scholarly journals Multi-sensor analysis of convective activity in Central Italy during the HyMeX SOP 1.1

2015 ◽  
Vol 8 (9) ◽  
pp. 9241-9287
Author(s):  
N. Roberto ◽  
E. Adirosi ◽  
L. Baldini ◽  
D. Casella ◽  
S. Dietrich ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Central Italy ◽  
Lightning Activity ◽  
Convective Precipitation ◽  
Dual Polarization ◽  
Precipitation Regime ◽  
Microphysical Properties ◽  
Raindrop Size Distribution ◽  
Sensor Analysis ◽  
Raindrop Size

Abstract. A multi-sensor analysis of convective precipitation events that occurred in central Italy, in autumn 2012 during the HyMeX (Hydrological cycle in the Mediterranean eXperiment) Special Observation Period (SOP) 1.1 is presented. Various microphysical properties of liquid and solid hydrometeors were examined to assess their relationship with lightning activity. The instrumentation used consisted of a C-band dual-polarization weather radar, a 2-D video disdrometer, and a lightning network. A fuzzy logic based hydrometeor classification algorithm was tuned and optimized for the detection of graupel from C-band dual-polarization radar measurements. Graupel ice water content was then retrieved and related to lightning activity. A linear correlation was found between the total mass of graupel above the 0° isothermal and the number of strokes detected by the lightning network in agreement with model outputs, which confirms the importance of ice in the electrical charging of convective clouds, although differences were noticed among events. Parameters of the gamma raindrop size distribution measured by a 2-D video disdrometer, revealed the transition from convective to stratiform regime during the event and where related. However, lightning activity was not always recorded when the precipitation regime was classified as convective. More robust relationships were found relating lightning activity to graupel.

scholarly journals Multi-sensor analysis of convective activity in central Italy during the HyMeX SOP 1.1

2016 ◽  
Vol 9 (2) ◽  
pp. 535-552 ◽  
Author(s):  
N. Roberto ◽  
E. Adirosi ◽  
L. Baldini ◽  
D. Casella ◽  
S. Dietrich ◽  
...  
Keyword(s):  
Case Studies ◽  
Hydrological Cycle ◽  
Central Italy ◽  
Lightning Activity ◽  
Convective Precipitation ◽  
Coefficient Of Determination ◽  
Dual Polarization ◽  
Radar Measurements ◽  
Sensor Analysis ◽  
Raindrop Size

Abstract. A multi-sensor analysis of convective precipitation events that occurred in central Italy in autumn 2012 during the HyMeX (Hydrological cycle in the Mediterranean experiment) Special Observation Period (SOP) 1.1 is presented. Various microphysical properties of liquid and solid hydrometeors are examined to assess their relationship with lightning activity. The instrumentation used consisted of a C-band dual-polarization weather radar, a 2-D video disdrometer, and the LINET lightning network. Results of T-matrix simulation for graupel were used to (i) tune a fuzzy logic hydrometeor classification algorithm based on Liu and Chandrasekar (2000) for the detection of graupel from C-band dual-polarization radar measurements and (ii) to retrieve graupel ice water content. Graupel mass from radar measurements was related to lightning activity. Three significant case studies were analyzed and linear relations between the total mass of graupel and number of LINET strokes were found with different slopes depending on the nature of the convective event (such as updraft strength and freezing level height) and the radar observational geometry. A high coefficient of determination (R2 = 0.856) and a slope in agreement with satellite measurements and model results for one of the case studies (15 October 2012) were found. Results confirm that one of the key features in the electrical charging of convective clouds is the ice content, although it is not the only one. Parameters of the gamma raindrop size distribution measured by a 2-D video disdrometer revealed the transition from a convective to a stratiform regime. The raindrop size spectra measured by a 2-D video disdrometer were used to partition rain into stratiform and convective classes. These results are further analyzed in relation to radar measurements and to the number of strokes. Lightning activity was not always recorded when the precipitation regime was classified as convective rain. High statistical scores were found for relationships relating lightning activity to graupel aloft.

scholarly journals Evaluation of Gamma Raindrop Size Distribution Assumption through Comparison of Rain Rates of Measured and Radar-Equivalent Gamma DSD

2014 ◽  
Vol 53 (6) ◽  
pp. 1618-1635 ◽  
Author(s):  
Elisa Adirosi ◽  
Eugenio Gorgucci ◽  
Luca Baldini ◽  
Ali Tokay
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Rain Rate ◽  
Hydrological Cycle ◽  
Drop Size Distribution ◽  
Dual Polarization ◽  
Raindrop Size Distribution ◽  
Radar Measurements ◽  
Raindrop Size ◽  
Rain Rates

AbstractTo date, one of the most widely used parametric forms for modeling raindrop size distribution (DSD) is the three-parameter gamma. The aim of this paper is to analyze the error of assuming such parametric form to model the natural DSDs. To achieve this goal, a methodology is set up to compare the rain rate obtained from a disdrometer-measured drop size distribution with the rain rate of a gamma drop size distribution that produces the same triplets of dual-polarization radar measurements, namely reflectivity factor, differential reflectivity, and specific differential phase shift. In such a way, any differences between the values of the two rain rates will provide information about how well the gamma distribution fits the measured precipitation. The difference between rain rates is analyzed in terms of normalized standard error and normalized bias using different radar frequencies, drop shape–size relations, and disdrometer integration time. The study is performed using four datasets of DSDs collected by two-dimensional video disdrometers deployed in Huntsville (Alabama) and in three different prelaunch campaigns of the NASA–Japan Aerospace Exploration Agency (JAXA) Global Precipitation Measurement (GPM) ground validation program including the Hydrological Cycle in Mediterranean Experiment (HyMeX) special observation period (SOP) 1 field campaign in Rome. The results show that differences in rain rates of the disdrometer DSD and the gamma DSD determining the same dual-polarization radar measurements exist and exceed those related to the methodology itself and to the disdrometer sampling error, supporting the finding that there is an error associated with the gamma DSD assumption.

Precipitation structure during the life cycle of cloud systems over Peru using satellite based observations

2020 ◽  
Author(s):  
Shailenda Kumar ◽  
Yamina Silva ◽  
Carlos Del Castillo ◽  
Jose Luis Flores Rojas ◽  
Aldo Moya S. Alveraz ◽  
...  
Keyword(s):  
Life Cycle ◽  
Rain Rate ◽  
Convective Precipitation ◽  
Mature Stage ◽  
Near Surface ◽  
Cloud Systems ◽  
Freezing Level ◽  
Microphysical Properties ◽  
Raindrop Size Distribution ◽  
Raindrop Size

<p>In the present study, a unique approach is applied to investigate the life cycle properties of the precipitation combining the satellite-based information. Data from Global Precipitation Measurement Dual Precipitation Radar (GPM-DPR) and brightness temperature (BT) form the GOES satellite. First, we used the GPM-DPR data to identify the precipitating cloud systems (PCSs) and then 9 (± 4 hours) hours of GOES BT data to identify the life phases for a particular PCSs e.g., a developing stage, a mature stage, or a dissipating stage. The case study of PCS related to different phases of the PCSs shows that PCSs consist of different systematic properties including the area of convective-stratiform precipitation, the convective rain rate and the storm-top height. The developing stage PCSs have the highest convective precipitation fraction (~26%) with highest near surface rain rate (RR, 4.97 mm h-1), whereas the dissipating stage PCSs have the largest precipitation area (11489 km2) with least near surface convective RR (~4.11 mm h-1). The vertical structure of precipitation and raindrop size distribution (DSD parameters) show the different characteristics above and below the freezing level and related with the different microphysical processes during different stages and related with the convective to stratiform area fraction and water vapour. The developing stage PCSs have the largest but sparse, droplets in convective precipitation, whereas the mature stage has the largest droplets below in the freezing level for all the vertical rainy profiles. The developing stage PCSs have the highest concentration of least sized of hydrometeors. Also, north-eastern continent of SA has higher near surface RR with higher sized of hydrometeors and even higher in developing stage PCSs. Our analysis indicates that the different microphysical properties for the PCSs in different phases are related to cloud and ice water path upward motion and related to the orographic influence.</p>

scholarly journals Attenuation correction for a high-resolution polarimetric X-band weather radar

2010 ◽  
Vol 8 ◽  
pp. 279-284
Author(s):  
T. Otto ◽  
H. W. J. Russchenberg
Keyword(s):  
Attenuation Correction ◽  
Hydrological Cycle ◽  
Correction Method ◽  
Phase Constraint ◽  
Spatial And Temporal Variability ◽  
Range Resolution ◽  
Raindrop Size Distribution ◽  
University Of Technology ◽  
X Band ◽  
Raindrop Size

Abstract. In 2007, IRCTR (Delft University of Technology) installed a new polarimetric X-band LFMCW radar (IDRA) at the meteorological observation site of Cabauw, The Netherlands. It provides plan position indicators (PPI) at a fixed elevation with a high range resolution of either 3 m or 30 m at a maximum observation range of 1.5 km and 15 km, respectively. IDRA aims to monitor precipitation events for the long-term analysis of the hydrological cycle. Due to the specifications of IDRA, the spatial and temporal variability of a large range of rainfall intensities (from drizzle to heavy convective rain) can be studied. Even though the usual observation range of IDRA is limited to 15 km, attenuation due to precipitation can be large enough to seriously affect the measurements. In this contribution we evaluate the application of a combined method to correct for the specific and the differential attenuation, and in the same vein estimate the parameters of the raindrop-size distribution. The estimated attenuations are compared to a phase constraint attenuation correction method.

scholarly journals STUDY ON SUMMER RAINDROP SIZE DISTRIBUTION AND RETRIEVED POLARIMETRIC RADAR PARAMETER OVER LEIZHOU PENINSULA

2019 ◽  
Vol XLII-3/W9 ◽  
pp. 245-250
Author(s):  
Z. B. Zhou ◽  
J. J. Lv ◽  
S. J. Niu
Keyword(s):  
Size Distribution ◽  
Gamma Distribution ◽  
Least Squares Method ◽  
Convective Precipitation ◽  
Polarimetric Radar ◽  
Leizhou Peninsula ◽  
Raindrop Size Distribution ◽  
Precipitation Estimation ◽  
Raindrop Size ◽  
Subtropical Monsoon Climate

Abstract. Leizhou peninsula is located in the south of Guangdong Province, near South China Sea, and has a tropical and subtropical monsoon climate. Based on observed drop size distribution (DSD) data from July 2007 to August 2007 with PARSIVEL disdrometers deployed at Zhanjiang and Suixi, the characterists of DSDs are studied. Non-linear least squares method is used to fit Gamma distribution. Convective and stratiform averaged DSDs are in good agreement with Gamma distribution, especially in stratiform case. Convective average DSDs have a wider spectrum and higher peak. Microphysical parameter differences between convective and stratiform are discussed, convective precipitation has a higher mass-weighted mean diameter (Dm) and generalized intercepts (Nw) in both areas. The constrained relations between Gamma distribution parameter (μ, Λ, N0) is derived. The retrieved polarimetric radar parameter (KDP, ZDR, Zh) have a good self-consistency, which can be used to improve the accuracy of KDP calculation. R-KDP-ZDR is superior to the R-KDP, R-ZDR-Zh in quantitative precipitation estimation (QPE), with a correlation coefficient higher than 0.98.

A Bayesian Approach for Integrated Raindrop Size Distribution (DSD) Retrieval on an X-Band Dual-Polarization Radar Network

2016 ◽  
Vol 33 (2) ◽  
pp. 377-389 ◽  
Author(s):  
Eiichi Yoshikawa ◽  
V. Chandrasekar ◽  
Tomoo Ushio ◽  
Takahiro Matsuda
Keyword(s):  
Size Distribution ◽  
Estimation Accuracy ◽  
Dual Polarization ◽  
Estimation Errors ◽  
Axis Ratio ◽  
Radar Network ◽  
Raindrop Size Distribution ◽  
X Band ◽  
Radar Measurements ◽  
Raindrop Size

AbstractA raindrop size distribution (DSD) retrieval method for a weather radar network consisting of several X-band dual-polarization radars is proposed. An iterative maximum likelihood (ML) estimator for DSD retrieval in a single radar was developed in the authors’ previous work, and the proposed algorithm in this paper extends the single-radar retrieval to radar-networked retrieval, where ML solutions in each single-radar node are integrated based on a Bayesian scheme in order to reduce estimation errors and to enhance accuracy. Statistical evaluations of the proposed algorithm were carried out using numerical simulations. The results with eight radar nodes showed that the bias and standard errors are −0.05 and 0.09 in log(Nw); and Nw (mm−1 m−3) and 0.04 and 0.09 in D0 (mm) in an environment with fluctuations in dual-polarization radar measurements (normal distributions with standard deviations of 0.8 dBZ, 0.2 dB, and 1.5° in ZHm, ZDRm, and ΦDPm, respectively). Further error analyses indicated that the estimation accuracy depended on the number of radar nodes, the ranges of varying μ, the raindrop axis ratio model, and the system bias errors in dual-polarization radar measurements.

Geographical characteristics of raindrop size distribution in the southern parts of Korea

2020 ◽  
Author(s):  
Sung–Ho Suh ◽  
Hyeon–Joon Kim ◽  
Dong–In Lee ◽  
Tae–Hoon Kim
Keyword(s):  
Size Distribution ◽  
Coastal Area ◽  
Sea Breeze ◽  
Convective Precipitation ◽  
Drop Diameter ◽  
Local Maxima ◽  
Raindrop Size Distribution ◽  
Precipitation Estimation ◽  
Raindrop Size ◽  
Stratiform Rainfall

AbstractThis study analyzed the regional characteristics of raindrop size distribution (DSD) in the southern coastal area of South Korea. Data from March 2016 to February 2017 were recorded by four PARSIVEL disdrometers installed at intervals of ~20 km from the coastline to inland. Within 20 km from the coastline, multiple local maxima in the probability density function (PDF) were observed at Dm (mass-weighted drop diameter) = 0.6 mm and logNw (normalized intercept parameter) = 5.2 for stratiform rainfall, but these features were not observed more than 20 km from the coastline. Based on mean Dm–logNw values, stratiform rainfall clearly differed between coastal and inland areas. For convective precipitation, there was a linear relationship between Dm and Nw with the distance from the coastline. PDF analyses of diurnal variation in DSD confirmed that in spring and autumn the multiple local maxima appear in the daytime. The multiple local maxima in Dm (logNw) values were lower (higher) at nighttime (NT) than DT in the spring and summer season. These features were highly dependent on the prevailing wind. There was a pattern of increasing A and decreasing b in the radar reflectivity–rainfall rate (Z–R) relationship (Z = ARb) with distance from the coastline, and these features were more pronounced in convective precipitation. These diurnal variabilities were regular in stratiform rainfall, and there were large differences in quantitative precipitation estimation depending on the land–sea breeze in the coastal area.

Rainfall and DSD Parameters Comparison between Micro Rain Radar, Two-Dimensional Video and Parsivel2 Disdrometers, and S-Band Dual-Polarization Radar

2020 ◽  
Vol 37 (4) ◽  
pp. 621-640 ◽  
Author(s):  
Elisa Adirosi ◽  
Luca Baldini ◽  
Ali Tokay
Keyword(s):  
Doppler Radar ◽  
Two Dimensional ◽  
Dual Polarization ◽  
Stratiform Rain ◽  
Convective Rain ◽  
Raindrop Size Distribution ◽  
Primary Reference ◽  
Absolute Bias ◽  
Raindrop Size ◽  
Rain Radar

AbstractA well-designed deployment of well-maintained surface instruments as well as abundant rainfall provided an excellent dataset with which to evaluate the Micro Rain Radar (MRR) performance for estimating raindrop size distribution (DSD) and its integral rainfall parameters with respect to the consolidated devices during the Iowa Flood Studies (IFloodS) field campaign. The MRR was collocated with two-dimensional video disdrometer (2DVD) and Autonomous Parsivel2 Unit (APU) at three different sites located at 5–70-km distances from the National Aeronautics and Space Administration’s S-band dual-polarization Doppler radar (NPOL). A comparative study between MRR, 2DVD, APU, and NPOL was conducted including all rainy minutes as well as minutes of stratiform rain and convective rain. Considering 2DVD as a primary reference, a good agreement was evident for reflectivity between MRR’s lowest reliable height and 2DVD with an absolute bias of less than 2 dB even in convective rain except for one site. For rainfall rate, the percent absolute bias between MRR and 2DVD ranged between 25% and 35% in stratiform rain and about 10% higher in convective rain. Agreement for mean mass-weighted raindrop diameter was good (bias less than 0.1 mm), whereas MRR overestimated the normalized intercept parameter of the gamma DSD [mean bias among the three sites was −0.13 log(mm−1 m−3)]. The agreement between MRR and APU was slightly worse than the one between MRR and 2DVD. When the horizontal and differential reflectivities of NPOL were compared with the ones derived from the MRR DSD resampled within the radar volume, we found an absolute bias of approximately 3 and 0.4 dB, respectively.

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