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Scott J. Richardson

Abstract

A low-cost (under $12,000), fully automated, relative humidity calibration chamber capable of testing up to six probes simultaneously over a range of humidifies from 5% to approximately 95% is designed, constructed, and tested for use by the Oklahoma mesonetwork. In addition, a low-cost (under $4,000) temperature calibration chamber is developed that can test seven probes over the entire meteorological range of interest.(≈ −30° to +50°C). These procedures were designed and developed for the Vaisala HMP 35C temperature and relative humidity probe but are applicable to any similar instrument. The initial implementation results are presented.

The relative humidity calibration uses an optical condensation dewpoint hygrometer as the laboratory reference. Two precision resistance temperature detectors are used in the temperature calibration. It should be noted that commercial temperature and relative humidity chambers are available that would have been sufficiently accurate. However, the systems developed here lend themselves to automation and can calibrate multiple probes simultaneously.

The facilities developed herein are capable of producing probes with an uncertainty of ±3% for relative humidifies from 5% to approximately 90%, and an error of ±3.5% for humidifies from 90% to 95%. An uncertainty of ±0.2°C can be attained using the temperature calibration.

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Jerald A. Brotzge and Scott J. Richardson

Abstract

A major challenge in meteorology is determining the manner and scale at which the land surface interacts with the atmosphere. A majority of field programs, designed to address this issue, have been limited in space and time and thus have been unable to span the seasonal cycle across a regional to a statewide area. In an effort to address this problem, data for one year were collected and archived from 89 sites during 2000 from the Oklahoma Mesonet and Oklahoma Atmospheric Surface-Layer Instrumentation System (OASIS). Mean and variance estimates of radiation, air and skin temperature, relative humidity, surface fluxes, and soil moisture were investigated. Site-to-site correlation coefficients of these variables also were examined. Furthermore, Hovmoeller diagrams of atmospheric and surface variables were plotted and were discussed in relation to statewide patterns of rainfall, vegetation, and topography. The data revealed complex interactions among the more slowly varying parameters, such as soil wetness and vegetation greenness, and the more rapidly changing variables, such as atmospheric temperature and moisture.

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Scott J. Richardson, Michael E. Splitt, and Barry M. Lesht

Abstract

This work describes in situ moisture sensor comparisons that were performed in conjunction with the first Water Vapor Intensive Observation Period (IOP) conducted at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site during September of 1996. Two Raman lidars, two Atmospheric Emitted Radiance Interferometers, (AERIs), and a suite of 13 microwave radiometers were assembled at the CART site during the IOP, and in situ measurements were used for calibration and verification. In addition, this work was meant to help assess the current observing strategy in an effort to make improvements to the routine continuous measurements. To accomplish these goals, verification of the in situ measurements was required. Therefore, a laboratory intercomparison of the in situ moisture sensors (nine capacitive chip relative humidity sensors and four chilled mirror sensors) was performed at the Oklahoma Mesonet temperature and relative humidity testing and calibration facility. Tests were conducted both before and after the instruments were used in the IOP, making it possible to detect instrument problems prior to the IOP and to determine if instrument failure or drift occurred during the IOP.

Preliminary results comparing in situ moisture measurements with remotely sensed atmospheric moisture will be presented and additional applications will be discussed.

As a consequence of this work, modifications were made to the ARM CART calibration procedures, and there are now redundant temperature and relative humidity measurements so that sensor drift or calibration errors may be detected. These modifications to the observation and calibration strategy led to improvements in the continuous routine measurements at the ARM CART site.

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Paul M. Markowski, Yvette P. Richardson, Scott J. Richardson, and Anders Petersson

Abstract

The severe storms research community lacks reliable, aboveground, thermodynamic observations (e.g., temperature, humidity, and pressure) in convective storms. These missing observations are crucial to understanding the behavior of both supercell storms (e.g., the generation, reorientation, and amplification of vorticity necessary for tornado formation) and larger-scale (mesoscale) convective systems (e.g., storm maintenance and the generation of damaging straight-line winds). This paper describes a novel way to use balloonborne probes to obtain aboveground thermodynamic observations. Each probe is carried by a pair of balloons until one of the balloons is jettisoned; the remaining balloon and probe act as a pseudo-Lagrangian drifter that is drawn through the storm. Preliminary data are presented from a pair of deployments in supercell storms in Oklahoma and Kansas during May 2017. The versatility of the observing system extends beyond severe storms applications into any area of mesoscale meteorology in which a large array of aboveground, in situ thermodynamic observations are needed.

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Joshua D. Hoover, David R. Stauffer, Scott J. Richardson, Larry Mahrt, Brian J. Gaudet, and Astrid Suarez

Abstract

To better understand the physical processes of the stable boundary layer and to quantify “submeso motions” in moderately complex terrain, exploratory case-study analyses were performed using observational field data supplemented by gridded North American Regional Reanalysis data and Pennsylvania State University real-time Weather Research and Forecasting Model output. Submeso motions are nominally defined as all motions between the largest turbulent scales and the smallest mesoscales. Seven nighttime cases from August and September of 2011 are chosen from a central Pennsylvania [“Rock Springs” (RS)] network of eight ground-based towers and two sound detection and ranging (sodar) systems . The observation network is located near Tussey Ridge, ~15 km southeast of the Allegheny Mountains. The seven cases are classified by the dominant synoptic-flow direction and proximity to terrain to assess the influence of synoptic conditions on the local submeso and mesogamma motions. It is found that synoptic winds with a large crossing angle over nearby Tussey Ridge can generate mesogamma wave motions and larger-magnitude submeso temperature and wind fluctuations in the RS network than do winds from the direction of the more distant Allegheny Mountains. Cases with synoptic winds that are nearly parallel to the topographic contours or are generally weak exhibit the smallest fluctuations. Changes in the magnitude of near-surface submeso temperature and wind fluctuations in response to local indicator variables are also analyzed. The observed submeso wind and temperature fluctuations are generally larger when the low-level wind speed and thermal stratification, respectively, are greater, but the synoptic flow and its relation to the terrain also play an important role.

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Scott J. Richardson, Fred V. Brock, Steven R. Semmer, and Cathy Jirak

Abstract

Multiplate radiation shield errors are examined using the following techniques: 1) ray tracing analysis, 2) wind tunnel experiments, 3) numerical flow simulations, and 4) field testing. The authors’ objectives are to develop guidelines for radiation shield and temperature sensor design, to build an improved shield, and to determine factors that influence radiational heating errors. Guidelines for reducing radiational heating errors are given that are based on knowledge of the temperature sensor to be used, with the shield chosen to match the sensor design.

A new class of shield called a part-time aspirated multiplate radiation shield is introduced. This type of shield consists of a multiplate design usually operated in a passive manner but equipped with fan-forced aspiration capability to be used when necessary (e.g., low wind speed). A prototype shield reduced radiational heating errors from 2° to 1.2°C. In addition, nighttime low wind speed errors were reduced from 1.6° to 0.3°C. Existing passive shields may be modified to incorporate part-time aspiration, thus making them cost effective.

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Nelson L. Seaman, Brian J. Gaudet, David R. Stauffer, Larry Mahrt, Scott J. Richardson, Jeffrey R. Zielonka, and John C. Wyngaard

Abstract

Numerical weather prediction models often perform poorly for weakly forced, highly variable winds in nocturnal stable boundary layers (SBLs). When used as input to air-quality and dispersion models, these wind errors can lead to large errors in subsequent plume forecasts. Finer grid resolution and improved model numerics and physics can help reduce these errors. The Advanced Research Weather Research and Forecasting model (ARW-WRF) has higher-order numerics that may improve predictions of finescale winds (scales <~20 km) in nocturnal SBLs. However, better understanding of the physics controlling SBL flow is needed to take optimal advantage of advanced modeling capabilities.

To facilitate ARW-WRF evaluations, a small network of instrumented towers was deployed in the ridge-and-valley topography of central Pennsylvania (PA). Time series of local observations and model forecasts on 1.333- and 0.444-km grids were filtered to isolate deterministic lower-frequency wind components. The time-filtered SBL winds have substantially reduced root-mean-square errors and biases, compared to raw data. Subkilometer horizontal and very fine vertical resolutions are found to be important for reducing model speed and direction errors. Nonturbulent fluctuations in unfiltered, very finescale winds, parts of which may be resolvable by ARW-WRF, are shown to generate horizontal meandering in stable weakly forced conditions. These submesoscale motions include gravity waves, primarily horizontal 2D motions, and other complex signatures. Vertical structure and low-level biases of SBL variables are shown to be sensitive to parameter settings defining minimum “background” mixing in very stable conditions in two representative turbulence schemes.

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Scott J. Richardson, Natasha L. Miles, Kenneth J. Davis, Eric R. Crosson, Chris W. Rella, and Arlyn E. Andrews

Abstract

Prevalent methods for making high-accuracy tower-based measurements of the CO2 mixing ratio, notably nondispersive infrared spectroscopy (NDIR), require frequent system calibration and sample drying. Wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) is an emerging laser-based technique with the advantages of improved stability and concurrent water vapor measurements. Results are presented from 30 months of field measurements from WS-CRDS systems at five sites in the upper Midwest of the United States. These systems were deployed in support of the North American Carbon Program’s Mid-Continent Intensive (MCI) from May 2007 to November 2009. Excluding one site, 2σ of quasi-daily magnitudes of the drifts, before applying field calibrations, are less than 0.38 ppm over the entire 30-month field deployment. After applying field calibrations using known tanks sampled every 20 h, residuals from known values are, depending on site, from 0.02 ±0.14 to 0.17 ±0.07 ppm. Eight months of WS-CRDS measurements collocated with a National Oceanographic and Atmospheric Administrations (NOAA)/Earth System Research Laboratory (ESRL) NDIR system at West Branch, Iowa, show median daytime-only differences of −0.13 ±0.63 ppm on a daily time scale.

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Thomas Lauvaux, Natasha L. Miles, Scott J. Richardson, Aijun Deng, David R. Stauffer, Kenneth J. Davis, Gloria Jacobson, Chris Rella, Gian-Paul Calonder, and Philip L. DeCola

Abstract

Anthropogenic emissions from urban areas represent 70% of the fossil fuel carbon emitted globally according to carbon emission inventories. The authors present here the first operational system able to monitor in near–real time daily emission estimates, using a mesoscale atmospheric inversion framework over the city of Davos, Switzerland, before, during, and after the World Economic Forum 2012 Meeting (WEF-2012). Two instruments that continuously measured atmospheric mixing ratios of greenhouse gases (GHGs) were deployed at two locations from 23 December 2011 to 3 March 2012: one site was located in the urban area and the other was out of the valley in the surrounding mountains. Carbon dioxide, methane, and carbon monoxide were measured continuously at both sites. The Weather Research and Forecasting mesoscale atmospheric model (WRF), in four-dimensional data assimilation mode, was used to simulate the transport of GHGs over the valley of Davos at 1.3-km resolution. Wintertime emissions prior to the WEF-2012 were about 40% higher than the initial annual inventory estimate, corresponding to the use of heating fuel in the winter. Daily inverse fluxes were highly correlated with the local climate, especially during the severe cold wave that affected most of Europe in early February 2012. During the WEF-2012, emissions dropped by 35% relative to the first month of the deployment, despite similar temperatures and the presence of several thousand participants at the meeting. On the basis of composite diurnal cycles of hourly CO/CO2 ratios, the absence of traffic peaks during the WEF-2012 meeting indicated that change in road emissions is potentially responsible for the observed decrease in the city emissions during the meeting.

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Howard B. Bluestein, Robert M. Rauber, Donald W. Burgess, Bruce Albrecht, Scott M. Ellis, Yvette P. Richardson, David P. Jorgensen, Stephen J. Frasier, Phillip Chilson, Robert D. Palmer, Sandra E. Yuter, Wen-Chau Lee, David C. Dowell, Paul L. Smith, Paul M. Markowski, Katja Friedrich, and Tammy M. Weckwerth

To assist the National Science Foundation in meeting the needs of the community of scientists by providing them with the instrumentation and platforms necessary to conduct their research successfully, a meeting was held in late November 2012 with the purpose of defining the problems of the next generation that will require radar technologies and determining the suite of radars best suited to help solve these problems. This paper summarizes the outcome of the meeting: (i) Radars currently in use in the atmospheric sciences and in related research are reviewed. (ii) New and emerging radar technologies are described. (iii) Future needs and opportunities for radar support of high-priority research are discussed. The current radar technologies considered critical to answering the key and emerging scientific questions are examined. The emerging radar technologies that will be most helpful in answering the key scientific questions are identified. Finally, gaps in existing radar observing technologies are listed.

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