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1. Empirical formulation for multiple groups of primary biological ice nucleating particles from field observations over Amazonia

Author

Vaughan T. J. Phillips, Cindy E. Morris, Paul J. DeMott, Susannah M. Burrows, Sachin Patade, Bettina Weber, Fábio Luiz Teixeira Gonçalves, Christopher Pöhlker, Pierre Amato, Jann Schrod, Heinz Bingemer, Carl Alwmark, Daniel A. Knopf, Paulo Artaxo, Department of Physical Geography and Ecosystem Science [Lund], Lund University [Lund], Institut de Chimie de Clermont-Ferrand (ICCF), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Institute for Atmospheric and Environmental Sciences [Frankfurt/Main] (IAU), Goethe-University Frankfurt am Main, Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory (PNNL), Department of Atmospheric Science [Fort Collins], Colorado State University [Fort Collins] (CSU), Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo = University of São Paulo (USP)-Universidade de São Paulo = University of São Paulo (USP), Institute for Terrestrial and Planetary Atmospheres [Stony Brook] (ITPA), School of Marine and Atmospheric Sciences [Stony Brook] (SoMAS), Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY)-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Unité de Pathologie Végétale (PV), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Geology [Lund], Universidade de São Paulo = University of São Paulo (USP), Multiphase Chemistry Department [Mainz], Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Karl-Franzens-Universität Graz, Swedish Research Council (‘Vetenskapsradet’), German Federal Ministry of Education and Research (BMBF contracts 01LB1001A, 01LK1602A and 01LK1602B), U.S. National Science Foundation Award #1660486, NASA award NNX17AJ12G, Deutsche Forschungsgemeinschaft (DFG) under the Research Unit FOR 1525 (INUIT), Max Planck Society, Brazilian Ministério da Ciência, Tecnologia e Inovação (MCTI/FINEP contract 01.11.01248.00), Amazon State University (UEA), FAPEAM, LBA/INPA, SDS/CEUC/RDS-Uatumã, U.S. Department of Energy, Office of Science (BER), Atmospheric System Research (DE-SC0018929, DE-SC0016370, DE-SC0020006), European Project: 603445,EC:FP7:ENV,FP7-ENV-2013-two-stage,BACCHUS(2013), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), Universidade de São Paulo (USP), Karl-Franzens-Universität [Graz, Autriche], and University of Graz

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, Detritus, 010504 meteorology & atmospheric sciences, Atmospheric models, biology, Amazon rainforest, medicine.disease_cause, Atmospheric sciences, biology.organism_classification, 01 natural sciences, Soot, 010305 fluids & plasmas, Aerosol, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Algae, FLORESTAS TROPICAIS, Pollen, 0103 physical sciences, medicine, Ice nucleus, Environmental science, [MATH]Mathematics [math], 0105 earth and related environmental sciences, Amazonie
Abstract

To resolve the various types of biological ice nuclei (IN) with atmospheric models, an extension of the empirical parameterization (EP) (Phillips et al. 2008; 2013) is proposed to predict the active IN from multiple groups of primary biological aerosol particles (PBAPs). Our approach is to utilize coincident observations of PBAP sizes, concentrations, biological composition, and ice-nucleating ability. The parameterization organizes the PBAPs into five basic groups: fungal spores, bacteria, pollen, viral particles, plant/animal detritus, algae, and their respective fragments. This new biological component of the EP was constructed by fitting predicted concentrations of PBAP IN to those observed at the Amazon Tall Tower Observatory (ATTO) site located in the central Amazon. The fitting parameters for pollen and viral particles, plant/animal detritus, which are much less active as IN than fungal and bacterial groups, are constrained based on their ice nucleation activity from the literature. The parameterization has empirically derived dependencies on the surface area of each group (except algae), and the effects of variability in their mean sizes and number concentrations are represented via their influences on the surface area. The concentration of active algal IN is estimated from literature-based measurements.Predictions of this new biological component of the EP are consistent with previous laboratory and field observations not used in its construction. The EP scheme was implemented in a 0D parcel model. It confirms that biological IN account for most of the total IN activation at temperatures warmer than −20°C and at colder temperatures dust and soot become increasingly more important to ice nucleation.

Published
2021
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2. The Forest Effects on the Isotopic Composition of Rainfall in the Northwestern Amazon Basin

Author

Renato Campello Cordeiro, Jhan Carlo Espinoza, Angela Ampuero, Valdir F. Novello, Nicola M. Stríkis, Francisco W. Cruz, Hubert B. Vonhof, James Apaéstegui, Victor C. Mayta, Mathias Vuille, Abdelfettah Sifeddine, V. Azevedo, Veridiana Teixeira de Souza Martins, Universidade Federal Fluminense [Rio de Janeiro] (UFF), Instituto Geofísico del Perú (IGP), Department of Atmospheric and Environmental Sciences [Albany] (DAES), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), Instituto de Geociências [São Paulo], Universidade de São Paulo = University of São Paulo (USP), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo = University of São Paulo (USP)-Universidade de São Paulo = University of São Paulo (USP), Variabilité à long terme du climat de l'océan (VALCO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), ANR-18-MPGA-0008,AMANECER,Connexion Amazone - Andes(2018), Universidade de São Paulo (USP), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)

Subjects
Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Amazon rainforest, Speleothem, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Isotopic composition, DEUTÉRIO, Geophysics, 13. Climate action, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Environmental science, Precipitation, Physical geography, Holocene, 0105 earth and related environmental sciences, Amazon basin
Abstract

International audience; In the Amazon basin, intense precipitation recycling across the forest significantly modifies the isotopic composition of rainfall (δ18O, δD). In the tropical hydrologic cycle, such an effect can be identified through deuterium excess (dxs), yet it remains unclear what environmental factors control dxs, increasing the uncertainty of dxs‐based paleoclimate reconstructions. Here we present a 4‐year record of the isotopic composition of rainfall, monitored in the northwestern Amazon basin. We analyze the isotopic variations as a function of the air mass history, based on atmospheric back trajectory analyses, satellite observations of precipitation upstream, leaf area index, and simulated moisture recycling along the transport pathway. We show that the precipitation recycling in the forest exerts a significant control on the isotopic composition of precipitation in the northwestern Amazon basin, especially on dxs during the dry season (r = 0.71). Applying these observations to existing speleothem and pollen paleorecords, we conclude that winter precipitation increased after the mid‐Holocene, as the expansion of the forest allowed for more moisture recycling. Therefore, forest effects should be considered when interpreting paleorecords of past precipitation changes.

Published
2020
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3. Simulation of the Unexpected Photosynthetic Seasonality in Amazonian Evergreen Forests by Using an Improved Diffuse Fraction-Based Light Use Efficiency Model

Author

Alexandru Rap, Natalia Restrepo Coupe, Hao Yan, Nathalie Butt, Shaoqiang Wang, Herman H. Shugart, Humberto Ribeiro da Rocha, Damien Bonal, China Meteorological Administration (CMA), Department of Environmental Sciences [Charlottesville], University of Virginia [Charlottesville], Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS), Departamento de Ciencias Atmosfericas, University of São Paulo (USP), School of Earth and Environment [Leeds] (SEE), University of Leeds, Ecologie et Ecophysiologie Forestières [devient SILVA en 2018] (EEF), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), School of Biological Sciences [Brisbane], University of Queensland [Brisbane], Department of Ecology and Evolutionary Biology [University of Arizona], University of Arizona, Plant Functional Biology and Climate Change Cluster (C3), University of Technology Sydney (UTS), National Natural Science Foundation of China 41571327,41171284, NASA 10-CARBON10-0068 09-IDS09-116, and Yan, Hao

Subjects
0106 biological sciences, GROSS PRIMARY PRODUCTIVITY, NET ECOSYSTEM EXCHANGE, RAIN-FOREST, LEAF-AREA, DRY SEASON, CARBON, RADIATION, WATER, FLUXES, VEGETATION, Atmospheric Science, 010504 meteorology & atmospheric sciences, Amazonian, [SDV]Life Sciences [q-bio], simulation models, forêt tropicale, Atmospheric sciences, 01 natural sciences, Evapotranspiration, FLORESTAS, Water Science and Technology, Ecology, Foundation (engineering), Forestry, rayonnement diffus, feuille persistante, tropical forest, forêt amazonienne, Soil Science, Fraction (chemistry), Aquatic Science, scattered radiation, Photosynthesis, modèle de simulation, medicine, photosynthèse, 0105 earth and related environmental sciences, photosynthesis, climat, Paleontology, Primary production, 15. Life on land, Seasonality, Evergreen, rayonnement incident, medicine.disease, 13. Climate action, saisonnalité, Environmental science, 010606 plant biology & botany
Abstract

Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain.[br/] Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R-2=0.45-0.69) with a root-mean-square error (RMSE) of 0.67-1.25gCm(-2)d(-1) and a Bias of -0.03-1.04gCm(-2)d(-1) for four evergreen forest sites.[br/] We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. In the transition from dry season to rainy season, incident total radiation (Q) decreased while LUE and diffuse fraction increased, which produced the large seasonal increase (similar to 34%) in GPP of evergreen forests.[br/] We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R-2=0.40-0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in tropical Amazon. Plain Language Summary Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R2= 0.45-0.69) for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light-use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R2= 0.40 similar to 0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in Amazon.

Published
2017
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4. Measured and modeled interactive effects of potassium deficiency and water deficit on gross primary productivity and light use efficiency in [i]Eucalyptus grandis[/i] plantations

Author

Guerric Le Maire, Christophe Jourdan, Jean-Paul Laclau, Yann Nouvellon, José Leonardo de Moraes Gonçalves, Patricia Battie-Laclau, Jean-Pierre Bouillet, Mathias Christina, Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA), Centro de Energia Nuclear na Agricultura (CENA ), University of São Paulo (USP), Departamento de Ciencias Atmosfericas, ESALQ - Escola Superior de Agricultura 'Luiz de Queiroz', Forest Science Departmen, Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), Institut National de la Recherche Agronomique (INRA)-Institut de Recherche pour le Développement (IRD)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Universidade Estadual Paulista Júlio de Mesquita Filho [São José do Rio Preto] (UNESP)

Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences, SECA, Rain, F62 - Physiologie végétale - Croissance et développement, Déficit hydrique du sol, eucalypt, Biomasse, Biomass, Photosynthèse, Radiation use efficiency, General Environmental Science, 2. Zero hunger, Global and Planetary Change, Eucalyptus, Ecology, U10 - Informatique, mathématiques et statistiques, Forestry, Throughfall, Plantation forestière, Droughts, Assimilation, Échantillonnage, nutrient shortage, Brazil, Modèle mathématique, Eucalyptus grandis, P40 - Météorologie et climatologie, Climate Change, Photosynthesis, Models, Biological, carbon assimilation, Sécheresse, Botany, Environmental Chemistry, Leaf area index, Engrais, Croissance, Changement climatique, Tropical agriculture, Tropics, Sowing, modeling, 15. Life on land, K10 - Production forestière, tree traits, Agronomy, fertilization, Potassium, Environmental science, Potassium deficiency, Cycle du carbone
Abstract

Global climate change is expected to increase the length of drought periods in many tropical regions. Although large amounts of potassium (K) are applied in tropical crops and planted forests, little is known about the interaction between K nutrition and water deficit on the physiological mechanisms governing plant growth. A process-based model (MAESPA) parameterized in a split-plot experiment in Brazil was used to gain insight into the combined effects of K deficiency and water deficit on absorbed radiation (aPAR), gross primary productivity (GPP), and light-use efficiency for carbon assimilation and stem biomass production (LUEC and LUEs ) in Eucalyptus grandis plantations. The main-plot factor was the water supply (undisturbed rainfall vs. 37% of throughfall excluded) and the subplot factor was the K supply (with or without 0.45 mol K m(-2 ) K addition). Mean GPP was 28% lower without K addition over the first 3 years after planting whether throughfall was partly excluded or not. K deficiency reduced aPAR by 20% and LUEC by 10% over the whole period of growth. With K addition, throughfall exclusion decreased GPP by 25%, resulting from a 21% decrease in LUEC at the end of the study period. The effect of the combination of K deficiency and water deficit was less severe than the sum of the effects of K deficiency and water deficit individually, leading to a reduction in stem biomass production, gross primary productivity and LUE similar to K deficiency on its own. The modeling approach showed that K nutrition and water deficit influenced absorbed radiation essentially through changes in leaf area index and tree height. The changes in gross primary productivity and light-use efficiency were, however, driven by a more complex set of tree parameters, especially those controlling water uptake by roots and leaf photosynthetic capacities.

Published
2015
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5. The surface radiation budget over South America in a set of regional climate models from the CLARIS-LPB project

Author

Silvina Alicia Solman, Daniela Jacob, Natalia Liz Pessacg, José A. Marengo, Enrique Sánchez, Armelle Reca Remedio, Laurent Li, Patrick Samuelsson, Rosmeri Porfírio da Rocha, Caroline Mourão, Centro Nacional Patagónico (CENPAT), Centro de Investigaciones del Mar y la Atmósfera (CIMA), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Rossby Centre, SMHI, Norrköping, 601 76, Sweden, Swedish Meteorological and Hydrological Institute (SMHI), Facultad de Ciencias Ambientales y Bioquímica [Toledo], Universidad de Castilla-La Mancha (UCLM), Centro de Ciencia do Sistema Terrestre-Instituto Nacional de Pesquisas Espaciais (CCST INPE), Rodovia Dutra km, 40, Cachoeira Paulista, São Paulo, 12630-000, Brazil, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), Climate Service Center, Hamburg, 20095, Germany, Universidad de Castilla-La Mancha = University of Castilla-La Mancha (UCLM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Universidade de São Paulo = University of São Paulo (USP)-Universidade de São Paulo = University of São Paulo (USP)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, REGIONAL CLIMATE MODELS, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], AMÉRICA DO SUL, 0207 environmental engineering, 02 engineering and technology, 01 natural sciences, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Set (abstract data type), Radiation budget, SOUTH AMERICA, 020701 environmental engineering, Physics::Atmospheric and Oceanic Physics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, HEAT FLUXES, Environmental science, Climate model, Meteorología y Ciencias Atmosféricas, SURFACE RADIATION BUDGET, CIENCIAS NATURALES Y EXACTAS
Abstract

The performance of seven regional climate models in simulating the radiation and heat fluxes at the surface over South America (SA) is evaluated. Sources of uncertainty and errors are identified. All simulations have been performed in the context of the CLARIS-LPB Project for the period 1990?2008 and are compared with the GEWEX-SRB, CRU, and GLDAS2 dataset and NCEPNOAA reanalysis. Results showed that most of the models overestimate the net surface short-wave radiation over tropical SA and La Plata Basin and underestimate it over oceanic regions. Errors in the short-wave radiation are mainly associated with uncertainties in the representation of surface albedo and cloud fraction. For the net surface long-wave radiation, model biases are diverse. However, the ensemble mean showed a good agreement with the GEWEX-SRB dataset due to the compensation of individual model biases. Errors in the net surface long-wave radiation can be explained, in a large proportion, by errors in cloud fraction. For some particular models, errors in temperature also contribute to errors in the net long-wave radiation. Analysis of the annual cycle of each component of the energy budget indicates that the RCMs reproduce generally well the main characteristics of the short- and long-wave radiations in terms of timing and amplitude. However, a large spread among models over tropical SA is apparent. The annual cycle of the sensible heat flux showed a strong overestimation in comparison with the reanalysis and GLDAS2 dataset. For the latent heat flux, strong differences between the reanalysis and GLDAS2 are calculated particularly over tropical SA. Fil: Pessacg, Natalia Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: Solman, Silvina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina Fil: Samuelsson, Patrick. Rossby Centre; Suecia Fil: Sanchez, Enrique. Universidad de Castilla-la Mancha; España Fil: Marengo, Jose. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Li, Laurent. Institut Pierre-Simon Laplace. Laboratoire de Météorologie Dynamique; Francia Fil: Remedio, Armelle Reca C.. Max Planck Institute for Meteorology; Alemania Fil: Da Rocha, Rosmeri P.. Universidade de São Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas. Departamento de Ciências Atmosféricas; Argentina Fil: Mourão, Caroline. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Jacob, Daniela. Climate Service Center; Alemania

Published
2014
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6. Simulation of rainfall anomalies leading to the 2005 drought in Amazonia using the CLARIS LPB regional climate models

Author

Daniela Jacob, Patrick Samuelsson, R. P. da Rocha, Armelle Reca Remedio, Natalia Liz Pessacg, Caroline Mourão, Silvina Alicia Solman, José A. Marengo, Sin Chan Chou, Iracema F. A. Cavalcanti, Enrique Sánchez, Laurent Li, Andrea F. Carril, Centro de Ciência do Sistema Terrestre, Instituto Nacional de Pesquisas Espaciais (CCST INPE), Rodovia Dutra km, 40, 12630-000 Cachoeira Paulista, São Paulo, Brazil, Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE), Centro de Investigaciones del Mar y la Atmósfera (CIMA), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Departamento de Ciencias de la Atmosfera y los Oceanos (DCAO), Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos [Buenos Aires] (IFAECI), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Centre National de la Recherche Scientifique (CNRS), Facultad de Ciencias Ambientales y Bioquímica [Toledo], Universidad de Castilla-La Mancha (UCLM), Rossby Centre, SMHI, Norrköping, 601 76, Sweden, Swedish Meteorological and Hydrological Institute (SMHI), Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centro Nacional Patagónico (CENPAT), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Climate Services Center (CSC), Hamburg, Germany, Universidad de Castilla-La Mancha = University of Castilla-La Mancha (UCLM), Universidade de São Paulo = University of São Paulo (USP)-Universidade de São Paulo = University of São Paulo (USP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, AMAZONIA, 0207 environmental engineering, 02 engineering and technology, Forcing (mathematics), Structural basin, Tropical Atlantic, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 01 natural sciences, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Precipitation, 020701 environmental engineering, AMAZÔNIA, DROUGHT, 0105 earth and related environmental sciences, Amazon rainforest, 15. Life on land, Annual cycle, DOWNSCALING, REGIONAL MODELS, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Environmental science, Climate model, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS, Downscaling
Abstract

The meteorological characteristics of the drought of 2005 in Amazonia, one of the most severe in the last 100 years were assessed using a suite of seven regional models obtained from the CLARIS LPB project. The models were forced with the ERA-Interim reanalyses as boundary conditions. We used a combination of rainfall and temperature observations and the low-level circulation and evaporation fields from the reanalyses to determine the climatic and meteorological characteristics of this particular drought. The models reproduce in some degree the observed annual cycle of precipitation and the geographical distribution of negative rainfall anomalies during the summer months of 2005. With respect to the evolution of rainfall during 2004–2006, some of the models were able to simulate the negative rainfall departures during early summer of 2005 (December 2004 to February 2005). The interannual variability of rainfall anomalies for both austral summer and fall over northern and southern Amazonia show a large spread among models, with some of them capable of reproducing the 2005 observed negative rainfall departures (four out of seven models in southern Amazonia during DJF). In comparison, all models simulated the observed southern Amazonia negative rainfall and positive air temperature anomalies during the El Nino-related drought in 1998. The spatial structure of the simulated rainfall and temperature anomalies in DJF and MAM 2005 shows biases that are different among models. While some models simulated the observed negative rainfall anomalies over parts of western and southern Amazonia during DJF, others simulated positive rainfall departures over central Amazonia. The simulated circulation patterns indicate a weaker northeasterly flow from the tropical North Atlantic into Amazonia, and reduced flows from southern Amazonia into the La Plata basin in DJF, which is consistent with observations. In general, we can say that in some degree the regional models are able to capture the response to the forcing from the tropical Atlantic during the drought of 2005 in Amazonia. Moreover, extreme climatic conditions in response to anomalous low-level circulation features are also well captured, since the boundary conditions come from reanalysis and the models are largely constrained by the information provided at the boundaries. The analysis of the 2005 drought suggests that when the forcing leading to extreme anomalous conditions is associated with both local and non-local mechanisms (soil moisture feedbacks and remote SST anomalies, respectively) the models are not fully capable of representing these feedbacks and hence, the associated anomalies. The reason may be a deficient reproduction of the land–atmosphere interactions. Fil: Marengo, J.. Instituto Nacional de Pesquisas Espaciais. Centro de Ciência do Sistema Terrestre; Brasil Fil: Chou, S.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Mourao, C.. Instituto Nacional de Pesquisas Espaciais. Centro de Ciência do Sistema Terrestre; Brasil Fil: Solman, Silvina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos; Argentina Fil: Sanchez, E.. Universidad de Castilla-La Mancha. Facultad Ciencias Ambientales y Bioquímica; España Fil: Samuelsson, P.. Rossby Centre, Meteorological And Hydrological Institute Of Sweden; Suecia Fil: Da Rocha, R. P.. Universidade de São Paulo. Departamento de Ciências Atmosféricas. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; Brasil Fil: Li, L.. Laboratoire de Me´te´orologie Dynamique; Francia Fil: Pessacg, Natalia Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: Remedio, A. R. C.. Max Planck Institute for Meteorology; Alemania Fil: Carril, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos; Argentina Fil: Cavalcanti, I. F.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Jacob. D.. Max Planck Institute for Meteorology; Alemania. Climate Services Center; Alemania

Published
2013
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7. Evaluation of an ensemble of regional climate model simulations over South America driven by the ERA-Interim reanalysis: Model performance and uncertainties

Author

José A. Marengo, Patrick Samuelsson, R. P. da Rocha, H. Le Treut, Sin Chan Chou, Armelle Reca Remedio, Silvina Alicia Solman, M. de Castro, Enrique Sánchez, Laurent Li, Natalia Liz Pessacg, Daniela Jacob, Hugo Berbery, Centro de Investigaciones del Mar y la Atmósfera (CIMA), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Facultad de Ciencias Ambientales y Bioquímica [Toledo], Universidad de Castilla-La Mancha (UCLM), Rossby Centre, SMHI, Norrköping, 601 76, Sweden, Swedish Meteorological and Hydrological Institute (SMHI), Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centro de Ciencia do Sistema Terrestre-Instituto Nacional de Pesquisas Espaciais (CCST INPE), Rodovia Dutra km, 40, 12630-000 Cachoeira Paulista, São Paulo, Brazil, Centro Nacional Patagónico (CENPAT), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE), Earth Science System Interdisciplinary Center [College Park] (ESSIC), College of Computer, Mathematical, and Natural Sciences [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System-University of Maryland [College Park], University of Maryland System-University of Maryland System, Climate Service Center, 20095 Hamburg, Germany, Universidad de Castilla-La Mancha = University of Castilla-La Mancha (UCLM), Universidade de São Paulo = University of São Paulo (USP)-Universidade de São Paulo = University of São Paulo (USP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Roura, Denis

Subjects
Atmospheric Science, REGIONAL CLIMATE MODELS, 010504 meteorology & atmospheric sciences, AMÉRICA DO SUL, 0207 environmental engineering, UNCERTAINTY, 02 engineering and technology, Subtropics, Structural basin, 01 natural sciences, Standard deviation, Ciencias de la Tierra y relacionadas con el Medio Ambiente, [SDU.STU.CL] Sciences of the Universe [physics]/Earth Sciences/Climatology, SOUTH AMERICA, Range (statistics), Precipitation, 020701 environmental engineering, 0105 earth and related environmental sciences, Tropics, CORDEX, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Environmental science, Climate model, Frequency distribution, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS
Abstract

The capability of a set of 7 coordinated regional climate model simulations performed in the framework of the CLARIS-LPB Project in reproducing the mean climate conditions over the South American conti- nent has been evaluated. The model simulations were forced by the ERA-Interim reanalysis dataset for the period 1990?2008 on a grid resolution of 50 km, follow- ing the CORDEX protocol. The analysis was focused on evaluating the reliability of simulating mean precipitation and surface air temperature, which are the variables most commonly used for impact studies. Both the common features and the differences among individual models have been evaluated and compared against several observational datasets. In this study the ensemble bias and the degree of agreement among individual models have been quantified. The evaluation was focused on the sea- sonal means, the area-averaged annual cycles and the frequency distributions of monthly means over target sub- regions. Results show that the Regional Climate Model ensemble reproduces adequately well these features, with biases mostly within ±2 °C and ±20 % for temperature and precipitation, respectively. However, the multi-model ensemble depicts larger biases and larger uncertainty (as defined by the standard deviation of the models) over tropical regions compared with subtropical regions. Though some systematic biases were detected particularly over the La Plata Basin region, such as underestimation of rainfall during winter months and overestimation of tem- perature during summer months, every model shares a similar behavior and, consequently, the uncertainty in simulating current climate conditions is low. Every model is able to capture the variety in the shape of the frequency distribution for both temperature and precipitation along the South American continent. Differences among indi- vidual models and observations revealed the nature of individual model biases, showing either a shift in the distribution or an overestimation or underestimation of the range of variability. Fil: Solman, Silvina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina Fil: Sanchez, E.. Universidad de Castilla-La Mancha. Facultad Ciencias Ambientales y Bioquímica; España Fil: Samuelsson, P.. Rossby Centre, Meteorological And Hydrological Institute Of Sweden; Suecia Fil: da Rocha, R. P.. Universidade de São Paulo. Departamento de Ciências Atmosféricas. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; Brasil Fil: Li, L.. Laboratoire de Météorologie Dynamique; Francia Fil: Marengo, J.. Instituto Nacional de Pesquisas Espaciais. Centro de Ciencia do Sistema Terrestre; Brasil Fil: Pessacg, Natalia Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: Remedio, A. R. C.. Max Planck Institute for Meteorology; Alemania Fil: Chou, S. C.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Berbery, Ernesto Hugo. University of Maryland. Earth System Science Interdisciplinary Center; Estados Unidos Fil: Le Treut, H.. Laboratoire de Météorologie Dynamique; Francia Fil: De Castro, M.. Universidad de Castilla-La Mancha. Facultad Ciencias Ambientales y Bioquímica; España Fil: Jacob, D.. Max Planck Institute for Meteorology; Alemania. Climate Service Center; Estados Unidos

Published
2013

8. An overview of the ultraviolet index and the skin cancer cases in Brazil

Author

Corrêa, M P, Dubuisson, P, Plana-Fattori, Artemio, Departamento de Ciencias Atmosfericas [São Paulo], Instituto de Astronomia, Geofisica e Ciencias Atmosfericas [Sao Paulo] (IAG), Universidade de São Paulo (USP)-Universidade de São Paulo (USP), UMR 8013 ELICO, Université du Littoral Côte d'Opale (ULCO), Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Ecosystèmes littoraux et côtiers (ELICO), Université de Lille, Sciences et Technologies-Université du Littoral Côte d'Opale (ULCO)-Centre National de la Recherche Scientifique (CNRS), ProdInra, Archive Ouverte, and Ecosystèmes littoraux et côtiers - UMR 8013 (ELICO)

Subjects
Skin Neoplasms, 010504 meteorology & atmospheric sciences, Ultraviolet Rays, Skin Pigmentation, rayleigh-scattering, [SDV.CAN]Life Sciences [q-bio]/Cancer, 01 natural sciences, Biochemistry, 010309 optics, Ozone, [SDU.STU.CL] Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDV.CAN] Life Sciences [q-bio]/Cancer, 0103 physical sciences, Humans, Physical and Theoretical Chemistry, 0105 earth and related environmental sciences, radiative-transfer, accuracy, uv models calculations, media, General Medicine, South America, uncertainties, 3. Good health, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Brazil, terrestrial atmosphere
Abstract

This study relates regional and seasonal UV index (UVI) variations, number of skin cancer cases and population skin-color distribution in Brazil. UVI calculations were performed using the UV Global Atmospheric Model (UVGAME), whose characteristics and validations are provided in thiis article. Health and racial data sets are based on the health and census data collected by Brazilian governmental agencies in the past. The discussion covers cultural customs and details of health and educational campaigns in Brazil. Despite lower UV levels in the South and Southeast regions, the results show a number of nonmelanoma skin cancer (NMSC) cases regions, where the white population is predominant. In general, in the southern regions about 50 new NMSC cases per 100000 inhabitants have been diagnosed each year. These rates decrease almost 40% in the Central-North regions and more than 80% in Northeast region, where miscegenation is common. In addition, the UVI evaluation is extended to other South American sites with singular characteristics, e.g. populous cities located in high altitudes or those affected by the Antarctic ozone hole in the extreme south of the continent.

Published
2003

9. Tropical forests are approaching critical temperature thresholds.

Author

Doughty CE, Keany JM, Wiebe BC, Rey-Sanchez C, Carter KR, Middleby KB, Cheesman AW, Goulden ML, da Rocha HR, Miller SD, Malhi Y, Fauset S, Gloor E, Slot M, Oliveras Menor I, Crous KY, Goldsmith GR, and Fisher JB

Subjects
Australia, Brazil, Global Warming, Puerto Rico, Sustainable Development legislation & jurisprudence, Sustainable Development trends, Plant Leaves physiology, Uncertainty, Acclimatization physiology, Extreme Heat adverse effects, Forests, Photosynthesis physiology, Trees physiology, Tropical Climate
Abstract

The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages approximately 46.7 °C (T crit ) 1 . However, it remains unclear whether leaf temperatures experienced by tropical vegetation approach this threshold or soon will under climate change. Here we found that pantropical canopy temperatures independently triangulated from individual leaf thermocouples, pyrgeometers and remote sensing (ECOSTRESS) have midday peak temperatures of approximately 34 °C during dry periods, with a long high-temperature tail that can exceed 40 °C. Leaf thermocouple data from multiple sites across the tropics suggest that even within pixels of moderate temperatures, upper canopy leaves exceed T crit 0.01% of the time. Furthermore, upper canopy leaf warming experiments (+2, 3 and 4 °C in Brazil, Puerto Rico and Australia, respectively) increased leaf temperatures non-linearly, with peak leaf temperatures exceeding T crit 1.3% of the time (11% for more than 43.5 °C, and 0.3% for more than 49.9 °C). Using an empirical model incorporating these dynamics (validated with warming experiment data), we found that tropical forests can withstand up to a 3.9 ± 0.5 °C increase in air temperatures before a potential tipping point in metabolic function, but remaining uncertainty in the plasticity and range of T crit in tropical trees and the effect of leaf death on tree death could drastically change this prediction. The 4.0 °C estimate is within the 'worst-case scenario' (representative concentration pathway (RCP) 8.5) of climate change predictions 2 for tropical forests and therefore it is still within our power to decide (for example, by not taking the RCP 6.0 or 8.5 route) the fate of these critical realms of carbon, water and biodiversity 3,4 ., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Published
2023
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10. Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements.

Author

Gatti LV, Gloor M, Miller JB, Doughty CE, Malhi Y, Domingues LG, Basso LS, Martinewski A, Correia CS, Borges VF, Freitas S, Braz R, Anderson LO, Rocha H, Grace J, Phillips OL, and Lloyd J

Subjects
Biomass, Biota, Brazil, Carbon Dioxide analysis, Carbon Monoxide analysis, Fires statistics & numerical data, Fresh Water analysis, Photosynthesis, Rain, Seasons, Trees metabolism, Tropical Climate, Atmosphere chemistry, Carbon Cycle, Droughts statistics & numerical data
Abstract

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48 ± 0.18 petagrams of carbon per year (Pg C yr(-1)) during the dry year but was carbon neutral (0.06 ± 0.1 Pg C yr(-1)) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25 ± 0.14 Pg C yr(-1), which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39 ± 0.10 Pg C yr(-1) previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

Published
2014
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