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Mahajan, A. S. . et. al.-- 9 pages, 6 figures, supplementary material related to this article is available online at: http://www.atmos-chem-phys.net/12/11609/2012/acp-12-11609-2012-supplement.pdf ; Ship-based Multi-Axis Differential Optical Absorption Spectroscopy measurements of iodine monoxide (IO) and atmospheric and seawater Gas Chromatography-Mass Spectrometer observations of methyl iodide (CH3I) were made in the Eastern Pacific marine boundary layer during April 2010 as a part of the HaloCarbon Air Sea Transect-Pacific (HaloCAST-P) scientific cruise. The presence of IO in the open ocean environment was confirmed, with a maximum differential slant column density of 5 × 1013 molecules cm -2 along the 1 elevation angle (corresponding to approximately 1 pptv) measured in the oligotrophic region of the Southeastern Pacific. Such low IO mixing ratios and their observed geographical distribution are inconsistent with satellite estimates and with previous understanding of oceanic sources of iodine. A strong correlation was observed between reactive iodine (defined as IO + I) and CH3I, suggesting common sources. In situ measurements of meteorological parameters and physical ocean variables, along with satellite-based observations of Chlorophyll a(Chl a) and Chromophoric Dissolved Organic Matter (CDOM) were used to gain insight into the possible sources of iodine in this remote environment. Surprisingly, reactive iodine showed a negative correlation (> 99% confidence) to Chl a and CDOM across the cruise transect. However, a significant positive correlation (> 99% confidence) with sea surface temperature (SST) and salinity instead suggests a widespread abiotic source related to the availability of aqueous iodine and to temperature. © Author(s) 2012. CC Attribution 3.0 License ; The Spanish Research Council and the Regional Government of Castilla-La Mancha funded this work. S. Yvon-Lewis acknowledges funding from the National Science Foundation (NSF/OCE 0927874) supporting the shiptime and the halocarbon measurements ; Peer Reviewed

We have analyzed the record-breaking drought that affected western and central Europe from July 2016 to June 2017. It caused widespread impacts on water supplies, agriculture, and hydroelectric power production, and was associated with forest fires in Iberia. Unlike common continental-scale droughts, this event displayed a highly unusual spatial pattern affecting both northern and southern European regions.Drought conditions were observed over 90% of central-western Europe, hitting record-breaking values (with respect to 1979-2017) in 25%of the area. Therefore, the event can be considered as themost severe European drought at the continental scale since at least 1979. Themain dynamical forcing of the drought was the consecutive occurrence of blocking and subtropical ridges, sometimes displaced from their typical locations. This led to latitudinal shifts of the jet stream and record-breaking positive geopotential height anomalies over most of the continent. The reduction in moisture transport from the Atlantic was relevant in the northern part of the region, where decreased precipitation and increased sunshine duration were the main contributors to the drought. On the other hand, thermodynamic processes, mostly associated with high temperatures and the resulting increase in atmospheric evaporative demand, were more important in the south. Finally, using flow circulation analogs we show that this drought was more severe than it would have been in the early past. ; J. M. G-P. was supported by the predoctoral research grant awarded by the Spanish Ministerio de Educación, Cultura y Deporte (FPU16/01972). C.O. acknowledges funding by the Ramón y Cajal Programme (Grant RYC-2014-15036) and the STEADY project (Grant CGL2017-83198-R) funded by the Spanish Ministerio de Economía y Competitividad. S.M.V-S. was supported by the DESEMON research project funded by the Spanish Ministerio de Economía y Competitividad and FEDER (Grant CGL2014-52135-C03-01), the IMDROFLOOD project financed by the Water Works 2014 co-funded call of the European Commission (Grant PCIN-2015-220), and the INDECIS project, which is part of ERA4CS, and ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462). R.N., L.G. and R.S. were partially supported by Xunta de Galicia under Project ED431C 2017/64-GRC "Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas (Grupos de Referencia Competitiva)." R.N and L.G were also supported by Water JPI—WaterWorks Programme under project Improving Drought and Flood Early Warning, Forecasting and Mitigation (IMDROFLOOD) (Code: PCIN-2015-243). L.G. was also supported by the Spanish Government and FEDER through the SETH project (Grant CGL2014-60849-JIN). R.S. would like to acknowledge funding by the Xunta of Galicia, Spain, in support of his doctoral research. P.Y. was supported by the ERC Grant 338965-A2C2. We acknowledge the E-OBS dataset from the EU-FP6 project ENSEMBLES (http://ensembles-eu.metoffice.com) and the data providers in the ECA&D project (http://www.ecad.eu), as well as the GPCC monthly land-surface precipitation dataset (https://www.dwd.de/EN/ourservices/gpcc/gpcc.html). ERA data products provided courtesy of ECMWF. NCEP–NCAR reanalysis data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their web site at http://www.esrl.noaa.gov/psd/. The authors thank two anonymous reviewers for their useful comments.