Further evidence for superterminal raindrops

Larsen, Michael L.; Kostinski, A. B.; Jameson, A. R.

doi:10.1002/2014gl061397

Cited by 36 publications

(30 citation statements)

References 20 publications

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“…It is evident here that the distribution of superterminal and subterminal drops vary with the drop diameter (Larsen et al, ). Superterminal raindrops are mainly observed at 0.5‐mm diameter, and subterminal raindrops become dominant above 0.5 mm in diameter.…”

Section: Resultsmentioning

confidence: 73%

“…Thurai et al () observed the broadening of fall speed distribution with a significant skewness during the passage of an intense convective rain event, which is due to the asymmetric horizontal mode of oscillations of raindrops. Larsen et al () and Montero‐Martínez and García‐García () evidenced the presence of superterminal (higher than terminal velocity) and subterminal (lower than terminal velocity) fall speeds in intense rain events. More recently, Bringi et al () also showed the existence of superterminal and subterminal raindrops from an optical probe and Two‐Dimensional Video Disdrometer (2DVD) measurements.…”

Section: Introductionmentioning

confidence: 97%

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Investigation of Raindrops Fall Velocity During Different Monsoon Seasons Over the Western Ghats, India

Das

Simon

Kolte

et al. 2020

Earth and Space Science

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Using the Two‐Dimensional Video Disdrometer measurements, we investigated the fall velocity of raindrops at Mahabaleshwar (17.92°N, 73.6°E, ~1.4 km above mean sea level, AMSL), a tropical site on the Western Ghats of India. The analysis is for different seasons during 2012–2015. To increase the reliability and accuracy of analysis, the raindrops with diameters in the range 0.5–2 mm and horizontal wind speed < 2 m s−1 are considered. The observed raindrop fall velocities have been corrected for the effect of air density. The ratio between the observed velocity and calculated terminal velocity is considered for estimating superterminal (positively skewed; higher than terminal velocity) and subterminal (negatively skewed; lower than terminal velocity) raindrops. The distribution of these skewed raindrops and its relationship with rain rate, drop diameter, and axis ratio for different seasons has been examined. Results indicate the presence of superterminal and subterminal raindrops in definite proportion in all the season with a majority of the drops have a diameter less than 1 mm. It is found that most of the superterminal raindrops occur at rain rates below 5 mm hr−1, while subterminal raindrops are relatively higher above this rain rate. It is observed that the superterminal raindrops are usually small in size and prolate in shape, while the subterminal raindrops are relatively large and oblate in shape. The diurnal variation of these raindrops during different seasons is also studied.

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Section: Resultsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 97%

Investigation of Raindrops Fall Velocity During Different Monsoon Seasons Over the Western Ghats, India

Das

Simon

Kolte

et al. 2020

Earth and Space Science

View full text Add to dashboard Cite

show abstract

“…The occurrence of super‐terminal drops with small sizes under calm wind conditions, particularly for the 31 August 2007 case when R was 75 mm h −1 , reinforces previous observations (Montero‐Martínez et al ., ; Larsen et al ., ) that indicate the preponderance of super‐terminal drops in the presence of large raindrops (i.e. during periods of high rainfall rates).…”

Section: Resultsmentioning

confidence: 99%

“…However, since Montero‐Martínez et al . () documented their presence, several authors have confirmed that super‐terminal drops are not the result of instrumental effects (Thurai et al, ; Larsen et al, ).…”

Section: Introductionmentioning

confidence: 99%

On the behaviour of raindrop fall speed due to wind

Montero-Martínez

García‐García

2016

Quart J Royal Meteoro Soc

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Measurements of raindrop fall speed gathered at the ground over several years are presented and analysed in view of the horizontal wind intensity during sampling. It is confirmed that super-terminal drops occur only for diameters less than about 0.7 mm and that their percentage numbers increase during windy periods. Furthermore, through statistical and post hoc data analyses, it is shown that wind affects the fall speed of individual raindrops. A remarkable feature is the detection of sub-terminal raindrops, i.e. those having slower fall speeds than their calculated terminal velocities, smaller than 2 mm. Evidence that wind affects raindrop behaviour includes observations showing that under windy conditions: (i) super-terminal drops exhibit larger fall speed departures from the expected terminal speeds than in calm wind periods; and (ii) the percentage number of sub-terminal drops with diameters between 1 and 2 mm increases. These two findings imply a general broadening of the corresponding velocity distributions. Potential explanations for the occurrence of sub-terminal drops are given based on turbulence (small raindrops respond faster to changes in air conditions), drop oscillations (which produce larger transit times through the instrument sampling volume) and the enhancement of transverse drifts and trajectory deviations with respect to the vertical. However, other possibilities should be also addressed for drops with the largest fall speed anomalies (greater than two times the instrument uncertainty) as well as their implications for microphysical processes.

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“…The other disdrometers in the array were used to confirm that two‐dimensional video disdrometer was operating properly during each of the events studied here. A thorough description of the instrument array and site environment is presented in Larsen et al [], Jameson et al [, ], Larsen and Teves [], and Larsen et al [], but a detailed site analysis is beyond the scope of this manuscript.…”

Section: Datamentioning

confidence: 99%

Sampling variability effects in drop‐resolving disdrometer observations

Larsen

O’Dell

2016

JGR Atmospheres

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Rain events are often studied with raindrop disdrometers—instruments designed to measure and record individual drop properties. Data from these instruments reveal that the instantaneous raindrop arrival rate is highly variable, with drop counts in consecutive time intervals occasionally changing by an order of magnitude or more. These drop count fluctuations result from some unknown combination of real physical changes in the underlying rainfall in conjunction with statistical fluctuations due to instrumental imperfections, limited sampling area, and the correlated nature of drop arrivals. Here empirical observations are used to drive a simulation that explores the degree to which observed variability in bulk rainfall observations might be produced by statistical fluctuations. It is shown that meaningful conclusions about true underlying rain properties require more drops than previously thought. Revisions to the interpretation of disdrometer data are discussed.

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Further evidence for superterminal raindrops

Cited by 36 publications

References 20 publications

Investigation of Raindrops Fall Velocity During Different Monsoon Seasons Over the Western Ghats, India

Investigation of Raindrops Fall Velocity During Different Monsoon Seasons Over the Western Ghats, India

On the behaviour of raindrop fall speed due to wind

Sampling variability effects in drop‐resolving disdrometer observations

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