3,806 research outputs found

    Modulation of Midtropospheric CO_2 by the South Atlantic Walker Circulation

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    Midtropospheric CO_2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO_2 over the South Atlantic Ocean. It was found that the area-averaged CO_2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December–March. This CO_2 contrast is due to the large-scale vertical circulation over this region. During December–March, there is sinking motion over the South Atlantic Ocean. The sinking motion brings high-altitude air with a slightly lower concentration of CO_2 to the midtroposphere. Meanwhile, air rising over South America brings near-surface air with a higher concentration of CO_2 to the midtroposphere. As a result, the AIRS midtropospheric CO_2 concentration is lower over the South Atlantic Ocean than over South America during December–March. The detrended AIRS midtropospheric CO_2 difference correlates well with the inverted and detrended 400-hPa vertical pressure velocity difference between the South Atlantic and South America. Results obtained from this study demonstrate the strong impact of large-scale circulation on the vertical distribution of CO_2 in the free troposphere and suggest that midtropospheric CO_2 measurements can be used as an innovative observational constraint on the simulation of large-scale circulations in climate models

    The influence of tropospheric biennial oscillation on mid-tropospheric CO_2

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    Mid-tropospheric CO_2 retrieved from the Atmospheric Infrared Sounder (AIRS) was used to investigate CO_2 interannual variability over the Indo-Pacific region. A signal with periodicity around two years was found for the AIRS mid-tropospheric CO_2 for the first time, which is related to the Tropospheric Biennial Oscillation (TBO) associated with the strength of the monsoon. During a strong (weak) monsoon year, the Western Walker Circulation is strong (weak), resulting in enhanced (diminished) CO_2 transport from the surface to the mid-troposphere. As a result, there are positive (negative) CO2 anomalies at mid-troposphere over the Indo-Pacific region. We simulated the influence of the TBO on the mid-tropospheric CO_2 over the Indo-Pacific region using the MOZART-2 model, and results were consistent with observations, although we found the TBO signal in the model CO_2 is to be smaller than that in the AIRS observations

    CO_2 Annual and Semiannual Cycles From Multiple Satellite Retrievals and Models

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    Satellite CO_2 retrievals from the Greenhouse gases Observing SATellite (GOSAT), Atmospheric Infrared Sounder (AIRS), and Tropospheric Emission Spectrometer (TES) and in situ measurements from the National Oceanic and Atmospheric Administration - Earth System Research Laboratory (NOAA-ESRL) Surface CO_2 and Total Carbon Column Observing Network (TCCON) are utilized to explore the CO_2 variability at different altitudes. A multiple regression method is used to calculate the CO_2 annual cycle and semiannual cycle amplitudes from different data sets. The CO_2 annual cycle and semiannual cycle amplitudes for GOSAT X_(CO2) and TCCON X_(CO2) are consistent but smaller than those seen in the NOAA-ESRL surface data. The CO_2 annual and semiannual cycles are smallest in the AIRS midtropospheric CO_2 compared with other data sets in the Northern Hemisphere. The amplitudes for the CO_2 annual cycle and semiannual cycle from GOSAT, TES, and AIRS CO_2 are small and comparable to each other in the Southern Hemisphere. Similar regression analysis is applied to the Model for OZone And Related chemical Tracers-2 and CarbonTracker model CO_2. The convolved model CO_2 annual cycle and semiannual cycle amplitudes are similar to those from the satellite CO_2 retrievals, although the models tend to underestimate the CO_2 seasonal cycle amplitudes in the Northern Hemisphere midlatitudes and underestimate the CO_2 semiannual cycle amplitudes in the high latitudes. These results can be used to better understand the vertical structures for the CO_2 annual cycle and semiannual cycle and help identify deficiencies in the models, which are very important for the carbon budget study

    Influence of El Niño on Midtropospheric CO_2 from Atmospheric Infrared Sounder and Model

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    The authors investigate the influence of El Niño on midtropospheric CO_2 from the Atmospheric Infrared Sounder (AIRS) and the Model for Ozone and Related Chemical Tracers, version 2 (MOZART-2). AIRS midtropospheric CO_2 data are used to study the temporal and spatial variability of CO_2 in response to El Niño. CO_2 differences between the central and western Pacific Ocean correlate well with the Southern Oscillation index. To reveal the temporal and spatial variability of the El Niño signal in the AIRS midtropospheric CO_2, a multiple regression method is applied to the CO_2 data from September 2002 to February 2011. There is more (less) midtropospheric CO_2 in the central Pacific and less (more) midtropospheric CO_2 in the western Pacific during El Niño (La Niña) events. Similar results are seen in the MOZART-2 convolved midtropospheric CO_2, although the El Niño signal in the MOZART-2 is weaker than that in the AIRS data

    Association of Trace Element Levels with Outcomes in Critically Ill COVID-19 Patients.

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    The primary objective of this study was to compare the plasma levels of copper, selenium, and zinc between critically ill COVID-19 patients and less severe COVID-19 patients. The secondary objective was to investigate the association of these trace element levels with adverse outcomes, including the duration of mechanical ventilation, occurrence of septic shock, and mortality in critically ill COVID-19 patients. All COVID-19 patients admitted to the ICU of the Geneva University Hospitals between 9 March 2020 and 19 May 2020 were included in the study. Plasma levels of copper, selenium and zinc were measured on admission to the ICU and compared with levels measured in COVID-19 patients hospitalized on the ward and in non-hospitalized COVID-19 patients. To analyze the association of trace elements with clinical outcomes, multivariate linear and logistic regressions were performed. Patients in the ICU had significantly lower levels of selenium and zinc and higher levels of copper compared to COVID-19 patients hospitalized on the ward and in non-hospitalized COVID-19 patients. In ICU patients, lower zinc levels tended to be associated with more septic shock and increased mortality compared to those with higher zinc levels (p = 0.07 for both). Having lower copper or selenium levels was associated with a longer time under mechanical ventilation (p = 0.01 and 0.04, respectively). These associations remained significant in multivariate analyses (p = 0.03 for copper and p = 0.04 for selenium). These data support the need for interventional studies to assess the potential benefit of zinc, copper and selenium supplementation in severe COVID-19 patients

    Capturing Complete Spatial Context in Satellite Observations of Greenhouse Gases

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    Scientific consensus from a 2015 pre-Decadal Survey workshop highlighted the essential need for a wide-swath (mapping) low earth orbit (LEO) instrument delivering carbon dioxide (CO_2), methane (CH_4), and carbon monoxide (CO) measurements with global coverage. OCO-2 pioneered space-based CO_2 remote sensing, but lacks the CH_4, CO and mapping capabilities required for an improved understanding of the global carbon cycle. The Carbon Balance Observatory (CARBO) advances key technologies to enable high-performance, cost-effective solutions for a space-based carbon-climate observing system. CARBO is a compact, modular, 15-30° field of view spectrometer that delivers high-precision CO_2, CH_4, CO and solar induced chlorophyll fluorescence (SIF) data with weekly global coverage from LEO. CARBO employs innovative immersion grating technologies to achieve diffraction-limited performance with OCO-like spatial (2x2 km^2) and spectral (λ/Δλ ≈ 20,000) resolution in a package that is >50% smaller, lighter and more cost-effective. CARBO delivers a 25- to 50-fold increase in spatial coverage compared to OCO-2 with no loss of detection sensitivity. Individual CARBO modules weigh < 20 kg, opening diverse new space-based platform opportunities

    Modulation of Midtropospheric CO_2 by the South Atlantic Walker Circulation

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    Midtropospheric CO_2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO_2 over the South Atlantic Ocean. It was found that the area-averaged CO_2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December–March. This CO_2 contrast is due to the large-scale vertical circulation over this region. During December–March, there is sinking motion over the South Atlantic Ocean. The sinking motion brings high-altitude air with a slightly lower concentration of CO_2 to the midtroposphere. Meanwhile, air rising over South America brings near-surface air with a higher concentration of CO_2 to the midtroposphere. As a result, the AIRS midtropospheric CO_2 concentration is lower over the South Atlantic Ocean than over South America during December–March. The detrended AIRS midtropospheric CO_2 difference correlates well with the inverted and detrended 400-hPa vertical pressure velocity difference between the South Atlantic and South America. Results obtained from this study demonstrate the strong impact of large-scale circulation on the vertical distribution of CO_2 in the free troposphere and suggest that midtropospheric CO_2 measurements can be used as an innovative observational constraint on the simulation of large-scale circulations in climate models

    Challenges of operational river forecasting

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    Skillful and timely streamflow forecasts are critically important to water managers and emergency protection services. To provide these forecasts, hydrologists must predict the behavior of complex coupled human–natural systems using incomplete and uncertain information and imperfect models. Moreover, operational predictions often integrate anecdotal information and unmodeled factors. Forecasting agencies face four key challenges: 1) making the most of available data, 2) making accurate predictions using models, 3) turning hydrometeorological forecasts into effective warnings, and 4) administering an operational service. Each challenge presents a variety of research opportunities, including the development of automated quality-control algorithms for the myriad of data used in operational streamflow forecasts, data assimilation, and ensemble forecasting techniques that allow for forecaster input, methods for using human-generated weather forecasts quantitatively, and quantification of human interference in the hydrologic cycle. Furthermore, much can be done to improve the communication of probabilistic forecasts and to design a forecasting paradigm that effectively combines increasingly sophisticated forecasting technology with subjective forecaster expertise. These areas are described in detail to share a real-world perspective and focus for ongoing research endeavors

    Credit bureaus between risk-management, creditworthiness assessment and prudential supervision

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    "This text may be downloaded for personal research purposes only. Any additional reproduction for other purposes, whether in hard copy or electronically, requires the consent of the author. If cited or quoted, reference should be made to the full name of the author, the title, the working paper or other series, the year, and the publisher."This paper discusses the role and operations of consumer Credit Bureaus in the European Union in the context of the economic theories, policies and law within which they work. Across Europe there is no common practice of sharing the credit data of consumers which can be used for several purposes. Mostly, they are used by the lending industry as a practice of creditworthiness assessment or as a risk-management tool to underwrite borrowing decisions or price risk. However, the type, breath, and depth of information differ greatly from country to country. In some Member States, consumer data are part of a broader information centralisation system for the prudential supervision of banks and the financial system as a whole. Despite EU rules on credit to consumers for the creation of the internal market, the underlying consumer data infrastructure remains fragmented at national level, failing to achieve univocal, common, or defined policy objectives under a harmonised legal framework. Likewise, the establishment of the Banking Union and the prudential supervision of the Euro area demand standardisation and convergence of the data used to measure debt levels, arrears, and delinquencies. The many functions and usages of credit data suggest that the policy goals to be achieved should inform the legal and institutional framework of Credit Bureaus, as well as the design and use of the databases. This is also because fundamental rights and consumer protection concerns arise from the sharing of credit data and their expanding use
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