scholarly journals SEA-POL Goes to Sea

2019 ◽  
Vol 100 (11) ◽  
pp. 2285-2301 ◽  
Author(s):  
Steven A. Rutledge ◽  
V. Chandrasekar ◽  
Brody Fuchs ◽  
Jim George ◽  
Francesc Junyent ◽  
...  
Keyword(s):  
Doppler Radar ◽  
The United States ◽  
Upper Ocean ◽  
State University ◽  
Dual Polarization ◽  
Regional Study ◽  
Ocean Turbulence ◽  
Colorado State University ◽  
Weather Radars ◽  
Microphysical Processes

AbstractA new, advanced radar has been developed at Colorado State University (CSU). The Sea-Going Polarimetric (SEA-POL) radar is a C-band, polarimetric Doppler radar specifically designed to deploy on research ships. SEA-POL is the first such weather radar developed in the United States. Ship-based weather radars have a long history, dating back to GATE in 1974. The GATE radars measured only reflectivity. After GATE, ship radars also provided Doppler measurements. SEA-POL represents the next advancement by adding dual-polarization technology, the ability to transmit and receive both horizontal and vertical polarizations. This configuration provides information about hydrometeor size, shape, and phase. As a result, superior rain-rate estimates are afforded by the dual-polarization technology, along with hydrometeor identification and overall improved data quality. SEA-POL made its first deployment as part of the Salinity Processes in the Upper Ocean Regional Study, second field phase (SPURS-2) fall 2017 cruise to the eastern tropical Pacific, sailing on the R/V Roger Revelle. SPURS-2 was a field project to investigate the fate of freshwater deposited on the ocean’s surface. Oceanographers are keenly interested in how fast these freshwater patches mix out by wind and upper-ocean turbulence, as the less dense rainfall sitting atop the salty ocean inhibits mixing through increased stability. To this end, during SPURS-2, SEA-POL produced rain maps identifying the location of freshwater lenses on the ocean’s surface thereby providing context for measurements of SST and salinity. Examples of SEA-POL polarization measurements are also discussed to assess microphysical processes within oceanic convection. Future ocean-based field campaigns will now benefit from SEA-POL’s advanced dual-polarization technology.

Insights into the Evolving Microphysical and Kinematic Structure of Northeastern U.S. Winter Storms from Dual-Polarization Doppler Radar

2017 ◽  
Vol 145 (3) ◽  
pp. 1033-1061 ◽  
Author(s):  
Matthew R. Kumjian ◽  
Kelly A. Lombardo
Keyword(s):  
Doppler Radar ◽  
Elevation Angle ◽  
Model Performance ◽  
Radar Data ◽  
Added Value ◽  
Dual Polarization ◽  
Differential Phase Shift ◽  
Winter Storms ◽  
Microphysical Processes ◽  
Ice Production

The recent Weather Surveillance Radar-1988 Doppler (WSR-88D) network upgrade to dual-polarization capabilities allows for bulk characterization of microphysical processes in northeastern U.S. winter storms for the first time. In this study, the quasi-vertical profile (QVP) technique (wherein data from a given elevation angle scan are azimuthally averaged and the range coordinate is converted to height) is extended and applied to polarimetric WSR-88D observations of six Northeast winter storms to survey their evolving, bulk vertical microphysical and kinematic structures. These analyses are supplemented using hourly analyses from the Rapid Refresh (RAP) model. Regions of ascent inferred from QVPs were consistently associated with notable polarimetric signatures, implying planar crystal growth when near −15°C, and riming and secondary ice production at higher temperatures. The heaviest snowfall occurred most often when ascent and enhanced propagation differential phase shift ([Formula: see text]) occurred near −15°C. When available, limited surface observations confirmed heavy snowfall rates and revealed large snow-to-liquid ratios at these times. Other cases revealed sudden, large melting-layer excursions associated with precipitation-type transitions near the surface. RAP analyses failed to capture such complex evolution, demonstrating the added value of dual-polarization radar observations in these scenarios and the potential use of radar data for assessing model performance in real time. These insights are a preliminary step toward better understanding the complex processes in northeastern U.S. winter storms.

A New Dual-Polarization Radar Rainfall Algorithm: Application in Colorado Precipitation Events

2011 ◽  
Vol 28 (3) ◽  
pp. 352-364 ◽  
Author(s):  
R. Cifelli ◽  
V. Chandrasekar ◽  
S. Lim ◽  
P. C. Kennedy ◽  
Y. Wang ◽  
...  
Keyword(s):  
Estimation Algorithm ◽  
State University ◽  
Dual Polarization ◽  
Rainfall Estimation ◽  
Radar Rainfall ◽  
Colorado State University ◽  
Differential Phase ◽  
Precipitation Estimation ◽  
The One ◽  
Differential Reflectivity

Abstract The efficacy of dual-polarization radar for quantitative precipitation estimation (QPE) has been demonstrated in a number of previous studies. Specifically, rainfall retrievals using combinations of reflectivity (Zh), differential reflectivity (Zdr), and specific differential phase (Kdp) have advantages over traditional Z–R methods because more information about the drop size distribution (DSD) and hydrometeor type are available. In addition, dual-polarization-based rain-rate estimators can better account for the presence of ice in the sampling volume. An important issue in dual-polarization rainfall estimation is determining which method to employ for a given set of polarimetric observables. For example, under what circumstances does differential phase information provide superior rain estimates relative to methods using reflectivity and differential reflectivity? At Colorado State University (CSU), an optimization algorithm has been developed and used for a number of years to estimate rainfall based on thresholds of Zh, Zdr, and Kdp. Although the algorithm has demonstrated robust performance in both tropical and midlatitude environments, results have shown that the retrieval is sensitive to the selection of the fixed thresholds. In this study, a new rainfall algorithm is developed using hydrometeor identification (HID) to guide the choice of the particular rainfall estimation algorithm. A separate HID algorithm has been developed primarily to guide the rainfall application with the hydrometeor classes, namely, all rain, mixed precipitation, and all ice. Both the data collected from the S-band Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) radar and a network of rain gauges are used to evaluate the performance of the new algorithm in mixed rain and hail in Colorado. The evaluation is also performed using an algorithm similar to the one developed for the Joint Polarization Experiment (JPOLE). Results show that the new CSU HID-based algorithm provides good performance for the Colorado case studies presented here.

Book Reviews

2015 ◽  
Vol 53 (4) ◽  
pp. 1029-1031
Keyword(s):  
United States ◽  
Environmental Sustainability ◽  
The United States ◽  
University Of California ◽  
State University ◽  
Colorado State University ◽  
Good People ◽  
The Earth ◽  
Global Environmental

Greg C. Wright of University of California, Merced reviews “How Many Is Too Many? The Progressive Argument for Reducing Immigration into the United States”, by Philip Cafaro. The Econlit abstract of this book begins: “Considers the question of annually limiting the number of immigrants allowed in the United States and presents a progressive argument for limiting the amount. Discusses good people, hard choices, and an inescapable question; immigration by the numbers; the wages of mass immigration; winners and losers; growth, or what an economy is for; population matters; the environmentalists' retreat from demography; defusing America's population bomb—or cooking the earth; solutions; and objections. Cafaro is Professor of Philosophy and an affiliated faculty member in the School of Global Environmental Sustainability at Colorado State University.”

Orthogonal Channel Coding for Simultaneous Co- and Cross-Polarization Measurements

2009 ◽  
Vol 26 (1) ◽  
pp. 45-56 ◽  
Author(s):  
V. Chandrasekar ◽  
Nitin Bharadwaj
Keyword(s):  
Channel Coding ◽  
Electromagnetic Waves ◽  
Polarization State ◽  
Dual Polarization ◽  
Colorado State University ◽  
Weather Radars ◽  
Current Implementation ◽  
Polarization States ◽  
Linear Depolarization Ratio ◽  
Orthogonal Phase

Abstract Dual-polarization weather radars typically measure the radar reflectivity at more than one polarization state for transmission and reception. Historically, dual-polarization radars have been operated at copolar and cross-polar states defined with respect to the transmit polarization states. Recently, based on the improved understanding of the propagation properties of electromagnetic waves in precipitation media, the simultaneous transmit and receive (STAR) mode has become common to simplify the hardware. In the STAR mode of operation, horizontal and vertical polarization states are transmitted simultaneously and samples of both horizontal and vertical copolar returns are obtained. A drawback of the current implementation of STAR mode is its inability to measure parameters obtained from cross-polar signals such as linear depolarization ratio (LDR). In this paper, a technique to obtain cross-polar signals with STAR mode waveform is presented. In this technique, the horizontally and vertically polarized transmit waveforms are coded with orthogonal phase sequences. The performance of the phase-coded waveform is determined by the properties of the phase codes. This orthogonal phase coding technique is implemented in the Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) radar. This paper outlines the methodology and presents the performance of the cross-polar and copolar parameter estimation based on the simulation as well as data collected from the CSU–CHILL radar.

scholarly journals Moored Turbulence Measurements using Pulse-Coherent Doppler Sonar

2021 ◽  
Author(s):  
Seth F. Zippel ◽  
J. Thomas Farrar ◽  
Christopher J. Zappa ◽  
Una Miller ◽  
Louis St. Laurent ◽  
...  
Keyword(s):  
Mechanical Design ◽  
Surface Fluxes ◽  
Upper Ocean ◽  
Data Sets ◽  
Regional Study ◽  
Ocean Turbulence ◽  
Dissipation Rates ◽  
Optimal Programming ◽  
Long Time ◽  
Surface Buoyancy

AbstractUpper-ocean turbulence is central to the exchanges of heat, momentum, and gasses across the air/sea interface, and therefore plays a large role in weather and climate. Current understanding of upper-ocean mixing is lacking, often leading models to misrepresent mixed-layer depths and sea surface temperature. In part, progress has been limited due to the difficulty of measuring turbulence from fixed moorings which can simultaneously measure surface fluxes and upper-ocean stratification over long time periods. Here we introduce a direct wavenumber method for measuring Turbulent Kinetic Energy (TKE) dissipation rates, ϵ, from long-enduring moorings using pulse-coherent ADCPs. We discuss optimal programming of the ADCPs, a robust mechanical design for use on a mooring to maximize data return, and data processing techniques including phase-ambiguity unwrapping, spectral analysis, and a correction for instrument response. The method was used in the Salinity Processes Upper-ocean Regional Study (SPURS) to collect two year-long data sets. We find the mooring-derived TKE dissipation rates compare favorably to estimates made nearby from a microstructure shear probe mounted to a glider during its two separate two-week missions for (10−8) ≤ ϵ ≤ (10−5) m2 s−3. Periods of disagreement between turbulence estimates from the two platforms coincide with differences in vertical temperature profiles, which may indicate that barrier layers can substantially modulate upper-ocean turbulence over horizontal scales of 1-10 km. We also find that dissipation estimates from two different moorings at 12.5 m, and at 7 m are in agreement with the surface buoyancy flux during periods of strong nighttime convection, consistent with classic boundary layer theory.

scholarly journals Seroprevalence of Leptospira spp. in Colorado equids and association with clinical disease

2020 ◽  
Vol 32 (5) ◽  
pp. 718-721 ◽  
Author(s):  
Anna C. Fagre ◽  
Christie E. Mayo ◽  
Kristy L. Pabilonia ◽  
Gabriele A. Landolt
Keyword(s):  
Reference Method ◽  
The United States ◽  
State University ◽  
Diagnostic Laboratory ◽  
Colorado State University ◽  
Equine Infectious Anemia ◽  
Sporadic Cases ◽  
Laboratory Submission ◽  
Apparently Healthy ◽  
Clinical Cases

Detection of Leptospira interrogans is difficult as a result of intermittent leptospiruria and brief leptospiremia. Hence, diagnosis relies heavily on serologic testing, the reference method of which is the microscopic agglutination test (MAT). In horses, clinical leptospirosis has been associated with abortion, recurrent uveitis, and sporadic cases of hepatic and renal disease. Little information exists on the seroprevalence of antibodies to L. interrogans in equids in the United States; past nationwide studies suggest that the seroprevalence in some areas is as high as 77% (reciprocal titer ≥ 100). We tested sera from 124 apparently healthy horses previously submitted for equine infectious anemia (EIA) serology using MAT for 6 serovars—Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona. When using a reciprocal MAT titer cutoff of ≥ 100, 102 of 124 (82%) of the samples were positive for at least one serovar. Seropositivity was significantly associated with increasing age. Query of specimens from clinical cases submitted to the Colorado State University Veterinary Diagnostic Laboratory for MAT since 2010 indicated significantly greater seroprevalence ( p = 0.015) of pathogenic serovar Pomona in clinical cases compared to sera submitted from healthy equids for routine EIA testing. Information from our diagnostic laboratory submission forms also suggests a correlation between uveitis or other ophthalmic problems and serovar Pomona.

scholarly journals Wideband Reception and Processing for Dual-Polarization Radars with Dual Transmitters

2007 ◽  
Vol 24 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Sutanay Choudhury ◽  
V. Chandrasekar
Keyword(s):  
Doppler Radar ◽  
Negative Impact ◽  
Spectral Width ◽  
Parameter Estimates ◽  
Dual Polarization ◽  
Mean Velocity ◽  
Colorado State University ◽  
State Water ◽  
Differential Reflectivity ◽  
The Impact

Abstract Oversampling pulsed Doppler radar returns at a rate larger than the pulse bandwidth, whitening the range samples, and subsequent averaging has been pursued as a potential way to decrease the measured standard deviation of signal parameter estimates. It has been shown that the application of oversampling, whitening, and subsequent averaging improves the quality of reflectivity, mean velocity, and spectral width estimates in agreement with theory. Application of this procedure to a dual-polarization radar with dual transmitters is evaluated in this paper. Oversampled data collected from the Colorado State University (CSU)-University of Chicago–Illinois State Water Survey (CHILL) radar using a wideband receiver are analyzed to evaluate the performance of dual-polarization parameter estimators, such as differential reflectivity and differential phase. The negative impact of relative phase characteristics of the transmitted pulses in two polarizations on the copolar correlation, and subsequently on polarimetric parameter estimation, is analyzed. CSU-CHILL radar’s transmitted pulse sampling capability is used to evaluate the impact of the transmitted waveform’s mismatch on whitening and estimation.

What Comes Naturally and Not So Naturally

2014 ◽  
Author(s):  
Michael H. Fox
Keyword(s):  
Nuclear Power ◽  
Fuel Cycle ◽  
The United States ◽  
Radiation Environment ◽  
State University ◽  
Annual Dose ◽  
Natural Sources ◽  
Colorado State University ◽  
Fort Collins

“How many of you who moved to Colorado from Texas or Florida took into account that you were nearly tripling your annual dose of natural radiation by studying here?” That is the first question I ask students in my radiation biology class at Colorado State University, and of course none of the students considered that they were increasing their exposure to radiation by a large factor simply by moving here to live. And none of them would have used that as a reason to not study here. In contrast, if they were moving near a nuclear power plant in their state, they might have had second thoughts, even though they would be exposed to far less radiation than by coming to Fort Collins, Colorado. There is no place on earth where you are not exposed to radiation. As I said in the previous chapter, life evolved in a radiation environment. But where does the radiation come from, and why is it higher in Colorado than elsewhere in the United States? Are there other areas in the world where it is even higher? Do we get a lot more cancer in Colorado than in other lower radiation states because we are exposed to more radiation? These are important questions—they help us to understand the risk from a particular dose of radiation and put into perspective the exposure to radiation from the nuclear fuel cycle. We are exposed to radiation that comes from the skies, from the earth, and from our food. These are all natural sources, and there is not much we can do about it except decide where we want to live. But our decisions as to where we want to live almost certainly do not take into account the exposure to background levels of radiation from natural sources. The other main not-so-natural source of radiation exposure comes from medical procedures, a source that is increasing rapidly.

78 EFFICACY OF USING IN VITRO-PRODUCED CATTLE EMBRYOS TO DEVELOP AN EQUINE EMBRYO CRYOPRESERVATION SYSTEM

2009 ◽  
Vol 21 (1) ◽  
pp. 139
Author(s):  
C. M. Syverson ◽  
A. M. Paprocki ◽  
R. W. Koppang ◽  
J. R. Dobrinsky
Keyword(s):  
The United States ◽  
Blastocyst Stage ◽  
Embryo Cryopreservation ◽  
State University ◽  
Pump System ◽  
In Vitro System ◽  
Colorado State University ◽  
Fetal Bovine

Unfortunately, there is no reliable in vitro system available to provide a routine and economical source of equine embryos for research and commercial use. We explore the use of standard in vitro-produced (IVP) cattle embryos for the development of a direct transfer (dt) equine embryo cryopreservation system. Ovaries were collected from mature females at an abattoir and transported to our laboratory. Cumulus–oocyte complexes (COC) were aspirated from 2- to 6-mm follicles with an 18-gauge needle fixed to a vacuum pump system. Only COC surrounded by 2 or more layers of compact cumulus investment and containing oocytes of equal size were placed into a commercial TCM-199-based IVM system (Minitube of America Inc., Verona, WI). After 22 h of IVM, mature COC were placed into standard IVF. Prospective embryos were cultured for 120 h in CR-1/BSA (Minitube of America Inc.), and then supplemented with 10% fetal bovine serum (FBS) and cultured for an additional 48 h. Only excellent to good morula-blastocyst stage IVP cattle embryos were used in this study. As a control, the Colorado State University equine embryo dt-vitrification system (CSU; Carnevale EM Vet. Clin. North Am. Equine Pract 22, 831–841) was used on IVP cattle blastocysts. Two different Minitube EquiPRO-based dt-media with either 10% FBS or Minitube BSA-V (Fraction-V; Minitube of America Inc.) were tested on IVP cattle embryos. Minitube BSA-V is highly defined and internationally compliant BSA approved for use in raw form or in culture medium in the United States and European Union. Of 103 IVP cattle embryos cryopreserved by the CSU method, 45 (43.7%) embryos were viable after 24 h of culture. Of 121 IVP cattle embryos cryopreserved with Minitube EquiPRO + 10% FBS, 52 (42.9%) embryos were viable after 24 h of culture. Of 90 IVP cattle embryos cryopreserved with Minitube EquiPRO + BSA-V, 40 (44.4%) embryos were viable after 24 h of culture. Minitube EquiPRO + BSA-V was used with in vivo-produced equine morulae (no capsule). A total of 9 mares were flushed on Day 6.5, and 8 excellent to good morulae were recovered. All 8 embryos were dt-vitrified in the Minitube EquiPRO + BSA-V system. All 8 embryos were later warmed and transferred to synchronous recipient mares. On Day 14 of presumptive pregnancy, 7 (87.5%) mares were confirmed pregnant by real-time ultrasound examination. Not all presumptive foals were needed, so 4 recipient mares were randomly selected and intentionally aborted. Three mares were selected to carry presumptive foals to term. All 3 mares produced live and healthy foals at the term of gestation. Standard IVP cattle embryos can serve as a relatively inexpensive model for the development and testing of equine embryo cryopreservation systems.

scholarly journals Increasing the Diversity of Your Graduate Program: Translating Best Practices into Success

2016 ◽  
Vol 97 (7) ◽  
pp. 1169-1172 ◽  
Author(s):  
Melissa A. Burt ◽  
Rebecca Haacker ◽  
Rebecca L. Batchelor ◽  
A. Scott Denning
Keyword(s):  
Graduate Program ◽  
Atmospheric Science ◽  
The United States ◽  
State University ◽  
Student Body ◽  
Atmospheric Sciences ◽  
Colorado State University ◽  
American Meteorological Society ◽  
American Indian Students ◽  
Graduate Enrollment

Abstract Despite awareness in the geosciences that our field has a substantial lack of diversity in our workforce and student body, and countless efforts to broaden participation, graduate enrollment in the atmospheric sciences by students who are from traditionally underrepresented groups (i.e., African American, Hispanic, and American Indian students) is only slowly increasing, from 6% in 2005 to about 8.5% currently. In 2005, the Department of Atmospheric Science at Colorado State University (CSU) had a minority enrollment of 3.5%, which was lower than the national enrollment statistics of 6.0%. Through a concerted effort to better reflect the demographic makeup of the United States, the department now boasts a figure closer to 16%. Our students do cutting-edge research, participate in field campaigns, and are actively involved in professional societies, such as the American Meteorological Society (AMS). We expect that many of our students will become faculty or researchers and hopefully will mentor students themselves one day. Our article highlights the strategic initiative we have used to increase the diversity in atmospheric science, in hopes that our findings can present a model that can be replicated in other geoscience departments across the nation.

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