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

This study describes the results obtained during two years of sequential sampling of wet precipitation in two sites: Mexico City and a rural area. The results indicated that the chemical constituents determined in the sequentially collected samples, decreased in ionic concentration in the early portion of the rainfall event, while it increased, decreased or remained the same during the latter part of the event. The non-parametric Mann-Whitney-Wilcoxon test when applied to data, clearly showed that there were significant differences between these two sampling sites. This study has also permitted to infer the most important scavenging mechanisms acting on the rainfall event and the possible origin of the major ions analyzed.

In this study, an agroclimatic classification is made based on the calculation of the solar radiation potentials, taking into consideration the altitude, the orientation and the tilt of the mountains. A clear (cloudless) atmosphere with a visibility of 23 km was considered. For the calculation of the solar radiation the Kuznetzov model was used. The zones of maximum radiation generated by the model are coincident with the hottest areas of the state. Therefore, the model and metodology are to be trusted for the planning of land use of a hilly zone. For 113 stations in the state of Guerrero, five micro zones of maximum radiation were found which appear for all the considered orientations and slopes. One of these micro zones corresponds to the region between Cutzamala de Pinzón, Altamirano and Tialchapa, another one to Chichihuaico, a third in Iguala, part of Huitzuco and part of Tepecoacuiico, a fourth in the region between Atlixtac and Atlamajalcingo del Monte and the last one where the municipalities of La Unión, Coyuca de Catalán, Tecpan de Galeana and Petatlán join together.  

Climatic variability arising from nonlinear interaction between atmosphere, ocean and continental ice is studied. Analitical and numerical solutions of the evolution equations are presented. These solutions testify to the existence of discontinuous autooscillations of the climatic system. A prominent feature of these autooscillations is the alternation of slow and jump—wise variations of ocean thermohaline circulation intensity and direction. The slow variations occur for a time of about 10 x 103 years in the regime of normal (present) circulation and for a time of about 50 x 103 years in the regime of abnormal (reverse) circulation. Transition from one regime to another is performed practically instantly (for a time of about 103 years) and is stipulated by jump-wise variations of the salinity differences. The ocean-averaged temperature and salinity as well as continental ice mass undergo the slow asymmetric oscillations without jumps.

In a previous work an energetic index for local instability (IR) was introduced. This index is defined as the difference between moist static energy (h) at 850 hPa pressure level and saturated static energy (h*) at 500 hPa pressure level. In this paper IR is evaluated from 245 soundings over Spain (Madrid-Barajas) and other European points (Rome, Berne, Vienne, Bordeaux and Paris). From this evaluation the operative applicability of this index is shown. In the same way index values are related to instability (taking into account several types of instability) and probability of convective hydrometeors. Furthermore a comparison between IR, Showalter, and Total Totals indexes is made.  

Besides their importance in meteorological and climatological processes natural and anthropogenic atmospheric aerosols, serve as adhesive surfaces on radioactive isotopes. One of these cases is the cosmogenic radionuclide 7Be. In this paper, the concentration of 7Be in surface air is presented, as it is detected at nine stations located in a tropical latitude in a coastal location on the Gulf of Mexico. 7Be concentrations and regional scale systems are found related, between the maxima and the fronts of polar air masses and between the minima with rainfall coincident with systems of tropical disturbances.

The interannual surface variability of pressure and temperature over Argentina is studied in connection with the Southern Oscillation (SO). Thirty nine surface records of the 1959-92 period from Argentina were used to study the anomaly pattern of the negative SO phase. Surface pressure is significantly lower over most of the country during the negative SO phase. The stronger signal is over the west and center of the country where throughout the year there is a low pressure center that appears in every mean monthly map. This west low (WL) tends to be enhanced in its center to be displaced to the south during the negative SO phase. Over Central Argentina the seasonal response varies throughout the year being negative except in summer and stronger, near 1 hPa negative, in winter. According to this anomaly pattern, except in summer, the meridional gradient over Patagonia is weakened while the zonal gradient over the center and east of the country is enhanced. It is discussed how this pressure anomaly pattern is consistent with the respective surface temperature anomalies. In Patagonia the negative SO phase coincides with cooler temperatures, while in Central Argentina except in summer, warmer temperatures are observed during this phase although they are not statistically significant. In the central part of Argentina there is a marked regularity in the pressure behavior during a period of about three years that starts in the year before the negative SO phase. In Central Argentina during almost all negative SO phases, pressure is usually lower than in the preceding and in the following year. For instance, in the eight negative SO phases studied, the pressure was lower than the average of the preceding and following year. The probability of the observed regular sequences to happen by chance was calculated with the cumulative binomial distribution and it is very low. A similar behavior, though less regular, is also observed in Patagonia. The marked regularity of the pressure response to the negative SO phase in Argentina suggests that this response is linked to features that are common to all ENSO events. The Andes mountain interaction with the anomaly circulation induced by the anomalous ENSO convection seems responsible for the strong response over the WL.

Large-scale modes of variations in sea surface temperatures (SSTs) and the tropospheric circulation are examined with major principal components utilizing-monthly mean fields of the global SSTs and Northern Hemisphere geo-potential height (Z) at 700, 500 and 300 mb levels. The data period covered is from 1955 to 1992. It is found that the heterogeneity of SST data due to availability of satellite observations and difference of analysis schemes may result in a large systematic bias in the dataset. However, the bias may be effectively corrected through elimination of an appropriate principal component. The first three components of monthly SST and Z fields during the 38-year period are presented. The El Niño-Southern Oscillation (ENSO) mode of variations is observed in both 1st and 2nd components of SSTs. The inter-annual viariations of principal components of monthly SST and Z fields are utilized to probe the association of SST components and Z components. Further, cross-correlation patterns of principal components of SSTs in reference to the tropospheric circulation are studied with 500 and 300 mb fields. It is hown that the tropospheric response to SST anomalies are consistent at 500 and 300 mb levels, and the seasonal-range predictability of the tropospheric circulation is recognized with SST anomaly fields.  

The analysis of surface monthly mean temperatures for stations of the Metereological Poligon of Camaguey, between 1980 and 1990, permits us to establish the decrement of the monthly mean temperature, of the order of 1° c, for may 1982 as a result of the decrease of the solar radiation produced by El Chichon stratospheric aerosols cloud that erupted between 28 march and 4 april of that year. the possible influence of clouds and precipitation is separated as a result of the analysis of sunshine and precipitation anomalies. the temporal avolution of the monthly mean temperature for the rest of 1982 was analyzed, showing a tendency to decrease in the longer term, as it has been reported by the scientific community.

A scientific experiment to investigate the atmospheric circulation, the mesoscale convective systems and the precipitation associated with the monsoon overnorthwestern mexico and southwestern united states was carried out during the northern summer of 1990. a number of institutions and universities participated in the experiment. special observations were made over the mexican states of Baja California, Baja California Sur, Sonora, Sinaloa, Durango, Coahuila, Chihuahua and in the United States, Arizona. a wide variety of metereological observations were made, including special pilot ballon and radiosonde soundings, research aircraft flights (including use of airborne doppler radar), special surface observations, as well as more routine satellite, surface and upper-air observations over the region. The observations have been processed and compiled bye the National Severa StormsLaboratory (NSSL) and the Center for Scientific Study and Higher Education of Ensenada (CICESE), in a data bank with the ooperation of Nationa Water Commission (CNA) and the Sonora Institute of Technology (ITSON). Different atmospheroc phenomena are being investigated, including the horizontal transport of water vapor and the studies to date using the 1990 data identify the ‘Sierra Madre Occidental’, particularly important to the formation from the tropical Americas converge. The Mexican watersheds from the Pacific and the Gulf of California show higher precipitation over the Sierra madre, as compared with the watersheds from Chihuahua and the Gulf o Mexico, suggesting the Pacific ocean as the main source of moisture for monsoon circulation over northwestern Mexico.

In the weakly nonlinear interaction theory of mid-latitude Rossby waves (RWs), a perturbative solution for the quasi-geostrophic (QG) stream function is sought in the form = (0) + ε(1) + ε2(2) + ..., where ε is the β-Rossby number. If the leading order solution (0) is any superposition of RWs, the second order perturbation equation for (2) always has resonant forcing. This is in contrast to first order nonlinear interactions where resonant triads form a very restricted set of all possible interactions. An example is worked out in a laterally unbounded ocean and taking (0) as the superposition of two arbitrary RWs. At second order, multiple time scales lead to an O(ε2) Doppler shift of the frequency of each wave, proportional to the amplitude squared of the other one. Using realistic wave parameters for wave-1 and the amplitude of wave-2, the frequency shift is not negligible in regions of wave number space of wave-2 near resonance at first order. It is thus conceivable to haw a field of weakly interacting RWs, such that at O(ε) there are no resonant interactions; however the Doppler shift in their frequencies, albeit small, will always take place due to resonance at O(ε2).