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In 2014, a satellite-based map of regional anomalies of atmospheric methane (CH4) column retrievals singled out the fossil fuel rich San Juan Basin (SJB) as the biggest CH4 regional anomaly (“hot spot”) in the United States. Over a 3-week period in April 2015, we conducted ground and airborne atmospheric measurements to investigate daily wind regimes and CH4 emissions in this region of SW Colorado and NW New Mexico. The SJB, similar to other topographical basins with local sources, experienced elevated surface air pollution under low wind and surface temperature inversion at night and early morning. Survey drives in the basin identified multiple CH4 and ethane (C2H6) sources with distinct C2H6-to-CH4 emission plume ratios for coal bed methane (CBM), natural gas, oil, and coal production operations. Air samples influenced by gas seepage from the Fruitland coal formation outcrop in La Plata County, CO, had enhanced CH4, with no C2-5 light alkane enhancements. In situ fast-response data from seven basin survey flights, all with westerly winds, were used to map and attribute the detected C2H6 and CH4 emission plumes. C2H6-to-CH4 plume enhancement correlation slopes increased from north to south, reflecting the composition of the natural gas and/or CBM extracted in different parts of the basin. Nearly 75% of the total detected CH4 and 85% of the total detected C2H6 hot spot were located in New Mexico. Emissions from CBM and natural gas operations contributed 66% to 75% of the CH4 hot spot. Emissions from oil operations in New Mexico contributed 5% to 6% of the CH4 hot spot and 8% to 14% of the C2H6 hot spot. Seepage from the Fruitland coal outcrop in Colorado contributed at most 8% of the total detected CH4, while gas venting from the San Juan underground coal mine contributed

With funding provided by the 2012 Disaster Relief Act (Sandy Supplemental), NOAA’s Earth System Research Laboratory Physical Sciences Division has installed three Doppler wind-profiling radars and surface meteorology towers along the U.S. Gulf and southeast coasts to help detect and monitor landfalling tropical storms and other high-impact weather events. This same combination of instruments has been used to monitor landfalling atmospheric rivers on the U.S. West Coast. For this reason, we refer to the whole collection of instruments at each site as an Atmospheric River Observatory (ARO). These three new AROs supported by the Sandy Supplemental complement a fourth ARO deployed in coastal North Carolina as part of NOAA’s Hydrometeorology Testbed Southeast Pilot Study. These four AROs were installed in time to capture the 2014 hurricane season and will be operated through the 2015 hurricane season.

Divergence in recent oil and gas related methane emission estimates between aircraft studies (basin total for a midday window) and emissions inventories (annualized regional and national statistics) indicate the need for better understanding the experimental design, including temporal and spatial alignment and interpretation of results. Our aircraft-based methane emission estimates in a major U.S. shale gas basin resolved from west to east show (i) similar spatial distributions for 2 days, (ii) strong spatial correlations with reported NG production (R2 = 0.75) and active gas well pad count (R2 = 0.81), and (iii) 2× higher emissions in the western half (normalized by gas production) despite relatively homogeneous dry gas and well characteristics. Operator reported hourly activity data show that midday episodic emissions from manual liquid unloadings (a routine operation in this basin and elsewhere) could explain ∼1/3 of the total emissions detected midday by the aircraft and ∼2/3 of the west–east differen...

The Howard A. Hanson Dam (HHD) has brought flood protection to Washington's Green River Valley for more than 40 years and opened the way for increased valley development near Seattle. However, following a record high level of water behind the dam in January 2009 and the discovery of elevated seepage through the dam's abutment, the U.S. Army Corps of Engineers declared the dam “unsafe.” NOAA's Office of Oceanic and Atmospheric Research (OAR) and National Weather Service (NWS) worked together to respond rapidly to this crisis for the 2009/10 winter season, drawing from innovations developed in NWS offices and in NOAA's Hydrometeorology Test-bed (HMT). New data telemetry was added to 14 existing surface rain gauges, allowing the gauge data to be ingested into the NWS rainfall database. The NWS Seattle Weather Forecast Office produced customized daily forecasts, including longer-lead-time hydrologic outlooks and new decision support services tailored for emergency managers and the public, new capabilities ena...

One year of observations from a network of five 915-MHz boundary-layer radar wind profilers equipped with radio acoustic sounding systems located in California’s Central Valley are used to investigate the annual variability of convective boundary-layer depth and its correlation to meteorological parameters and conditions. Results from the analysis show that at four of the sites, the boundary-layer height reaches its maximum in the late-spring months then surprisingly decreases during the summer months, with mean July depths almost identical to those for December. The temporal decrease in boundary-layer depth, as well as its spatial variation, is found to be consistent with the nocturnal low-level lapse rate observed at each site. Multiple forcing mechanisms that could explain the unexpected seasonal behaviour of boundary-layer depth are investigated, including solar radiation, precipitation, boundary-layer mesoscale convergence, low-level cold-air advection, local surface characteristics and irrigation patterns and synoptic-scale subsidence. Variations in solar radiation, precipitation and synoptic-scale subsidence do not explain the shallow summertime convective boundary-layer depths observed. Topographically forced cold-air advection and local land-use characteristics can help explain the shallow CBL depths at the four sites, while topographically forced low-level convergence helps maintain larger CBL depths at the fifth site near the southern end of the valley.

A DeHavilland DHC-6 Twin Otter, operated by the National Oceanic and Atmospheric Administration, was deployed in Tampa, FL to measure aerosols and primary and secondary trace gases in support of the Bay Regional Atmospheric Chemistry Experiment (BRACE). The Twin Otter repeatedly overflew the surface chemistry monitoring super site near Sydney, FL to assess the comparability of surface and airborne datasets and the spatial representativeness of the surface measurements. Prior to comparing the chemical datasets, we evaluated the comparability of the standards used to calibrate surface and airborne detectors, as well as the uniformity of wind fields aloft and at the surface. Under easterly flow, when the dearth of significant upwind emission sources promoted chemical homogeneity at Sydney, trace gas concentrations at the surface and aloft were generally well correlated; R2 ranged from 0.4396 for H2O2 to 0.9738 for O3, and was typically better than 0.70 for NO, NO2, NOY, HNO3, HCHO, and SO2. Mean ratios of aircraft-to-surface concentrations during 10 overflights of Sydney were as follows: 1.002±0.265 (NO), 0.948±0.183 (NO2), 1.010±0.214 (NOY), 0.941±0.263 (HCHO), and 0.952±0.046 (O3). Poorer agreement and larger variability in measured ratios were noted for SO2 (1.764±0.559), HNO3 (1.291±0.391), and H2O2 (1.200±0.657). Under easterly flow, surface measurements at Sydney were representative of conditions over horizontal scales as large as 50 km and agreed well with airborne values throughout the depth of the turbulently mixed boundary layer at mid-day. Westerly flow advected the Tampa urban plume over the site; under these conditions, as well as during transitional periods associated with the development of the land–sea breeze, surface conditions were representative of smaller spatial scales. Finally, we estimate possible errors in future measurement-model comparisons likely to arise from fine scale (or subgrid; 4 km) in coherent plumes. Variability at the edges of the well-mixed urban plume, and at the interface of the land–sea breeze circulation, was significantly smaller. This suggests that even a failure of modeled wind fields to resolve the sea breeze return can induce moderate, but not overwhelming, errors in simulated concentration fields and dependent chemical processes.

The CALINE4 roadway dispersion model has been applied to concentrations of NO x and NO 2 measured near Gandy Boulevard in Tampa, FL (USA) during May 2002. A NO x emission factor of 0.86 gr mi −1 was estimated by treating NO+NO 2 (NO x ) as a conserved species and minimizing the differences between measured and calculated NO x concentrations. This emission factor was then used to calculate NO 2 concentrations using the NO/NO 2 transformation reactions built into CALINE4. A comparison of measured and calculated NO 2 concentrations indicates that for ambient O 3 concentrations less than 40 ppb the model under-predicts the chemical transformation of NO. The enhanced transformation of NO may be due to reactions of NO with oxidants such as peroxy radicals that are present either in the atmosphere or in vehicle exhaust.

The North American Monsoon Experiment (NAME) is an internationally coordinated process study aimed at determining the sources and limits of predictability of warm-season precipitation over North America. The scientific objectives of NAME are to promote a better understanding and more realistic simulation of warm-season convective processes in complex terrain, intraseasonal variability of the monsoon, and the response of the warm-season atmospheric circulation and precipitation patterns to slowly varying, potentially predictable surface boundary conditions. During the summer of 2004, the NAME community implemented an international (United States, Mexico, Central America), multiagency (NOAA, NASA, NSF, USDA) field experiment called NAME 2004. This article presents early results from the NAME 2004 campaign and describes how the NAME modeling community will leverage the NAME 2004 data to accelerate improvements in warm-season precipitation forecasts for North America.

The 10th Prospectus Development Team (PDT-10) of the U.S. Weather Research Program was charged with iden- tifying research needs and opportunities related to the short-term prediction of weather and air quality in urban forecast zones. Weather has special and significant impacts on large numbers of the U.S. population who live in major urban areas. It is recognized that urban users have different weather information needs than do their rural counterparts. Further, large urban areas can impact local weather and hydrologic processes in various ways. The recommendations of the team emphasize that human life and well-being in urban areas can be protected and enjoyed to a significantly greater degree. In particular, PDT-10 supports the need for 1) improved access to real-time weather information, 2) improved tailoring of weather data to the specific needs of individual user groups, and 3) more user-specific forecasts of weather and air quality. Specific recommendations fall within nine thematic areas: 1) development of a user-oriented weather database; 2) focused research on the impacts of visibility and icing on transportation; 3) improved understanding and forecasting of winter storms; 4) improved understanding and forecasting of convective storms; 5) improved forecasting of intense/ severe lightning; 6) further research into the impacts of large urban areas on the location and intensity of urban convec- tion; 7) focused research on the application of mesoscale forecasting in support of emergency response and air quality; 8) quantification and reduction of uncertainty in hydrological, meteorological, and air quality modeling; and 9) the need for improved observing systems. An overarching recommendation of PDT-10 is that research into understanding and predicting weather impacts in urban areas should receive increased emphasis by the atmospheric science community at large, and that urban weather should be a focal point of the U.S. Weather Research Program.

Vertical profiles of drainage winds were monitored continuously by a Doppler-Mini-Sodar during case studies in two valleys, on both sides of the U. S. Continental Divide. A tethered balloon provided additional information on the vertical temperature and wind structure up to the Divide level. Ambient wind data were collected by a radar wind profiler on the west side, and a tower on the crest of the Divide. The onset, evolution and breakup of the drainage flow were studied on two nights, when the ridge-top winds were westerly and skies were clear. To study the influence of the ambient flow on drainage winds, changes in drainage wind speed, direction and depth, along with the volume flux were examined. It was found that, on the leeward side, the drainage was strongly influenced by the ambient winds (King, 1995b), which led to interruption and erosion of the locally generated valley flow. The drainage on the windward side of the Divide was almost undisturbed. A comparison of balloon and sodar wind profiles showed very good agreement during steady drainage conditions.

A boundary layer field experiment in the Mexico City basin during the period 24 February–22 March 1997 is described. A total of six sites were instrumented. At four of the sites, 915-MHz radar wind profilers were deployed and radiosondes were released five times per day. Two of these sites also had sodars collocated with the profilers. Radiosondes were released twice per day at a fifth site to the south of the basin, and rawinsondes were flown from another location to the northeast of the city three times per day. Mixed layers grew to depths of 2500–3500 m, with a rapid period of growth beginning shortly before noon and lasting for several hours. Significant differences between the mixed-layer temperatures in the basin and outside the basin were observed. Three thermally and topographically driven flow patterns were observed that are consistent with previously hypothesized topographical and thermal forcing mechanisms. Despite these features, the circulation patterns in the basin important for the...

A new portable, monostatic, high-frequency minisodar for investigating the structure and dynamics of the lower planetary boundary layer is described. The minisodar's digital system was designed to be flexible and portable. A special microantenna system using arrays of small piezoelectric tweeters was developed. Examples of facsimile records from measurements in the Arctic with Doppler-analysis of the vertical velocity demonstrate the capabilities of the minisodar

An experimental and modeling investigation of nocturnal drainage flows within the Mesa Creek valley in western Colorado revealed their wind and temperature characteristics and the effects of the ambient meteorology on their development. The valley, located about 30 km east of Grand Junction, is situated on the north slopes of the Grand Mesa. It is surrounded by ridges on three sides with low terrain toward the north. The terrain at the higher elevations is characterized by steep slopes that become shallower at the lower elevations. A network of seven meteorological towers and a monostatic solar collected data within the study area from December 1988 through November 1989. Analysis of the experimental data indicated that shallow drainage flows generated over the many individual slopes at the higher elevations converge at the lower elevations to form deeper flows that join with those generated within adjacent drainage areas. The characteristics of the flows generally deviated from those displayed b...

[1] This paper investigates linkages between weather, climate, and air quality that contributed to the large difference in the number of ozone exceedances encountered in the northeastern United States (U.S.) during 2002 and 2004. Major air quality research field campaigns were conducted in the northeast during July and August of each year. Both the 2002 New England Air Quality Study (NEAQS-02) and the International Consortium for Atmospheric Research on Transport and Transformation 2004 field study (ICARTT-04) had research components focused on regional air quality. The primary environmental difference between the two field campaigns was the underlying climatic conditions. The July–August period in 2002 was much sunnier, warmer, and drier than normal. In contrast, the July–August period in 2004 was cloudier, cooler, and much wetter than normal. We conclude that these extreme climatic conditions were the underlying cause for the significant difference in the number of ozone exceedances that occurred during NEAQS-02 and ICARTT-04. We rule out the impact of other meteorological processes as the primary cause of this difference. We gauge horizontal transport using surface and upper air wind observations collected on Appledore Island (ADI), off the coast of New Hampshire and Maine, along with back trajectories based solely on wind observations collected by profiler networks deployed for each study. The wind conditions that favor pollutant transport to the northeast were more prevalent in 2004 than in 2002, yet the number of ozone exceedances in 2004 was more than a factor of three less than in 2002. Neither was daytime boundary layer mixing the cause for this discrepancy. Unlike other parts of the U.S. where poor air quality is generally associated with shallow boundary layers, in New England the boundary layers were deeper on high-ozone days than on clean days because the same sunny, warm, and dry conditions that favor boundary layer ozone production also produce deeper boundary layers. Both field campaigns were synoptically active. Lulls in synoptic activity explained most of the high-ozone events observed in 2002, whereas even an extended lull in synoptic activity during the summer of 2004 did not produce a single high-ozone day.

The next generation of ground-based extremely large telescopes of 30 m to 100 m aperture calls for the manufacture of several hundred sub-aperture segments of 1 m to 2 m diameter. Each annulus of the overall aperture is formed from separate elements of the appropriate off-axis conic section (usually a paraboloid). Manufacture of these segments requires a systematic approach to in- and post-process metrology for all stages of manufacture, including the grinding stage, despite the fact that the resulting ground surface is generally not amenable to optically reflective measurement techniques. To address the need for measurements on such 1 m to 2 m telescope segments, a swing arm profilometer has been constructed as part of a collaborative project between University College London (UCL) and the UK National Physical Laboratory (NPL). The current swing-arm profilometer is intended as a proof-of-concept device and has the capability to measure concave and convex surfaces of up to 1 m in diameter with a minimum radius of curvature of 1.75 m for concave and 1.25 m for convex surfaces. Results will be traceable to national length standards. Principles of the swing-arm instrument will be described together with the mechanics of the arm design, its bearing and adjustment arrangements and surface probe options. We assess the performance requirements of 20 nm RMS form measurement accuracy in the context of the tolerances of the selected profilometer components, the error budget, and preliminary system measurements. Initial results are presented with a Solartron linear encoder. We also plan to mount optical sensors on the end of the arm as an alternative to traditional contact probes. Initially these will include an Arden AWS-50 wavefront curvature sensor and a Fisba μ-phase interferometer. The method of attachment of the Arden AWS-50 is outlined. The swing arm profilometer is to be located at a specialised facility, the OPtiC Technium, Denbigh, North Wales, where it will form part of a tool-kit of metrology and polishing devices for researching the production of large aspheric surfaces.

Medical records and radiologic studies of 238 patients with non-small cell lung cancer who had preoperative evaluation by chest radiography and CT were reviewed. Thirty-six patients were staged as T1N0M0 by chest radiograph. Of this group, 18 (50%) had abnormalities on CT requiring additional evaluation. Confirmation of abnormalities was by tissue sampling or clinical follow-up. Evidence for unresectable spread of disease was obtained in 12 (33%). We conclude that routine preoperative staging of T1N0M0 lung cancer with CT has a positive impact on patient management.

[1] This study investigates the impact of surface heterogeneity on the timing of the morning transitions observed during the 1999 Southern Oxidants Study Nashville/Middle Tennessee Intensive (SOS99N). The end of the morning transition occurs at a measurement site located in the Cumberland River Valley approximately 8 km northeast of downtown Nashville, on average, 1.25 h earlier than at three rural sites surrounding Nashville. This study shows that the early morning behavior of the boundary layers observed at the river valley site is dominated by local terrain features, whereas a previous study showed that the afternoon boundary layers observed at this site are more strongly influenced by its urban characteristics. Profiles of backscatter intensity recorded by monostatic sodars and Doppler wind profilers are analyzed to provide the evolution of boundary layer depth on days when a nocturnal inversion formed. These measurements indicate that the early morning growth rate of the convective boundary layer was faster, on average, at the river valley site in Nashville than at a rural, non-river valley site where similar measurements were made (125 m h−1 versus 73 m h−1 from 0600 to 0800 h CST). A comparison of temperature profiles measured with radio acoustic sounding systems indicates that low-level stability resulting from the nocturnal boundary layer had a stronger influence than surface energetics on the observed variations in boundary layer depth and morning transition end times. A single case study is shown to demonstrate the potential impact of the morning transition on gas phase chemistry measurements collected at a rural site. Case study and diurnally averaged time series show how surface-layer humidity can be an effective tracer for diagnosing the end of the morning transition.

Wind data collected by a Doppler lidar in a deep mountain valley are used to determine the representativeness of single vertical profiles for approximating the volume flux. A method is described that interpolates these profiles to be representative of an entire valley cross section and provides guidance for placing vertically profiling sensors in future mountain valley studies. It is shown that the horizontal homogeneity assumption leads to large overestimates when volume fluxes are calculated using single vertical wind profiles. Proper sensor placement and a Knowledge of the morphology of the wind field within the valley leads to greater accuracies in estimated volume fluxes.

Smoke pot and oil fog smoke tracers have been used to plan meteorological instrument placement and quantitatively estimate air volume flow from a tributary during nocturnal drainage wind conditions. The estimated volume flow agrees well with estimates of the flow using tethered-balloon and remotely obtained wind velocity measurements. The smoke visualization shows a very complex flow structure caused by tributary flow interactions with the flow down the main valley. The magnitude of the outflow volume from the tributary was greater than expected. If the tributary studied is representative of the other tributaries in the valley, most of the volume flow in the main valley may enter through the tributaries.

We describe a sequence of tethersonde and solar measurements showing the effects of the pooling of cold air drainages in a basin located along the Colorado River below the Brush drainage. Results obtained during periods of weak ambient winds show that the basin fills over a period of several hours, then eventually overflows. The depth of the pool is such as to affect tributary drainages, such as that of Brush Creek, and to cause the accumulating drainage jets to become elevated as they flow down the larger drainage channels into the basin.

This paper presents an analysis of nocturnal drainage flows in a mountainous coastal environment where the elevation of the terrain is comparable with the elevation of the marine temperature inversion. The analysis traces the initiation, evolution, and breakup of the drainage flow using acoustic sounder facsimile data and tethered sonde measurements of wind and temperature. Conditions addressed include (1) opposing seabreeze flow ranging from 2 to 8m s-1, (2) aiding flow, and (3) large-scale and drainage-induced subsidence. The effect of deep marine temperature inversions pervades the observations, as seen in deeper, more stratified echo layers, weaker drainage, and delayed destruction of the inversion in the morning.

Acoustic sounders have now been used extensively in a series of noctural drainage flow experiments carried out by the U.S. Department of Energy's Atmospheric Studies in Complex Terrain (ASCOT) program. Doppler acoustic sounders, located in three different valleys during the sequence of experiments, reveal drainage-wind profiles that depend strongly on the ambient meteorological conditions and the elevation of each observing site relative to surrounding terrain. In elevated sites that drain easily, Doppler-sounder derived wind profiles show a simply-structured flow; in lower lying areas, subject to topographic constriction and cold-air pooling, and where Archimedean forces are comparable to those due to synoptic and mesoscale pressure gradients, the wind profiles show considerable vertical and temporal variation. In particular, in the Geysers area of northern California, the seabreeze and the depth of the Pacific Coast marine inversion affect not only the initiation of drainage winds but also their subsequent evolution.

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The determination of the behavior of large electric networks confronts the engineer or mathematician with the necessity of solving a large number of equilibrium equations determined by the network and the restraints imposed on it. This task has been sufficiently formidable to bring about the development and construction of large analog computers such as the d-c and a-c network calculators. In recent years, the availability of medium- and large-scale digital computers has provided a new facility for solving network problems. Considerable attention has been given to applying digital computers to load flow, transient stability, and short-circuit calculations.

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The manual development and economic evaluation of many alternate, long-range transmission system expansions represents a tedious and difficult task. To speed this planning process, a computer program has been developed to plan automatically the new transmission facilities needed to meet a particular generator addition schedule. The program uses an economic dispatch to allocate generation, and a d-c power flow to discover circuit overloads. The program checks the ability of the transmission system to meet both normal and emergency situations. When an overload is detected, the program checks a logical sequence of methods of alleviating the overload. Suggestions are made for further developments in the area of automatic transmission planning.

1. Some existing types of rennet tests are briefly reviewed.2. A viscosity type of rennet test is described and results from its use are given.3. A mathematical treatment of the problems involved is given, which leads on to4. Construction of graphs showing progressive variation in “Dying away of amplitude”, “Logarithmic decrement” and “Viscosity coefficients” of milk under the action of rennet. Since viscosity determinations on liquids and gases have been commonly carried out with a disk type of viscosimeter, such a type is now introduced and similar graphs constructed from observations during its use. A close similarity in graphs to those furnished by the cylinder type of viscosimeter is obtained. The cylinder type of apparatus, we find, is more convenient in use with milk in reference to rennet action.5. Arising from the graphs a more precise method of terminating a rennet test with the present type of apparatus is indicated.

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Since publication (1) the apparatus previously described by the authors has been altered and improved. The alterations have been concerned mainly with excluding draughts and securing a better form of support. In using the apparatus we have found that the absence of vibration is important for the agreement of duplicates. It would seem that vibration tends to break the cohesion between the curd and the surface of cylinder A. For this reason a part of the laboratory as free as possible from vibrational disturbances was chosen and the support fixed to the wall.

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The characteristics of calcium fluoride under adverse conditions have received increasing attention in the last several years. Many workshops and symposia have focused on laser induced damage in calcium fluoride and other materials when used as laser windows.

A new process for producing large, single, oriented crystals of calcium fluoride (CaF2) has been developed which overcomes the limitations of current growing methods. This process has been reduced to practice and has yielded oriented crystals 17.5 3 x 17.5 x 5 cm3. Currently nearing completion is a system for producing 35 x 35 x 7.5 cm3 single crystals. A scale up to one-meter-square is considered feasible. This crystal growing process makes possible the fabrication of very large CaF2 windows. Suitability for very high power lasers, however, requires attention to properties beyond mere size. A process to generate higher purity growth stock (starting material) was also developed. The additional purification of the growth stock contributes to lower bulk absorption, the absence of color centers and increased radiation hardness. Also identified were several specific impurities which correlate with radiation hardness. A correlation was found between color centers induced by laser radiation and ionizing radiation. The ability of the new process to produce oriented single crystals permits entire laser windows to be fabricated with the direction parallel to the direction of propagation. This orientation is known to reduce thermo-optic distortion and stress induced birefringence. Other CaF2 crystal properties such as tensile strength, absorption and laser damage thresholds were studied and are discussed.

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