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Casey D. Burleyson, Zhe Feng, Samson M. Hagos, Jerome Fast, Luiz A. T. Machado, and Scot T. Martin

Abstract

The isolation of the Amazon rain forest makes it challenging to observe precipitation forming there, but it also creates a natural laboratory to study anthropogenic impacts on clouds and precipitation in an otherwise pristine environment. Observations were collected upwind and downwind of Manaus, Brazil, during the “Observations and Modeling of the Green Ocean Amazon 2014–2015” experiment (GoAmazon2014/5). Besides aircraft, most of the observations were point measurements made in a spatially heterogeneous environment, making it hard to distinguish anthropogenic signals from naturally occurring spatial variability. In this study, 15 years of satellite data are used to examine the spatial and temporal variability of deep convection around the GoAmazon2014/5 sites using cold cloud tops (infrared brightness temperatures colder than 240 K) as a proxy for deep convection. During the rainy season, convection associated with the inland propagation of the previous day’s sea-breeze front is in phase with the diurnal cycle of deep convection near Manaus but is out of phase a few hundred kilometers to the east and west. Convergence between the river breezes and the easterly trade winds generates afternoon convection up to 10% more frequently (on average ~4 mm day−1 more intense rainfall) at the GoAmazon2014/5 sites east of the Negro River (T0e, T0t/k, and T1) relative to the T3 site, which was located west of the river. In general, the annual and diurnal cycles of precipitation during 2014 were similar to climatological values that are based on satellite data from 2000 to 2013.

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Manfred Wendisch, Ulrich Pöschl, Meinrat O. Andreae, Luiz A. T. Machado, Rachel Albrecht, Hans Schlager, Daniel Rosenfeld, Scot T. Martin, Ahmed Abdelmonem, Armin Afchine, Alessandro C. Araùjo, Paulo Artaxo, Heinfried Aufmhoff, Henrique M. J. Barbosa, Stephan Borrmann, Ramon Braga, Bernhard Buchholz, Micael Amore Cecchini, Anja Costa, Joachim Curtius, Maximilian Dollner, Marcel Dorf, Volker Dreiling, Volker Ebert, André Ehrlich, Florian Ewald, Gilberto Fisch, Andreas Fix, Fabian Frank, Daniel Fütterer, Christopher Heckl, Fabian Heidelberg, Tilman Hüneke, Evelyn Jäkel, Emma Järvinen, Tina Jurkat, Sandra Kanter, Udo Kästner, Mareike Kenntner, Jürgen Kesselmeier, Thomas Klimach, Matthias Knecht, Rebecca Kohl, Tobias Kölling, Martina Krämer, Mira Krüger, Trismono Candra Krisna, Jost V. Lavric, Karla Longo, Christoph Mahnke, Antonio O. Manzi, Bernhard Mayer, Stephan Mertes, Andreas Minikin, Sergej Molleker, Steffen Münch, Björn Nillius, Klaus Pfeilsticker, Christopher Pöhlker, Anke Roiger, Diana Rose, Dagmar Rosenow, Daniel Sauer, Martin Schnaiter, Johannes Schneider, Christiane Schulz, Rodrigo A. F. de Souza, Antonio Spanu, Paul Stock, Daniel Vila, Christiane Voigt, Adrian Walser, David Walter, Ralf Weigel, Bernadett Weinzierl, Frank Werner, Marcia A. Yamasoe, Helmut Ziereis, Tobias Zinner, and Martin Zöger

Abstract

Between 1 September and 4 October 2014, a combined airborne and ground-based measurement campaign was conducted to study tropical deep convective clouds over the Brazilian Amazon rain forest. The new German research aircraft, High Altitude and Long Range Research Aircraft (HALO), a modified Gulfstream G550, and extensive ground-based instrumentation were deployed in and near Manaus (State of Amazonas). The campaign was part of the German–Brazilian Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitation Measurement) (ACRIDICON– CHUVA) venture to quantify aerosol–cloud–precipitation interactions and their thermodynamic, dynamic, and radiative effects by in situ and remote sensing measurements over Amazonia. The ACRIDICON–CHUVA field observations were carried out in cooperation with the second intensive operating period of Green Ocean Amazon 2014/15 (GoAmazon2014/5). In this paper we focus on the airborne data measured on HALO, which was equipped with about 30 in situ and remote sensing instruments for meteorological, trace gas, aerosol, cloud, precipitation, and spectral solar radiation measurements. Fourteen research flights with a total duration of 96 flight hours were performed. Five scientific topics were pursued: 1) cloud vertical evolution and life cycle (cloud profiling), 2) cloud processing of aerosol particles and trace gases (inflow and outflow), 3) satellite and radar validation (cloud products), 4) vertical transport and mixing (tracer experiment), and 5) cloud formation over forested/deforested areas. Data were collected in near-pristine atmospheric conditions and in environments polluted by biomass burning and urban emissions. The paper presents a general introduction of the ACRIDICON– CHUVA campaign (motivation and addressed research topics) and of HALO with its extensive instrument package, as well as a presentation of a few selected measurement results acquired during the flights for some selected scientific topics.

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