scholarly journals On Raindrop-size Distribution in Warm Rain (I)

1971 ◽  
Vol 22 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Miyuki Fujiwara ◽  
Toshiko Yanase
Keyword(s):  
Size Distribution ◽  
Warm Rain ◽  
Raindrop Size Distribution ◽  
Raindrop Size

scholarly journals Statistical characteristics of raindrop size distribution over Western Ghats of India: wet versus dry spells of Indian Summer Monsoon

2019 ◽  
Author(s):  
Uriya Veerendra Murali Krishna ◽  
Subrata Kumar Das ◽  
Ezhilarasi Govindaraj Sulochana ◽  
Bhowmik Utsav ◽  
Sachin Madhukar Deshpande ◽  
...  
Keyword(s):  
Size Distribution ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Diurnal Cycle ◽  
Western Ghats ◽  
Warm Rain ◽  
Raindrop Size Distribution ◽  
Dry Spells ◽  
Western Ghats Of India ◽  
Raindrop Size

Abstract. The nature of raindrop size distribution (DSD) is analyzed during wet and dry spells of the Indian Summer Monsoon (ISM) over Western Ghats (WGs) using Joss-Waldvogel Disdrometer (JWD) measurements. The observed DSDs are fitted with gamma distribution, and the characteristic DSDs are studied during the summer monsoon seasons (June–September) of 2012–2015. The DSD spectra show distinct diurnal variation during wet and dry spells. The dry spells exhibit a strong diurnal cycle with two peaks, while the diurnal cycle is not prominent in the wet spells. The observational results reveal the microphysical characteristics of warm rain during both the wet and dry spells. Even though the warm rain processes are dominant over WGs during monsoon, the underlying dynamical processes cause the differences in DSD characteristics during wet and dry spells. In addition, the differences in DSD spectra with different rain rates are also observed during the wet and dry spells. The DSD spectra are further analyzed by separating into stratiform and convective types. Finally, an empirical relation between slope parameter, Λ and shape parameter, μ is derived by best fitting the quadratic polynomial for the observed data during both wet and dry spells as well as for the stratiform and convective types of precipitation. The Λ–μ relations obtained in the present study are slightly different in comparison with the earlier studies.

scholarly journals Statistical characteristics of raindrop size distribution over Western Ghats of India: wet versus dry spells of Indian Summer Monsoon

2020 ◽  
Author(s):  
Uriya Veerendra Murali Krishna ◽  
Subrata Kumar Das ◽  
Ezhilarasi Govindaraj Sulochana ◽  
Bhowmik Utsav ◽  
Sachin Madhukar Deshpande ◽  
...  
Keyword(s):  
Size Distribution ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Diurnal Cycle ◽  
Western Ghats ◽  
Warm Rain ◽  
Raindrop Size Distribution ◽  
Dry Spells ◽  
Western Ghats Of India ◽  
Raindrop Size

Abstract. The nature of raindrop size distribution (DSD) is analyzed during wet and dry spells of the Indian Summer Monsoon (ISM) in the Western Ghats (WGs) region by using Joss-Waldvogel Disdrometer (JWD) measurements. The observed DSDs are fitted with gamma distribution, and the DSD characteristics are studied during ISM season (June–September) of 2012–2015. The DSD spectra show distinct diurnal variation during the wet and dry spells. The dry spells exhibit a strong diurnal cycle with two peaks, while the diurnal cycle is not so prominent in the wet spells. Results reveal the microphysical characteristics of warm rain during both the wet and dry periods. Even though the warm rain processes are dominant in the WGs region, the underlying dynamical processes cause the differences in DSD characteristics during the wet and dry spells. In addition, the differences in DSD spectra with different rain rates are also observed. The DSD spectra are further analyzed by separating into stratiform and convective types. Finally, an empirical relationship between the slope parameter, Λ and shape parameter, µ is derived by best fitting the quadratic polynomial for the observed data during both wet and dry spells as well as for the stratiform and convective types of rain. The µ-Λ relations obtained in the present study are slightly different in comparison with the previous studies.

Diagnosing the Intercept Parameter for Exponential Raindrop Size Distribution Based on Video Disdrometer Observations: Model Development

2008 ◽  
Vol 47 (11) ◽  
pp. 2983-2992 ◽  
Author(s):  
Guifu Zhang ◽  
Ming Xue ◽  
Qing Cao ◽  
Daniel Dawson
Keyword(s):  
Size Distribution ◽  
Sampling Error ◽  
Model Development ◽  
Parameterization Scheme ◽  
Clear Correlation ◽  
Rainfall Estimation ◽  
Warm Rain ◽  
Raindrop Size Distribution ◽  
Single Moment ◽  
Raindrop Size

Abstract The exponential distribution N(D) = N0 exp(−ΛD) with a fixed intercept parameter N0 is most commonly used to represent raindrop size distribution (DSD) in rainfall estimation and in single-moment bulk microphysics parameterization schemes. Disdrometer observations show that the intercept parameter is far from constant and systematically depends on the rain type and intensity. In this study, a diagnostic relation of N0 as a function of rainwater content W is derived based on two-dimensional video disdrometer (2DVD) measurements. The data reveal a clear correlation between N0 and W in which N0 increases as W increases. To minimize the effects of sampling error, a relation between two middle moments is used to derive the N0–W relation. This diagnostic relation has the potential to improve rainfall estimation and bulk microphysics parameterizations. A parameterization scheme for warm rain processes based on the diagnostic N0 DSD model is formulated and presented. The diagnostic N0-based parameterization scheme yields less evaporation and accretion for stratiform rain than that using fixed N0.

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.

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