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Using Routinely Available Information to Estimate Tropical Cyclone Wind Structure

MONTHLY WEATHER REVIEW 2016年第4期144卷 1233-1247页

作者： Knaff, John A. Slocum, Christopher J. Musgrave, Kate D. Sampson, Charles R. Strahl, Brian R. NOAA Ctr Satellite Applicat & Res Ft Collins CO 80523 USA Colorado State Univ Dept Atmospher Sci Ft Collins CO 80523 USA Colorado State Univ Cooperat Inst Res Atmosphere Ft Collins CO 80523 USA Naval Res Lab Monterey CA USA Joint Typhoon Warning Ctr Honolulu HI USA

A relatively simple method to estimate tropical cyclone (TC) wind radii from routinely available information including storm data (location, motion, and intensity) and TC size is introduced. The method is based on a combination of techniques presented in previous works and makes an assumption that TCs are largely symmetric and that asymmetries are based solely on storm motion and location. The method was applied to TC size estimates from two sources: infrared satellite imagery and global model analyses. The validation shows that the methodology is comparable with other objective methods based on the error statistics. The technique has a variety of practical research and operational applications, some of which are also discussed.

关键词： Satellite observations Hurricanes/typhoons observational techniques and algorithms Atm/Ocean Structure/ Phenomena Hurricanes algorithms Models and modeling Diagnostics Circulation/ Dynamics

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Hydrometeor Mixing Ratio Retrievals for Storm-Scale Radar Data Assimilation: Utility of Current Relations and Potential Benefits of Polarimetry

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MONTHLY WEATHER REVIEW 2016年第8期144卷 2981-3001页

作者： Carlin, Jacob T. Ryzhkov, Alexander V. Snyder, Jeffrey C. Khain, Alexander Univ Oklahoma Cooperat Inst Mesoscale Meteorol Studies Norman OK 73019 USA NOAA OAR Natl Severe Storms Lab Norman OK USA Hebrew Univ Jerusalem Jerusalem Israel

The assimilation of radar data into storm-scale numerical weather prediction models has been shown to be beneficial for successfully modeling convective storms. Because of the difficulty of directly assimilating reflectivity (Z), hydrometeor mixing ratios, and sometimes rainfall rate, are often retrieved from Z observations using retrieval relations, and are assimilated as state variables. The most limiting (although widely employed) cases of these relations are derived, and their assumptions and limitations are discussed. To investigate the utility of these retrieval relations for liquid water content (LWC) and ice water content (IWC) in rain and hail as well as the potential for improvement using polarimetric variables, two models with spectral bin microphysics coupled with a polarimetric radar operator are used: a one-dimensional melting hail model and the two-dimensional Hebrew University Cloud Model. The relationship between LWC and Z in pure rain varies spatially and temporally, with biases clearly seen using the normalized number concentration. Retrievals using Z perform the poorest while specific attenuation and specific differential phase shift (K-DP) perform much better. Within rain-hail mixtures, separate estimation of LWC and IWC is necessary. Prohibitively large errors in the retrieved LWC may result when using Z. The quantity K-DP can be used to effectively retrieve the LWC and to isolate the contribution of IWC to Z. It is found that the relationship between Z and IWC is a function of radar wavelength, maximum hail diameter, and principally the height below the melting layer, which must be accounted for in order to achieve accurate retrievals.

关键词： Atm/Ocean Structure/ Phenomena Precipitation observational techniques and algorithms Radars/Radar observations Models and modeling Cloud resolving models Data assimilation

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Lake-Effect Mode and Precipitation Enhancement over the Tug Hill Plateau during OWLeS IOP2b

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MONTHLY WEATHER REVIEW 2016年第5期144卷 1729-1748页

作者： Campbell, Leah S. Steenburgh, W. James Veals, Peter G. Letcher, Theodore W. Minder, Justin R. Univ Utah Dept Atmospher Sci 135 South 1460 EastRoom 819 Salt Lake City UT 84112 USA SUNY Albany Dept Atmospher & Environm Sci Albany NY 12222 USA

Improved understanding of the influence of orography on lake-effect storms is crucial for weather forecasting in many lake-effect regions. The Tug Hill Plateau of northern New York (hereafter Tug Hill), rising 500 m above eastern Lake Ontario, experiences some of the most intense snowstorms in the world. Herein the authors investigate the enhancement of lake-effect snowfall over Tug Hill during IOP2b of the Ontario Winter Lake-effect Systems (OWLeS) field campaign. During the 24-h study period, total liquid precipitation equivalent along the axis of maximum precipitation increased from 33.5 mm at a lowland (145 m MSL) site to 62.5 mm at an upland (385 m MSL) site, the latter yielding 101.5 cm of snow. However, the ratio of upland to lowland precipitation, or orographic ratio, varied with the mode of lake-effect precipitation. Strongly organized long-lake-axis parallel bands, some of which formed in association with the approach or passage of upper-level short-wave troughs, produced the highest precipitation rates but the smallest orographic ratios. Within these bands, radar echoes were deepest and strongest over Lake Ontario and the coastal lowlands and decreased in depth and median intensity over Tug Hill. In contrast, nonbanded broad-coverage periods exhibited the smallest precipitation rates and the largest orographic ratios, the latter reflecting an increase in the coverage and frequency of radar echoes over Tug Hill. These findings should aid operational forecasts and, given the predominance of broad-coverage lake-effect periods during the cool season, help explain the climatological snowfall maximum found over the Tug Hill Plateau.

关键词： Circulation/ Dynamics Lake effects Atm/Ocean Structure/ Phenomena Precipitation Snowfall Winter/cool season Physical Meteorology and Climatology Orographic effects observational techniques and algorithms Radars/Radar observations

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A Unique Satellite-Based Sea Surface Wind Speed Algorithm and Its Application in Tropical Cyclone Intensity Analysis

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第7期33卷 1363-1375页

作者： Hong, Sungwook Seo, Hwa-Jeong Kwon, Young-Joo Sejong Univ Dept Environm Energy & Geoinfomat 209 Neungdong Ro Seoul South Korea Korea Meteorol Adm Natl Meteorol Satellite Ctr Gwanghyewon Myeon South Korea

This study proposes a sea surface wind speed retrieval algorithm (the Hong wind speed algorithm) for use in rainy and rain-free conditions. It uses a combination of satellite-observed microwave brightness temperatures, sea surface temperatures, and horizontally polarized surface reflectivities from the fast Radiative Transfer for TOVS (RTTOV), and surface and atmospheric profiles from the European Centre for Medium-Range Weather Forecasts (ECMWF). Regression relationships between satellite-observed brightness temperature and satellite-simulated brightness temperatures, satellite-simulated brightness temperatures, rough surface reflectivities, and between sea surface roughness and sea surface wind speed are derived from the Advanced Microwave Scanning Radiometer 2 (AMSR-2). Validation results of sea surface wind speed between the proposed algorithm and the Tropical Atmosphere Ocean (TAO) data show that the estimated bias and RMSE for AMSR-2 6.925- and 10.65-GHz bands are 0.09 and 1.13 m s(-1), and -0.52 and 1.21 m s(-1), respectively. Typhoon intensities such as the current intensity (CI) number, maximum wind speed, and minimum pressure level based on the proposed technique (the Hong technique) are compared with best-track data from the Japan Meteorological Agency (JMA), the Joint Typhoon Warning Center (JTWC), and the Cooperative Institute for Mesoscale Meteorological Studies (CIMSS) for 13 typhoons that occurred in the northeastern Pacific Ocean throughout 2012. Although the results show good agreement for low-and medium-range typhoon intensities, the discrepancy increases with typhoon intensity. Consequently, this study provides a useful retrieval algorithm for estimating sea surface wind speed, even during rainy conditions, and for analyzing characteristics of tropical cyclones.

关键词： algorithms Applications Microwave observations observational techniques and algorithms Remote sensing Satellite observations Surface observations Wind effects

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Arbitrary-Order Conservative and Consistent Remapping and a Theory of Linear Maps: Part II

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MONTHLY WEATHER REVIEW 2016年第4期144卷 1529-1549页

作者： Ullrich, Paul A. Devendran, Dharshi Johansen, Hans Univ Calif Davis Dept Land Air & Water Resources 1 Shields Ave Davis CA 95616 USA Univ Calif Berkeley Lawrence Berkeley Natl Lab Berkeley CA 94720 USA

This paper extends on the first part of this series by describing four examples of 2D linear maps that can be constructed in accordance with the theory of the earlier work. The focus is again on spherical geometry, although these techniques can be readily extended to arbitrary manifolds. The four maps include conservative, consistent, and (optionally) monotone linear maps (i) between two finite-volume meshes, (ii) from finite-volume to finite-element meshes using a projection-type approach, (iii) from finite-volume to finite-element meshes using volumetric integration, and (iv) between two finite-element meshes. Arbitrary order of accuracy is supported for each of the described nonmonotone maps.

关键词： Interpolation schemes Interpolation schemes Numerical analysis/modeling Models and modeling Mathematical and statistical techniques Data processing algorithms observational techniques and algorithms

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Phase-Resolved Wave Field Simulation Calibration of Sea Surface Reconstruction Using Noncoherent Marine Radar

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第6期33卷 1135-1149页

作者： Qi, Yusheng Xiao, Wenting Yue, Dick K. P. MIT Dept Mech Engn 77 Massachusetts Ave Cambridge MA 02139 USA

The possibility of reconstructing sea surface wave fields from a noncoherent X-band marine radar return has much potential for maritime operations and ocean engineering. The existing reconstruction method extracts the signal associated with gravity waves that satisfy the dispersion relationship. The process involves parameters related to how the radar signal is modulated by waves of different lengths, propagation directions, amplitudes, and phases. In the absence of independent wave measurements, these reconstruction parameters cannot be rationally adjusted according to wave field conditions, and the predictions are generally of uneven accuracy and reliability. A new reconstruction method based on concurrent phase-resolved wave field simulations is proposed. By maximizing the correlation between the reconstructed and simulated wave fields over time, optimal values of the reconstruction parameters are obtained that are found to vary appreciably with the wave field properties and with the location and size of the subdomain being sensed and reconstructed. With this phase-resolved simulation calibrated (PRSC) approach, the correlation between the evolving reconstructed wave field and that based on phase-resolved simulation, which measures the consistency and fidelity of the reconstruction, is improved significantly (by up to a factor of 2) and is obtained in a substantially broader range of sea states compared to existing methods.

关键词： Circulation/ Dynamics Ocean dynamics Waves oceanic observational techniques and algorithms Radars/Radar observations Mathematical and statistical techniques Fourier analysis Models and modeling Numerical analysis/modeling Optimization

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A Bayesian Approach to Assess the Performance of Lightning Detection Systems

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第3期33卷 563-578页

作者： Bitzer, Phillip M. Burchfield, Jeffrey C. Christian, Hugh J. Univ Alabama Ctr Earth Syst Sci Huntsville AL 35899 USA

Historically, researchers explore the effectiveness of one lightning detection system with respect to another system;that is, the probability that system A detects a discharge given that system B detected the same discharge is estimated. Since no system detects all lightning, a more rigorous comparison should include the reverse process-that is, the probability that system B detects a discharge given that system A detected it. Further, the comparison should use the fundamental physical process detected by each system. Of particular interest is the comparison of ground-based radio frequency detectors with space-based optical detectors. Understanding these relationships is critical as the availability and use of lightning data, both ground based and space based, increases. As an example, this study uses Bayesian techniques to compare the effectiveness of the Earth Networks Total Lightning Network (ENTLN), a ground-based wideband network, and the Lightning Imaging Sensor (LIS), a space-based optical detector. This comparison is completed by matching LIS groups and ENTLN pulses, each of which correspond to stroke-type discharges. The comparison covers the period from 2009 to 2013 over several spatial domains. In 2013 LIS detected 52.0% of the discharges ENTLN reported within the LIS field of view globally and 53.2% near North America. Conversely, ENTLN detected 5.9% of the pulses detected by LIS globally and 26.9% near North America in 2013. Using these results in the Bayesian-based methodology outlined, the study finds that LIS detected 80.1% of discharges near North America in 2013, while ENTLN detected 40.1%.

关键词： Remote sensing Bayesian methods Mathematical and statistical techniques Satellite observations Lightning algorithms Instrumentation/sensors observational techniques and algorithms Atm/Ocean Structure/ Phenomena

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Intercomparison of Unmanned Aircraftborne and Mobile Mesonet Atmospheric Sensors

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第8期33卷 1569-1582页

作者： Houston, Adam L. Laurence, Roger J., III Nichols, Tevis W. Waugh, Sean Argrow, Brian Ziegler, Conrad L. Univ Nebraska Dept Earth & Atmospher Sci 214 Bessey Hall Lincoln NE 68588 USA Univ Colorado Dept Aerosp Engn Sci Boulder CO 80309 USA Univ Oklahoma Cooperat Inst Mesoscale Meteorol Studies Norman OK 73019 USA NOAA Natl Severe Storms Lab Norman OK 73069 USA

Results are presented from an intercomparison of temperature, humidity, and wind velocity sensors of the Tempest unmanned aircraft system (UAS) and the National Severe Storms Laboratory (NSSL) mobile mesonet (NSSL-MM). Contemporaneous evaluation of sensor performance was facilitated by mounting the Tempest wing with attached sensors to the NSSL-MM instrument rack such that the Tempest and NSSL-MM sensors could collect observations within a nearly identical airstream. This intercomparison was complemented by wind tunnel simulations designed to evaluate the impact of the mobile mesonet vehicle on the observed wind velocity. The intercomparison revealed strong correspondence between the temperature and relative humidity (RH) data collected by the Tempest and the NSSL-MM with differences generally within sensor accuracies. Larger RH differences were noted in the presence of heavy precipitation;however, despite the exposure of the Tempest temperature and humidity sensor to the airstream, there was no evidence of wet bulbing within precipitation. Wind tunnel simulations revealed that the simulated winds at the location of the NSSL-MM wind monitor were similar to 4% larger than the expected winds due to the acceleration of the flow over the vehicle. Simulated vertical velocity exceeded 1 m s(-1) for tunnel inlet speeds typical of a vehicle moving at highway speeds. However, the theoretical noncosine reduction in winds that should result from the impact of vertical velocity on the laterally mounted wind monitor was found to be negligible across the simulations. Comparison of the simulated and observed results indicates a close correspondence, provided the crosswind component of the flow is small.

关键词： Data quality control In situ atmospheric observations observational techniques and algorithms

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"Deep-Arvor": A New Profiling Float to Extend the Argo Observations Down to 4000-m Depth

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第5期33卷 1039-1055页

作者： Le Reste, Serge Dutreuil, Vincent Andre, Xavier Thierry, Virginie Renaut, Corentin Le Traon, Pierre-Yves Maze, Guillaume IFREMER Brest France IFREMER Lab Oceanog Phys & Spatiale F-29280 Plouzane France

The international Argo program, consisting of a global array of more than 3000 free-drifting profiling floats, has now been monitoring the upper 2000m of the ocean for several years. One of its main proposed evolutions is to be able to reach the deeper ocean in order to better observe and understand the key role of the deep ocean in the climate system. For this purpose, Ifremer has designed the new "Deep-Arvor" profiling float: it extends the current operational depth down to 4000 m, and measures temperature and salinity for up to 150 cycles with CTD pumping continuously and 200 cycles in spot sampling mode. High-resolution profiles (up to 2000 points) can be transmitted and data are delivered in near-real time according to Argo requirements. Deep-Arvor can be deployed everywhere at sea without any preballasting operation and its light weight (;26 kg) makes its launching easy. Its design was done to target a cost-effective solution. Predefined spots have been allocated to add an optional oxygen sensor and a connector for an extra sensor. Extensive laboratory tests were successful. The results of the first at-sea experiments showed that the expected performances of the operational prototypes had been reached (i.e., to perform up to 150 cycles). Meanwhile, the industrialization phase was completed in order to manufacture the Deep-Arvor float for the pilot experiment in 2015. This paper details all the steps of the development work and presents the results from the at-sea experiments.

关键词： Atmosphere-ocean interaction Energy budget/balance Heating In situ oceanic observations Instrumentation/sensors observational techniques and algorithms Physical Meteorology and Climatology Profilers, oceanic

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Observations of Large Wind Shear above the Marine Boundary Layer near Point Buchon, California

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JOURNAL OF THE ATMOSPHERIC SCIENCES 2016年第8期73卷 3059-3077页

作者： Rahn, David A. Parish, Thomas R. Leon, David Univ Kansas Dept Geog & Atmospher Sci 1475 Jayhawk Blvd201 Lindley Hall Lawrence KS 66045 USA Univ Wyoming Dept Atmospher Sci Laramie WY 82071 USA

Particularly strong winds along the coast of Southern California on 24 May 2012 were measured by the Wyoming King Air research aircraft during the Precision Atmospheric Marine Boundary Layer Experiment (PreAMBLE). The fast flow is bounded laterally by the coastal topography and vertically by a pronounced temperature inversion separating the cool, moist air in the marine boundary layer (MBL) from the warm, dry air aloft. Many studies have investigated the response of this two-layer flow to changes in the coastline by invoking hydraulic theory, which explains the essential characteristics including changes in MBL depth and the attendant wind. Processes occurring just above the MBL are important to the low-level thermodynamic and kinematic structure. Observations on this day demonstrate how the large shear above the MBL can impact the lower atmosphere. A typical two-layer system was observed north of Point Buchon, which was supercritical. Around Point Buchon, the depth of the MBL decreased and wind increased, characteristic of an expansion fan. As a result, the Richardson number becomes reduced and favors shear instability that breaks down into turbulence. Observations indicate that a secondary well-mixed layer develops above the MBL that is bounded by narrow layers of high stability separating the secondary layer from the MBL below and the free troposphere above. It is hypothesized that the secondary layer develops as a result of Kelvin-Helmholtz instability, although more targeted observations are needed to confirm or reject that hypothesis.

关键词： Circulation/ Dynamics Wind shear Atm/Ocean Structure/ Phenomena Marine boundary layer observational techniques and algorithms Aircraft observations Variability Kelvin-Helmholtz instabilities Applications Coastal meteorology

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