Search results for "RCA"

High gas-phase mixing ratios of formic and acetic acid in the High Arctic

2018

Abstract. Formic and acetic acid are ubiquitous and abundant in the Earth's atmosphere and are important contributors to cloud water acidity, especially in remote regions. Their global sources are not well understood, as evidenced by the inability of models to reproduce the magnitude of measured mixing ratios, particularly at high northern latitudes. The scarcity of measurements at those latitudes is also a hindrance to understanding these acids and their sources. Here, we present ground-based gas-phase measurements of formic acid (FA) and acetic acid (AA) in the Canadian Arctic collected at 0.5 Hz with a high-resolution chemical ionization time-of-flight mass spectrometer using the iodide …

Iron mineralogy and aqueous alteration from Husband Hill through Home Plate at Gusev Crater, Mars: Results from the Mössbauer instrument on the Spiri…

2008

[1] Spirit's Mossbauer (MB) instrument determined the Fe mineralogy and oxidation state of 71 rocks and 43 soils during its exploration of the Gusev plains and the Columbia Hills (West Spur, Husband Hill, Haskin Ridge, northern Inner Basin, and Home Plate) on Mars. The plains are predominantly float rocks and soil derived from olivine basalts. Outcrops at West Spur and on Husband Hill have experienced pervasive aqueous alteration as indicated by the presence of goethite. Olivine-rich outcrops in a possible mafic/ultramafic horizon are present on Haskin Ridge. Relatively unaltered basalt and olivine basalt float rocks occur at isolated locations throughout the Columbia Hills. Basalt and oliv…

Further examination of the thermodynamic modification of the inflow layer of tropical cyclones by vertical wind shear

2013

Recent work has developed a new framework for the impact of vertical wind shear on the intensity evolution of tropical cyclones. A focus of this framework is on the frustration of the tropical cyclone's power machine by shear-induced, persistent downdrafts that flush relatively cool and dry (lower equivalent potential temperature, θ<sub>e</sub>) air into the storm's inflow layer. These previous results have been based on idealised numerical experiments for which we have deliberately chosen a simple set of physical parameterisations. Before efforts are undertaken to test the proposed framework with real atmospheric data, we assess here the robustness of our previous res…

Relationship between the effective cloud optical depth and different atmospheric transmission factors

2015

This study examines the sensitivity of cloud optical depth (COD) for overcast conditions to radiation transmission using data collected in Valencia, Spain. These relationships are provided as simple empirical functions, therefore avoiding the need to apply complex model minimisation schemes to obtain COD. Comparisons are presented between COD obtained by a minimization method and several radiation transmission factors comprising a clearness index (kt), a modified version (kt'), a cloud modification factor (CMF) and its modified version (CMF'). Additionally, a statistical model of COD proposed by J.C. Barnard and C.N. Long (2004) is tested with our data. Statistical relationships between COD…

Reproducing cloud microphysical and irradiance measurements using three 3D cloud generators

2007

Using three cloud generators, three-dimensional (3D) cloud fields are reproduced from microphysical cloud data measured in situ by aircraft. The generated cloud fields are used as input to a 3D radiative transfer model to calculate the corresponding fields of downward and upward irradiance, which are then compared with airborne and ground-based radiation measurements. One overcast stratocumulus scene and one broken cumulus scene were selected from the European INSPECTRO field experiment, which was held in Norwich, UK, in September 2002. With these data, the characteristics of the three different cloud reproduction techniques are assessed. Besides vertical profiles and histograms of measured…

Influence of cloudiness over the values of erythemal radiation in Valencia, Spain

2009

The influence of cloudiness over experimental UV erythemal radiation (UVER) has been studied. This influence has been analysed considering total cloudiness and low clouds. The measurements of cloudiness correspond to the daily values registered at 13:00 GMT at the Meteorological Centre of Valencia, which is part of the State Agency of Meteorology of Spain (AEMET). The UVER measurements were made using a YES UVB-1 radiometer located on the roof terrace of the Physics Faculty at the Burjassot Campus, Valencia (latitude 39.508° , longitude − 0.418° , 60 m above sea level). First, a statistical analysis of cloudiness at 13:00 GMT in Valencia was carried out, confirming that the situation is mai…

Effective cloud optical depth for overcast conditions determined with a UV radiometers

2014

Using a sky camera, episodes characterized by overcast low clouds in the Valencia region of Spain have been selected for analysis. One year of cloud optical depth data have been produced by inverting UV erythemal irradiance measured with a UVB-1 radiometer from Yankee Environmental Systems using the LibRadtran radiative transfer model. Measurement uncertainties, aerosol single scattering albedo and cloud properties are, in order of decreasing importance, the most important factors influencing the accuracy of cloud optical depth retrieval when using UV erythemal radiometers. Statistics for cloud optical depth show a highly skewed frequency distribution best described by a gamma distribution …

Impaired circadian heart rate variability in Parkinson’s disease: a time-domain analysis in ambulatory setting

2020

Abstract Background Heart rate variability (HRV) decreases in Parkinson’s disease (PD) and it can be considered a marker for cardiovascular dysautonomia. The purpose of this pilot study is to evaluate long-term time-domain analysis of HRV of PD patients and compare the results with those of matched healthy individuals. Methods Idiopathic PD patients without comorbidity impairing HRV, and age-matched healthy individuals were recruited in a pilot study. A long-term time domain analysis of HRV using 24-h ambulatory ECG was performed. Results Overall, 18 PD patients fulfilling inclusion criteria completed the evaluation (mean age was 55.6 ± 8.8, disease duration: 5.0 ± 4.7). Mean SCOPA-AUT scor…

Fútbol, dinero, mafias

2002

Le intese restrittive della concorrenza nell'attività dell'AGCM (anno 2012)

2013

La rassegna analizza sinteticamente le decisioni in materia di intese restrittive della concorrenza, adottate, nel corso del 2012, dall’Autorità garante della concorrenza e del mercato (qui di seguito « Agcm »). In quest’arco temporale, non si ravvisa alcuna significativa inversione di tendenza nella prassi dell’Agcm; in particolar modo, per quel che concerne le nozioni di « pregiudizio al commercio tra gli Stati membri », « mercato rilevante », « impresa » e « intesa », ai sensi dell’art. 2 della l. n. 287/1990 e dell’art. 101 del Tfue. Si segnala, inoltre, il fatto che, in ottemperanza ad alcune decisioni del tribunale amministrativo, in più occasioni l’Agcm ha dovuto rideterminare le san…