Differential Reflectivity and Angle Resolved Photoemission of PbS(100)

2001 ◽  
Author(s):  
M. Tallarida ◽  
A. Cricenti ◽  
C. Ottaviani ◽  
B. J. Kowalski ◽  
E. Guziewicz ◽  
...  
Keyword(s):  
Differential Reflectivity

scholarly journals Polarimetric Radar Characteristics of Tornadogenesis Failure in Supercell Thunderstorms

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 581
Author(s):  
Matthew Van Den Broeke
Keyword(s):  
Polarimetric Radar ◽  
Low Level ◽  
Supercell Storms ◽  
Supercell Thunderstorms ◽  
Near Term ◽  
Tornadic Storms ◽  
Differential Reflectivity

Many nontornadic supercell storms have times when they appear to be moving toward tornadogenesis, including the development of a strong low-level vortex, but never end up producing a tornado. These tornadogenesis failure (TGF) episodes can be a substantial challenge to operational meteorologists. In this study, a sample of 32 pre-tornadic and 36 pre-TGF supercells is examined in the 30 min pre-tornadogenesis or pre-TGF period to explore the feasibility of using polarimetric radar metrics to highlight storms with larger tornadogenesis potential in the near-term. Overall the results indicate few strong distinguishers of pre-tornadic storms. Differential reflectivity (ZDR) arc size and intensity were the most promising metrics examined, with ZDR arc size potentially exhibiting large enough differences between the two storm subsets to be operationally useful. Change in the radar metrics leading up to tornadogenesis or TGF did not exhibit large differences, though most findings were consistent with hypotheses based on prior findings in the literature.

scholarly journals Prospects of the WSR-88D Radar for Cloud Studies

2011 ◽  
Vol 50 (4) ◽  
pp. 859-872 ◽  
Author(s):  
Valery M. Melnikov ◽  
Dusan S. Zrnić ◽  
Richard J. Doviak ◽  
Phillip B. Chilson ◽  
David B. Mechem ◽  
...  
Keyword(s):  
Signal Processing ◽  
Real Time ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Doppler Velocity ◽  
Cloud Data ◽  
Three Dimensional Mapping ◽  
Spectrum Width ◽  
Differential Reflectivity ◽  
Dimensional Mapping

AbstractSounding of nonprecipitating clouds with the 10-cm wavelength Weather Surveillance Radar-1988 Doppler (WSR-88D) is discussed. Readily available enhancements to signal processing and volume coverage patterns of the WSR-88D allow observations of a variety of clouds with reflectivities as low as −25 dBZ (at a range of 10 km). The high sensitivity of the WSR-88D, its wide velocity and unambiguous range intervals, and the absence of attenuation allow accurate measurements of the reflectivity factor, Doppler velocity, and spectrum width fields in clouds to ranges of about 50 km. Fields of polarimetric variables in clouds, observed with a research polarimetric WSR-88D, demonstrate an abundance of information and help to resolve Bragg and particulate scatter. The scanning, Doppler, and polarimetric capabilities of the WSR-88D allow real-time, three-dimensional mapping of cloud processes, such as transformations of hydrometeors between liquid and ice phases. The presence of ice particles is revealed by high differential reflectivities and the lack of correlation between reflectivity and differential reflectivity in clouds in contrast to that found for rain. Pockets of high differential reflectivities are frequently observed in clouds; maximal values of differential reflectivity exceed 8 dB, far above the level observed in rain. The establishment of the WSR-88D network consisting of 157 polarimetric radars can be used to collect cloud data at any radar site, making the network a potentially powerful tool for climatic studies.

scholarly journals Improved Attenuation-Based Radar Precipitation Estimation Considering the Azimuthal Variabilities of Microphysical Properties

2020 ◽  
Vol 21 (7) ◽  
pp. 1605-1620
Author(s):  
Hao Huang ◽  
Kun Zhao ◽  
Haonan Chen ◽  
Dongming Hu ◽  
Peiling Fu ◽  
...  
Keyword(s):  
Variational Approach ◽  
Optimization Approach ◽  
Radar Rainfall ◽  
Microphysical Properties ◽  
Quantitative Precipitation Estimation ◽  
Hourly Rainfall ◽  
Precipitation Estimation ◽  
Raindrop Size ◽  
Differential Reflectivity ◽  
The Impact

AbstractThe attenuation-based rainfall estimator is less sensitive to the variability of raindrop size distributions (DSDs) than conventional radar rainfall estimators. For the attenuation-based quantitative precipitation estimation (QPE), the key is to accurately estimate the horizontal specific attenuation AH, which requires a good estimate of the ray-averaged ratio between AH and specific differential phase KDP, also known as the coefficient α. In this study, a variational approach is proposed to optimize the coefficient α for better estimates of AH and rainfall. The performance of the variational approach is illustrated using observations from an S-band operational weather radar with rigorous quality control in south China, by comparing against the α optimization approach using a slope of differential reflectivity ZDR dependence on horizontal reflectivity factor ZH. Similar to the ZDR-slope approach, the variational approach can obtain the optimized α consistent with the DSD properties of precipitation on a sweep-to-sweep basis. The attenuation-based hourly rainfall estimates using the sweep-averaged α values from these two approaches show comparable accuracy when verified against the gauge measurements. One advantage of the variational approach is its feasibility to optimize α for each radar ray, which mitigates the impact of the azimuthal DSD variabilities on rainfall estimation. It is found that, based on the optimized α for radar rays, the hourly rainfall amounts derived from the variational approach are consistent with gauge measurements, showing lower bias (1.0%), higher correlation coefficient (0.92), and lower root-mean-square error (2.35 mm) than the results based on the sweep-averaged α.

scholarly journals MESOCYCLONE OBSERVATION BY MULTI-PARAMETER METEOROLOGICAL RADAR

2020 ◽  
pp. 9-19
Author(s):  
D.A. Denisenkov ◽  
V.Y. Zhukov ◽  
G.G. Shchukin
Keyword(s):  
Radial Velocity ◽  
Sequential Analysis ◽  
Echo Signal ◽  
Large Size ◽  
Weather Phenomenon ◽  
Meteorological Radar ◽  
The One ◽  
Differential Reflectivity ◽  
Upper Boundary ◽  
Local Speed

The article deals in detail with the case of observation of a cloud array characterized by a large (15 km) height of the upper boundary of cloud cover and the presence of areas with radar reflectivity of more than 60 dBZ by the DMRL-S meteorological radar installed in Valday (Novgorod region). Integrated application of the estimates of all measured parameters makes it possible to identify in this array the area where a rare weather phenomenon - a supercell - develops. The fact of formation of the hail area of large size is ascertained. It leads to the effect of depolarization attenuation - negative values of differential reflectivity of the echo signal of the meteorological targets. The coordinates of vertical flows are determined by analyzing data on the cross-correlation coefficient of polarization constituents of received signal. Then the obtained result is compared with the one obtained by means of estimations of the average radial velocity of particles, their much coincidence being shown. At an altitude of 5 km, areas with sharp local speed changes are observed, indicating the existence of strong vortices. Sequential analysis of the data obtained during the whole time of existence of the supercell leads to identification of a zone 5 km in diameter with a “jump” of magnitude radial velocity of particles in a layer 1 km high at a distance of 100 km. The scale of this zone, its location and the magnitudes of the parameters of the signal received from it indicate the formation of another rare weather phenomenon in it – the mesocyclone

scholarly journals Quantitative data analysis of ESAR data

2013 ◽  
Vol 11 ◽  
pp. 291-295
Author(s):  
N. Phruksahiran ◽  
M. Chandra
Keyword(s):  
Ground Surface ◽  
Quantitative Information ◽  
Polarization Property ◽  
Data Sets ◽  
Program Code ◽  
Quantitative Data Analysis ◽  
Linear Depolarization Ratio ◽  
German Aerospace ◽  
Differential Reflectivity

Abstract. A synthetic aperture radar (SAR) data processing uses the backscattered electromagnetic wave to map radar reflectivity of the ground surface. The polarization property in radar remote sensing was used successfully in many applications, especially in target decomposition. This paper presents a case study to the experiments which are performed on ESAR L-Band full polarized data sets from German Aerospace Center (DLR) to demonstrate the potential of coherent target decomposition and the possibility of using the weather radar measurement parameter, such as the differential reflectivity and the linear depolarization ratio to obtain the quantitative information of the ground surface. The raw data of ESAR has been processed by the SAR simulator developed using MATLAB program code with Range-Doppler algorithm.

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