scholarly journals Using Dual-Polarized Radar and Dual-Frequency Profiler for DSD Characterization: A Case Study from Darwin, Australia

2009 ◽  
Vol 26 (10) ◽  
pp. 2107-2122 ◽  
Author(s):  
V. N. Bringi ◽  
C. R. Williams ◽  
M. Thurai ◽  
P. T. May
Keyword(s):  
Elevation Angle ◽  
Angle Distribution ◽  
Polarimetric Radar ◽  
Dual Frequency ◽  
Continuous Transition ◽  
Stratiform Rain ◽  
Convective Rain ◽  
Median Volume ◽  
Distribution Parameters ◽  
Rain Events

Abstract Comparisons are made between the reflectivity Z, median volume diameter D0, and rain rate R from a dual-frequency profiler and the C-band polarimetric radar (C-POL), which are both located near Darwin, Australia. Examples from the premonsoon “buildup” regime and the monsoon (oceanic) regime are used to illustrate the excellent agreement between the dual-profiler retrievals and the polarimetric radar-based retrievals. This work builds on similar works that were limited in scope to shallow tropical showers and predominantly stratiform rain events. The dual-frequency profiler retrievals of D0 and R herein are based on ensemble statistics, whereas the polarimetric radar retrievals are based on algorithms derived by using one season of disdrometer data from Darwin along with scattering simulations. The latest drop shape versus D relation is used as well as the canting angle distribution results obtained from the 80-m fall bridge experiment in the scattering simulations. The scatterplot of D0 from dual-frequency profiler versus Zdr measurements from C-POL is shown to be consistent not only with the theoretical simulations and prior data but also within prior predicted error bars for both stratiform rain as well as convective rain. Based on dual-frequency profiler–retrieved gamma drop size distribution parameters, a new smoothly varying “separator” indexing scheme has been developed that classifies between stratiform and convective rain types, including a continuous “transition” region between the two. This indexing technique has been applied on a number of low-elevation-angle plan position indicator (PPI) sweeps with the C-POL from the two regime examples, to construct “unconditioned” histograms of D0 in stratiform and convective rain (to within the sensitivity of the radar). With reference to the latter, it is demonstrated that the distribution of D0 is different in the buildup example than in the monsoon example, because of the differences in both the microphysical and kinematic features between the two regimes. In particular, (i) the mean D0 is significantly larger in the buildup example than in the monsoon example, irrespective of rain type; (ii) the histogram width (or standard deviation) is much larger for the buildup example than the monsoon example, irrespective of rain type; and (iii) the histogram skewness is negative for the monsoon regime example because of a lack of larger D0 values, whereas the buildup histogram is positively skewed irrespective of rain type.

On the Influence of Assumed Drop Size Distribution Form on Radar-Retrieved Thunderstorm Microphysics

2006 ◽  
Vol 45 (2) ◽  
pp. 259-268 ◽  
Author(s):  
Edward A. Brandes ◽  
Guifu Zhang ◽  
Juanzhen Sun
Keyword(s):  
Drop Size ◽  
Liquid Water Content ◽  
Polarimetric Radar ◽  
Stratiform Rain ◽  
Distribution Form ◽  
Median Volume ◽  
Strong Convection ◽  
Radar Measurements ◽  
Size Model ◽  
Drop Size Distributions

Abstract Polarimetric radar measurements are used to retrieve drop size distributions (DSD) in subtropical thunderstorms. Retrievals are made with the single-moment exponential drop size model of Marshall and Palmer driven by radar reflectivity measurements and with a two-parameter constrained-gamma drop size model that utilizes reflectivity and differential reflectivity. Results are compared with disdrometer observations. Retrievals with the constrained-gamma DSD model gave better representation of total drop concentration, liquid water content, and drop median volume diameter and better described their natural variability. The Marshall–Palmer DSD model, with a fixed intercept parameter, tended to underestimate the total drop concentration in storm cores and to overestimate significantly the concentration in stratiform regions. Rainwater contents in strong convection were underestimated by a factor of 2–3, and drop median volume diameters in stratiform rain were underestimated by 0.5 mm. To determine possible DSD model impacts on numerical forecasts, evaporation and accretion rates were computed using Kessler-type parameterizations. Rates based on the Marshall–Palmer DSD model were lower by a factor of 2–3 in strong convection and were higher by about a factor of 2 in stratiform rain than those based on the constrained-gamma model. The study demonstrates the potential of polarimetric radar measurements for improving the understanding of precipitation processes and microphysics parameterization in numerical forecast models.

Influence of Ground Clutter Contamination on Polarimetric Radar Parameters

2009 ◽  
Vol 26 (2) ◽  
pp. 251-269 ◽  
Author(s):  
Katja Friedrich ◽  
Urs Germann ◽  
Pierre Tabary
Keyword(s):  
Reference Data ◽  
Critical Level ◽  
Elevation Angle ◽  
Convective Precipitation ◽  
Polarimetric Radar ◽  
Mountain Ranges ◽  
Ground Clutter ◽  
The Mean ◽  
Rain Events ◽  
Differential Reflectivity

Abstract The influence of ground clutter contamination on the estimation of polarimetric radar parameters, horizontal reflectivity (Zh), differential reflectivity (Zdr), correlation coefficient (ρhυ), and differential propagation phase (ϕdp) was examined. This study aims to derive the critical level of ground clutter contamination for Zh, Zdr, ρhυ, and ϕdp at which ground clutter influence exceeds predefined precision thresholds. Reference data with minimal ground clutter contamination consist of eight precipitation fields measured during three rain events characterized by stratiform and convective precipitation. Data were collected at an elevation angle of 0.8° by the Météo-France operational, polarimetric Doppler C-band weather radar located in Trappes, France, ∼30 km southwest of Paris. Nine different ground clutter signatures, ranging from point targets to more complex signatures typical for mountain ranges or urban obstacles, were added to the precipitation fields. This is done at the level of raw in-phase and quadrature component data in the two polarimetric channels. For each ground clutter signature, 30 simulations were conducted in which the mean reflectivity of ground clutter within the resolution volume varied between being 30 dB higher to 30 dB lower than the mean reflectivity of precipitation. Differences in Zh, Zdr, ρυ, and ϕdp between simulation and reference were shown as a function of ratio between ground clutter and precipitation intensities. As a result of this study, horizontal reflectivity showed the lowest sensitivity to ground clutter contamination. Furthermore, a precision of 1.7 dBZ in Zh is achieved on average when the precipitation and ground clutter intensities are equal. Requiring a precision of 0.2 dB in Zdr and 3° in ϕdp, the reflectivity of precipitation needs to be on average ∼5.5 and ∼6 dB, respectively, higher compared to the reflectivity of ground clutter. The analysis also indicates that the highest sensitivity to the nine clutter signatures was derived for ρhυ. To meet a predefined precision threshold of 0.02, reflectivity of precipitation needs to be ∼13.5 dB higher than the reflectivity of ground clutter.

scholarly journals PENGAMATAN KEJADIAN HUJAN DENGAN DISDROMETER DAN MICRO RAIN RADAR DI SERPONG

2017 ◽  
Vol 18 (1) ◽  
pp. 1
Author(s):  
Findy Renggono
Keyword(s):  
Size Distribution ◽  
Rainy Season ◽  
Drop Size ◽  
Drop Size Distribution ◽  
Rain Event ◽  
Stratiform Rain ◽  
Convective Rain ◽  
Rain Events ◽  
Rain Radar

IntisariPengamatan hujan dengan menggunakan beberapa peralatan yang mempunyai metode berbeda telah dilakukan di wilayah Serpong. Peralatan yang digunakan adalah Disdrometer dan Micro Rain Radar (MRR). Kedua peralatan tersebut dipasang pada satu lokasi yang sama agar dapat mengukur kejadian hujan yang sama. Pengamatan dilakukan pada akhir tahun 2016 selama 5 bulan, disesuaikan dengan kondisi dimana musim hujan sudah mulai masuk untuk wilayah ini. Perbandingan pengukuran yang telah dilakukan menunjukkan kesesuaian hasil antara kedua peralatan tersebut.  Pengamatan distribusi ukuran butir air pada empat kejadian hujan antara bulan Agustus-Desember 2016 menunjukkan bahwa hujan konvektif mempunyai distribusi ukuran yang lebih besar dibandingkan hujan stratiform.  AbstractRain observation by using several instruments having different method has been done in Serpong area. The instrument used is Disdrometer and Micro Rain Radar (MRR). Both instruments are installed in the same location in order to measure the same rain events. Observations were made at the end of 2016 for 5 months, adjusted to the conditions in which the rainy season has begun to enter for the region. Comparison of measurements that have been done indicate the suitability of the results between the two instrument. Drop size distribution of four rain event during August - December 2016 shows that the drop size distribution on convective rain broaden than on stratiform rain. 

scholarly journals Comparison of Radar-Based Hail Detection Using Single- and Dual-Polarization

2019 ◽  
Vol 11 (12) ◽  
pp. 1436 ◽  
Author(s):  
Skripniková ◽  
Řezáčová
Keyword(s):  
Comparative Analysis ◽  
Heavy Rain ◽  
Radar Data ◽  
Severe Weather ◽  
Detection Methods ◽  
Polarimetric Radar ◽  
Dual Polarization ◽  
Rain Events ◽  
Single Polarization ◽  
Strong Agreement

The comparative analysis of radar-based hail detection methods presented here, uses C-band polarimetric radar data from Czech territory for 5 stormy days in May and June 2016. The 27 hail events were selected from hail reports of the European Severe Weather Database (ESWD) along with 21 heavy rain events. The hail detection results compared in this study were obtained using a criterion, which is based on single-polarization radar data and a technique, which uses dual-polarization radar data. Both techniques successfully detected large hail events in a similar way and showed a strong agreement. The hail detection, as applied to heavy rain events, indicated a weak enhancement of the number of false detected hail pixels via the dual-polarization hydrometeor classification. We also examined the performance of hail size detection from radar data using both single- and dual-polarization methods. Both the methods recognized events with large hail but could not select the reported events with maximum hail size (diameter above 4 cm).

Evaluation of GPM Dual-Frequency Precipitation Radar Algorithms to Estimate Drop Size Distribution Parameters, Using Ground-Based Measurement over the Central Andes of Peru

2021 ◽  
Author(s):  
Carlos Del Castillo-Velarde ◽  
Shailendra Kumar ◽  
Jairo M. Valdivia-Prado ◽  
Aldo S. Moya-Álvarez ◽  
Jose Luis Flores-Rojas ◽  
...  
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Central Andes ◽  
Drop Size Distribution ◽  
Dual Frequency ◽  
Precipitation Radar ◽  
Distribution Parameters

scholarly journals Possible Misidentification of Rain Type by TRMM PR over Tibetan Plateau

2007 ◽  
Vol 46 (5) ◽  
pp. 667-672 ◽  
Author(s):  
Yunfei Fu ◽  
Guosheng Liu
Keyword(s):  
Tibetan Plateau ◽  
Common Knowledge ◽  
Tropical Rainfall Measuring Mission ◽  
Stratiform Rain ◽  
Freezing Level ◽  
Central Tibetan Plateau ◽  
Standard Product ◽  
Trmm Pr ◽  
Trmm Precipitation ◽  
Rain Events

Abstract Rain-type statistics derived from Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) standard product show that some 70% of raining pixels in the central Tibetan Plateau summer are stratiform—a clear contradiction to the common knowledge that rain events during summer in this region are mostly convective, as a result of the strong atmospheric convective instability resulting from surface heating. In examining the vertical distribution of the stratiform rain-rate profiles, it is suspected that the TRMM PR algorithm misidentifies weak convective rain events as stratiform rain events. The possible cause for this misidentification is believed to be that the freezing level is close to the surface over the plateau, so that the ground echo may be mistakenly identified as the melting level in the PR rain classification algorithm.

scholarly journals The Role of Weather Types in Assessing the Rainfall Key Factors for Erosion in Two Different Climatic Regions

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 443 ◽  
Author(s):  
María Fernández-Raga ◽  
Roberto Fraile ◽  
Covadonga Palencia ◽  
Elena Marcos ◽  
Ana María Castañón ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Weather Type ◽  
Key Factors ◽  
Weather Types ◽  
Climatic Regions ◽  
Distribution Parameters ◽  
Study Zone ◽  
Raindrop Size ◽  
Rain Events ◽  
One Year

This paper compares two different geographical sites, Aveiro and León, from different climatic regions, oceanic and continental, but which share the same type of weather (according to Lamb’s classification). The analysis was carried out over one year, and has revealed that rainfall in Aveiro is heavier and more abundant, with a higher number of raindrops and a longer duration of rain events (on average, 10 min longer than in Leon). Mean raindrop size is 0.45 mm in Aveiro and slightly smaller (0.37 mm) in Leon; in addition, the kinetic energy and linear momentum values in Aveiro are three times higher than those in Leon. A comparison of raindrop size distributions by weather type has shown that for both locations westerly weather presented a higher probability of rainfall, and the gamma distribution parameters for each weather type were independent of the study zone. When the analysis is done for the characteristics of rain related with erosion, the westerly cyclonic weather types (cyclonic west (CW) and cyclonic south-westerly (CSW)) are among the most energetic ones in both locations. However, comparing their five weather types with higher kinetic energy, in Aveiro a westerly component implies higher kinetic energy, while in Leon a southerly component involves more energy in the rain.

scholarly journals Characterization of S-Band Dual-Polarized Radar Data for the Convective Rain Melting Layer Detection in A Tropical Region

2018 ◽  
Vol 10 (11) ◽  
pp. 1740 ◽  
Author(s):  
Feng Yuan ◽  
Yee Lee ◽  
Yu Meng ◽  
Jin Ong
Keyword(s):  
Radar Data ◽  
Tropical Region ◽  
Rain Event ◽  
Melting Layer ◽  
Convective Rain ◽  
Radar Measurements ◽  
Dual Polarized ◽  
Rain Events ◽  
Differential Reflectivity

In the tropical region, convective rain is a dominant rain event. However, very little information is known about the convective rain melting layer. In this paper, S-band dual-polarized radar data is studied in order to identify both the stratiform and convective rain melting layers in the tropical region, with a focus on the convective events. By studying and analyzing the above-mentioned two types of rain events, amongst three radar measurements of reflectivity ( Z ), differential reflectivity ( Z DR ), and cross correlation coefficient ( ρ HV ), the latter one is the best indicator for convective rain melting layer detection. From two years (2014 and 2015) of radar and radiosonde observations, 13 convective rain melting layers are identified with available 0 °C isothermal heights which are derived from radiosonde vertical profiles. By comparing the melting layer top heights with the corresponding 0 °C isothermal heights, it is found that for convective rain events, the threshold to detect melting layer should be modified to ρ HV = 0.95 for the tropical region. The melting layer top and bottom heights are then estimated using the proposed threshold, and it is observed from this study that the thickness of convective rain melting layer is around 2 times that of stratiform rain melting layer which is detected by using the conventional ρ HV = 0.97 .

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