Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Geostationary satellite and radar analyses clearly illustrate preferential regions of thunderstorm occurrences over south Florida. A synoptic analysis of the associated weather patterns suggests that a moister lower and middle troposphere is conducive to a greater percentage of coverage by these storms. The observed patterning of deep convection can be explained to a large extent by regions of enhanced mesoscale horizontal boundary layer convergence and resultant accumulation of lower tropospheric moisture. This convergence is enhanced in south Florida by the favorable curvature of the coastline (Pieike, 1984, pg. 458). A mesoscale model provides an effective tool to simulate the oberved patterns as a function of synoptic wind and thermodynamic structure. In general, mesoscale atmospheric flow influences the preexisting synoptic environment so as to provide preferential areas of thunderstorm activity. Using a combination of radar, satellite, synoptic observations, and mesoscale modeling tools, effective predictions of the percent coverage, and spatial and temporal distribution of thunderstorms in the sea breeze environment anywhere in the world appears possible.

Radar and direct aircraft measurements are used to characterize the precipitation development up to the mature stage at the high levels of some long-lived cumulus congestus and to estimate the precipitation efficiency at their cloud base The observations at about the -12ºC level are studied as a function of the overall particle growth environment and of the atmospheric conditions. The results indicated that the concentration of ice particles or alternatively the maximum attained reflectivity are sensitive functions of the cloud lifetime and correlate positively with the atmospheric static energy. Precipitation efficiency was estimated from 0 to 30% for these clouds. Contrary to the well known findings for large storms the clouds studied have no apparent influence from the vertical wind structure.

Six months series of meteoroligal and sea level data, corresponding to summer and winter periods, were analyzed by complex empirical orthogonal functions on time domain, in 0.25 to 0.01 cpd frequency band. five cases were analyzed: summer of 1962, winter of 1965, summers average, winters average and all semesters average (incluiding summer and winter). results show sea level events propagating northward during the summer, this venets are not present during winter. this is concordant with other authors studies for the same zone, using other methods. wavelength is of about 9000 km and there is two kinds: one that propagates from Salina Cruz to Mazatlan, not enetring the Gulf of California, and other (longer that the first), that travels from Acapulco to Guaymas, entering the Gulf of California.

Measurements of microphysical characteristics of up-slope fog were carried out on a rural, mountain site in the Sierra Madre Oriental of eastern Mexico. Fog droplet-size distributions were obtained with a Forward Scattering Spectrometer Probe (FSSP) mounted on an instrumented ground-based vehicle. Data were gathered during one week in winter, but only the results for one day are presented here. Measured total droplet concentrations and liquid water contents (LWC) had average values of 150 cm-3 and 0.44 g/m3, respectively, with mean volume diameters between 14 and 19 µm. Liquid water contents as high as 0.85 g/m3, with LWC peak diameters close to 30 µm, indicate that these fogs could have ideal characteristics for artificial water removal for human consumption. The potential for fog-water to be collected and used as a water supply in areas downwind of the study site, where average rainfall diminishes and semi-arid conditions prevail, is briefly discussed.

The implications of cascade processes in barotropic and quasi-geostrophic models are reviewed using conservation of kinetic energy and enstrophy in the barotropic case and conservation of the sum of available potential and kinetic energy and of potential, quasi-geostrophic enstrophy in the baroclinic case. The upper limit for energy cascades across a given spherical wave number, obtained from Fj0rtofts theorem, is in the barotropic case used to estimate the resolution necessary to prevent almost all cascades across the maximum wave number in the computational spectrum. The generalization to quasi-geostrophic, baroclinic models gives the possibility to estimate the horizontal and vertical resolutions required to limit the cascade of total energy across the maximum three-dimensional, spherical wave number in the computational resolution to a small fraction of the initial total energy.

This paper describes the capabilities of the Florida State University (FSU) global spectral model in the area of precipitation forecasting over the tropics. Results for the resolution T106 over the monsoon area and for resolution T170 from typhoon forecasts are highlighted. An example of a precipitation forecast from a very high resolution regional model highlights detailed hurricane rainbands and suggests the need to further increase the resolution of global models. The cumulus parameterization is described in the Appendix of this paper.  

A hydrodynamical numerical model is used to predict the wind-induced circulation in Todos Santos Bay for wind conditions representative of summer, winter and the aperiodic westerly "Santana" winds. Maximum velocities along the coast and return flows are apparently induced by topographic effects. Some effects of this circulation are discussed in relation to pollution problems.  

Global solar irradiance is determined for Mexico from GOES satellite data using, the statistical method of Tarpley (1979). Seven daily digital images taken from GOES satellite over Mexico for the period July 1982 - December 1984 are analysed. Monthly and seasonal means are evaluated by computing monthly averages of the daily totals at a 1º x 1º latitude-longitude grid points. Values of the monthly average daily totals are plotted on a physiographic map of Mexico. Tridimensional surfaces of the distribution of global solar irradiance on Mexico are obtained as a function of latitude and longitude. The standard error of the estimates with respect to ground-truth data is between 3 to 5. The results show clearly the existence of two-well defined patterns of solar irradiance over Mexico from October to April the isopleths are very regular on the monthly maps whereas the latitudinal and longitudinal energy surfaces are uniform in most of the country indicating a weak cloud modulation of the radiation field denoting the so-called "dry season". The maximum value is found during April. The exception is presented at the northern part of Mexico where maximum values are reached during June and July. The other pattern of solar irradiance flux is presented from May to September, coincident with the rainy season and frequent cloudiness; the isopleths show distorsions and nodes particularly over the sierras. September reaches the minimum values; these results indicate modulation of the radiation field by an enhanced clouds amount and atmospheric water vapor absorption. As a consequence of this distribution, it is found a latitudinal solar irradiance gradient such that E/ ≥ 0 occurs during the dry season. The condition E/ ≥ 0 is fulfiled during the wet season. These facts indicate polewards transport of energy during spring and summer through a fine combination of astronomical and geographical parameters, i.e, a longer sunshine duration and absence of clouds during summer at the northern part of the country, whereas the southern part is strongly modulated through the constant presence of clouds reducing the incoming radiation flux. Finally, it is shown that the geographical distribution of the solar radiation flux strongly depends on the irregular relief of the country.

A two-dimensional, slab-symmetric cloud model with detailed microphysics is presented. Drops were classified into 37 size classes representing a droplet spectrum from 1 µm to 4 mm radius. Each class of droplet was subjected to condensation and collection processes. New droplets were formed by the nucleation process. Results show that the model is capable of simulating the life history of a warm cloud from the initiation to the dissipation stages. A warm, moist perturbation or impulse, 1 km wide and 1 km deep with base at 800 m, is used to trigger convection in the model. Comparison of our study on isolated clouds with actual observations based on Day 261 of GATE reveal some realistic features of the model. Numerical experiments on cloud interactions show that merging occurs when a calm environment is initially used. No merging occurs when a sheared flow is incorporated in the model. When the two impulses are introduced simultaneously, the upshear cell develops more strongly compared with an isolated cell or its downshear counterpart. The growth of the downshear cell seems suppressed. When the second impulse is introduced 15 minutes later, the newer cell develops more vigorously while the older cell dissipates. The lifetime is longer and the rainfall heavier when the new cell is located upshear of the older cell. The formation of rainfall from the simulation is quite rapid; the rainfall lasted for about 10 to 15 minutes. This feature is attributed to the use of a top-hat profile of the temperature and humidity for triggering initially the cloud growth and to the use of detailed microphysics in the model.  

This work is directed to establish how the linear relation h2 – h1 = -0,03 - 3,586(T2 – T1), which is suppose to be valid at any point on the Earth and time of the year, and whose coefficients are obtained using synchronous series of three hourly data of relative humidity and temperature obtained from observations made in the Meteorological Observatory of Matacán (6, 794 data points), is verified if variable time intervals to establish the relative humidity and temperature variations are considered. To do this, the equation coefficients were recalculated, with the same methodology, using values of the variables which were obtained in the same observatory during the whole year of 1978 (268 data points). The results are compared with the corresponding values of the studied relation and the differences are justified. In function of this results it is possible to infer that the study equation is also valid when the time intervals used to determine the variations of relative humidity and temperature of the air are variable.