Differences in cyclonic raindrop size distribution from southwest to northeast monsoon season and from that of noncyclonic rain

2010 ◽  
Vol 115 (D16) ◽  
Author(s):  
B. Radhakrishna ◽  
T. Narayana Rao
Keyword(s):  
Size Distribution ◽  
Monsoon Season ◽  
Northeast Monsoon ◽  
Raindrop Size Distribution ◽  
Raindrop Size

scholarly journals Statistical Characteristics of Raindrop Size Distribution in Southwest Monsoon Season

2008 ◽  
Vol 47 (2) ◽  
pp. 576-590 ◽  
Author(s):  
N. V. P. Kirankumar ◽  
T. Narayana Rao ◽  
B. Radhakrishna ◽  
D. Narayana Rao
Keyword(s):  
Size Distribution ◽  
Case Studies ◽  
Monsoon Season ◽  
Parameter Distribution ◽  
Convective Rain ◽  
Raindrop Size Distribution ◽  
Precipitation Regimes ◽  
Raindrop Size ◽  
Microphysical Processes ◽  
Vertical Variability

Abstract Raindrop size distribution (DSD) parameters are retrieved from dual-frequency (UHF and VHF) wind profiler measurements made at Gadanki, India, in a summer monsoon season. The convoluted UHF spectra are first corrected for vertical air motion and spectral broadening (using VHF measurements) and later are used for deriving DSD parameters. Two distinctly different case studies, a mesoscale convective system and a pure stratiform precipitation system, have been considered for a detailed study. DSD parameters obtained in these case studies reveal systematic variations of DSD from case to case and also from one rain regime to another within the same precipitating system. A statistical study has been carried out using the profiler data collected during the passage of 16 rain events. The retrieved DSD profiles are divided into separate rain regimes (stratiform and convection), based on reflectivity, to examine salient microphysical characteristics and the vertical variability of DSD in different precipitation regimes. The distribution of DSD parameters is, in general, wider in the convective rain regime than in the stratiform regime, particularly below 2.4 km. The vertical variation of the gamma parameter distribution in the stratiform rain regime is minimal, indicating that the microphysical processes (growth and decay), which alter the rain DSD, may be in equilibrium. On the other hand, the distribution in the convective rain regime appears to be more complex, with the mean profile of the shape parameter varying significantly with height. The observed vertical variability of the gamma parameters and the median volume diameter in the convective rain regime is attributed to two major microphysical processes: evaporation and breakup. The role of other processes, like drop sorting and collision–coalescence, in altering the DSD parameters is also discussed. The present statistics, representing continental monsoon rainfall, are compared with the existing statistics at Darwin, Australia, and the results are discussed in light of DSD differences in oceanic and continental monsoon precipitation.

scholarly journals Statistical Characteristics of Raindrop Size Distribution in Monsoon Season over South China Sea

2021 ◽  
Vol 13 (15) ◽  
pp. 2878
Author(s):  
Chaoying Huang ◽  
Sheng Chen ◽  
Asi Zhang ◽  
Ying Pang
Keyword(s):  
South China Sea ◽  
Size Distribution ◽  
Summer Monsoon ◽  
South China ◽  
Southern China ◽  
Monsoon Season ◽  
Statistical Characteristics ◽  
China Sea ◽  
Raindrop Size Distribution ◽  
Raindrop Size

The South China Sea (SCS) is the largest and southernmost sea in China. Water vapor from the SCS is the primary source of precipitation over coastal areas during the summer monsoon season and may cause the uneven distribution of rainfall in southern China. Deep insight into the spatial variability of raindrop size distribution (DSD) is essential for understanding precipitation microphysics, since DSD contains abundant information about rainfall microphysics processes. However, compared to the studies of DSDs over mainland China, very little is known about DSDs over Chinese ocean areas, especially over the South China Sea (SCS). This study investigated the statistical characteristics of the DSD in summer monsoon seasons using the second-generation Particle Size and Velocity (Parsivel2) installed on the scientific research vessel that measured the size and velocity of raindrops over the SCS. In this study, the characteristics of precipitation over the SCS for daytime and nighttime rains were analyzed for different precipitation systems and upon different rain rates. It was found that: 1) rain events were more frequent during the late evening to early morning; 2) more than 78.2% of the raindrops’ diameters were less than 2 mm, and the average value of mass-weighted mean diameter (1.46 mm) of the SCS is similar to that over land in the southern China; 3) the stratiform precipitation features a relatively high concentration of medium to large-sized rain drops compared to other regions; 4) the DSD in the SCS agreed with a three-parameter gamma distribution for the small raindrop diameter. Furthermore, a possible factor for significant DSD variability in the ocean compared with the coast and large islands is also discussed.

Rain Droplets Size Distributions Statistical analysis for pre-Monsoon and Monsoon Season over the Western Ghats

2021 ◽  
Author(s):  
Amit Kumar ◽  
Atul Kumar Srivastava ◽  
Kaustav Chakravarty ◽  
Manoj Kumar Srivastava
Keyword(s):  
Statistical Analysis ◽  
Size Distribution ◽  
Western Ghats ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Convective Precipitation ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
The Western Ghats

<p>Four years (2015-2018), Joss-Waldvogel disdrometer (JWD) data are utilized for the statistical analysis of Raindrop size distribution (RSD) of pre-monsoon and monsoon season over the Western Ghats. JWD Instrument installed at High Altitude Cloud Physics Laboratory (HACPL, 17.92°N, 73.66°E), Mahabaleshwar in the core of heavy rainfall region of Western Ghats. Variation in raindrop size distribution characteristics features in pre-monsoon and monsoon season for convective and stratiform precipitation of windward side of Western Ghats analysis, using long-term in-situ JWD instrument data done. Convective and stratiform rainfall classification is based on the number of concentrations of rain droplets and rain rates. Tropical Rainfall Measuring Mission (TRMM) and ERA-Interim data sets are also integrated with disdrometer data to establish microphysical and dynamical features of pre-monsoon and monsoon season rain. Long-term trends of rain droplet size spectra are not studied until now over the Western Ghats.   Rain droplet spectra of pre-monsoon and monsoon seasons show notable differences. The rain droplets of monsoon display considerably higher divergence compared to pre-monsoon rainfall.  Monsoon rainfall has a higher concentration of smaller drops, while pre-monsoon rainfall contains a significantly higher concentration of large droplets. RSD classified on the rain rate demonstrates a higher mass-weighted mean diameter (D<sub>m</sub>) and a lower normalized intercept parameter (log<sub>10</sub>N<sub>w</sub>) in monsoon than winter. Similarly, the Diurnal variation of RSD reveals higher D<sub>m</sub> with a lower value of log<sub>10</sub>N<sub>w</sub> in pre-monsoon season. Also, in both seasons, the higher value of mean D<sub>m</sub> in convective precipitation than stratiform.  Convective activities with increased ground temperature alter RSD in pre-monsoon season rather than monsoon season through droplet classification, evaporation, and collision-coalescence processes.</p>

Differences in raindrop size distribution from southwest monsoon to northeast monsoon at Gadanki

2009 ◽  
Vol 135 (643) ◽  
pp. 1630-1637 ◽  
Author(s):  
T. Narayana Rao ◽  
B. Radhakrishna ◽  
K. Nakamura ◽  
N. Prabhakara Rao
Keyword(s):  
Size Distribution ◽  
Southwest Monsoon ◽  
Northeast Monsoon ◽  
Raindrop Size Distribution ◽  
Raindrop Size

scholarly journals Analysis of the Vertical Air Motions and Raindrop Size Distribution Retrievals of a Squall Line Based on Cloud Radar Doppler Spectral Density Data

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 348
Author(s):  
Ningkun Ma ◽  
Liping Liu ◽  
Yichen Chen ◽  
Yang Zhang
Keyword(s):  
Spectral Density ◽  
Size Distribution ◽  
Squall Line ◽  
Vertical Profiles ◽  
Air Velocity ◽  
Density Data ◽  
Cloud Radar ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Reflectivity Factor

A squall line is a type of strongly organized mesoscale convective system that can cause severe weather disasters. Thus, it is crucial to explore the dynamic structure and hydrometeor distributions in squall lines. This study analyzed a squall line over Guangdong Province on 6 May 2016 that was observed using a Ka-band millimeter-wave cloud radar (CR) and an S-band dual-polarization radar (PR). Doppler spectral density data obtained by the CR were used to retrieve the vertical air motions and raindrop size distribution (DSD). The results showed the following: First, the CR detected detailed vertical profiles and their evolution before and during the squall line passage. In the convection time segment (segment B), heavy rain existed with a reflectivity factor exceeding 35 dBZ and a velocity spectrum width exceeding 1.3 m s−1. In the PR detection, the differential reflectivity factor (Zdr) was 1–2 dB, and the large specific differential phase (Kdp) also represented large liquid water content. In the transition and stratiform cloud time segments (segments B and C), the rain stabilized gradually, with decreasing cloud tops, stable precipitation, and a 0 °C layer bright band. Smaller Kdp values (less than 0.9) were distributed around the 0 °C layer, which may have been caused by the melting of ice crystal particles. Second, from the CR-retrieved vertical air velocity, before squall line passage, downdrafts dominated in local convection and weak updrafts existed in higher-altitude altostratus clouds. In segment B, the updraft air velocity reached more than 8 m s−1 below the 0 °C layer. From segments C to D, the updrafts changed gradually into weak and wide-ranging downdrafts. Third, in the comparison of DSD values retrieved at 1.5 km and DSD values on the ground, the retrieved DSD line was lower than the disdrometer, the overall magnitude of the DSD retrieved was smaller, and the difference decreased from segments C to D. The standardized intercept parameter (Nw) and shape parameter (μ) of the DSD retrieved at 1.8 km showed good agreement with the disdrometer results, and the mass-weighted mean diameter (Dm) was smaller than that on the ground, but very close to the PR-retrieved Dm result at 2 km. Therefore, comparing with the DSD retrieved at around 2 km, the overall number concentration remained unchanged and Dm got larger on the ground, possibly reflecting the process of raindrop coalescence. Lastly, the average vertical profiles of several quantities in all segments showed that, first of all, the decrease of Nw and Dm with height in segments C and D was similar, reflecting the collision effect of falling raindrops. The trends were opposite in segment B, indicating that raindrops underwent intense mixing and rapid collision and growth in this segment. Then, PR-retrieved Dm profiles can verify the rationality of the CR-retrieved Dm. Finally, a vertical velocity profile peak generated a larger Dm especially in segments C and D.

scholarly journals On the Shape–Slope Relation of Drop Size Distributions in Convective Rain

2005 ◽  
Vol 44 (7) ◽  
pp. 1146-1151 ◽  
Author(s):  
Axel Seifert
Keyword(s):  
Size Distribution ◽  
Gamma Distribution ◽  
Drop Size ◽  
Empirical Relation ◽  
Size Distributions ◽  
Shape Parameters ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Drop Size Distributions ◽  
Good Agreement

Abstract The relation between the slope and shape parameters of the raindrop size distribution parameterized by a gamma distribution is examined. The comparison of results of a simple rain shaft model with an empirical relation based on disdrometer measurements at the surface shows very good agreement, but a more detailed discussion reveals some difficulties—for example, deviations from the gamma shape and the overestimation of collisional breakup.

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