On rainfall type classification to improve rain attenuation prediction

2020 ◽  
Author(s):  
Karel Pitas ◽  
Ondrej Fiser
Keyword(s):  
Rain Attenuation ◽  
Rainfall Type ◽  
Type Classification

scholarly journals Attenuation Correction of X-Band Radar Reflectivity Using Adjacent Multiple Microwave Links

2020 ◽  
Vol 12 (13) ◽  
pp. 2133
Author(s):  
Min-Seong Kim ◽  
Byung Hyuk Kwon
Keyword(s):  
Attenuation Correction ◽  
Rain Attenuation ◽  
Physical Structure ◽  
Radar Reflectivity ◽  
Correction Coefficient ◽  
Polarimetric Radar ◽  
Weather Radars ◽  
X Band ◽  
Rainfall Type ◽  
Microwave Link

Rain attenuation can hinder the implementation of quantitative precipitation estimations using X-band weather radar. Numerous studies have been conducted on correcting the attenuation of radar reflectivity by utilizing a dual-polarimetric radar and an arbitrary-oriented microwave link; however, there is a need to optimize the required number of microwave links and their locations. In this study, we tested four attenuation correction methods and proposed a novel algorithm based on the sole use of adjacent multiple microwave links. The attenuation of the X-band radar reflectivity was corrected by performing forward iterations at each link, and the correction coefficients were statistically analyzed to reduce the instability problem. The algorithms of each method were evaluated by studying the cases of convective and stratiform rainfall, and then validated by comparing the corrected reflectivity of the X-band radar with the qualitatively controlled reflectivity of the S-band radar. The new method was as efficient as the conventional method based on the specific differential phase of dual-polarimetric radar. Furthermore, the correction coefficient was more effectively optimized and stabilized using seven microwave links rather than a single link, and no further independent reference data were required. In addition, the attenuation correction also accounted for spatiotemporal differentiation depending on the rainfall type, and could recover the physical structure of the rainfall. The method developed herein can facilitate estimations of quantitative rainfall in developing countries where dual-polarization weather radars are not common. The exploitation of microwave link data is a promising method for rainfall remote sensing.

scholarly journals Polarimetric Radar Observation of the Melting Layer in a Convective Rainfall System during the Rainy Season over the East China Sea

2011 ◽  
Vol 50 (2) ◽  
pp. 354-367 ◽  
Author(s):  
Yukari Shusse ◽  
Nobuhiro Takahashi ◽  
Katsuhiro Nakagawa ◽  
Shinsuke Satoh ◽  
Toshio Iguchi
Keyword(s):  
East China Sea ◽  
East China ◽  
Polarimetric Radar ◽  
The East China Sea ◽  
Convective Rainfall ◽  
China Sea ◽  
Stratiform Region ◽  
Convective Region ◽  
Rainfall Type ◽  
Type Classification

Abstract During the rainy season over the East China Sea, convective rainfalls often show melting layer (ML) characteristics in polarimetric radar variables. In this research, the appearance ratio of the ML (the ratio of rainfall area accompanied by polarimetric ML signatures) and the variation in height of the level of the ML signature maximum (MLSM level; defined by the level of the ρhv minimum in the ML) in a convective rainfall region in a rainfall system over the East China Sea observed on 2 June 2006 were studied using C-band polarimetric radar (COBRA). For this analysis, a method of rainfall type classification that evaluates the presence of an ML in addition to providing conventional convective–stratiform classification using range–height indicator (RHI) observation data was developed. This rainfall type classification includes two steps: conventional convective–stratiform separation using the horizontal distribution of Zh at 2-km altitude, and ML detection using the vertical profile of ρhv at each horizontal grid point. Using a combination of these two classifications, the following four rainfall types were identified: 1) convective rainfall with an ML, 2) convective rainfall with no ML, 3) stratiform rainfall with an ML, and 4) stratiform rainfall with no ML. An ML was detected in 53.9% of the convective region in the rainfall system. Using the same definition, an ML was detected in 83.1% of the stratiform region. The ML in the convective region showed a marked decrease in ρhv coincident with an increase in ZDR around the ambient 0°C level, as did that in the stratiform region. Melting aggregated snow was the likely cause of the ML signature in the convective region. The average height of the MLSM level in the convective region was 4.64 km, which is 0.46 km higher than that in the stratiform region (4.18 km) and 0.27 km higher than the ambient 0°C level (4.37 km).

scholarly journals An Automatic Rainfall‐Type Classification Algorithm Combining Diverse 3‐D Features of Radar Echoes

2019 ◽  
Vol 6 (12) ◽  
pp. 2273-2290 ◽  
Author(s):  
Bo Lei ◽  
Zi‐Xin Xu ◽  
Ling Yang ◽  
Xuehua Li ◽  
Xiaoqiong Zhen
Keyword(s):  
Classification Algorithm ◽  
Radar Echoes ◽  
Rainfall Type ◽  
Type Classification

Spatial Distribution of Pre-Warm Front Rainfall in the Mediterranean Area

1988 ◽  
Vol 19 (1) ◽  
pp. 53-64 ◽  
Author(s):  
C. Corradini ◽  
F. Melone
Keyword(s):  
Mediterranean Area ◽  
Compact Structure ◽  
Large Variability ◽  
Air Mass ◽  
Orographic Effects ◽  
Warm Front ◽  
Average Rainfall ◽  
Convective Motions ◽  
Rainfall Type ◽  
The Mediterranean

Evidence is given of the distribution of pre-warm front rainfall at the meso-γ scale, together with a discussion of the main mechanisms producing this variability. An inland region in the Mediterranean area is considered. The selected rainfall type is commonly considered the most regular inasmuch as it is usually unaffected by extended convective motions. Despite this, within a storm a large variability in space was observed. For 90% of measurements, the typical deviations from the area-average total depth ranged from - 40 to 60 % and the storm ensemble-average rainfall rate over an hilly zone was 60 % greater than that in a contiguous low-land zone generally placed upwind. This variability is largely explained in terms of forced uplift of air mass over an envelope type orography. For a few storms smaller orographic effects were found in locations influenced by an orography with higher slopes and elevations. This feature is ascribed to the compact structure of these mountains which probably determines a deflection of air mass in the boundary layer. The importance of this type of analysis in the hydrological practice is also emphasized.

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