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354 p., Más del 98% de la población europea está expuesta a niveles nocivos de ozono troposférico según la OMS. En el Sur de Europa, la situación es todavía más grave debido a que, las mayores temperaturas y horas de luz solar que se registran en la época estival incrementan la producción fotoquímica de este contaminante secundario. La elaboración de estrategias efectivas de reducción de ozono requiere un mayor conocimiento de mecanismos de producción y transporte de este contaminante. En esta tesis doctoral se muestra cómo la combinación de sistemas de modelización meteorológicos-fotoquímicos de última generación junto con datos experimentales permite identificar y cuantificar los principales mecanismos de transporte y producción de ozono en la Península Ibérica. Se han analizado dos episodiosocurridos en julio de 2016 y agosto de 2018, prestando especial atención a la situación característica de la Comunidad Autónoma del País Vasco como caso de estudio. Los resultados muestran el transporte de ozono y/o precursores de ozono desde la costa atlántica francesa y cuencas aéreas contiguas hacia esta región. También se ha documentado el transporte entre las distintas cuencas de la Península Ibérica (Valle del Ebro, Duero, Tajo y Guadalquivir) y el impacto del ozono producido en las regiones periféricas receptoras de las zonas metropolitanas de Madrid, Barcelona y Lisboa. Además, se han cuantificado las aportaciones a través de las principales vías de transporte del ozono a la Comunidad Autónoma Vasca.

354 p., Más del 98% de la población europea está expuesta a niveles nocivos de ozono troposférico según la OMS. En el Sur de Europa, la situación es todavía más grave debido a que, las mayores temperaturas y horas de luz solar que se registran en la época estival incrementan la producción fotoquímica de este contaminante secundario. La elaboración de estrategias efectivas de reducción de ozono requiere un mayor conocimiento de mecanismos de producción y transporte de este contaminante. En esta tesis doctoral se muestra cómo la combinación de sistemas de modelización meteorológicos-fotoquímicos de última generación junto con datos experimentales permite identificar y cuantificar los principales mecanismos de transporte y producción de ozono en la Península Ibérica. Se han analizado dos episodiosocurridos en julio de 2016 y agosto de 2018, prestando especial atención a la situación característica de la Comunidad Autónoma del País Vasco como caso de estudio. Los resultados muestran el transporte de ozono y/o precursores de ozono desde la costa atlántica francesa y cuencas aéreas contiguas hacia esta región. También se ha documentado el transporte entre las distintas cuencas de la Península Ibérica (Valle del Ebro, Duero, Tajo y Guadalquivir) y el impacto del ozono producido en las regiones periféricas receptoras de las zonas metropolitanas de Madrid, Barcelona y Lisboa. Además, se han cuantificado las aportaciones a través de las principales vías de transporte del ozono a la Comunidad Autónoma Vasca.

This paper investigates cold outbreaks that form offshore density currents within the whole mesoscale over the Western Mediterranean basin. Reflectivity radar and satellite images are used to detect clouds and precipitation that are associated with these density currents in the meso- 훼 ,meso- 훽 , and meso- 훾 over the Western Mediterranean basin (WMB). Version 3.3 of the WRF-ARW model is used to describe the formation and evolution of these density currents and to estimate their lifetime as well as horizontal and vertical scales. Based on the observations and simulations, this paper suggests that a new perspective could effectively be adopted regarding the WMB region delineated by the Balearic Islands, the northeastern Iberian Peninsula, and the Gulf of Lion, where inland cold outbreaks develop into density currents that move offshore and can produce precipitation ranging from raincells to rainbands at the whole mesoscale., Peer Reviewed, Postprint (published version)

Large shore-parallel and quasi-stationary snow bands are occasionally observed over the Baltic Sea (Andersson et al, 1990; Gustafsson et al., 1998; Vihma et al., 2002) and the Gulf of Finland during wintertime, when the sea is not frozen (Savijärvi, 2012). By using WRF-ARW mesoscale model the physical mechanisms producing the snow bands occurred on 15-22 January 2006 and 1-4 February 2012 along the Gulf of Finland are investigated. These two events are chosen among many others because, the first event had a large uncommon duration, and the second was particularly destructive causing multiple car accident in Helsinki. According to the simulations, common dynamics is found: (a) the open sea that produces the known lake effect, (b) a cold, easterly large-scale flow along the Gulf, and (c) cold local flows in the form of two land-breeze from the two near and opposite coastlines of Estonia and Finland. These two flows collide offshore producing strong rising motions over the interacting zone. At the second part of these episodes, the previously mentioned easterly flow veers to southerly, enhancing the formation of horizontal convective rolls over the sea, forming several cloud streets perpendicular to the Finnish coastline. The land breeze coming from the Estonian coast is enhanced, while the cold air remains stagnant inland over the Finnish coast, acting as an orographic barrier lifting the marine air mass upwards. Consequently, a line of convective precipitation composed by several cells is formed along the Finnish coast. In both events, the simulations also show two low-level jets generated by the combined effects of the land-breeze cells and baroclinicity over the coast of Finland and Estonia., Peer Reviewed, Postprint (published version)

As mesoscale models increase in resolution there is a greater need to understand predictability on smaller scales. The predictability of a model is related to forecast skill. It is possible that the uncertainty of one scale of motion can affect the other scales due to the nonlinearity of the atmosphere. Some suggest that topography is one factor that can lead to an increase of forecast skill and therefore predictability. This study examines the uncertainty of a mesoscale model and attempts to characterize the predictability of the wind field. The data collected is from the summer, when the synoptic forcing is relatively benign. Mesoscale Model 5 (MM5) lagged forecasts are used to create a three-member ensemble over a 12-hour forecast cycle. The differences in these forecasts are used to determine the spread of the wind field. Results show that some mesoscale features have high uncertainty and others have low uncertainty, shedding light on the potential predictability of these features with a mesoscale model. Results indicate that topography is a large source of uncertainty. This is seen in all data sets, contrary to other studies. The ability of the model to properly forecast the diurnal cycle also impacted substantially on the character and evolution of forecast spread. The persistent mesoscale features were represented reasonably well, however the detailed structure of these features had a fair amount of uncertainty., http://archive.org/details/anumericalinvest109451145, Lieutenant Junior Grade, United States Navy, Approved for public release; distribution is unlimited.

In this thesis, multi-scale modelling is used to study the mesoscale and microscale meteorology (MMM) in complex terrain and building geometry. The first part of this thesis couples a mesoscale model (MM5) and a microscale model (CALMET) to provide more detailed and realistic wind field simulations over Guangdong (GD), Pearl River Delta (PRD) and Hong Kong (HK), well known as regions with complex terrain. After model validation, the MM5/CALMET system is utilized to generate wind maps over GD, PRD and HK with resolutions of 3 km, 250 m and 100 m respectively. The wind maps are utilized to analyze year-to-year variations (2004-2006) of wind availability over southern China and investigate the wind energy potential over GD, PRD and HK. The second part of the thesis couples the MM5/CALMET system with a multi-layer, non-steady-state puff dispersion model, “CALPUFF”. This is used to identify the SO2 contribution of PRD and HK power plants, road vehicles and marine vessels to the air quality of HK in summer and winter. In this study, the observation data at 11 general Environmental Protection Department (EPD) stations and simulation results are analyzed. In-zone and out-zone stations are defined to examine the SO2 contribution of emission sources to different parts of HK. Beside large-scale pollution problems, this thesis also investigates the finer scale (microscale) pollutions, as the “wall effect” in the urban area is a concern in HK. In this study, computational fluid dynamics (CFD) is utilized to achieve a deeper understanding of the wind speed reduction at the pedestrian level (2 m above ground) due to differing height of frontal high-rise buildings. The retention time of pollutants emitted from road vehicles is also investigated to quantify the influence of pollutant dispersion in a street canyon environment.

This study investigates the role of mechanical forcing within the boundary layer in enhancing low-level precipitation and initiating/intensifying convective precipitation during cases of high intensity precipitation in the wider Auckland region, New Zealand. Eight cases, that occurred between 2001 and 2008 have been investigated. All cases were observed to be strongly dynamically forced, resulting from the passage of mid-latitude cyclones. These features were observed to be centred mainly to the north and west of the study area, with surface winds from the northeast quadrant over the wider Auckland region. Radar imagery is characterised by regions of both convective and stratiform precipitation for all the cases investigated; areas of convection are often observed to be embedded in areas of larger scale precipitation. These cases were subdivided into eleven heavy precipitation events. Nine of these events were subject to further investigation. Environmental conditions during these events were characterised by steady low-level winds from the northeast quadrant, weak to moderate convective instability, with 0-3km wind shear indicating a high level of directional shear in the lower atmosphere. To investigate mechanical forcing in the boundary layer, low-level Doppler velocity and reflectivity fields measured by the Mt Tamahunga radar, were examined. These data revealed mesoscale structures of the Doppler velocity field not previously documented in this region. Mechanical forcing was identified by the presence of mesoscale zones of radar radial shear, resulting from horizonal convergence and/or zones of horizontal shear. These features were observed to be semi-permanent on the windward side of Little Barrier and Great Barrier islands, the windward side of the Coromandel ranges, and along the west coast of the Auckland region. Further, zones of semi-permanent radar radial shear were observed to extend downstream (lee side) of Mt Moehau and Great Barrier, Little Barrier a

This document describes a prototype software system that automates the generation of weather related templates used in the Aerial Intelligence Preparation of the Battlefield (AIPB) process. The software system is called the Terrain and Weather PB Software Toolkit (TWIST). The primary purpose of the prototype is to demonstrate that software using artificial intelligence technology can be developed to effectively integrate weather, terrain, and doctrinal information and to accurately generate AIPB templates. TWIST consists of two major modules. One module serves as the user interface and performs weather and terrain analyses that generate gridded data bases covering the battlescale region of interest. The second module combines the information to create templates that can, among other things, define the Air Avenues of Approach.

The main activity during this period was the Meeting of the European Mesometeorology panel along with members of ASL in Traben-Trarbach, West Germany, 23rd - 27 April, 1990. This report consists entirely of the report of that meeting with its 10 recommendations. These all refer to the strengthening of the mesoscale modelling activity at ASL and exploitation of the data from the project WIND. The panel is most concerned that this most excellent data set be made available, as soon as possible, to the many mesoscale modelling groups in the U.S. and Europe in order that all can contribute to the development of mesoscale modelling at ASL for the benefit of the U.S. Army. Keywords: Atmosphere models/wind; Mesometeorology; Great Britain.

One of the main objectives of the NROSS mission is the daily production of mesoscale feature maps of selected ocean areas. The NROSS payload will include a SEASAT-class altimeter for the production of these maps and a scatterometer to measure wind speed and direction over the oceans. These wind measurements will be used in conjunction with the precision altimetry from TOPEX to examine the relationship between ocean circulation and winds. The authors conclude that the applicability of a particular tracking network would appear to depend strongly on orbit accuracy requirements. One- to two-meter radial orbit accuracies are fairly easily obtained with current gravity models and almost any tracking scenario if the arcs are long enough. However, if more accurate orbits are required, either the arcs must be shortened to reduce dynamical model error effects, the gravity models must be improved significantly, or some postlaunch gravity 'tuning' is necessary. The latter technique can be successfully employed only if the tracking is fairly global, or geographically correlated errors will occur in the resulting geopotential field. In this case, all the permanent sites and possibly many of the portable sites may be required. The same is true if the arcs are merely shortened, since there must be enough well distributed data to average out measurement model errors. Thus only the denser tracking networks are likely to provide radial orbit accuracies significantly below the 1 meter level.

Occurrence and air/sea effects of the winter shamal, a subsynoptic- scale wind phenomenon in the Persian Gulf region, are examined by means of a conceptual model which relates upper air and surface features to mesoscale weather events and conditions. Two case studies based on surface data and satellite imagery are presented to illustrate the model. A regional wind climatology and a collection of rules of thumb for shamal forecasting are provided.

This report describes a simple technique to blend surface and rawinsonde observations in the planetary boundary layer (PBL) using a Barnes- type objective analysis. This goal is to improve the mesoscale detail of boundary layer input fields for a mesoscale numerical weather prediction model. The technique uses both surface and rawinsonde data in the boundary layer, where it is known that mesoscale details are inadequately resolved by the rawinsonde network and where the influence of the ground surface is strongest. Our challenge is to blend the signals contained in the denser surface observations that capture at least some mesoscale detail with those contained in the denser surface observations that capture at least some mesoscale detail with those contained in the boundary layer rawinsonde data. This is accomplished simply by comparing two analyses at the ground, one containing both rawinsonde data-resolvable and surface-data-resolvable information and the other, only the rawinsonde scale information. Differences between these two fields are assumed to be the signals undetected by the rawinsonde network. These mesoscale signals are then incorporated into the PBL analyses as a function of the distance from the ground. Results show a positive impact on boundary layer analyses due to the blending of surface and rawinsonde data, demonstrating that he technique is useful for providing improved mesoscale detail at and near the ground. Also discussed is the relative impact of data density and reference topography on the analysis of model parameters on terrain-following surfaces.

This report contains an account of the Mesoscale Panel's activities and a list of its recommendations to ASL. (Army Atmospheric Science Lab.) The Panel's work has been concentrated into the mesometeorology workshop held at the Risoe National Lab. Roskilde, Denmark, 12th-15th May, 1987, 2 Panel Meetings (Risoe, 14th-15th May, Sept. 14th-16th, 1988. This report includes the report of the last Panel Meeting, together with a separate list of its recommendation. Recommendations R1-R9 reflect the Panel's concern with the status and direction of the mesoscale modelling activities at ASL and propose radical changes which must be implemented if the Army's needs are to make effective use of modern developments elsewhere in this rapidly developing area of research. Recommendations R10-R13 relate to the project WIND database and reflect the importance the Panel attaches to making this data as widely and speedily accessible as possible. The excellent work of the field phase now needs to be followed up by exploitation of the data by the wider commitments of atmospheric mesoscale modelling if the Army is to benefit from modelling advances elsewhere and improved predictions of mesoscale phenomena. Atmosphere models; Great Britain.

A unique case of mid-Atlantic coastal frontogenesis on December 21-22, 1983 is examined to determine the evolution of the three dimensional structure of this mesoscale phenomena. Analysis of synoptic and mesoscale surface maps suggest a coastal front which moves steadily inland. However, review of temperature and wind profiles at individual stations reveals that frontogenesis actually occurs over the land in North Carolina and southern Virginia. Lagrangian and Eulerian frontogenesis process is found to be largely a result of the ageostropic flow within the cold wedge which results in weak cold air advection over the land. This northerly flow combines with a strong southerly flow over the Atlantic to increase the temperature gradient near the coastline. Analysis of kinematic variables indicates regions of relatively strong convergence and cyclonic vorticity in the region of the coastal front. Geostrophic deformation maxima coincide with the ridge of the anticyclonic bulge east of the Appalachians. Three-dimensional Lagrangian frontogenesis computations identify the shear and confluence terms as frontogenetical within the frontal zone. The tilting term is frontolytical within the frontal zone. Precipitation analyses identify the cold air side of the coastal front as favorable for enhanced precipitation. Relationships between precipitation bands and convective instability are also discussed.

Rainfall, wind and temperature data at the surface and winds in the lower 1-2 km for a mesoscale area surrounding St. Louis, Missouri, for 7 summer days in 1975 were used in a study to determine the relationship between the surface kinematic fields and the occurrence and intensity of rainfall, and to determine if the surface kinematic fields are representative of the subcloud layer. It was found that, on some case days, patterns of convergence collocated favorably with raincells, were predictive of rainfall onset, and were positively related with rainfall amount. However, the relationships were nonexistent or negative on other case days. The statistics support the premise of the predictability of rain amount or rain mass based upon the preceding convergence on the cell scale and on the scale of the network, especially if some method that stratifies the convergence-rainfall relations can be found. Subsynoptic and/or mesoscale disturbances that tend to increase the potential for convective precipitation were present on all 7 case study days. These disturbances formed over the dense St. Louis surface network on three case study days. Although occurring under different synoptic conditions, these systems were similar structurally, being strongest near the surface and extending through a depth of 550 to 750 meters. (Author)

Subsynoptic convective areas are isloated, monitored and forecast through extrapolation and advection using McIDAS, (Man-Computer Interactive Data Access System), and interactive computer video-display system. Research on isolating the convective areas focuses on development of statistics using digital visual and IR GOES satellite data to delineate areal coverage and intensity. McIDAS algorithms have been developed to: (1) compute the brightness centroid; (2) form a best-fit ellipse to the region; and (3) compute areal average IR and normalized-visual brightness. Sequences of brightness centers and geometric outlines serve as input extrapolation routines to project system movement and change in area coverage and intensity. Research also has been initiated on using vertically-integrated wind fields to advect meteorological fields and disturbances. Preliminary results using these techniques for short-range forecast are presented.

This report details research efforts in three areas of meteorology. In atmospheric analysis, a number of modeling experiments were performed which explored the flux-profile relationships in the atmospheric surface layer. In mesoscale forecasting, automated procedures were developed to: (1) specify the type and intensity of surface weather phenomena and (2) exploit indirect methods to specify and predict landing zone slant visual range. In satellite studies, data acquired by the McIDAS (Man-computer Interactive Data Access System) were used to perform analyses in the following areas: the physical properties of clouds; the objective extraction of satellite-sensed vertical surroundings; the use of imagery data for investigating automated short range forecasting techniques; the objective specification of cloud type from DMSP (Defense Meteorological Satellite Program) very high resolution satellite imagery.

The purpose of this study was twofold: to evaluate the ability of a circularly symmetric two-cylinder model of a precipitating cumulus cell to simulate radar-observed cells, and to ascertain to what accuracy the model input variables need to be known to obtain realistic results. Data from GATE were used, in part because the tropical atmosphere during the experiment contained relatively little vertical wind shear. Cells organized into two types of mesoscale features, a line and a cluster, were simulated. Because of the variability observed in the cell characteristics, the mesoscale features were idealized into geometrically simple configurations of 'representative' cells. The representative cells were geometrically compatible with the model and had dimensions based on the average sizes of observed cells. The size of the model inner cylinder, assumed to be the region of active convection, was estimated from the areas of observed reflectivity cores. The size of the outer cylinder, analogous to the environment of the cells, was estimated from distances between cells in the mesoscale features. This idealization process produced what appeared to be realistic dimensions.

A three-dimensional, primitive equation model by Anthes and Warner (1978) was used to predict five typhoon cases. The five-layer model on a 40X40 staggered grid with 120 km resolution included a moisture cycle, sensible and latent heat flux at the earth's surface, and a bulk parameterization of the planetary boundary layer. The model is initialized using operational wind fields and two forms of a wind bogus. Due to the lack of a representative moisture analysis in the vicinity of tropical cyclones, simulated moisture fields were used to initialize the model. Initial experiments conducted with these fields produced widespread convection and heating which developed circulations in areas well removed from the actual storm. The associated modifications to the steering flow, and the overly intense storm circulations resulted in premature recurvature. Use of a second moisture bogus, which provided less available moisture (especially at upper levels), reduced the amount of convection over the entire grid and the effect on the steering current. A second wind bogus was also tested. This technique resulted in a smaller and less intense initial storm, which also resulted in considerably less convection.

Two programs have been developed for using both Air Force Global Weather Central (GWC) prognostic data and Army rawinsonde data for improving the accuracy of meteorological corrections applied in aiming cannon artillery. The first program, the Prognostic Data Reanalysis Routine (PDRR), updates the GWC prognoses using the available Army rawinsonde observations. The program options include data editing, updating for both current and later times, divergence alteration, and height balancing. The second program, the Artillery Applications Routine (AAR), uses the updated GWC results in addition to the best available sounding, to generate a Computer Meteorological Message for use in computing ballistic corrections for artillery firings. The options that are to be used in either program are determined by control parameter values that are initially read from data cards into the computer. A description of the numerical techniques and the computer program input and output are given in this report, along with a listing of the programs and an example case. (Author), Prepared in cooperation with Stanford Research Inst., Menlo Park, CA.

Defense Meteorological Satellite Program (DMSP) and National Oceanic and Atmospheric Administration satellite imagery are used to supplement conventional radiosonde and aircraft data in an investigation of synoptic and associated mesoscale weather patterns leading to significant weather at McMurdo Station and the adjacent Ross Ice Shelf. Three case studies, 8-11 January 1976, 22-25 December 1975, and 11-13 October 1973, are analyzed, with concentration on the 700 and 400 mb levels. Meridional advection associated with ridging over the Ross Ice Shelf and/or the polar plateau serves as the moisture intrusion mechanism for significant weather in each case study. Mesoscale features about the McMurdo area serve as both triggering and blocking mechanisms preceding the significant weather events. Katabatic winds associated with glacial valley warming, originating from the polar plateau near McMurdo, are detected on DMSP infrared satellite imagery. Comparisons between Fleet Numerical Weather Central's 700 mb analyses with those of the author demonstrate the inadequacy of satellite-void analyses over the sparse data ice/snow covered south polar region.

Atmospheric dispersion characteristics in the coastal zone are unique in that physical processes of air, sea, and land combine at the shoreline to create motions on many scales which differ in important respects from processes over land or over water. Some of these differences in coastal Louisiana are reviewed. Synoptic-scale characteristics indicate that the coastal zone is superior to areas farther inland for dispersing pollutants. However, mesoscale and microscale studies reveal that diurnal circulation of land-breeze and sea-breeze systems and the development of an internal boundary layer because of aerodynamic roughness changes across the shoreline may actually increase pollution concentration in the nearshore region. Specific studies on these scales of atmospheric motion in relation to the optimum siting for industrial plants are outlined and recommended. (Author)

The formation and dissipation of Santa Ana marine fog along the coast of Southern California was investigated, using multiple remote sensor data taken on land at NOSC and other data taken by means of aircraft, ship, and satellite. The simultaneous measurements provided excellent, unique data concerning the horizontal distribution of factors controlling the formation and dissipation of marine fog. Santa Ana marine fog appears to form in regions where the sea surface temperature is decreasing in the direction of air flow and where low-level convergence is present after subsidence aloft has attained a maximum. Satellite and aircraft data can provide valuable information on marine fog over the offshore regions. More information on horizontal and temporal variation in air flow and sea surface temperature must be considered to improve fog forecasts related to Santa Ana conditions along the coast of Southern California. An unusally detailed sea surface temperature pattern was obtained by aircraft IR data over the ocean near San Diego. Vertical profiles of the horizontal wind measured by acoustic techniques were found to provide valuable information on moisture distribution during one fog event. (Author)

Space-time relationships between the wind and temperature fields have been examined using rawinsonde observations taken over White Sands Missile Range and nearby locations during the period 21 August 1973 - 1 March 74. This required the bringing into operation of multivariate analysis of variance (MANOVA) and regression computer programs. (Author)

The Meteorological Office (MO) mesoscale model has been run for the simulation of the summer flow on 27 June 1985 in the Sacramento Valley, California. The purpose is to examine its predictive capability using the meso-Beta high resolution observations that were obtained during Phase I of U.S. Army Project WIND and compare with it similar runs made with the ASL SIGMET model. The simulated region is a 460 X 460 km area centered at (39.75 N, 121.8 W) as in the SIGMET simulation by Williams et al., (1986). Three simulations were performed with the same topography, horizontal grid spacing (Delta-x Delta-y = 20 km) and period of integration, and also the same radiosonde initialization (that for Orchard, 1700 GMT) as in the SIGMET run. Fig. 1 illustrates the topography of the region, which includes an artificial apron following the SIGMET run. Three simulations were performed and their characteristics are summarized in Table 1. In the first simulation, the MO model was modified to run with vertical levels as in the SIGMET run (36, 116, 213, 330, 471, 4779, 6219 m) while the other experiments, Nos. 2 and 3, were run with the vertical spacings and number of levels (16) used by the operational MO mesoscale model simulations. In the third run the evaporation resistance was increased from 100 to 500 s/m resulting in effectively reducing the evaporation to nearly zero. This reflects the relatively dry conditions over the Sacramento Valley at that time.

The time and height variations of temperature, wind speed, and moisture content observed at the Cedar Hill tower during the dissipation of a low-level jet on the morning of 14 May 1962 are presented and discussed. Three distinct stages of significant variations occur before sunrise at the upper levels of the tower. The three stages are: 1) a period of an abrupt and simultaneous warming and drying; 2) a period of steady temperature, mixing ratio, and wind speed; and 3) a period of pronounced decreases in temperature and wind speed and a marked increase in mixing ratio that occur progressively later with increasing height. It is proposed that these variations are produced by horizontal and vertical advection and by turbulent mixing., Revision of manuscript submitted 2 Jul 1965. Published in Journal of Applied Meteorology v5 n1 p36-42 Feb 1966.

In the atmosphere various kinds of air movements are occurring, the dimensions of which, in space and time, are yielding a continuous spectral distribution. In the course of the past decade the main emphasis has been placed on the investigation of only two dimensional classes of atmospheric processes: namely of the so-called macrosynoptical and, on the other hand, of the microsynoptical ones. However, by the organization of some peculiar microsynoptical networks in the United States of America possessing a very high station density, attention was drawn to another dimensional class of movements in the atmosphere. This new realm, the investigation of which is forming the subject of mesosynoptics, is directly related to the occurrence of weather phenomena of a local character. It has been proved by experience that through the application of the techniques of mesosynoptical analysis and forecasting, the task of preparing short-range provisions of local weather phenomena is rendered much easier and a possibility is achieved for using a more objective type of procedure, while, up-to-now, the methods employed have been in the majority of cases entirely subjective in character. (Author), Trans. of Idojaras (Hungary) v66 n6 p361-6 1962.

A description is given of observations and analysis of nine case studies of data obtained from a detailed mesometeorological surface observing system coincident with the collection of PPI and RHI data from an AN/CPS-9 weather radar and a vertically-pointing radar. The surface observations included measurements of the dropsize distributions, occasionally hail samples, charge on precipitation, and earth-air current in addition to the usual observations. Primary emphasis in this sudy centers on the orographic effects on the precipitation distribution. Use of stepped receiver gain permitted detailed analysis of radar data to reveal orographic effects and other factors operating in the precipitation process. (Author)