African monsoons Part 1 : Climatological structure and circulation

A recent (1979-1996) NCEP/NCAR reanalysis dataset is utilized to study the structure and characteristics of the time-mean meteorological fields over the continent of Africa and surrounding oceans during February and August when the seasonal monsoons are normally at their peak intensity. The vertical structure, revealed in zonal and meridional sections over different parts of the continent, bring out the dominant influences of the neighbouring oceans and topography in the formation and distribution of monsoon troughs and ridges and associated dry and wet zones. Vertical circulations reveal a symbiotic relationship between the tropical monsoons and the subtropical deserts of the two hemispheres. Some salient features of the African monsoons, such as the formation of double equatorial troughs and their movement following change of season, are discussed and compared with similar features observed elsewhere over the world.

Investigation of the vertical structure of the lower atmosphere during heat wave conditions

<p>The research on heat waves is strongly motivated by their impacts on human<br />life and the economy. Consequently, less research has been done on the<br />state of the lower atmosphere as a whole during these extreme events,<br />although it may play a role in the formation and persistence of heat<br />waves. Miralles et al. (2014) show that different factors must come<br />together to produce extremes such as the pronounced heat waves<br />in the year 2003 in France and 2010 in Russia. One interesting phenomenon<br />in this context is the emergence of an unusually deep boundary layer. The aim<br />of this work is to analyse whether this feature is a common trait of European<br />heat waves in general. To this end, we systematically investigate the vertical<br />structure and evolution of the lower atmosphere during heat waves in the<br />time period from 2014 to 2018. COSMO-REA6 data is used to find heatwaves<br />and provides vertical profiles of the atmosphere which we also compare<br />to radio sonde measurements. The results of our work could possibly be<br />used to improve the discriminability of different severity levels of heat waves or to<br />formulate a heat wave measure that is not based solely on surface variables.</p>

Some explicit solutions of the three-dimensional Euler equations with a free surface

We present a family of radial solutions (given in Eulerian coordinates) to the three-dimensional Euler equations in a fluid domain with a free surface and having finite depth. The solutions that we find exhibit vertical structure and a non-constant vorticity vector. Moreover, the flows described by these solutions display a density that depends on the depth. While the velocity field and the pressure function corresponding to these solutions are given explicitly through (relatively) simple formulas, the free surface defining function is specified (in general) implicitly by a functional equation which is analysed by functional analytic methods. The elaborate nature of the latter functional equation becomes simpler when the density function has a particular form leading to an explicit formula of the free surface. We subject these solutions to a stability analysis by means of a Wentzel–Kramers–Brillouin (WKB) ansatz.

Antarctic ozone depletion measured by balloonsondes at Maitri - 1992

ABSTRACT. Profiles from a series of balloon borne ozonesonde ascents are used to chart the development of the Antarctic depletion over Maitri in the austral spring of 1992. The vertical structure of the ozone layer is discussed, including the presence of stratification, which occurs at all stages of development. The main feature of 1992 ozonesonde flights is depletion of 97% in the months of September and October between 15-23 km, which is unique.

A Vertical stratification of arthropods in the dry ecosystems of Colombian Guyana: morphological patterns and their ecological implications

Introduction: Despite growing interest by the ecosystems derived from the Guyanese formations, the vertical structure of the communities and relationships of the biota with the climatic conditions in these ecosystems are unknown. Objective: Characterize the structure and vertical composition of the arthropod fauna associated with three of the most representative ecosystems of the Northern area of the serranía de La Lindosa in Colombia based on morphological and ecological parameters. Methods: The arthropod fauna was sampled, from the subsurface soil level to the shrub and tree stratum. The fauna was determined up to the level of family or supraspecific group and the values of Alfa and Beta diversity were determined. Body length measurements were made, and the coloration and trophic level of each group were determined. Results: The composition and diversity of the arthropod fauna was different in each ecosystem and vertical stratum and most of the groups in all the ecosystems studied present low abundances. Groups of phytophagous and predatory habits were frequent in all ecosystems and the highest biomass of arthropod fauna comes from groups of polyphagous habits, of medium size and great abundance. Light and dark colorations are the most frequent in landscape-scale. Conclusion: The ecosystems studied are characterized by the low values of diversity and replacement and the large number of non-shared groups that apparently respond to the microclimatic characteristics; however, there are some generalities on a landscape scale such as the greater richness and abundance of groups in the intermediate strata, the greater proportion of groups with phytophagous habits and medium body sizes, and the predominance of dark colorations in the lower strata.

Spectropolarimetry as a tool for understanding the diversity of planetary atmospheres

The polarization state of starlight reflected by a planetary atmosphere uniquely reveals coverage, particle size, and composition of aerosols as well as changing cloud patterns. It is not possible to obtain a comparable level of detail from flux-only observations. It is therefore a powerful tool to better understand the crucial role played by clouds and aerosols in the chemistry, dynamics, and radiative balance of a planet. Furthermore, polarization observations can probe the atmosphere of planets independently of the orbital geometry (hence it applies to both transiting and non-transiting exoplanets). A high-resolution spectropolarimeter with a broad wavelength coverage, particularly if attached to a large space telescope, would enable simultaneous study of the polarimetric planetary properties of the continuum and to look for and characterize the polarimetric signal due to scattering from single molecules, providing detailed information about the composition and vertical structure of the atmosphere.

Assessment and quantification of meteorological data for implementation of weather radar in mountainous regions

The scope of this paper is to improve observation and detection of hydro-meteorological hazard over the Grenoble region which is characterised by significant changes of terrain in altitude and geomorphology. The city of Grenoble is located at a height between 200 up to 500 m, installing the weather radar in this range of elevation leads to better quality measurements, but visibility and as well coverage capability will be reduced at the other sites of the affected region. Two locations are shortlisted for the implementation of the future weather radar in Grenoble; (i) Moucherotte (1920 m a.s.l.) and (ii) Saint Eynard (1365 m a.s.l.). Several simulation and data analysis are performed to get the clear picture about precipitation variability by considering meteorological data from individual ground stations and radio sounding data as well. Compared to previous work, in this study is considered climatology of the vertical structure of the rainfall. In this context, several statistical computations are done regarding 0°C isotherm altitude. Concerning rainfall error estimation, ground clutter and screening effect, statistical calculations by using VISHYDRO code, are performed by for different quintiles for several elevation angles in both shortlisted sites. The results obtained from calculations carried out on two locations are almost similar. Also, significant under and over-estimation of rainfall error due to screening and ground clutter effect are detected. To achieve more accurate results, other sites need to be tested for further simulation. On the other hand since ground clutter, and screening effect at the Moucherotte is not too high compare with Saint Eynard, this site may be considered for implementing the future weather radar for observation of the meteorological processes over the Grenoble region.