RICARDO SANTANA DOS SANTOS

RICARDO SANTANA DOS SANTOS

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Variação Interanual do Balanço de Gases de Efeito Estufa na Bacia Amazônica e seus controles em um mundo sob aquecimento e mudanças climáticas
2019 - GATTI, LUCIANA V.; DOMINGUES, LUCAS; ARAGAO, LUIZ; MILLER, JOHN; BASSO, LUANA; MARANI, LUCIANO; TEJADA, GRACIELA; CASSOL, HENRIQUE; CORREIA, CAIO; IPIA, ALBER; ANDERSON, LIANA; RANDOW, CELSO V.; GLOOR, MANUEL; PETERS, WOUTER; LOPES, RAIANE; SANTOS, RICARDO; CRISPIM, STEPHANE
Ao longo dos últimos 40-‐50 anos a Amazônia vem sofrendo muitas alterações devido ao desmatamento, queima da biomassa, mudança do uso da terra, expansão urbana, malha viária, construção de hidrelétricas, exploração de mineração, petróleo e gás, etc. Esta alteração na Floresta Amazônica vem promovendo o aumento da temperatura nesta região acima do esperado e intensificação da estação seca. Estas alterações, além das alterações climáticas vem causando impacto no Balanço de Carbono da Bacia Amazônica.
Background concentrations of CO2, CO and N2O in Brazilian coast
2020 - MARANI, L.; BORGES, V.F.; GATTI, L.V.; DOMINGUES, L.G.; CORREIA, C.S.C.; BASSO, L.S.; SANTOS, R.S. dos; CRISPIM, S.P.; NEVES, R.A.L.; GLOOR, M.; MILLER, J.B.
Estudo da concentração de hexafluoreto de enxofre (SF6) na costa norte e nordeste do Brasil
2019 - CRISPIM, STEPHANE P.; GATTI, LUCIANA V.; BASSO, LUANA S.; SANTOS, RICARDO S. dos; BORGES, VIVIANE F.; NEVES, RAIANE A.L.
A new background method for greenhouse gases flux calculation based in back-trajectories over the Amazon
2020 - DOMINGUES, LUCAS G.; GATTI, LUCIANA V.; AQUINO, AFONSO; SÁNCHEZ, ALBER; CORREIA, CAIO; GLOOR, MANUEL; PETERS, WOUTER; MILLER, JOHN; TURNBULL, JOCELYN; SANTANA, RICARDO; MARANI, LUCIANO; CÂMARA, GILBERTO; NEVES, RAIANE; CRISPIM, STÉPHANE
The large amount of carbon stored in trees and soils of the Amazon rain forest is under pressure from land use as well as climate change. Therefore, various efforts to monitor greenhouse gas exchange between the Amazon forest and the atmosphere are now ongoing, including regular vertical profile (surface to 4.5 km) greenhouse gas measurements across the Amazon. These profile measurements can be used to calculate fluxes to and from the rain forest to the atmosphere at large spatial scales by considering the enhancement or depletion relative to the mole fraction of air entering the Amazon basin from the Atlantic, providing an important diagnostic of the state, changes and sensitivities of the forests. Previous studies have estimated greenhouse gas mole fractions of incoming air (‘background’) as a weighted mean of mole fractions measured at two background sites, Barbados (Northern Hemisphere) and Ascension (Southern hemisphere) in the Tropical Atlantic, where the weights were based on sulphur hexafluoride (SF6) measured locally (in the Amazon vertical profiles) and at the two background sites. However, this method requires the accuracy and precision of SF6 measurements to be significantly better than 0.1 parts per trillion (picomole mole􀀀1), which is near the limit for the best SF6 measurements and assumes that there are no SF6 sources in the Amazon basin. We therefore present here an alternative method. Instead of using SF6, we use the geographical position of each air-mass back-trajectory when it intersects the limit connecting these two sites to estimate contributions from Barbados versus Ascension. We furthermore extend the approach to include an observation site further south, Cape Point, South Africa. We evaluate our method using CO2 vertical profile measurements at a coastal site in Brazil comparing with values obtained using this method where we find a high correlation (r2 = 0.77). Similarly, we obtain good agreement for CO2 background when comparing our results with those based on SF6, for the period 2010–2011 when the SF6 measurements had excellent precision and accuracy. We also found high correspondence between the methods for background values of CO, N2O and CH4. Finally, flux estimates based on our new method agree well with the CO2 flux estimates for 2010 and 2011 estimated using the SF6-based method. Together, our findings suggest that our trajectory-based method is a robust new way to derive background air concentrations for the purpose of greenhouse gas flux estimation using vertical profile data.
Estudo do crescimento da concentração de hexafluoreto de enxofre (SF6) nas regiões norte e nordeste do Brasil
2019 - SANTOS, RICARDO S. dos
O hexafluoreto de enxofre (SF6) não figura como um dos gases de efeito estufa com as maiores concentrações no planeta Terra, no entanto, é um gás com um potencial de aquecimento global extremamente grande. Portanto, uma quantidade relativamente pequena pode ter um impacto importante nas mudanças climáticas do globo. Ele é um gás antropogênico, suas emissões são provenientes, principalmente, na distribuição de energia elétrica; é o gás preferido da indústria para interrupção de corrente elétrica e como isolamento de segurança na transmissão e distribuição de eletricidade. Ele é utilizado em disjuntores e equipamentos de alta tensão e na indústria de fundição de magnésio. Este estudo foi desenvolvido com o objetivo de elucidar se existe uma contribuição da Bacia Amazônica, e costa Norte e Nordeste brasileiras nas emissões deste gás, além de mostrar um amplo banco de dados de suas concentrações ao longo do tempo, com início das medições deste o ano 2000. A quantificação do SF6 foi realizada por meio da coleta do ar atmosférico utilizando aviões de pequeno porte que descreveram um perfil vertical em quatro locais, estrategicamente posicionados na Bacia Amazônica, e utilizando sistemas semiautomáticos de coleta de ar em 17 ou 12 altitudes diferentes, juntamente com coletas em 3 locais nas costas Norte e Nordeste brasileiras, com armazenamento das amostras em frascos de vidro. Para a comparação da concentração com estações globais, foram utilizadas as concentrações medidas pela NOAA na Ilha de Ascension e Barbados. Não foi encontrado um caráter emissor da Amazônia e da costa brasileira. Os resultados de uma maneira geral mostram a ocorrência de um crescimento nas concentrações médias obtidas em todos os locais de amostragem com o passar dos anos, acompanhando o crescimento mundial.
Invited Keynote: Inter-annual variation of Amazon greenhouse balances 2010- 2014
2017 - GATTI, LUCIANA V.; GLOOR, MANUEL; MILLER, JOHN B.; DOMINGUES, LUCAS G.; SILVA, MARCELO G.; ARAGAO, LUIZ E.O.C.; MARANI, LUCIANO; CORREIA, CAIO C.S.; PETERS, WOUTER; BORGES, VIVIANE F.; IPIA, ALBER H.S.; BASSO, LUANA S.; ANDERSON, LIANA O.; ALDEN, CAROLINE B.; VAN DER LAAN-LUIJKX, INGRID; BARICHIVICH, JONATHAN; SANTOS, RICARDO S.; CRISPIM, STEPHANE P.; COSTA, WELLISSON R.; ROSAN, THAIS M.
Net carbon exchange between tropical land and the atmosphere is potentially important because the vast amounts of carbon in forests and soils can be released on short time-scales e.g. via deforestation or changes in temperature and moisture. Such changes may thus cause feedbacks on global climate, as have been predicted in earth system models. In the tropics, the Amazon is most significant in the global carbon cycle, hosting by far the largest carbon vegetation and soil carbon pools (~200 PgC). Because of the very large precipitation amounts, approximately 20-25% of its area is seasonally flooded and thus it is also an important region for methane emissions. From 2010 onwards we have extended an earlier greenhouse gas measurement program to include regular vertical profiles of CO2, CH4, N2O, CO, SF6, from the ground up to 4.5 km height at four sites along the main air-stream over the Amazon Basin. Our measurements demonstrate that surface flux signals are primarily concentrated to the lower 2 km and thus vertical profile measurements are ideally suited to estimate greenhouse gas balances. Clearly a higher measurement density is desirable. We are in the process of expanding the number of surface and airborne sampling sites as well as the number of trace gases measured. Nonetheless, because of the homogeneity of the vegetation (forests) and the coherent east to west trade-winds over the Basin, these data already permit a range of insights about the magnitude, seasonality, inter-annual variation of carbon fluxes and their controls. Most recent years have been anomalously hot with the southern part of the Basin having warmed the most. Precipitation regimes also seem to have shifted with an increase in extreme floods. Approximately 20 percent of Amazon forests have been deforested by now and development pressure on forests continues. For the specific period we will discuss the year 2010 was anomalously dry, followed by 4 years wet (2011, 2012, 2013 and 2014) and another dry year (2015/16 -El Nino year). This period provides an interesting contrast of climatic conditions in a warming world with increasing human pressures. We will analyze the effect of this climate variability on annual and seasonal carbon balances for these five years using our atmospheric data. We will estimate fluxes using a simple, but powerful back-trajectory based atmospheric mass balance approach. Our data permit us not only to estimate net CO2 and CH4 fluxes, but using carbon monoxide we estimate carbon release via fires and thus the net carbon balance of the unburned land vegetation. We will relate fire emissions to controls of land vegetation functioning and independent diagnostics like fire counts. We will also discuss what our results suggest for the role of the tropics of the global carbon balance.
A New Approach to estimate GHG content of air entering the Amazon basin for purpose of GHG fluxes using air column budgets
2017 - GATTI, LUCIANA V.; DOMINGUES, LUCAS G.; CORREIA, CAIO S.C.; SANCHEZ, ALBER; GLOOR, MANUEL; MILLER, JOHN B.; ALDEN, CAROLINE; MARANI, LUCIANO; SANTOS, RICARDO S.; COSTA, WELLISON R.; CRISPIM, STEPHANE P.; BORGES, VIVIANE F.; AQUINO, AFONSO R.
Amazon humid forests are an important part of the tropical climate system and are a large pool of organic carbon which can be released rapidly both as a result of human destruction as well possibly in response to changing climate. In 2000 we started to measure regularly vertical profiles over the Brazilian Amazon Basin to estimate GHG balances as a large scale diagnostic of longer-term changes and short term responses to climate anomalies. To estimate Amazon Basin regional fluxes based on vertical profile data, we use an air column budget technique. To do so we profit from the primary air flow pattern over the basin with trade winds entering the basin along the North-east Atlantic coast, then travelling westwards towards the Andes, from where the air flow is bent south-eats-wards returning back towards the sea. Thus we can estimate fluxes from the difference in air column greenhouse gas content at a site in the Amazon basin and the air column content of air entering the basin, and an estimate of the time it takes for air parcels to travel from the Atlantic coast to the site in the Amazon. To estimate travel time we use back-trajectories calculated based on meteorological fields [Hysplit1 GDAS 1degree] One approach to estimate the greenhouse gas air column content of air entering the basin is to express air entering the basin as a mixture of northern hemisphere and southern hemisphere air. Specifically we use as end-members air concentrations measured at Barbados (RPB, NOAA site) and Ascension (ASC, NOAA site) respectively. To estimate fractional contributions we use a linear mixing model expressing in situ measured SF6 as a weighted sum of SF6 measured at the two NOAA background sites. Because flux estimates are very sensitive to SF6 precision and accuracy we have developed an alternative approach. Instead of determining weights from SF6 we base the weights on the latitude where a back-trajectory extending backwards in time from the site intersects a line connecting RPB, ASC (until 30°S). Now we use RPB, ASC and CPT (Cape Point; 34.35°S, 18.49°E). We will describe in detail the method and show tests of the approach using the SF6 based method which we trust for the years 2010 and 2011, but less for the following years because the NOAA quantification method change and our continue during more 4 years in the old linear quantification method. This difference produce slightly bias over time. While we developed this method for the Amazon it similarly could be applied to other regions with clearly defined wind patterns.
Amazon Basin biomass burning emission and its correlation with climatology and deforestation
2017 - DOMINGUES, LUCAS G.; GATTI, LUCIANA V.; GLOOR, MANUEL; MILLER, JOHN B.; AQUINO, AFONSO R.; ARAGAO, LUIZ E.O. e C.; ANDERSON, LIANA O.; MARANI, LUCIANO; CORREIA, CAIO S. de C.; SILVA, MARCELO G.; BORGES, VIVIANE F.; IPIA, ALBER H.S.; BASSO, LUANA S.; SANTOS, RICARDO S.; CRISPIM, STEPHANI P.; COSTA, WELLISON R.
Tropical rainforests have great potential to affect the global carbon budget considering their large quantities of labile carbon stored in forests and soils. Among the tropical regions, the Amazon forest covers the largest area and also hosts the largest carbon pool (~200 PgC), corresponding for 50% of its biome globally. It has a total area of approximately 6.7 million km2, of which, 4.2 million km2 is in Brazil, which corresponds to approximately 60 % of Amazon territory, and contains one quarter of global biodiversity. Over recent years, the Amazon Basin hydrological cycle has changed considerably which presented severe droughts in 2005, 2010 and 2015. 2015 is likely the largest drought over the past 15 years. Droughts in the Amazon are intrinsically correlated to extensive wildfires. At 2004/2005 the number of fire hot spots reached its maximum, coincident with the peak in deforestation. However, in the recent years, despite the decrease in deforestation rates, increase in fire hot spots have been observed, particularly during the years of extreme drought, 2010 and 2015. 2011 had the fewest number of fire hot spots, but since 2013 a positive trend was identified, reaching the maximum peak in 2015. Although deforestation estimation has decreased strongly over the last decade (71% reduction from 2004 to 2012), estimates of fire related carbon fluxes to the atmosphere estimated using regular atmospheric carbon monoxide concentration measurements indicate that there may be a discrepancy. These data do suggest a much smaller decrease, which lead us to believe that deforestation, as observed from satellite, is not the only process causing release of carbon by fires. Thus, understanding the relation between carbon emissions from biomass burning and climate, fire hot spots based on remote sensing and deforestation is important as it may reveal biases in remote sensing based estimates of deforestation. In turn it may help to evaluate the effectiveness of actions to preserve the forests. To elucidate the actual contribution and the carbon emission from biomass burning in the Amazon Basin, measurements of carbon monoxide are an important tool. We will report the results from a recently established pan Amazon lower troposphere biweekly to monthly atmospheric sampling program for the years 2010 to 2014. Amazon Basin biomass burning carbon emissions have been determined by applying a mass balance technique to carbon monoxide measured from vertical profiles in four sites over the Amazon Basin. We will present these results from biomass burning and compare the carbon monoxide emissions with those from carbon dioxide, resulting in a ratio of carbon biomass burning emission which we will analyze with respect to climate, deforestation and number of fire hot spots.
Amazon Atlantic outflow region carbon cycling constrained by atmospheric greenhouse gas data
2017 - BORGES, VIVIANE F.; GATTI, LUCIANA V.; GLOOR, EMANUEL U.; MILLER, JOHN B.; BOESCH, HARTMUT; DOMINGUES, LUCAS G.; CORREIA, CAIO S. de C.; BASSO, LUANA S.; SANTOS, RICARDO S.
Estuaries and near-coastal regions may process substantial amounts of carbon causing a nonnegligible carbon uptake from the atmosphere. For purpose of characterizing the greenhouse gas levels of air entering the Amazon basin from the Atlantic we have been measuring regularly greenhouse gas concentrations at several sites along the North-East Atlantic coast of Brazil over approximately the past six years (at some of the sites for much longer). At some of the sites sampling is restricted close to the surface while at other sites we have been measuring vertical profiles. At Salinopolis which is located close to the Amazon outflow region to the Atlantic seasonally strong CO2 depletion in both surface records and aircraft vertical profiles compared to background sites like Ascension Island is clearly discernible. The seasonality is synchronous with increases in chlorophyll observed from space e.g. by the SeaWiFS mission. Incidentally during the CO2 depletion period airmass trajectories tend to pass over the shelf region along the Brazilian coast travelling from the South along the coast. This enables us to apply an air column mass balance approach to estimate the magnitude of the CO2 flux into the sea along the coast during the blooms. Using the chlorophyll maps we may furthermore extrapolate the flux estimates spatially to obtain an area integrated flux. We will discuss our findings and put our flux estimates into perspective with estimates for productivity and carbon uptake in coastal regions of major tropical rivers as well as the extra-tropics. Acknowledgment: CNPq, NERC, FAPESP, MCTI, NOAA, IPEN and INPE.