Column aerosol optical properties and aerosol radiative forcing during a serious haze-fog month over North China Plain in 2013 based on ground-based sunphotometer measurements

In January 2013, North China Plain experienced several serious haze events. Cimel sunphotometer measurements at seven sites over rural, suburban and urban regions of North China Plain from 1 to 30 January 2013 were used to further our understanding of spatial-temporal variation of aerosol optical parameters and aerosol radiative forcing (ARF). It was found that Aerosol Optical Depth at 500 nm (AOD500 nm) during non-pollution periods at all stations was lower than 0.30 and increased significantly to greater than 1.00 as pollution events developed. The Angstrom exponent (Alpha) was larger than 0.80 for all stations most of the time. AOD500 nm averages increased from north to south during both polluted and non-polluted periods on the three urban sites in Beijing. The fine mode AOD during pollution periods is about a factor of 2.5 times larger than that during the non-pollution period at urban sites but a factor of 5.0 at suburban and rural sites. The fine mode fraction of AOD675 nm was higher than 80% for all sites during January 2013. The absorption AOD675 nm at rural sites was only about 0.01 during pollution periods, while ~0.03–0.07 and 0.01–0.03 during pollution and non-pollution periods at other sites, respectively.This work is financially supported by grants from the National Key Project of Basic Research (2011CB403401 and 2014CB441201), the Project (41005086, 41275167 and 41130104) supported by NSFC, the Strategic Priority Research Programme of the Chinese Academy of Sciences (Grant no. XDA05100301), CAMS Basis Research Project (2012Y02 and 2013Z007). Cimel master calibration of CARSNET was performed at the AERONET-EUROPE calibration center (LOA and AEMET-Tenerife), supported by ACTRIS (European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 262254

Evaluation of night-time aerosols measurements and lunar irradiance models in the frame of the first multi-instrument nocturnal intercomparison campaign

The first multi-instrument nocturnal aerosol optical depth (AOD) intercom-parison campaign was held at the high-mountain Iza ̃na Observatory (Tener-ife, Spain) in June 2017, involving 2-minutes synchronous measurements fromtwo different types of lunar photometers (Cimel CE318-T and Moon Preci-sion Filter Radiometer, LunarPFR) and one stellar photometer. The Robotic Lunar Observatory (ROLO) model developed by the U.S. Geological Survey(USGS) was compared with the open-access ROLO Implementation for Moonphotometry Observation (RIMO) model. Results showed rather small differ-ences at Iza ̃na over a 2-month time period covering June and July, 2017(±0.01 in terms of AOD calculated by means of a day/night/day coherencetest analysis and±2 % in terms of lunar irradiance). The RIMO model hasbeen used in this field campaign to retrieve AOD from lunar photometricmeasurements. No evidence of significant differences with the Moon’s phase angle wasfound when comparing raw signals of the six Cimel photometers involved inthis field campaign.The raw signal comparison of the participating lunar photometers (Cimeland LunarPFR) performed at coincident wavelengths showed consistent mea-surements and AOD differences within their combined uncertainties at 870 nmand 675 nm. Slightly larger AOD deviations were observed at 500 nm, point-ing to some unexpected instrumental variations during the measurement pe-riod.Lunar irradiances retrieved using RIMO for phase angles varying between0◦and 75◦(full Moon to near quarter Moon) were compared to the irradi-ance variations retrieved by Cimel and LunarPFR photometers. Our resultsshowed a relative agreement within±3.5 % between the RIMO model andthe photometer-based lunar irradiances.The AOD retrieved by performing a Langley-plot calibration each nightshowed a remarkable agreement (better than 0.01) between the lunar pho-tometers. However, when applying the Lunar-Langley calibration using RIMO,AOD differences of up to 0.015 (0.040 for 500 nm) were found, with differ-ences increasing with the Moon’s phase angle. These differences are thoughtto be partly due to the uncertainties in the irradiance models, as well asinstrumental deficiencies yet to be fully understood.High AOD variability in stellar measurements was detected during thecampaign. Nevertheless, the observed AOD differences in the Cimel/stellarcomparison were within the expected combined uncertainties of these twophotometric techniques. Our results indicate that lunar photometry is amore reliable technique, especially for low aerosol loading conditions.The uncertainty analysis performed in this paper shows that the com-bined standard AOD uncertainty in lunar photometry is dependent on thecalibration technique (up to 0.014 for Langley-plot with illumination-basedcorrection, 0.012-0.022 for Lunar-Langley calibration, and up to 0.1 for the 2 Sun-Moon Gain Factor method). This analysis also corroborates that theuncertainty of the lunar irradiance model used for AOD calculation is withinthe 5-10 % expected range.This campaign has allowed us to quantify the important technical diffi-culties that still exist when routinely monitoring aerosol optical propertiesat night-time. The small AOD differences observed between the three typesof photometers involved in the campaign are only detectable under pristinesky conditions such as those found in this field campaign. Longer campaignsare necessary to understand the observed discrepancies between instrumentsas well as to provide more conclusive results about the uncertainty involvedin the lunar irradiance model

Assessment of Sun photometer Langley calibration at the high-elevation sites Mauna Loa and Izaña

The aim of this paper is to analyze the suitability of the high-mountain stations Mauna Loa and Izaña for Langley plot calibration of Sun photometers. Thus the aerosol optical depth (AOD) characteristics and seasonality, as well as the cloudiness, have been investigated in order to provide a robust estimation of the calibration uncertainty as well as the number of days that are suitable for Langley calibrations. The data used for the investigations belong to the AERONET and GAW-PFR networks, which maintain reference Sun photometers at these stations with long measurement records: 22 years at Mauna Loa and 15 years at Izaña. In terms of clear-sky and stable aerosol conditions, Mauna Loa (3397&thinsp;m&thinsp;a.s.l.) exhibits on average 377 Langley plots (243 morning and 134 afternoon) per year suitable for Langley plot calibration, whereas Izaña (2373&thinsp;m&thinsp;a.s.l.) shows 343 Langley plots (187 morning and 155 afternoon) per year. The background AOD (500&thinsp;nm) values, on days that are favorable for Langley calibrations, are in the range 0.01–0.02 throughout the year, with well-defined seasonality that exhibits a spring maximum at both stations plus a slight summer increase at Izaña. The statistical analysis of the long-term determination of extraterrestrial signals yields to a calibration uncertainty of  ∼ &thinsp;0.25–0.5&thinsp;%, this uncertainty being smaller in the visible and near-infrared wavelengths and larger in the ultraviolet wavelengths. This is due to atmospheric variability produced by changes in several factors, mainly the AOD. The uncertainty cannot be reduced based only on quality criteria of individual Langley plots and averaging over several days is shown to reduce the uncertainty to the needed levels for reference Sun photometers.</p

Coalition governance and foreign policy decision making

This article explores processes of coalition governance in foreign policy. Specifically, it argues that such processes are shaped by two interrelated dimensions of coalition set-up: first, the allocation of the foreign ministry to the senior or a junior coalition partner and, second, the degree of policy discretion which is delegated to that ministry. Bringing these two dimensions together, the article distinguishes four types of coalition arrangement for the making of foreign policy, which are expected to have predictable implications for the process of foreign policy-making and, ultimately, for the foreign policy outputs of multi-party coalitions and their quality

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high levels of atmospheric pollutants or intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign, with the main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 and 0.6 (at 440 nm) over the western and central Mediterranean basins. One important point of this experiment concerns the direct observations of aerosol extinction onboard the ATR-42, using the CAPS system, showing local maxima reaching up to 150Mm(-1) within the dust plume. Non-negligible aerosol extinction (about 50Mm(-1)) has also been observed within the marine boundary layer (MBL). By combining the ATR- 42 extinction coefficient observations with absorption and scattering measurements, we performed a complete optical closure revealing excellent agreement with estimated optical properties. This additional information on extinction properties has allowed calculation of the dust single scattering albedo (SSA) with a high level of confidence over the western Mediterranean. Our results show a moderate variability from 0.90 to 1.00 (at 530 nm) for all flights studied compared to that reported in the literature on this optical parameter. Our results underline also a relatively low difference in SSA with values derived near dust sources. In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea spray and pollution located within the MBL, and mineral dust and/or aged North American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations allow one to investigate the vertical structure of the aerosol size distribution showing particles characterized by a large size (> 10 μm in diameter) within dust plumes. In most of cases, a coarse mode characterized by an effective diameter ranging between 5 and 10 μm, has been detected above the MBL. In terms of shortwave (SW) direct forcing, in situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the aerosol direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to (-90)Wm(-2) at noon). Aircraft observations provide also original estimates of the vertical structure of SW and LW radiative heating revealing significant instantaneous values of about 5 K per day in the solar spectrum (for a solar angle of 30 ) within the dust layer. Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about -10 to -20Wm(-2) (for the whole period) over the Mediterranean Sea together with maxima (-50Wm(-2)) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa. Finally, a multiyear simulation, performed for the 2003 to 2009 period and including an ocean–atmosphere (O–A) coupling, underlines the impact of the aerosol direct radiative forcing on the sea surface temperature, O–A fluxes and the hydrological cycle over the Mediterranean.French National Research Agency (ANR) ANR-11-BS56-0006ADEMEFrench Atomic Energy CommissionCNRS-INSU and Meteo-France through the multidisciplinary programme MISTRALS (Mediterranean Integrated Studies aT Regional And Local Scales)CORSiCA project - Collectivite Territoriale de Corse through Fonds Europeen de Developpement Regional of the European Operational ProgramContrat de Plan Etat-RegionEuropean Union's Horizon 2020 research and innovation program 654169Spanish Ministry of Economy and Competitivity TEC2012-34575Science and Innovation UNPC10-4E-442European Union (EU)Department of Economy and Knowledge of the Catalan Autonomous Government SGR 583Andalusian Regional Government P12-RNM-2409Spanish Government CGL2013-45410-R 26225

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Coping Strategies in Post-War Rural Mozambique

This paper analyses post-war coping strategies by farm households in developing countries. The analysis is based on a portfolio model of activity choices in war-affected rural Sub- Saharan Africa. A case study using farm household survey data estimates the determinants of agricultural coping strategies in post-war Mozambique. Post-war coping strategies differ from pre- and mid-crisis coping strategies. War-affected households are forced to adopt very risky coping strategies that re-enforce their vulnerability. Households choose between market and non-market forms of exchange and even consider exiting markets entirely. Post-war reconstruction policy should focus on re-capitalizing households, providing public goods and establishing markets

Nuclear contestation in South Asia

India's claims for regional hegemony have regularly been contested since its independence in 1947. The self-proclaimed emerging power is locked in an enduring rivalry with the South Asian secondary power, Pakistan. This article outlines the evolution of Pakistan's contestation since independence and seeks to demonstrate how, when and why Pakistan adapted its foreign policy toward India. While the goals of Pakistan's contestation remained constant, its means varied at two points in post-independence history. From 1947 to 1971, territorial disputes combined with a nascent nationalism drove the secondary power's foreign policy elite to engage in war and open resistance, and the divergent domestic political ideologies of both countries complicated conflict resolution. With Pakistan's devastating war defeat in 1971, direct means of contestation were no longer an immediate option, and a period of reluctant acquiescence ensued. The alleged involvement of Pakistani intelligence proxies in a crisis in Jammu and Kashmir in 1987 marked the beginning of a renewed phase of resistance, though now through indirect means of nuclear coercion and subconventional warfare. This form of contestation has increasingly manifested itself in bilateral crises with high potential of escalation and primarily targeted symbols of India's South Asian hegemony, including its political and commercial centres in Delhi and Mumbai in 2001 and 2008 respectively or India's diplomatic representations in Afghanistan. The article concludes that the current conditions of regional contestation in South Asia, most importantly the persistent revisionist versus status-quo domestic agendas, the presence of growing nuclear arsenals, and multi-tiered Asian rivalry constellations, undermine prospects for conflict resolution and complicate modelling future strategic behaviour in the region.The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020

Opening the Black Box of Finance: North–South Investment, Political Risk, and US Military Intervention

In this article, we examine the foreign policy implications of different types of investment flows. North–South investment is more sensitive to political risks (expropriation, default, civil war) than North–North investment. We argue that North–South investment flows create a constituency within the US financial sector that is likely to support stabilising intervention – military intervention aimed at reducing political risk abroad. Examining political action committee donations from Fortune 500 financial firms with a cross-sectional Tobit model, we find that US financial firms with greater exposure to the Global South are likely to favour congressional candidates with a record of voting for intervention in developing countries. This study contributes to the literature on economic interdependence and peace, proposes an original method for capturing the revealed preferences of political actors, and enhances our understanding of the sectoral underpinnings of foreign policy-making.The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020

Coalitions and foreign policy making: Insights from the global south

The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020