bluuebunny/crossref_metadata_2025 huggingface dataset:
Inovação organizacional em compras públicas pelo SRP: análise da acurácia do planejamento participativo do Instituto Federal do Triângulo Mineiro (IFTM)
Authors: Avigo Ricardo Oliveira , João-Roland Iraci de Souza
Published: August 2019

O Sistema de Registro de Preços (SRP) tem sido amplamente utilizado pelos órgãos públicos no planejamento de suas compras. Contudo, um dos grandes desafios em sua utilização é evitar a superestimação dos quantitativos registrados, isto é, adequá-los às reais demandas do órgão. No intuito de tornar as demandas do SRP mais próximas da realidade, o IFTM promoveu uma inovação em seu processo de planejamento de compras a partir de 2013, tornando-o participativo. Essa pesquisa teve por objetivo avaliar a inovação implementada por meio da análise dos resultados da efetivação das demandas dos registros de preços, a fim de verificar se estes refletiram a demanda real. Para isto, realizou-se um levantamento de todos os itens do planejamento participativo no período de 2013 a 2016, comparando os quantitativos registrados com os efetivamente adquiridos, por meio do indicador GARP – grau de aproximação entre o real e o planejado. Os dados foram submetidos ao teste de duas amostras de Kolmogorov-Smirnov e à escala GARP. Constatou-se que o planejamento participativo não atingiu o objetivo de aproximar as demandas do SRP às reais necessidades do órgão. Como propostas de melhoria, sugeriu-se: adoção do índice do período anterior como subsídio para planejamento de quantitativos; conciliação dos valores licitados com o orçamento; capacitação dos servidores envolvidos; ações de monitoramento e controle e revisão da política de uso do SRP
New Insights into ECCU's Tourism Sector Competitiveness
Authors: Ghazanchyan Manuk , Zhao Li , Brito Steve , Parlak Vivian
Published: August 2019

Tourism has become the main driver of economic growth and employment and the most important source of income in the ECCU. Preserving and, possibly, enhancing the competitiveness of the tourism product is key for these countries. Unfortunately, the evidence shows that tourism arrivals to the ECCU have been declining slightly while global demand for tourism is on the rise. The objective of this paper is to study the structural determinants of competitiveness for the ECCU, defined as the relative cost advantage over other touristic regions (Di Bella, Lewis, and Martin 2007). Using a gravity model, we show that proximity to North American and European markets is indeed an important competitive advantage for the ECCU. However, despite this advantage, and, in some cases, specialization in high-end tourism, regression analysis shows that arrivals to the ECCU are sensitive to relative prices. Our simulations show that mitigating supply-side constraints would improve the ECCU’s competitiveness and allow the region to regain global market shares.
The Interaction of Monetary and Macroprudential Policies - Background Paper
Authors:   International Monetary Fund
Published: August 2019

This paper provides background material to support the Board paper on the interaction of monetary and macroprudential policies. It analyzes the scope for and evidence on interactions between monetary and macroprudential policies. It first reviews a recent conceptual literature on interactive effects that arise when both macroprudential and monetary policy are employed. It goes on to explore the “side effects” of monetary policy on financial stability and their implications for macroprudential policy. It finally addresses the strength of possible effects of macroprudential policies on output and price stability, and draws out implications for the conduct of monetary policy.
Poverty Reduction and Growth Trust - Borrowing Agreement with the National Bank of Belgium
Authors:   International Monetary Fund
Published: August 2019

Effective November 12, 2012, the Fund, as Trustee of the Poverty Reduction and Growth Trust (PRGT), entered into a borrowing agreement (the “Agreement”) with the National Bank of Belgium, by which Belgium will provide new loan resources of up to SDR 350 million (see attachment). With this Agreement, the Fund has concluded fourteen new borrowing agreements providing total resources of SDR 9,811 million in the context of fundraising under the 2009 Low-Income Countries (LICs) financing package.
Fifth Periodic Monitoring Report on the Status of Implementation Plans in Response to Board-Endorsed IEO Recommendations
Authors:   International Monetary Fund
Published: August 2019

Periodic Monitoring Reports update the status on Management Implementation Plans (MIPs) in response to Executive Board-endorsed IEO recommendations. The last Periodic Monitoring Report (PMR) was discussed by the Board Evaluation Committee (EVC) and then agreed by the Board in August 2011. That report concluded that all key performance benchmarks related to the MIPs covered in that report had either been met or were on track for timely completion, that no new remedial actions were proposed, and that there were no outstanding performance benchmarks to be reviewed in the next PMR. In their assessment to the Executive Board, the EVC did, however, note that further work was needed on three other issues—staff mobility, enhanced coverage of previous implementation plans, and the process for following up on IEO recommendations. This fifth report therefore updates work on these three issues, including a consolidated picture of recent progress on all Board-endorsed recommendations made since the first PMR in 2007. This PMR also presents progress on the Implementation Plan in response to Board-endorsed recommendations arising from the IEO Evaluation of IMF Interactions with Member Countries (hereafter, Interactions Evaluation).
Safeguards Assessments - 2012 Update
Authors:   International Monetary Fund
Published: August 2019

The safeguards policy was introduced in 2000 to reduce the risks of misuse of Fund resources and misreporting of program monetary data to the Fund. It supports the Fund’s approach to prudent lending and complements other safeguards such as program design, conditionality, and access limits, to name a few. Some 242 assessments of 92 central banks have been completed since 2000. Assessments are followed by a period of monitoring for as long as Fund credit is outstanding.
Eligibility to Use the Fund's Facilities for Concessional Financing - Republic of South Sudan
Authors:   International Monetary Fund
Published: August 2019

Having become a Fund member in April 2012, South Sudan can now be considered for PRGT eligibility. In February 2012, the Executive Board reviewed the framework for eligibility to use the Fund’s concessional financing facilities and the list of PRGT-eligible countries. During that review, Directors agreed to maintain the PRGT eligibility framework with a modification of the population threshold used to define small countries. Directors also decided to keep the list of PRGT-eligible countries unchanged. Under the framework to assess PRGT eligibility, decisions on entry onto the list of PRGT-eligible countries can be adopted in the period between reviews. As noted in the staff paper for the 2012 review of PRGT eligibility, given the available data, it was expected that South Sudan would be proposed for entry onto the PRGT-eligibility list after it had joined the Fund. Accordingly, this paper proposes that South Sudan now be added to the list of PRGT-eligible countries.
List of IMF Member Countries with Delays in Completion of Article IV Consultations or Mandatory Financial Stability Assessments over 18 Months
Authors:   International Monetary Fund
Published: August 2019

The following table lists the IMF members for which the Article IV consultation or the mandatory financial stability assessment has been delayed by more than 18 months. The delay is counted past the scheduled expected date, plus applicable grace period.
Moldova - Technical Assistance Report on Taking Compliance Management Further
Authors:   International Monetary Fund
Published: August 2019

This report concerns the delivery of a tax administration mission to Moldova during February 8 – 21, 2012 by the Fiscal Affairs Department (FAD) of the IMF as a component of implementing FAD's technical assistance strategy for Southeast Europe.
Statement by the Managing Director on the Work Program of the Executive Board - Executive Board Meeting
Authors:   International Monetary Fund
Published: August 2019

Agenda. Last April was an important milestone for the institution. The commitment to increase Fund resources by over $430 billion on a temporary basis attests to the membership’s willingness to act collectively and decisively to get ahead of the crisis. For our part, we must continue to support these efforts with clear and pointed advice on macro financial policies, and strong and well-designed programs. This is true not only for Europe, where the risks to stability have been acute, but across the span of the membership. We need to continue to offer pragmatic remedies to the main risks confronting the global economy, help members address spillovers, and support their economic transitions and development agendas. We need also to strengthen our internal processes, with reforms of surveillance, quotas and governance. These points, which draw on my Action Plan of last month and feedback from members during the Spring Meetings, are elaborated in the work plan below
Review of the Fund's Income Position for FY 2012 and FY 2013-14
Authors:   International Monetary Fund
Published: August 2019

This paper reviews the Fund’s income position for FY 2012 and FY 2013?14.1 The paper updates projections provided at the FY 2012 midyear review and proposes decisions for the current and next two financial years. These decisions include setting the margin for the rate of charge under the new Rule I-6(4) that the Executive Board adopted in December 2011.2 The new rule is based on principles endorsed by the Executive Board in April 2008 and that have guided decisions on setting the margin since FY 2009. Section II reviews the FY 2012 income position and main changes from the midyear projections; Section III makes proposals on the disposition of net income, and placement to reserves; Section IV discusses the margin on the rate of charge for FY 2013?14, the income outlook for that period, and projected burden sharing adjustments; and Section V reviews special charges.
Framework Administered Account for Select Fund Activities - The Republic of South Sudan Macroeconomic Capacity Building
Authors:   International Monetary Fund
Published: August 2019

In March 2009, the Fund established a new Framework Administered Account to administer external financial resources for Selected Fund Activities (the “SFA Instrument”). The financing of activities under the terms of the SFA Instrument is implemented through the establishment and operation of a subaccount within the SFA. This paper requests Executive Board approval to establish the Republic of South Sudan Macroeconomic Capacity Building Subaccount (the “Subaccount”) under the terms of the SFA Instrument.
Implementation Plan in Response to the Board-Endorsed Recommendations for the IEO Evaluation Report of IMF Response to the Financial and Economic Crisis
Authors:   International Monetary Fund
Published: August 2019

This paper sets out Management’s response to the Independent Evaluation Office’s (IEO) evaluation of IMF Response to the Financial and Economic Crisis.

The implementation plan proposes specific actions focusing on the three of the four recommendations that received broad support from the Executive Board, namely (i) ensuring that the IMF as a quota-based institution has sufficient resources to contribute to future crisis resolution; (ii) developing guidelines for structuring engagements with other organizations, and (iii) consolidating and simplifying the current framework to identify and assess risks and vulnerabilities.

Some of the proposed actions to address the Board-endorsed IEO recommendations are underway as part of the 2014 Triennial Surveillance Report (TSR) Action Plan, the FY2016–18 Medium-Term Budget and the ongoing efforts to ratify the 2010 Quota and Governance Reforms. The paper also explains how implementation will be monitored.
Implementation Plan in Response to the Board-Endorsed Recommendations for the IEO Evaluation of IMF Forecasts - Process, Quality, and Country Perspective
Authors:   International Monetary Fund
Published: August 2019

This paper sets out Management’s response to the Independent Evaluation Office’s (IEO) evaluation of IMF Forecasts: Process, Quality, and Country Perspectives.
The implementation plan proposes specific actions to address the five recommendations that received broad support from the Executive Board, namely
(i) maintaining the practice of commissioning external evaluations of IMF forecasts,
(ii) enhancing the processes and incentives for learning from past forecast performance,
(iii) extending guidance to desk economists on forecasting methodologies,
(iv) publishing a description of the WEO forecasting process, and
(iv) improving the public availability of data related to forecasts and outturns.

Several of the proposed actions to address the Board-endorsed IEO recommendations have already been implemented following the Board discussion, while the implementation of some other actions is underway. This paper also explains how implementation will be monitored.
Update on the Financing of the Fund's Concessional Assistance and Debt Relief to Low-Income Member Countries
Authors:   International Monetary Fund
Published: August 2019

Better targeted support to LICs. In July 2015, the Executive Board approved measures to strengthen the financial safety net for low-income countries. Specifically, access norms and limits to the Poverty Reduction and Growth Trust (PRGT) resources were increased by 50 percent and the Rapid Credit Facility (RCF) interest rate was set permanently at zero. In addition, four countries graduated from PRGT eligibility. Together with a rebalancing of the mix of blended financing towards more use of general Fund resources for better-off PRGT-eligible countries, these reforms were broadly resource neutral and left the PRGT self-sustaining framework intact.

Demand for PRGT resources up strongly. In 2015, demand reached SDR 1.5 billion, largely in response to shocks to commodity prices and adverse global financial market conditions. Demand is expected to remain elevated in 2016, as the global environment continues to be challenging.
State-Contingent Debt Instruments for Sovereigns
Authors:   International Monetary Fund
Published: August 2019

Background. The case for sovereign state-contingent debt instruments (SCDIs) as a countercyclical and risk-sharing tool has been around for some time and remains appealing; but take-up has been limited. Earlier staff work had advocated the use of growth-indexed bonds in emerging markets and contingent financial instruments in low-income countries. In light of recent renewed interest among academics, policymakers, and market participants—staff has analyzed the conceptual and practical issues SCDIs raise with a view to accelerate the development of self-sustaining markets in these instruments. The analysis has benefited from broad consultations with both private market participants and policymakers.

The economic case for SCDIs. By linking debt service to a measure of the sovereign’s capacity to pay, SCDIs can increase fiscal space, and thus allow greater policy flexibility in bad times. They can also broaden the sovereign’s investor base, open opportunities for risk diversification for investors, and enhance the resilience of the international financial system. Should SCDI issuance rise to account for a large share of public debt, it could also significantly reduce the incidence and cost of sovereign debt crises. Some potential complications require mitigation: a high novelty and liquidity premium demanded by investors in the early stage of market development; adverse selection and moral hazard risks; undesirable pricing effects on conventional debt; pro-cyclical investor demand; migration of excessive risk to the private sector; and adverse political economy incentives.
Making Trade an Engine of Growth for All
Authors:   International Monetary Fund
Published: August 2019

The role of trade in the global economy is at a critical juncture. Increased trade integration helped to drive economic growth in advanced and developing economies in the latter part of the 20th century. Since the early 2000’s, however, a slowdown in the pace of trade reform, a post-crisis uptick in protectionism, and risk of further reversals have been a drag on trade, productivity, and income growth. At the same time, trade is leaving too many individuals and communities behind, notably also in advanced economies. To be sure, job losses in certain sectors or regions in advanced economies have resulted to a large extent from technological changes rather than from trade. But adjustment to trade can bring a human and economic downside that is frequently concentrated, sometimes harsh, and has too often become prolonged. It need not be that way. With the right policies, countries can benefit from the great opportunities that trade brings and lift up those who have been left behind. Those polices ease adjustment to trade, as well as strengthen overall economic flexibility and performance.
Machine learning for observation bias correction with application to dust storm data assimilation
Authors: Jin Jianbing , Lin Hai Xiang , Segers Arjo , Xie Yu , Heemink Arnold
Published: August 2019

Abstract. Data assimilation algorithms rely on a basic assumption of an unbiased
observation error. However, the presence of inconsistent measurements with
nontrivial biases or inseparable baselines is unavoidable in practice.
Assimilation analysis might diverge from reality since the data assimilation
itself cannot distinguish whether the differences between model simulations
and observations are due to the biased observations or model deficiencies.
Unfortunately, modeling of observation biases or baselines which show strong
spatiotemporal variability is a challenging task. In this study, we report
how data-driven machine learning can be used to perform observation bias
correction for data assimilation through a real application, which is the
dust emission inversion using PM10 observations. PM10 observations are considered unbiased; however, a bias correction is necessary if they are used as a proxy for dust during dust storms since they actually represent a sum of dust particles and non-dust aerosols. Two observation bias correction methods have been designed in order to use PM10 measurements as proxy for the dust storm loads under severe dust conditions. The first one is the conventional chemistry transport model (CTM) that simulates life cycles of non-dust aerosols. The other one
is the machine-learning model that describes the relations between the
regular PM10 and other air quality measurements. The latter is trained
by learning using 2 years of historical samples. The machine-learning-based non-dust model is shown to be in better agreement with
observations compared to the CTM.
The dust emission inversion tests have been performed, through
assimilating either the raw measurements or the bias-corrected dust observations
using either the CTM or machine-learning model. The emission field, surface
dust concentration, and forecast skill are evaluated. The worst case is when
we directly assimilate the original observations. The forecasts driven by the
a posteriori emission in this case even result in larger errors than the
reference prediction. This shows the necessities of bias correction in data
assimilation. The best results are obtained when using the machine-learning
model for bias correction, with the existing measurements used more
precisely and the resulting forecasts close to reality.
Comparison of equatorial wave activity in the tropical tropopause layer and stratosphere represented in reanalyses
Authors: Kim Young-Ha , Kiladis George N. , Albers John R. , Dias Juliana , Fujiwara Masatomo , Anstey James A. , Song In-Sun , Wright Corwin J. , Kawatani Yoshio , Lott François , Yoo Changhyun
Published: August 2019

Abstract. Equatorial Kelvin and mixed Rossby–gravity (MRG) waves in the tropical tropopause layer and stratosphere represented in recent reanalyses for the period of 1981–2010 are compared in terms of spectral characteristics, spatial structures, long-term variations, and their forcing of the quasi-biennial oscillation (QBO).
For both wave types, the spectral distributions are broadly similar among most of the reanalyses, while the peak amplitudes exhibit considerable spread.
The longitudinal distributions and spatial patterns of wave perturbations show reasonable agreement between the reanalyses.
A few exceptions to the similarity of the spectral shapes and spatial structures among them are also noted.
While the interannual variations of wave activity appear to be coherent for both the Kelvin and MRG waves, there is substantial variability in long-term trends among the reanalyses.
Most of the reanalyses which assimilate satellite data exhibit large increasing trends in wave variance (∼15 %–50 % increase in 30 years at 100–10 hPa), whereas one reanalysis (Japanese 55-year Reanalysis assimilating conventional observations only; JRA-55C) produced without satellite data does not.
Several discontinuities are found around 1998 in the time series of the Kelvin and MRG wave variances, which manifest in different ways depending on the reanalysis, and are indicative of impacts of the transition of satellite measurements during that year.
The equatorial wave forcing of the QBO, estimated by the Eliassen–Palm (EP) flux divergence, occurs in similar phase-speed ranges in the lower stratosphere among the reanalyses.
However, the EP flux and its divergence are found to be dependent on the zonal-mean winds represented in reanalyses, exhibiting different magnitudes, altitudes, and phase-speed ranges of the Kelvin wave forcing between the reanalyses, especially at 20–10 hPa.
In addition, at around 20 hPa, a wave signal which appears only in easterly mean winds with westward phase speeds is found and discussed.
MAX-DOAS measurements of tropospheric NO2 and HCHO in Nanjing and a comparison to ozone monitoring instrument observations
Authors: Chan Ka Lok , Wang Zhuoru , Ding Aijun , Heue Klaus-Peter , Shen Yicheng , Wang Jing , Zhang Feng , Shi Yining , Hao Nan , Wenig Mark
Published: August 2019

Abstract. In this paper, we present long-term observations of atmospheric nitrogen dioxide (NO2) and formaldehyde (HCHO) in Nanjing using a
Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument. Ground-based MAX-DOAS measurements were performed from April 2013 to February 2017. The MAX-DOAS measurements of NO2 and HCHO vertical column densities (VCDs) are used to validate ozone monitoring instrument (OMI) satellite observations over Nanjing. The comparison shows that the OMI observations of NO2 correlate well with the MAX-DOAS data with Pearson correlation coefficient (R) of 0.91. However, OMI observations are on average a factor of 3 lower than the MAX-DOAS measurements. Replacing the a priori NO2 profiles by the MAX-DOAS profiles in the OMI NO2 VCD retrieval would increase the OMI NO2 VCDs by ∼30 % with correlation nearly unchanged. The comparison result of MAX-DOAS and OMI observations of HCHO VCD shows a good agreement with R of 0.75 and the slope of the regression line is 0.99. An age-weighted backward-propagation approach is applied to the MAX-DOAS measurements of NO2 and HCHO to reconstruct the spatial distribution of NO2 and HCHO over the Yangtze River Delta during summer and winter time. The reconstructed NO2 fields show a distinct agreement with OMI satellite observations. However, due to the short atmospheric lifetime of HCHO, the backward-propagated HCHO data do not show a strong spatial correlation with the OMI HCHO observations. The result shows that the MAX-DOAS measurements are sensitive to the air pollution transportation in the Yangtze River Delta, indicating the air quality in Nanjing is significantly influenced by regional transportation of air pollutants. The MAX-DOAS data are also used to evaluate the effectiveness of air pollution control measures implemented during the Youth Olympic Games 2014. The MAX-DOAS data show a significant reduction of ambient aerosol, NO2 and HCHO (30 %–50 %) during the Youth Olympic Games. Our results provide a better understanding of the transportation and sources of pollutants over the Yangtze River Delta as well as the effect of emission control measures during large international events, which are important for the future design of air pollution control policies.
Cloud-venting induced downward mixing of the Central
African biomass burning plume during the West Africa
summer monsoon
Authors: Dajuma Alima , Ogunjobi Kehinde O. , Vogel Heike , Knippertz Peter , Silué Siélé , N'Datchoh Evelyne Touré , Yoboué Véronique , Vogel Bernhard
Published: August 2019

Abstract. Between June and September large amounts of biomass burning aerosol are released into the atmosphere from agricultural fires in Central and southern Africa. Recent studies have suggested that this plume is carried westward over the Atlantic Ocean at altitudes between 2 and 4 km and then northward with the monsoon flow at low levels to increase the atmospheric aerosol load over coastal cities in southern West Africa (SWA), thereby exacerbating air pollution problems. However, the processes by which these fire emissions are transported into the planetary boundary layer are still unclear. One potential factor is the large-scale subsidence related to the southern branch of the monsoon Hadley cell over the tropical Atlantic. Here we use convection-permitting model simulations with COSMO-ART to investigate for the first time to what extent mixing related to cloud venting contributes to the downward transport of the biomass burning plume. Based on a monthly climatology, model simulations compare satisfactory with wind fields from reanalysis data, cloud observations, and satellite retrieved CO mixing ratio. For a case study on 02 July 2016, modelled clouds and rainfall show overall good agreement with Spinning Enhanced Visible and InfraRed Imager (SEVIRI) cloud products and Global Precipitation Measurement Integrated Multi-satellite Retrievals (GPM-IMERG) rainfall estimates. However, there is a tendency for the model to produce too much clouds and rainfall over the Gulf of Guinea. Looking into the CO dispersion, used as an indicator for the biomass burning plume, we identified individual mixing events south of the coast of Côte d’Ivoire due to midlevel convective clouds injecting parts of the biomass burning plume into the boundary layer. This cloud venting is modulated by the underlying sea surface temperatures. Idealized tracer experiments suggest that about 20 % of the CO mass from the 2–4 km layer are mixed below 1km within two days over the Gulf of Guinea. There is even stronger vertical mixing when the biomass burning plume reaches land due to daytime heating. In that case, the long-range transported biomass burning plume is mixed with local anthropogenic emissions. Future work should provide more robust statistics on the cloud venting effect over the Gulf of Guinea and include aspects of aerosol deposition.
Atmospheric fate of a series of Methyl Saturated Alcohols (MSA): Kinetic and Mechanistic study
Authors: Colmenar Inmaculada , Martin Pilar , Cabañas Beatriz , Salgado Sagrario , Tapia Araceli , Aranda Inmaculada
Published: August 2019

Abstract. The atmospheric fate of a series of Methyl Saturated Alcohols (MSA) has been evaluated through the kinetic and reaction product studies with the main atmospheric oxidants. Rate coefficients (in cm3 molecule−1 s−1 unit) measured at ~ 298 K and atmospheric pressure (~ 740 Torr) were as follows: (3.71 ± 0.53) × 10−10, (1.91 ± 0.65) × 10−11 and (2.92 ± 1.38) × 10−15 for reaction of E-4-methyl-cyclohexanol with Cl, OH and NO3, respectively. (2.70 ± 0.55) × 10−10 and (5.57 ± 0.66) × 10−12 for reaction of 3,3-dimethyl-1-butanol with Cl and OH radical respectively and (1.21 ± 0.37) × 10−10 and (10.51 ± 0.81) × 10−12 for reaction of 3,3-dimethyl-2-butanol with Cl and OH radical respectively. The main detected products were 4-methylcyclohexanone, 3,3-dimethylbutanal and 3,3-dimethyl-2-butanone for the reactions of E-4-methyl-cyclohexanol, 3,3-dimethyl-1-butanol and 3,3-dimethyl-2-butanol respectively with the three oxidants. A tentative estimation of yields have been done obtaining the following ranges (25–60) % for 4-methylcyclohexanone, (40–60) % for 3,3-dimethylbutanal and (40–80) % for 3,3-dimethyl-2-butanone. Other products as HCOH, 2,2-dimethylpropanal and acetone have been identified in the reaction of 3,3-dimethyl-1-butanol and 3,3-dimethyl-2-butanol. The yields of these products indicate a hydrogen abstraction mechanism at different sites of the alkyl chain in the case of Cl reaction and a predominant site in the case of OH and NO3 reactions, supported by SAR methods prediction. Tropospheric lifetimes (τ) of these MSA have been calculated using the experimental rate coefficients. Lifetimes are in the range of 0.6–2 days for OH reactions, 8–13 days for NO3 radical reactions and 1–3 months for Cl atoms. In coastal areas the lifetime due to the reaction with Cl decreases to hours. The global tropospheric lifetimes calculated, and the polyfunctional compounds detected as reaction products in this work, imply that the Methyl Saturated Alcohols could contribute to ozone and nitrated compound formation at local, but also regional and even to global scale. Therefore, the use of large saturated alcohols as additives in biofuels must be taken with caution.
Accuracy assessment of MODIS land aerosol optical thickness algorithms using AERONET measurements over North America
Authors: Jethva Hiren , Torres Omar , Yoshida Yasuko
Published: August 2019

Abstract. The planned simultaneous availability of visible and near-IR observations
from the geostationary platforms of Tropospheric Emissions: Monitoring of
Pollution (TEMPO) and Geostationary Operational Environmental Satellites
(GOES) 16/17 Advanced Base Imager (ABI) will present the opportunity of
deriving an accurate aerosol product taking advantage of both ABI's high
spatial resolution in the visible range and TEMPO's sensitivity to aerosol
absorption in the near-UV range. Because the wavelengths of ABI are similar to
those of the Moderate Resolution Imaging Spectroradiometer (MODIS), existing
aerosol algorithms of MODIS can be applied to ABI observations. In this
work, we evaluate three distinct aerosol algorithms of MODIS deriving
aerosol optical thickness (AOT) over land surfaces using visible and near-IR
observations. The Dark Target (DT), Deep Blue (DB), and Multiangle
Implementation of Atmospheric Correction (MAIAC) algorithms are all applied
to the radiance measurements of MODIS on board the Aqua satellite. We have
evaluated each algorithm by comparing the satellite-retrieved AOT to
space-time collocated ground-based sun photometer measurements of the same
parameter at 171 sites of the Aerosol Robotic Network (AERONET) over North
America (NA). A spatiotemporal scheme collocating the satellite retrievals
with the ground-based measurements was applied consistently to all three
retrieval datasets. We find that the statistical performance of all three
algorithms is comparable over darker surfaces over eastern NA with the MAIAC
algorithm providing relatively better comparison over western NA sites
characterized by inhomogeneous elevation and bright surfaces. The higher
spatial resolution of the MAIAC product (1 km) allows a substantially larger
number of matchups than DB 10 km and DT 10 km (DT 3 km) products by 115 %
and 120 % (86 %), respectively, over eastern NA and by 150 % and
220 % (197 %) over western NA. The characterization of the error in AOT
for the three aerosol products as a function of bidirectional surface
reflectance derived from both MAIAC and an
independent MOD09 atmospheric correction shows a systematic positive bias in DT retrievals over brighter
surfaces, whereas DB and MAIAC retrievals show no such bias throughout the
wide range of surface brightness, with MAIAC offering the lowest spread in
errors. The results reported here represent an objective, unbiased
evaluation of existing over-land aerosol retrieval algorithms of MODIS. The
detailed statistical evaluation of the performance of each of these three
algorithms may be used as guidance in the development of inversion schemes
to derive aerosol properties from ABI or other MODIS-like sensors.
Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements
Authors: Cuevas Emilio , Romero-Campos Pedro Miguel , Kouremeti Natalia , Kazadzis Stelios , Räisänen Petri , García Rosa Delia , Barreto Africa , Guirado-Fuentes Carmen , Ramos Ramón , Toledano Carlos , Almansa Fernando , Gröbner Julian
Published: August 2019

Abstract. A comprehensive comparison of more than 70 000 synchronous 1 min aerosol optical depth (AOD) data from three Global Atmosphere Watch precision-filter radiometers (GAW-PFR), traceable to the World AOD reference, and 15 Aerosol Robotic Network Cimel radiometers (AERONET-Cimel), calibrated individually with the Langley plot technique, was performed for four common or “near” wavelengths, 380, 440, 500 and 870 nm, in the period 2005–2015. The goal of this study is to assess whether, despite the marked technical differences between both networks (AERONET, GAW-PFR) and the number of instruments used, their long-term AOD data are comparable and consistent. The percentage of data meeting the World Meteorological Organization (WMO) traceability requirements (95 % of the AOD differences of an instrument compared to the WMO standards lie within specific limits) is >92 % at 380 nm, >95 % at 440 nm and 500 nm, and 98 % at 870 nm, with the results being quite similar for both AERONET version 2 (V2) and version 3 (V3). For the data outside these limits, the contribution of calibration and differences in the calculation of the optical depth contribution due to Rayleigh scattering and O3 and NO2 absorption have a negligible impact. For AOD >0.1, a small but non-negligible percentage (∼1.9 %) of the AOD data outside the WMO limits at 380 nm can be partly assigned to the impact of dust aerosol forward scattering on the AOD calculation due to the different field of view of the instruments. Due to this effect the GAW-PFR provides AOD values, which are ∼3 % lower at 380 nm and ∼2 % lower at 500 nm compared with AERONET-Cimel. The comparison of the Ångström exponent (AE) shows that under non-pristine conditions (AOD >0.03 and AE <1) the AE differences remain <0.1. This long-term comparison shows an excellent traceability of AERONET-Cimel AOD with the World AOD reference at 440, 500 and 870 nm channels and a fairly good agreement at 380 nm, although AOD should be improved in the UV range.
Morphology and Raman spectra of aerodynamically classified soot samples
Authors: Baldelli Alberto , Rogak Steven Nicholas
Published: August 2019

Abstract. Airborne soot is emitted from combustion processes as aggregates
of primary particles. The size of the primary particles and the overall
aggregate size control soot transport properties, and prior research shows
that these parameters may be related to the soot nanostructure. In this
work, a laminar, inverted nonpremixed burner has been used as a source of
soot that is almost completely elemental carbon. The inverted burner was
connected to an electrical low-pressure impactor, which collected
particles on stages according to the aerodynamic diameter, from 0.03 to 10 µm. The morphology was analyzed using a transmission electron
microscope followed by image processing to extract projected area and
average primary particle size for each aggregate (approximately 1000
aggregates analyzed in total for the nine impactor stages). Carbon
nanostructure was analyzed using a Raman spectrometer, and five vibrational
bands (D4, D1, D3, G, and D2) were fitted to the spectra to obtain an
estimate of the carbon disorder. The average primary particle diameter
increases from 15 to 30 nm as the impactor stage aerodynamic diameter
increases. The D1, D3, D2, and D4 bands decreased (relative to the G band)
with the particle size, suggesting that the larger aggregates have larger
graphitic domains.
kCARTA: A fast pseudo line-by-line radiative transfer algorithmwith analytic Jacobians, fluxes, Non-Local ThermodynamicEquilibrium and scattering for the infrared
Authors: DeSouza-Machado Sergio , Strow L. Larrabee , Motteler Howard , Hannon Scott
Published: August 2019

Abstract. A fast pseudo-monochromatic radiative transfer package using a Singular Value Decomposition (SVD) compressed atmospheric optical depth database has been developed, primarily for use with hyperspectral sounding instruments. The package has been tested extensively for clear sky radiative transfer cases, using field campaign data and satellite instrument data. The current database uses HITRAN 2016 line parameters and is primed for use in the spectral region spanning 605 cm−1 to 2830 cm−1 (with a point spacing of 0.0025 cm−1), but can easily be extended to other regions. The clear sky radiative transfer model computes the background thermal radiation quickly and accurately using a layer-varying diffusivity angle at each spectral point; it takes less than 20 seconds (on a 2.8 GHz core using 4 threads) to complete a radiance calculation spanning the infrared. The code can also compute Non Local Thermodynamic Equilibrium effects for the 4 μm CO2 region, as well as analytic temperature, gas and surface jacobians. The package also includes flux and heating rate calculations, and an interface to a scattering model.
A novel isotope pool dilution approach to quantify gross rates of key abiotic and biological processes in the soil phosphorus cycle
Authors: Wanek Wolfgang , Zezula David , Wasner Daniel , Mooshammer Maria , Prommer Judith
Published: August 2019

Abstract. Efforts to understand and model the current and future behavior of the global
phosphorus (P) cycle are limited by the availability of global data on rates of soil P processes, as well as their environmental controls. Here, we present a novel isotope pool dilution approach using 33P labeling of live and sterile soils, which allows for high-quality data on gross fluxes of soil inorganic P (Pi) sorption and desorption, as well as of gross fluxes of organic P mineralization and microbial Pi uptake to be obtained. At the same time, net immobilization of 33Pi by soil microbes and abiotic
sorption can be easily derived and partitioned. Compared with other approaches, we used short incubation times (up to 48 h), avoiding tracer
remineralization, which was confirmed by the separation of organic P and Pi using isobutanol fractionation. This approach is also suitable for strongly weathered and P-impoverished soils, as the sensitivity is increased by the extraction of exchangeable bioavailable Pi (Olsen Pi; 0.5 M NaHCO3)
followed by Pi measurement using the malachite green assay. Biotic
processes were corrected for desorption/sorption processes using adequate
sterile abiotic controls that exhibited negligible microbial and
extracellular phosphatase activities. Gross rates were calculated using
analytical solutions of tracer kinetics, which also allowed for the study of gross
soil P dynamics under non-steady-state conditions. Finally, we present major
environmental controls of gross P-cycle processes that were measured for
three P-poor tropical forest and three P-rich temperate grassland soils.
Seeking enlightenment of fluvial sediment pathways by optically stimulated luminescence signal bleaching of river sediments and deltaic deposits
Authors: Chamberlain Elizabeth L. , Wallinga Jakob
Published: August 2019

Abstract. Reconstructing sediment pathways in fluvial and deltaic systems
beyond instrumental records is challenging due to a lack of suitable
methods. Here we explore the potential of luminescence methods for such
purposes, focusing on bleaching of the optically stimulated luminescence
(OSL) signal of quartz sediments in a large fluviodeltaic system across time
and space. We approach this by comparing residual doses of sand and silt
from the modern Mississippi River channel with estimated residual doses of
sand isolated from Late Holocene Mississippi Delta mouth bar and overbank
deposits. Further insight is obtained from a comparison of burial ages of
paired quartz sand and silt of Mississippi Delta overbank deposits.
In contrast to some previous investigations, we find that the bleaching of the
OSL signal is at least as likely for finer sediment as for coarser sediment
of the meandering Mississippi River and its delta. We attribute this to the
differences in light exposure related to transport mode (bedload vs.
suspended load). In addition, we find an unexpected spatiotemporal pattern in
OSL bleaching of mouth bar sand deposits. We suggest this may be caused by
changes in upstream pathways of the meandering channel belt(s) within the
alluvial valley or by distributary channel and coastal dynamics within the
delta. Our study demonstrates that the degree of OSL signal bleaching of
sand in a large delta can be highly time- and/or space-dependent. Silt is
shown to be generally sufficiently bleached in both the modern Mississippi
River and associated paleo-deposits regardless of age, and silt may therefore provide a
viable option for obtaining OSL chronologies in megadeltas. Our work
contributes to initiatives to use luminescence signals to fingerprint
sediment pathways within river channel networks and their deltas and also
helps inform luminescence dating approaches in fluviodeltaic environments.
Weakly coupled atmospheric-ocean data assimilation in the Canadian global prediction system (v1)
Authors: Skachko Sergey , Buehner Mark , Laroche Stéphane , Lapalme Ervig , Smith Gregory , Roy François , Surcel-Colan Dorina , Bélanger Jean-Marc , Garand Louis
Published: August 2019

Abstract. A fully coupled atmosphere-ocean-ice model has been used to produce global weather forecasts at Environment and Climate Change Canada (ECCC) since November 2017. Currently, the system relies on four uncoupled data assimilation (DA) components for initializing the fully coupled global atmosphere-ocean-ice forecast model: atmosphere, ocean, sea ice and sea surface temperature (SST). The goal of the present study is to implement a weakly coupled data assimilation (WCDA) between the atmosphere and the ocean components and evaluate its performance against uncoupled DA. The WCDA system uses coupled atmosphere-ocean-ice short-term forecasts as background states for the atmospheric and the ocean DA components that independently compute atmospheric and ocean analyses. This system leads to better agreement between the coupled atmosphere-ocean analyses and the coupled atmosphere-ocean-ice forecasts than between the uncoupled analyses and the coupled forecasts. The use of WCDA improves the atmospheric forecast score near the surface, but a slight increase in the atmospheric temperature bias is observed. A small positive impact from using the short-term SST forecast on the satellite radiance Observation-minus-Forecast statistics is noted. Ocean temperature and salinity forecasts are also improved near the surface. Next steps toward stronger DA coupling are highlighted.
Replication of ecologically relevant hydrological indicators following a modified covariance approach to hydrological model parameterization
Authors: Visser-Quinn Annie , Beevers Lindsay , Patidar Sandhya
Published: August 2019

Abstract. Hydrological models can be used to assess the impact of
hydrologic alteration on the river ecosystem. However, there are
considerable limitations and uncertainties associated with the replication
of ecologically relevant hydrological indicators. Vogel and
Sankarasubramanian's 2003 (Water Resources Research) covariance approach to
model evaluation and parameterization represents a shift away from
algorithmic model calibration with traditional performance measures
(objective functions). Using the covariance structures of the observed input
and simulated output time series, it is possible to assess whether the
selected hydrological model is able to capture the relevant underlying
processes. From this plausible parameter space, the region of parameter
space which best captures (replicates) the characteristics of a hydrological
indicator may be identified. In this study, a modified covariance approach
is applied to five hydrologically diverse case study catchments with a view
to replicating a suite of ecologically relevant hydrological indicators
identified through catchment-specific hydroecological models. The
identification of the plausible parameter space (here n≈20) is
based on the statistical importance of these indicators. Evaluation is with
respect to performance and consistency across each catchment, parameter set,
and the 40 ecologically relevant hydrological indicators considered. Timing
and rate of change indicators are the best and worst replicated
respectively. Relative to previous studies, an overall improvement in
consistency is observed. This study represents an important advancement
towards the robust application of hydrological models for ecological flow
studies.
Estimation of evapotranspiration by FAO Penman–Monteith Temperature and Hargreaves–Samani models under temporal and spatial criteria. A case study in Duero Basin (Spain)
Authors: Moratiel Rubén , Bravo Raquel , Saa Antonio , Tarquis Ana M. , Almorox Javier
Published: August 2019

Abstract. Use of the Evapotranspiration based scheduling method is the most common one for irrigation programming in agriculture. There is no doubt that the estimation of the reference evapotranspiration (ETo) is a key factor in irrigated agriculture. However, the high cost and maintenance of agrometeorological stations and high number of sensors required to estimate it creates a non-plausible situation especially in rural areas. For this reason the estimation of ETo using air temperature, in places where wind speed, solar radiation and air humidity data are not readily available, is particularly attractive. Daily data record of 49 stations distributed over Duero basin (Spain), for the period 2000–2018, were used for estimation of ETo based on seven models against Penman–Monteith FAO 56 with temporal (annual or seasonal) and spatial perspective. Two Hargreaves–Samani models (HS), with and without calibration, and five Penman–Monteith temperature models (PMT) were used in this study. The results show that the models' performance changes considerably depending on whether the scale is annual or seasonal. The performance of the seven models was acceptable from an annual perspective (R2 > 0.91, NSE > 0.88, MAE
Periodic dynamic induction control of wind farms: proving the potential in simulations and wind tunnel experiments
Authors: Frederik Joeri , Weber Robin , Cacciola Stefano , Campagnolo Filippo , Croce Alessandro , Bottasso Carlo , van Wingerden Jan-Willem
Published: August 2019

Abstract. In this paper, the potential of Dynamic Induction Control (DIC), which has shown promising results in recent simulation studies, is further investigated. When this control strategy is implemented, a turbine varies its induction factor dynamically over time. In this paper, only periodic variation, where the input is a sinusoid, are studied. A proof of concept for this periodic DIC approach will be given by execution of scaled wind tunnel experiments, showing for the first time that this approach can yield power gains in real-world wind farms. Furthermore, the effects on the Damage Equivalent Loads (DEL) of the turbine are evaluated in a simulation environment. These indicate that the increase in DEL on the excited turbine is limited.