Measurement of Flare Size Distribution and Simulation of Seeding Effect with a Spectral Bin Parcel Model

Konwar, Mahen; Malap, Neelam; Hazra, Anupam; Axisa, Duncan; Prabha, Thara V.; Хаин, А.

doi:10.1007/s00024-023-03293-z

Cited by 3 publications

(3 citation statements)

References 50 publications

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“…• With more CCN near the cloud base, there is a delay in the initiation of rain (Prabha et al 2011;Konwar et al 2012). • The high liquid water content in less diluted cores leads to drizzle near cloud tops (Khain et al 2013;Patade et al 2019).…”

Section: Historical Perspectivementioning

confidence: 99%

“…onsoon rains are the lifeline of millions of people, during which seasonal southwesterly winds bring moisture over the Indian subcontinent. The moisture-laden monsoon winds coming from the Arabian Sea are orographically lifted over the Western Ghats (WG) in the Indian peninsular region (Sarker 1966;Houze 2012) and forced to condense and precipitate on the windward side of the WG (Konwar et al 2014). The annual rainfall over the leeward side is only 10% (600 mm) of the total rainfall received on the windward slopes of the WG.…”

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confidence: 99%

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CAIPEEX: Indian Cloud Seeding Scientific Experiment

Prabhakaran,

Murugavel,

Konwar

et al. 2023

Bulletin of the American Meteorological Society

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The demand for effective methods to augment precipitation over arid regions of India has been increasing over the past several decades as the changing climate brings warmer average temperatures. In the fourth phase of the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX-IV), a scientific investigation was conducted over a rain shadow region of the Western Ghats mountains in India. The primary objective was to investigate the efficacy of hygroscopic seeding in convective clouds and to develop a cloud seeding protocol. CAIPEEX IV followed the World Meteorological Organization (WMO) recommendations (WMO, 2018a) in the peer-reviewed report (WMO, 2018b) with physical, statistical, and numerical investigations. The initial results of the campaign in the monsoon period of 2018 and 2019 with two instrumented aircraft, a ground-based dual-polarization C-band radar, a network of rain gauges, radiosondes, and surface aerosol measurements are reported here. The hygroscopic seeding material was detected in cloud droplets and key cloud microphysical processes in the seeding hypothesis were tracked. The formidable challenges of assessing seeding impacts in convective clouds and the results from 150 seed and 122 no-seed samples of randomized experiments are illustrated. Over 5000 cloud passes from the airborne campaign provided details about the convective cloud properties as the key indicators for a seeding strategy and the evaluation protocol. The experimental results suggest that cloud seeding can be approached scientifically to reduce uncertainty. The results from this study should interest the scientific community and policymakers concerned with climate change’s impact on precipitation and how to mitigate rainfall deficiencies.

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Section: Historical Perspectivementioning

confidence: 99%

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confidence: 99%

CAIPEEX: Indian Cloud Seeding Scientific Experiment

Prabhakaran,

Murugavel,

Konwar

et al. 2023

Bulletin of the American Meteorological Society

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“…Dispersal of giant cloud condensation nuclei (CCN), hygroscopic particles with diameter, D, between 1-10 μm, in the updraft region of a cloud base adds larger drops to the tail of the natural cloud droplet size distribution (DSD), known as the 'tail effect.' This effect further accelerates the formation of raindrops through CC (Segal et al, 2004;Segal, et al, 2007;Kuba and Murakami, 2010; Konwar et al, 2023). With the initial activation and growth of these larger CCNs, the supersaturation over water droplets (SS w ) decreases above the cloud base.…”

Section: Introductionmentioning

confidence: 99%

Identifying the seeding signature in cloud particles from hydrometeor residuals

Konwar,

Werden,

Fortner

et al. 2023

Preprint

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Abstract. Cloud seeding experiments for modifying cloud and precipitation have been underway for nearly a century; yet practically all the attempts to link precipitation enhancement or suppression to the presence of seeding materials remained inclusive. In 2019, the Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) implemented a novel method to detect seeded clouds during its operations in Solapur, India. In this experiment, residuals of cloud hydrometeors in seeded and non-seeded clouds were analyzed with an airborne mini-Aerosol Mass Spectrometer (mAMS). The mAMS instrument was utilized in conjunction with a counterflow virtual impactor (CVI) inlet, which had a cutoff diameter size of approximately 7 µm. Upon traversing the CVI inlet, the cloud droplets underwent a drying process, enabling the subsequent examination of cloud residuals through the mAMS instrument to identify potential seeding signatures. The Chlorine (Cl) associated with hygroscopic materials, i.e., Calcium Chloride (CaCl2) and potassium (K), which serve as the oxidizing agents in the flares, is found in relatively higher concentrations in the seeded clouds compared to the non-seeded clouds. After seeding, small-size cloud droplet concentrations increased in the convective and stratus clouds. In the convective clouds, flare particles propagated to higher cloud depths (≈ 2.25 km, vertical distance from cloud base) and modulate cloud microphysical properties to initiate warm rain. This new technique help to trace activated flare particles in seeded clouds and identify the post-seeding chain of cloud microphysical processes.

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Identifying the seeding signature in cloud particles from hydrometeor residuals

Konwar,

Werden,

Fortner

et al. 2024

Atmos. Meas. Tech.

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Abstract. Cloud seeding experiments for modifying clouds and precipitation have been underway for nearly a century; yet practically all the attempts to link precipitation enhancement or suppression to the presence of seeding materials within clouds remain elusive. In 2019, the Cloud–Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) investigated residuals of cloud hydrometeors in seeded and non-seeded clouds with an airborne mini aerosol mass spectrometer (mAMS). The mAMS was utilized in conjunction with a counterflow virtual impactor (CVI) inlet with a cutoff diameter size of approximately 7 µm. The evaporated cloud droplets from the CVI inlet as cloud residuals were evaluated through the mAMS. The chlorine (Cl) associated with hygroscopic materials, i.e. calcium chloride (CaCl2) and potassium (K), which serve as the oxidizing agents in the flares, is found in relatively higher concentrations in the seeded clouds compared to the non-seeded clouds. In convective clouds, Cl and K as cloud residuals were found even at a vertical distance of 2.25 km from the cloud base. Major findings from the seeding impact are an increase in the number concentration of small (< 20 µm) droplets and an indication of raindrop formation at 2.25 km above the cloud base. It is demonstrated that the seed particle signature can be traced inside clouds along with the microphysical impacts.

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Measurement of Flare Size Distribution and Simulation of Seeding Effect with a Spectral Bin Parcel Model

Cited by 3 publications

References 50 publications

CAIPEEX: Indian Cloud Seeding Scientific Experiment

CAIPEEX: Indian Cloud Seeding Scientific Experiment

Identifying the seeding signature in cloud particles from hydrometeor residuals

Identifying the seeding signature in cloud particles from hydrometeor residuals

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