Biosphere-Atmosphere Experiment In Amazonia Research Articles

DOWNWARD LONGWAVE RADIATION ESTIMATES FOR CLEAR AND ALL-SKY CONDITIONS IN CENTRAL AMAZONIA

The downward longwave radiation (L↓), really is difficult of the net radiation the measured values component. Therefore, different parameterizations have been proposed to estimate it. Thus, in this study we evaluated the performance of various parameterizations for the L↓ flows estimated and their interaction with other variables measured as well as the air temperature and water vapour pressure interactions with L↓. In this study evaluates the performance of the downward longwave radiation parameters for clear and cloudy sky days applied in Central Amazonia region. The datasets used in this study was measured from micrometeorological tower controlled by Large Scale Biosphere Atmosphere experiment in Amazonia (LBA) from Manaus city, Amazonas. It was also found that precipitation and water vapour pressure exert enough on L↓ flows influence, especially in the wet season. The models for clear-sky conditions proposed, using their original coefficients trend to underestimate the L↓ flows measured. Best results for clear-sky were obtained with Idso & Jackson (1969), Brutsaert (1975) and Prata (1996) .

Energy balance closure in the Southwest Amazon forest site—a statistical approach

Energy balance closure is the main indicator of the quality of energy flux measurements obtained by the eddy covariance technique. Many researchers use a simple linear regression model between energy balance components to evaluate closure. However, these studies typically fail to verify the appropriateness of the statistical assumptions of regression analysis, which can lead to erroneous conclusions if the model is not satisfactory. Thus, the aim of this study was to calibrate and validate simple and robust with bootstrap and cross-validation linear regression models to verify the efficiency of energy balance closure in the Amazon ecosystem. Measurements of net radiation and latent, sensible, and ground heat fluxes were made from January to December 2008 in a tropical rain forest area in South West Amazonia in an experimental site belonging to the network of flux towers of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). The results demonstrated that simple linear regression models are not appropriate for analyzing energy balance closure. However, robust linear regression models with bootstrap and cross-validation improved the fit to the data. Despite the better fit, there was an increase in energy balance closure residuals suggesting that the eddy covariance technique is underestimating the values of energy fluxes in Amazon forest areas more than what were reported in previous researches.

Evaluation of MODIS-based estimates of water-use efficiency in Amazonia

ABSTRACTThis study aimed to assess the spatial-temporal patterns of water-use efficiency (WUE) obtained through MODIS gross primary productivity (GPP) and evapotranspiration (ET) products (MOD17 for GPP and MOD16 for ET) in the Upper Tapajos and Curua-Una River basins, located in the oriental flank of the Amazon region, and to validate the results with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. The spatial variation of WUE was primarily related to the larger presence of forested areas in the Upper Tapajos River basin (western part) compared with the Curua-Una River basin (eastern part), which is situated within the so-called arc of deforestation. Temporally, WUE showed a pronounced seasonal pattern, varying with the dry and wet seasons in the region. A decrease of ~3% in WUE was observed during the dry season, which was related to the low water availability and increased vapour pressure deficit during the dry period, which induces stomatal closure, leading to a decline in the photosynthetic rate. Comparison between the WUE estimates obtained by MODIS data and observations from the LBA towers showed an average error of 17%, varying between ~12% and ~28% for the different sites. MODIS WUE depends on the accuracy of both GPP and ET estimation. In this sense, we highlight that improvements in both MODIS GPP and ET products are necessary and should focus on reducing the uncertainties related to the biophysical vegetation parameters and meteorological data that serve as input information in the algorithms.

Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin

Abstract. Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET) and evaporation (λEE) flux components of the terrestrial latent heat flux (λE), which has important implications for global climate change and water resource management. By physical integration of radiometric surface temperature (TR) into an integrated framework of the Penman–Monteith and Shuttleworth–Wallace models, we present a novel approach to directly quantify the canopy-scale biophysical controls on λET and λEE over multiple plant functional types (PFTs) in the Amazon Basin. Combining data from six LBA (Large-scale Biosphere-Atmosphere Experiment in Amazonia) eddy covariance tower sites and a TR-driven physically based modeling approach, we identified the canopy-scale feedback-response mechanism between gC, λET, and atmospheric vapor pressure deficit (DA), without using any leaf-scale empirical parameterizations for the modeling. The TR-based model shows minor biophysical control on λET during the wet (rainy) seasons where λET becomes predominantly radiation driven and net radiation (RN) determines 75 to 80 % of the variances of λET. However, biophysical control on λET is dramatically increased during the dry seasons, and particularly the 2005 drought year, explaining 50 to 65 % of the variances of λET, and indicates λET to be substantially soil moisture driven during the rainfall deficit phase. Despite substantial differences in gA between forests and pastures, very similar canopy–atmosphere "coupling" was found in these two biomes due to soil moisture-induced decrease in gC in the pasture. This revealed the pragmatic aspect of the TR-driven model behavior that exhibits a high sensitivity of gC to per unit change in wetness as opposed to gA that is marginally sensitive to surface wetness variability. Our results reveal the occurrence of a significant hysteresis between λET and gC during the dry season for the pasture sites, which is attributed to relatively low soil water availability as compared to the rainforests, likely due to differences in rooting depth between the two systems. Evaporation was significantly influenced by gA for all the PFTs and across all wetness conditions. Our analytical framework logically captures the responses of gC and gA to changes in atmospheric radiation, DA, and surface radiometric temperature, and thus appears to be promising for the improvement of existing land–surface–atmosphere exchange parameterizations across a range of spatial scales.

VARIÁVEIS METEOROLÓGICAS EM ÁREAS DE FLORESTA E PASTAGEM NA AMAZÔNIA OCIDENTAL EM ANOS DE EVENTOS EXTREMOS

Deforestation in the Amazon comes from historical contexts which date from the colonization of the region. Several studies have identified climate change from the conversion of forests into agricultural systems. So, this study aimed to identify possible differences in the behavior of the specific humidity, air temperature and net radiation due to conversion of forest to pasture, using data corresponding to extreme event years, once these have occurred in short period of time. Therefore, it was used measures of the variables of a tropical rain forest area and a pasture area, where there are two towers belonging to the Large Scale Biosphere-Atmosphere Experiment in Amazonia - LBA. The measurements correspond to the years of 2005 and 2010, which occurred drought events, and 2009, a year that occurred a flood period. For each variable were calculated hourly means of each site, separated by year and by period. It was found that the years with dry events showed greater variability in all variables, especially in the dry period of the mentioned years, being the pasture the most affected area. Understanding this dynamic enables better planning in agricultural activities in the region.

Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia.

In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001–December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance.

The effect of atmospheric aerosol particles and clouds on net ecosystem exchange in the Amazon

Abstract. Carbon cycling in the Amazon is closely linked to atmospheric processes and climate in the region as a consequence of the strong coupling between the atmosphere and biosphere. This work examines the effects of changes in net radiation due to atmospheric aerosol particles and clouds on the net ecosystem exchange (NEE) of CO2 in the Amazon region. Some of the major environmental factors affecting the photosynthetic activity of plants, such as air temperature and relative humidity, were also examined. An algorithm for clear-sky irradiance was developed and used to determine the relative irradiance, f, which quantifies the percentage of solar radiation absorbed and scattered due to atmospheric aerosol particles and clouds. Aerosol optical depth (AOD) was calculated from irradiances measured with the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, onboard the Terra and Aqua satellites, and was validated with ground-based AOD measurements from AERONET (Aerosol Robotic Network) sun photometers. Carbon fluxes were measured using eddy covariance technique at the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) flux towers. Two sites were studied: the Jaru Biological Reserve (RBJ), located in Rondonia, and the Cuieiras Biological Reserve at the K34 LBA tower (located in a preserved region in the central Amazon). Analysis was performed continuously from 1999 to 2009 at K34 and from 1999 to 2002 at RBJ, and includes wet, dry and transition seasons. In the Jaru Biological Reserve, a 29% increase in carbon uptake (NEE) was observed when the AOD ranged from 0.10 to 1.5 at 550 nm. In the Cuieiras Biological Reserve, the aerosol effect on NEE was smaller, accounting for an approximate 20% increase in NEE. High aerosol loading (AOD above 3 at 550 nm) or high cloud cover leads to reductions in solar flux and strong decreases in photosynthesis up to the point where NEE approaches zero. The observed increase in NEE is attributed to an enhancement (~50%) in the diffuse fraction of photosynthetic active radiation (PAR). The enhancement in diffuse PAR can be done through increases in aerosols and/or clouds. In the present study, it was not possible to separate these two components. Significant changes in air temperature and relative humidity resulting from changes in solar radiation fluxes under high aerosol loading were also observed at both sites. Considering the long-range transport of aerosols in the Amazon, the observed changes in NEE for these two sites may occur over large areas in the Amazon, significantly altering the carbon balance in the largest rainforest in the world.

What drives the seasonality of photosynthesis across the Amazon basin? A cross-site analysis of eddy flux tower measurements from the Brasil flux network

We investigated the seasonal patterns of Amazonian forest photosynthetic activity, and the effects thereon of variations in climate and land-use, by integrating data from a network of ground-based eddy flux towers in Brazil established as part of the ‘Large-Scale Biosphere Atmosphere Experiment in Amazonia’ project. We found that degree of water limitation, as indicated by the seasonality of the ratio of sensible to latent heat flux (Bowen ratio) predicts seasonal patterns of photosynthesis. In equatorial Amazonian forests (5° N–5° S), water limitation is absent, and photosynthetic fluxes (or gross ecosystem productivity, GEP) exhibit high or increasing levels of photosynthetic activity as the dry season progresses, likely a consequence of allocation to growth of new leaves. In contrast, forests along the southern flank of the Amazon, pastures converted from forest, and mixed forest-grass savanna, exhibit dry-season declines in GEP, consistent with increasing degrees of water limitation. Although previous work showed tropical ecosystem evapotranspiration (ET) is driven by incoming radiation, GEP observations reported here surprisingly show no or negative relationships with photosynthetically active radiation (PAR). Instead, GEP fluxes largely followed the phenology of canopy photosynthetic capacity (Pc), with only deviations from this primary pattern driven by variations in PAR. Estimates of leaf flush at three non-water limited equatorial forest sites peak in the dry season, in correlation with high dry season light levels. The higher photosynthetic capacity that follows persists into the wet season, driving high GEP that is out of phase with sunlight, explaining the negative observed relationship with sunlight. Overall, these patterns suggest that at sites where water is not limiting, light interacts with adaptive mechanisms to determine photosynthetic capacity indirectly through leaf flush and litterfall seasonality. These mechanisms are poorly represented in ecosystem models, and represent an important challenge to efforts to predict tropical forest responses to climatic variations.

Limits and Limitlessness: Exploring Time in Scientific Practice

This article explores some of the ways that time figures in the scientific practices of instrumental micrometeorology and climatic and weather modeling. It draws on ethnographic work done with the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), an international scientific project that aims to assess the role of the Amazon forest in the global carbon cycle and to provide sustainable techniques for the future management of the region. An examination of the knowl- edge practices that have emerged from this ethnography (such as cali- bration and prediction) provides an opportunity to rethink the relation between ‘natural time’ and ‘social time(s)’. This allows for a discussion of the roles that certainty, uncertainty, finiteness, and limitlessness play in both scientific and ethnographic practice.

The Contributions of Regional Knowledge Networks Researching Environmental Changes in Latin America and Africa: a Synthesis of what they can do and why they can be policy relevant

We provide a synthesis of what regional scientific research networks in less developed regions of the world can do and why they might be relevant for societal decisions and practice. We do so through a focus on three regional science network initiatives that aim to enhance understanding of the multiscalar dynamics of global environmental change (GEC) regionally and globally, namely the Southern Africa Regional Science Initiative (SAFARI 2000), the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), and the Inter-American Institute for Global Change (IAI). With a view to aiding future efforts at regional research network formation, we assess whether and how these three networks enhanced regional science, and the extent to which they sought and managed to bridge the science-policy gap that challenges GEC science as a whole. Identifying key decisions and attributes bearing on their successes, the analysis attends specifically to how the three networks sought to build capacity, how differences and similarities between them affected their level of autonomy from governments, and how this and other factors influenced their functioning and achievements.

Características de cristais de gelo observados em um sistema de nuvens na Amazônia durante o experimento TRMM-LBA

Durante os meses de janeiro e fevereiro de 1999 foi realizada a campanha do TRMM/LBA (Tropical Rainfall Measuring Mission/Large Scale Biosphere-Atmosphere Experiment in Amazonia), na qual foram investigadas propriedades microfísicas de nuvens convectivas profundas. Este experimento fez parte de um esforço internacional para calibrar os equipamentos, no satélite TRMM, com o objetivo de estudar processos físicos tais como precipitação, radiação e eletricidade atmosférica. Os dados utilizados neste trabalho foram obtidos por instrumentos instalados na aeronave Citation II pertencente à Universidade de Dakota do Norte, USA, que incluem um conjunto de sondas espectrométricas, as quais medem a concentração e tamanho de partículas de gelo e de água, com destaque para a sonda bidimensional 2DC (Two-dimensional Cloud probe). Esta sonda identifica não apenas concentração e tamanho dos hidrometeoros, mas também as diferentes formas dos cristais de gelo. A aeronave realizou diversos vôos no experimento TRMM/LBA, sendo escolhido para análise o dia 10 de fevereiro de 1999. Foram observados cristais de gelo com uma grande variedade de formas e dimensões. Verificou-se certa concordância entre a forma dos cristais e os padrões de temperatura e umidade presente no ambiente, assim como foram observadas superposições de hábitos de cristais, sugerindo a existência de mistura entre diferentes regiões das nuvens e indicando que a sedimentação dos cristais pode ter grande importância para a evolução das propriedades microfísicas de nuvens convectivas profundas. Foi observado que a distribuição de tamanho dos cristais de gelo em função do diâmetro segue uma lei de potência.

Evaluation of the carbon content of aerosols from the burning of biomass in the Brazilian Amazon using thermal, optical and thermal-optical analysis methods

Abstract. Aerosol samples were collected at a pasture site in the Amazon Basin as part of the project LBA-SMOCC-2002 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate: Aerosols from Biomass Burning Perturb Global and Regional Climate). Sampling was conducted during the late dry season, when the aerosol composition was dominated by biomass burning emissions, especially in the submicron fraction. A 13-stage Dekati low-pressure impactor (DLPI) was used to collect particles with nominal aerodynamic diameters (Dp) ranging from 0.03 to 0.10 μm. Gravimetric analyses of the DLPI substrates and filters were performed to obtain aerosol mass concentrations. The concentrations of total, apparent elemental, and organic carbon (TC, ECa, and OC) were determined using thermal and thermal-optical analysis (TOA) methods. A light transmission method (LTM) was used to determine the concentration of equivalent black carbon (BCe) or the absorbing fraction at 880 nm for the size-resolved samples. During the dry period, due to the pervasive presence of fires in the region upwind of the sampling site, concentrations of fine aerosols (Dp<2.5 μm: average 59.8 μg m−3) were higher than coarse aerosols (Dp> 2.5 μm: 4.1 μg m−3). Carbonaceous matter, estimated as the sum of the particulate organic matter (i.e., OC × 1.8) plus BCe, comprised more than 90% to the total aerosol mass. Concentrations of ECa (estimated by thermal analysis with a correction for charring) and BCe (estimated by LTM) averaged 5.2 ± 1.3 and 3.1 ± 0.8 μg m−3, respectively. The determination of EC was improved by extracting water-soluble organic material from the samples, which reduced the average light absorption Ångström exponent of particles in the size range of 0.1 to 1.0 μm from >2.0 to approximately 1.2. The size-resolved BCe measured by the LTM showed a clear maximum between 0.4 and 0.6 μm in diameter. The concentrations of OC and BCe varied diurnally during the dry period, and this variation is related to diurnal changes in boundary layer thickness and in fire frequency.

Runoff sources and land cover change in the Amazon: an end-member mixing analysis from small watersheds

The flowpaths by which water moves from watersheds to streams has important consequences for the runoff dynamics and biogeochemistry of surface waters in the Amazon Basin. The clearing of Amazon forest to cattle pasture has the potential to change runoff sources to streams by shifting runoff to more surficial flow pathways. We applied end-member mixing analysis (EMMA) to 10 small watersheds throughout the Amazon in which solute composition of streamwater and groundwater, overland flow, soil solution, throughfall and rainwater were measured, largely as part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia. We found a range in the extent to which streamwater samples fell within the mixing space determined by potential flowpath end-members, suggesting that some water sources to streams were not sampled. The contribution of overland flow as a source of stream flow was greater in pasture watersheds than in forest watersheds of comparable size. Increases in overland flow contribution to pasture streams ranged in some cases from 0% in forest to 27–28% in pasture and were broadly consistent with results from hydrometric sampling of Amazon forest and pasture watersheds that indicate 17- to 18-fold increase in the overland flow contribution to stream flow in pastures. In forest, overland flow was an important contribution to stream flow (45–57%) in ephemeral streams where flows were dominated by stormflow. Overland flow contribution to stream flow decreased in importance with increasing watershed area, from 21 to 57% in forest and 60–89% in pasture watersheds of less than 10 ha to 0% in forest and 27–28% in pastures in watersheds greater than 100 ha. Soil solution contributions to stream flow were similar across watershed area and groundwater inputs generally increased in proportion to decreases in overland flow. Application of EMMA across multiple watersheds indicated patterns across gradients of stream size and land cover that were consistent with patterns determined by detailed hydrometric sampling.

Natural and drought scenarios in an east central Amazon forest: Fidelity of the Community Land Model 3.5 with three biogeochemical models

[1] Recent development of general circulation models involves biogeochemical cycles: flows of carbon and other chemical species that circulate through the Earth system. Such models are valuable tools for future projections of climate, but still bear large uncertainties in the model simulations. One of the regions with especially high uncertainty is the Amazon forest where large-scale dieback associated with the changing climate is predicted by several models. In order to better understand the capability and weakness of global-scale land-biogeochemical models in simulating a tropical ecosystem under the present day as well as significantly drier climates, we analyzed the off-line simulations for an east central Amazon forest by the Community Land Model version 3.5 of the National Center for Atmospheric Research and its three independent biogeochemical submodels (CASA', CN, and DGVM). Intense field measurements carried out under Large Scale Biosphere-Atmosphere Experiment in Amazonia, including forest response to drought from a throughfall exclusion experiment, are utilized to evaluate the whole spectrum of biogeophysical and biogeochemical aspects of the models. Our analysis shows reasonable correspondence in momentum and energy turbulent fluxes, but it highlights three processes that are not in agreement with observations: (1) inconsistent seasonality in carbon fluxes, (2) biased biomass size and allocation, and (3) overestimation of vegetation stress to short-term drought but underestimation of biomass loss from long-term drought. Without resolving these issues the modeled feedbacks from the biosphere in future climate projections would be questionable. We suggest possible directions for model improvements and also emphasize the necessity of more studies using a variety of in situ data for both driving and evaluating land-biogeochemical models.

Engage Students in Education Reform—Response

COMMENTARY Facing up to vexing problems A nod to nodules LETTERS I BOOKS I POLICY FORUM I EDUCATION FORUM I PERSPECTIVES LETTERS edited by Jennifer Sills A. REGALADO’S NEWS FOCUS STORY “BRAZILIAN SCIENCE: RIDING A GUSHER” (3 DECEMBER 2010, p. 1306) rightly highlights the “dearth of Brazilian-led science” in the Amazon and the “very delicate question” of Brazil’s dependence on foreign knowledge production. However, based on my experience and publication statistics from the Large-Scale Biosphere-Atmosphere experiment in Amazonia (1), I would challenge the statement that the “majority of publications on the Amazon don’t have a Brazilian author.” In fact, many papers have Brazilian co-authors. Brazilians (and Amazonian researchers) are involved in the majority of Amazonian research projects, but often in a subsidiary role as data providers and fi eld workers rather than leading the research and developing the scientifi c arguments. Clearly, foreign researchers, resources, technology, and expertise have been instru- mental in developing Amazonian science and raising Brazilian capacity in this biologically unique and important part of world. However, Brazilian researchers need to stop gratefully receiving fi sh and quickly learn how to use the rod and the line. ANA C. M. MALHADO Laboratory of Analysis and Processing of Imaging Satellites, LAPIS, Federal University of Alagoas, Maceio, Alagoas, Brazil. E-mail: anaclaudiamalhado@gmail.com Reference Research in Brazil. Many Amazon projects are led by foreign researchers. CREDIT: DEVA RODRIGUES/EMBRAPA Boosting CITES Through Research IN THEIR POLICY FORUM “BOOSTING CITES” (24 December 2010, p. 1752), J. Phelps et al. propose improvements to the implementation of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Most of their recommendations would involve the negotiation of cross-Party agreements and procurement of additional fi nancial resources, both of which are likely to delay or prevent their implementation. We suggest a more straightforward improve- ment to CITES implementation: Scientists should consider choosing CITES-listed taxa as model taxa for their research. At a workshop in 2008, more than 100 1. Ministerio de Ciencia e Tecnologia, Programa de Grande Escala da Biosfera-Atmosfera na Amazonia (http://lba.inpa.gov.br/lba/) [in Portuguese]. scientists and regulators compiled 60 case studies covering a wide range of CITES- listed taxa. The group outlined how infor- mation on the biology, harvesting, and man- agement could be used to determine whether international trade in CITES-listed taxa is detrimental to their survival in the wild. Most of those case studies (78%) mentioned that more basic information on the biology of the taxa in the wild (including taxonomy, biology, and ecology) would improve their ability to make this determination (1). A lot of scientifi c research is done on spe- cies that are chosen out of convenience. We recommend that, all else being equal, sci- entists coordinate with national scientific authorities, local communities, and com- mercial traders to work on CITES-listed taxa instead. Such research could directly address www.sciencemag.org SCIENCE VOL 331 Published by AAAS Downloaded from www.sciencemag.org on August 8, 2014 Amazon Science Needs Brazilian Leadership sustainable exploitation practices or could simply aim to generate relevant information as a by-product (for example, by generat- ing additional information on the basic tax- onomy, biology, and ecology of taxa). Either way, those implementing CITES would ben- efi t from the additional information and sci- entists would achieve additional impact from their research. MATTHEW J. SMITH,* RICHARD J. WILLIAMS, DREW W. PURVES Computational Science Laboratory, Microsoft Research, 7 J J Thompson Avenue, Cambridge, CB3 0FB, UK. *To whom correspondence should be addressed. E-mail: Matthew.Smith@microsoft.com Reference 1. M. J. Smith et al., Biol. Conserv. 144, 82 (2011). Response WE AGREE WITH SMITH ET AL. THAT BASIC BIO- logical information is the cornerstone of CITES effectiveness and sustainable resource management, and that scientists should be encouraged to select CITES-listed species as research taxa. However, many of the most important and delicate issues for CITES go far beyond biology of species under threat. Biological data provide a critical, lowest common denominator for CITES decision- making, but strengthening CITES funding, checks and balances, analyses, and accompa- nying human institutions and capacities are equally critical to conservation. Smith et al. suggest that collecting biologi- cal research would be a more straightforward approach to improving CITES implementa- tion than our solutions, many of which would require substantial fi nancial support and polit- ical will. In fact, even issues of basic biologi- cal research on vulnerable species are about Party funding, negotiations, safeguards, and collaboration. Bridging the logistical, fi nan- cial, political, and permit-laden gulf to attract signifi cantly more researchers to study these vulnerable species is not a simple process. For example, obtaining research per- mits for work on CITES-listed or locally threatened (e.g., Red List) species is time- 18 FEBRUARY 2011

Horizontal and Vertical Turbulent Fluxes Forced by a Gravity Wave Event in the Nocturnal Atmospheric Surface Layer Over the Amazon Forest

A nocturnal gravity wave was detected over a south-western Amazon forest dur- ing the Large-Scale Biosphere-Atmosphere experiment in Amazonia (LBA) in the course of the dry-to-wet season campaign on October 2002. The atmospheric surface layer was stably stratified and had low turbulence activity, based on friction velocity values. How- ever, the passage of the wave, an event with a period of about 180-300 s, caused negative turbulent fluxes of carbon dioxide (CO2) and positive sensible heat fluxes, as measured by the eddy-covariance system at 60 m (≈30 m above the tree tops). The evolution of vertical profiles of air temperature, specific humidity and wind speed during the wave movement revealed that cold and drier air occupied the sub-canopy space while high wind speeds were measured above the vegetation. The analysis of wind speed and scalars high frequency data was performed using the wavelet technique, which enables the decomposition of signals in several frequencies allowed by the data sampling conditions. The results showed that the time series of vertical velocity and air temperature were −90 ◦ out of phase during the pas- sage of the wave, implying no direct vertical transport of heat. Similarly, the time series of vertical velocity and CO2 concentration were 90 ◦ out of phase. The wave was not directly associated with vertical fluxes of this variable but the mixing induced by its passage resulted in significant exchanges in smaller scales as measured by the eddy-covariance system. The phase differences between horizontal velocity and both air temperature and CO2 concen- tration were, respectively, zero and 180 ◦ , implying phase and anti-phase relationships. As a result, the wave contributed to positive horizontal fluxes of heat and negative horizontal fluxes of carbon dioxide. Such results have to be considered in nocturnal boundary-layer surface-atmosphere exchange schemes for modelling purposes.

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

Abstract. As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O3, NO, NO2, CO, VOC, CO2, and H2O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h−1. Within the plume core, aerosol concentrations were strongly enhanced, with ΔCN/ΔCO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. ΔCN/ΔCO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60–80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16±12%) of the plume particles were CCN. The fresh plume aerosols showed relatively weak light scattering efficiency. The CO-normalized CCN concentrations and light scattering coefficients increased with plume age in most cases, suggesting particle growth by condensation of soluble organic or inorganic species. We used a Single Column Chemistry and Transport Model (SCM) to infer the urban pollution emission fluxes of Manaus City, implying observed mixing ratios of CO, NOx and VOC. The model can reproduce the temporal/spatial distribution of ozone enhancements in the Manaus plume, both with and without accounting for the distinct (high NOx) contribution by the power plants; this way examining the sensitivity of ozone production to changes in the emission rates of NOx. The VOC reactivity in the Manaus region was dominated by a high burden of biogenic isoprene from the background rainforest atmosphere, and therefore NOx control is assumed to be the most effective ozone abatement strategy. Both observations and models show that the agglomeration of NOx emission sources, like power plants, in a well-arranged area can decrease the ozone production efficiency in the near field of the urban populated cores. But on the other hand remote areas downwind of the city then bear the brunt, being exposed to increased ozone production and N-deposition. The simulated maximum stomatal ozone uptake fluxes were 4 nmol m−2 s−1 close to Manaus, and decreased only to about 2 nmol m−2 s−1 within a travel distance >1500 km downwind from Manaus, clearly exceeding the critical threshold level for broadleaf trees. Likewise, the simulated N deposition close to Manaus was ~70 kg N ha−1 a−1 decreasing only to about 30 kg N ha−1 a−1 after three days of simulation.

Hygroscopic properties of Amazonian biomass burning and European background HULIS and investigation of their effects on surface tension with two models linking H-TDMA to CCNC data

Abstract. HUmic-LIke Substances (HULIS) have been identified as major contributors to the organic carbon in atmospheric aerosol. The term "HULIS" is used to describe the organic material found in aerosol particles that resembles the humic organic material in rivers and sea water and in soils. In this study, two sets of filter samples from atmospheric aerosols were collected at different sites. One set of samples was collected at the K-puszta rural site in Hungary, about 80 km SE of Budapest, and a second was collected at a site in Rondônia, Amazonia, Brazil, during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) biomass burning season experiment. HULIS were extracted from the samples and their hygroscopic properties were studied using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) at relative humidity (RH) <100%, and a cloud condensation nucleus counter (CCNC) at RH >100%. The H-TDMA measurements were carried out at a dry diameter of 100 nm and for RH ranging from 30 to 98%. At 90% RH the HULIS samples showed diameter growth factors between 1.04 and 1.07, reaching values of 1.4 at 98% RH. The cloud nucleating properties of the two sets of aerosol samples were analysed using two types of thermal static cloud condensation nucleus counters. Two different parameterization models were applied to investigate the potential effect of HULIS surface activity, both yielding similar results. For the K-puszta winter HULIS sample, the surface tension at the point of activation was estimated to be lowered by between 34% (47.7 mN/m) and 31% (50.3 mN/m) for dry sizes between 50 and 120 nm in comparison to pure water. A moderate lowering was also observed for the entire water soluble aerosol sample, including both organic and inorganic compounds, where the surface tension was decreased by between 2% (71.2 mN/m) and 13% (63.3 mN/m).

O uso da energia radiativa do fogo para estimar as emissões de queimadas para a América do Sul

A cada ano grandes extensões terrestres sofrem com a ação antropogênica e natural das queimadas. Estima-se que mais de 100 milhões de toneladas de aerossóis provenientes da fumaça sejam lançados na atmosfera, dos quais 80% ocorrem em regiões tropicais do globo. O processo de combustão da biomassa libera para a atmosfera gases traços e partículas de aerossóis que afetam significativamente a qualidade do ar, a química troposférica e estratosférica, o balanço de radiação e a dinâmica e microfísica das nuvens. O presente trabalho tem como objetivo principal utilizar a energia radiativa do fogo (ERF) derivada do sensor MODIS (Moderate Resolution Imaging Spectroradiometer) e do GOES (Geostationary Operational Environmental Satellite) para estimar as emissões de monóxido de carbono (CO) e de material particulado com diâmetro menor que 2.5µm (PM2,5µm) para o período de queimadas de 2002 na América do Sul, e modelar estas emissões no CCATT-BRAMS (Coupled Chemistry-Aerosol-Tracer Transport model coupled to Brazilian Regional Atmospheric Modeling System). Com uma correlação superior a 86% entre os dados de emissão de aerossóis (kg.s -1) e a ERF (MJ.s -1), originaram-se três coeficientes para os dados provenientes do satélite GOES. O uso da ERF e dos coeficientes de emissão para estimar o PM2,5µm e CO emitido na queimada mostrou uma correlação de aproximadamente 91 % entre os dados estimados e os dados utilizados como verdade terrestre obtidos a partir dos experimentos do LBA (Large Scale Biosphere-Atmosphere Experiment in Amazônia) SMOCC (Smoke, Aerosols, Clouds, rainfall, and Climate) e RaCCI (Radiation, Cloud, and Climate Interactions).

A comparison of dry and wet season aerosol number fluxes over the Amazon rain forest

Abstract. Vertical number fluxes of aerosol particles and vertical fluxes of CO2 were measured with the eddy covariance method at the top of a 53 m high tower in the Amazon rain forest as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment. The observed aerosol number fluxes included particles with sizes down to 10 nm in diameter. The measurements were carried out during the wet and dry season in 2008. In this study focus is on the dry season aerosol fluxes, with significant influence from biomass burning, and these are compared with aerosol fluxes measured during the wet season. Net particle deposition fluxes dominated in daytime in both seasons and the deposition flux was considerably larger in the dry season due to the much higher dry season particle concentration. The particle transfer velocity increased linearly with increasing friction velocity in both seasons. The difference in transfer velocity between the two seasons was small, indicating that the seasonal change in aerosol number size distribution is not enough for causing any significant change in deposition velocity. In general, particle transfer velocities in this study are low compared to studies over boreal forests. The reasons are probably the high percentage of accumulation mode particles and the low percentage of nucleation mode particles in the Amazon boundary layer, both in the dry and wet season, and low wind speeds in the tropics compared to the midlatitudes. In the dry season, nocturnal particle fluxes behaved very similar to the nocturnal CO2 fluxes. Throughout the night, the measured particle flux at the top of the tower was close to zero, but early in the morning there was an upward particle flux peak that is not likely a result of entrainment or local pollution. It is possible that these morning upward particle fluxes are associated with emission of primary biogenic particles from the rain forest. Emitted particles may be stored within the canopy during stable conditions at nighttime, similarly to CO2, and being released from the canopy when conditions become more turbulent in the morning.