Illustration of microphysical processes in Amazonian deep convective clouds in the gamma phase space: introduction and potential applications

Author(s):Show less -

Cecchini, Micael A. ^{[1, 2]} ; Machado, Luiz A. T. ^[1] ; Wendisch, Manfred ^[3] ; Costa, Anja ^[4] ; Kraemer, Martina ^[4] ; Andreae, Meinrat O. ^{[5, 6, 7, 8]} ; Afchine, Armin ^[4] ; Albrecht, Rachel I. ^[2] ; Artaxo, Paulo ^[9] ; Borrmann, Stephan ^{[5, 6, 7, 10]} ; Fuetterer, Daniel ^[11] ; Klimach, Thomas ^{[5, 6, 7]} ; Mahnke, Christoph ^{[5, 6, 7, 10]} ; Martin, Scot T. ^{[12, 13]} ; Minikin, Andreas ^{[11, 14]} ; Molleker, Sergej ^[10] ; Pardo, Lianet H. ^[1] ; Poehlker, Christopher ^{[5, 6, 7]} ; Poehlker, Mira L. ^{[5, 6, 7]} ; Poeschl, Ulrich ^{[5, 6, 7]} ; Rosenfeld, Daniel ^[15] ; Weinzierl, Bernadett ^{[11, 16, 17]}

Affiliation:Show less -

^[1] Inst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, Cachoeira Paulista - Brazil

^[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer IAG, Dept Ciencias Atmosfer, Sao Paulo - Brazil

^[3] Univ Leipzig, LIM, Stephanstr 3, D-04103 Leipzig - Germany

^[4] Forschungszentrum Julich, Inst Energie & Klimaforsch IEK 7, Julich - Germany

^[5] Max Planck Inst Chem, Biogeochem Dept, POB 3060, D-55020 Mainz - Germany

^[6] Max Planck Inst Chem, Multiphase Chem Dept, POB 3060, D-55020 Mainz - Germany

^[7] Max Planck Inst Chem, Particle Chem Dept, POB 3060, D-55020 Mainz - Germany

^[8] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92037 - USA

^[9] Univ Sao Paulo, Inst Fis, Sao Paulo - Brazil

^[10] Johannes Gutenberg Univ Mainz, IPA, Mainz - Germany

^[11] Deutsch Zentrum Luft & Raumfahrt DLR, Inst Phys Atmosphare, D-82234 Oberpfaffenhofen, Wessling - Germany

^[12] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 - USA

^[13] Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 - USA

^[14] Deutsch Zentrum Luft & Raumfahrt DLR, Flugexperimente, Oberpfaffenhofen - Germany

^[15] Hebrew Univ Jerusalem, Inst Earth Sci, Jerusalem - Israel

^[16] Univ Vienna, Fac Phys, Boltzmanngasse 5, A-1090 Vienna - Austria

^[17] Ludwig Maximilians Univ Munchen, Meteorol Inst, Munich - Germany

• Document type: Journal article
• Source: Atmospheric Chemistry and Physics; v. 17, n. 23, p. 14727-14746, DEC 11 2017.
• Web of Science Citations: 3

Abstract

The behavior of tropical clouds remains a major open scientific question, resulting in poor representation by models. One challenge is to realistically reproduce cloud droplet size distributions (DSDs) and their evolution over time and space. Many applications, not limited to models, use the gamma function to represent DSDs. However, even though the statistical characteristics of the gamma parameters have been widely studied, there is almost no study dedicated to understanding the phase space of this function and the associated physics. This phase space can be defined by the three parameters that define the DSD intercept, shape, and curvature. Gamma phase space may provide a common framework for parameterizations and intercomparisons. Here, we introduce the phase space approach and its characteristics, focusing on warm-phase microphysical cloud properties and the transition to the mixed-phase layer. We show that trajectories in this phase space can represent DSD evolution and can be related to growth processes. Condensational and collisional growth may be interpreted as pseudo-forces that induce displacements in opposite directions within the phase space. The actually observed movements in the phase space are a result of the combination of such pseudo-forces. Additionally, aerosol effects can be evaluated given their significant impact on DSDs. The DSDs associated with liquid droplets that favor cloud glaciation can be delimited in the phase space, which can help models to adequately predict the transition to the mixed phase. We also consider possible ways to constrain the DSD in two-moment bulk microphysics schemes, in which the relative dispersion parameter of the DSD can play a significant role. Overall, the gamma phase space approach can be an invaluable tool for studying cloud microphysical evolution and can be readily applied in many scenarios that rely on gamma DSDs. (AU)

• FAPESP's process: 14/08615-7 - Precipitation formation processes: a study about microphysics, aerosols interactions and cloud life cycle using radar and airplane data
• Grantee: Micael Amore Cecchini
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 09/15235-8 - Cloud processes of the main precipitation systems in Brazil: a contribution to cloud resolving modeling and to the GPM (Global Precipitation Measurement)
• Grantee: Luiz Augusto Toledo Machado
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 14/21189-7 - Amazonian cloud microphysical properties lifecycle and interactions with aerosols
• Grantee: Micael Amore Cecchini
• Support type: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 15/14497-0 - Nowcasting of intense thunderstorms and understanding of the physical processes inside clouds: the SOS-CHUVA (Severe Weather Observation System)
• Grantee: Luiz Augusto Toledo Machado
• Support type: Research Program on Global Climate Change - Thematic Grants