical Western Pacific locale.
Date: December 1, 1998
Creator: Clements, W.E.; Barnes, F.J.; Ackerman, T.P. & Mather, J.H.
Partner: UNT Libraries Government Documents Department