Linear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CHUVA campaign - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2021

Linear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CHUVA campaign

Ramon Campos Braga
  • Fonction : Auteur
Daniel Rosenfeld
  • Fonction : Auteur
Ovid Krüger
  • Fonction : Auteur
Barbara Ervens
Bruna Holanda
  • Fonction : Auteur
Manfred Wendisch
Trismono Krisna
  • Fonction : Auteur
Ulrich Pöschl
Meinrat Andreae
Christiane Voigt
Mira Pöhlker
  • Fonction : Auteur

Résumé

Abstract. Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth's hydrological cycle. We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The data for this study were collected during the ACRIDICON–CHUVA campaign on the HALO research aircraft in clean and polluted conditions over the Amazon Basin and over the western tropical Atlantic in September 2014. Our results indicate a threshold of re∼13 µm for warm rain initiation in convective clouds, which is in agreement with previous studies. In clouds over the Atlantic Ocean, warm rain starts at smaller re, likely linked to the enhancement of coalescence of drops formed on giant cloud condensation nuclei. In cloud passes where precipitation starts as ice hydrometeors, the threshold of re is also shifted to values smaller than 13 µm when coalescence processes are suppressed and precipitating particles are formed by accretion. We found a statistically significant linear relationship between PWC and re for measurements at cloud tops, with a correlation coefficient of ∼0.94. The tight relationship between re and PWC was established only when particles with sizes large enough to precipitate (drizzle and raindrops) are included in calculating re. Our results emphasize for the first time that re is a key parameter to determine both initiation and amount of precipitation at the top of convective clouds.

Domaines

Chimie

Dates et versions

hal-03483606 , version 1 (16-12-2021)

Identifiants

Citer

Ramon Campos Braga, Daniel Rosenfeld, Ovid Krüger, Barbara Ervens, Bruna Holanda, et al.. Linear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CHUVA campaign. Atmospheric Chemistry and Physics, 2021, 21 (18), pp.14079-14088. ⟨10.5194/acp-21-14079-2021⟩. ⟨hal-03483606⟩
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