Results 1 - 10 of 34407
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[en] Papers on the photochemistry of the early atmosphere, the troposphere, stratosphere, and upper atmosphere are presented. Consideration is given to the effect of chemical constituents on the climate and atmosphere. Topics discussed include the composition of the atmospheres of Venus, Mars, the outer planets and their satellites, and the chemical changes which occur in comets
[en] The intercontinental transportation of mineral material from Africa to the Caribbean, North America and South America is an international phenomenon of research interest. Several studies have drawn attention of meteorological effects and climatic implications resulting from the presence of this aerosol in the atmosphere, as we as its potential adverse effects on human health. The Colombian Caribbean region is not immune to this problem, although there are few studies about it. Therefore, the aim of this paper is to identify events of intrusion of African dust over the Caribbean region of Colombia. The procedure followed in this investigation was the analysis of dust concentration maps generated by the GEOS-5, SKIRON, NAAPS and CALIPSO models between 01 January and 31 December 2012. Images generated by the MODIS satellite sensor and data from regional air quality monitoring network were also used. According to the results obtained, there are evidences that confirm that in the north of Colombia, specifically in the Caribbean region, events of intrusion of African dust are detected. The period of time with higher levels of concentration are presented between March and September, with prominent levels in March, June, July and August.
[en] Diagnostics of prevalent atmospheric conditions during the life cycle of meso-scale convective systems (MCSs) over Colombia and the eastern tropical pacific are developed using satellite data from the tropical rainfall measuring mission (TRMM), and from the NCEP/NCAR reanalysis project. Atmospheric stability indices such as CAPE, CINE, LI, and equivalent potential temperature are quantified, as well as kinematical indices such as relative vertical vorticity and vertical wind shear. Atmospheric environments associated with MCS are studied for 1998; both as long-term means but also in terms of the seasonal cycle large-scale atmospheric indices are quantified for the most intense precipitation events within MCSs. Relationships between those indices are estimated, and atmospheric conditions are studied for the life cycle of MCSs, including antecedent and subsequent conditions surrounding MCSs activity
[en] Complete text of publication follows. This paper will give an overview of what we have recently learned about the impact of Energetic Particle Precipitation (EPP) on the polar middle atmosphere, the area of the Earth's atmosphere covered by altitudes from about 20 to 120 km (stratosphere - mesosphere - lower-thermosphere). Much new information of the EPP impact on the polar middle and upper atmosphere has been gained in the recent years thanks to new kinds of observations becoming available. Of key role have been especially the observations made from satellite platforms such as the European Space Agency's Envisat satellite and the utilisation of ground based measurements, such as Very Low Frequency (VLF) radio waves, in novel ways. The focus of this presentation will be particularly on observations of the effects of EPP on the chemical composition, such as ozone, NOx, and HOx, and dynamics of the polar middle and upper atmosphere.
[en] Performance of high-sensitive semiconductor photoreceivers in the wavelength range of 0.45-12 μm is investigated. The values of the threshold power of the photodiode and photoresistor receivers are comparable assuming that a hypothetic amplifier of the load resistance signal can be used. On account of the behaviour of the laser radiation propagation in the turbulence atmosphere the requirements for the heterodyne detection system are determined. The system sensitivity is shown to depend greatly on the receiving aperture parameters, diffractional beam parameters and atmospheric turbulence. The synchronous frequency re-tuning of the reference and transmitted radiation enables to conduct selective optical meteorological parameter measurements
[en] The global hydrosphere is formed by various reservoirs, world oceans, ice masses and snow deposits, the terrestrial waters, the atmosphere and the biosphere, interconnected by the transfers of water in any of its three phases. The classic equation of hydrology and the balance equation for water vapor are recalled and related to the balance of global mean evaporation and global mean precipitation, and to the mean planetary water balance (divergence of water vapor, aerial runoff) and the general circulation of the atmosphere
[en] This paper introduces three quantitative indicators to conduct research for characterizing Northeast China cold vortex persistence activity: cold vortex persistence, generalized “cold vortex,” and cold vortex precipitation. As discussed in the first part of paper, a hindcast is performed by multiple regressions using Northeast China precipitation from 2012 to 2014 combination with the previous winter 144 air-sea system factors. The results show that the mentioned three cold vortex index series can reflect the spatial and temporal distributions of observational precipitation in 2012–2014 and obtain results. The cold vortex factors are then added to the Forecast System on Dynamical and Analogy Skills (FODAS) to carry out dynamic statistical hindcast of precipitation in Northeast China from 2003 to 2012. Based on the characteristics and significance of each index, precipitation hindcast is carried out for Northeast China in May, June, July, August, May–June, and July–August. It turns out that the Northeast Cold Vortex Index Series, as defined in this paper, can make positive corrections to the FODAS forecast system, and most of the index correction results are higher than the system’s own correction value. This study provides quantitative index products and supplies a solid technical foundation and support for monthly precipitation forecast in Northeast China.
[en] The research has the purpose to acknowledge a diagnosis in relation to rainfalls motivated by the action of a frontal system and its negative impacts in the second Region-Antofagasta taken place on Tuesday 18 of June In 1991. The study looks at the synoptic situation that prevails in the Region, historical rainfalls period 1904-1991, floods caused by the effect of rain, the atmospheric situation that has affected the region on days June 17 and 18, lessons, education and propositions, in order to diminish in the future the negative impacts, human danger, technology-housing-located in the zones of high risks