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

In the present study an attempt has been made to compare the differences in human bioclimatological conditions 2 m above the ground between three different land surfaces: asphalt concrete, soil and grass surfaces, using a data set obtained on 15 clear and calm days in August 2005, and an appropriate bioclimatological index, the thermohygrometric index (THI) in the city of Erzurum, Turkey. In the respect of human thermal comfort, soil surface was found to be the most advantageous surface but for the mean THI values grass surface exhibits more favourable features while the least favourable features were presented by the asphalt concrete surface.

This work studies the relation between UV-B radiation and global radiation over Egypt. The relationships between the global solar radiation and UV-B radiation at four stations in Egypt have been studied, and linear empirical formulas for estimating UV-B from global radiation at these stations has been deduced. The deduced equations were applied to calculate the UV-B radiation for other stations where measurements were unavailable, using records of global radiation at these stations. Because of the periodicity of variations in solar radiation, global and UV-B radiation, the non-dimensional values are expanded in Fourier series. Fourier coefficients were determined by using measured global solar radiation data of the selected stations. These coefficients were used to calculate UV-B radiation based on global solar radiation for the same stations. A comparison between observed and calculated UV-B radiation arising from the two methods of estimation is presented. The comparison showed a good agreement between the observed and estimated UV-B radiation. The application of linear regression method to calculate solar radiation for other stations where UV-B radiation measurements were unavailable was better than Fourier coefficients method.

As an example of a developing megacity the Greater Cairo (GC) area in Egypt has been evaluated with respect to atmospheric particulate matter (PM) and lead (Pb). Particulate matter was collected during 2001-2002 in the two size fractions PM2.5 and PM10 at 17 sites representing different activities (industrial, urban, residential and background condition). The PM concentrations were generally high, with yearly average PM2.5 and PM10 values of 85 ± 12 and 170 ± 25 μg/m-3, respectively. On an annual scale, the high PM levels were due to many sources that included traffic, waste burning and wind blown dust particles emitted from the desert outside GC and the Moqattam hill inside GC. On a seasonal scale, the PM concentrations were highest in the industrial sector during spring, the dusty season, due to the combined effect of dust storm events and anthropogenic emissions over GC. The lowest seasonal concentrations were recorded in the summer season at the background sites. There was a marked increase in PM levels during the period October to December due to burning of waste from harvested rice in the agriculture area in the Nile Delta (north of Cairo). The highest PM2.5/PM10 ratio was recorded in the urban sector (0.59) while the lowest ratio was recorded in the residential sector (0.32). The PM2.5 and PM10 samples were also analyzed for Pb in order to address the influence of different emission sources. The monthly average concentrations of Pb in both PM2.5 (Pb2.5) and PM10 (Pb10) varied between 0.4 and 1.8 ± μg m-3 at the non industrial sites. The concentrations were significantly higher in the industrial areas, where concentration up to a maximum of 16 ± g m-3 could be observed. Both the high lead and PM concentrations measured are contributing to local environmental pollution. GC is subjected to high concentrations of particulates most of the year. There is no annual limit for PM10 concentrations in the Egyptian law of environment, but comparing to the 24 hour average, PM10 is representing health risks on the long-term that will give both regionally and globally environmental effects. High volume samplers measuring PM10 as daily average shows that the air quality limit value has been exceeded at sites Heliopolis (35), Maadi (6) and 6th October (13) during 60.47, 79.07, and 62.96% of the measuring period of 2001, and at Shoubra El-Kheima (20), El-Qolaly Sq (1), and Abbasiya (36) during 100.0, 91.7, and 89.8% of the measuring period of 2002. Thus, the evaluation of the data presented in this paper will serve as a basis for future regional and global modelling and source apportionment.

Radiance measurements from satellites offer the opportunity to retrieve atmospheric variables at much higher horizontal resolution than is presently afforded by in-situ measurements (e.g., radiosondes). However, the accuracy of these retrievals is crucial to their usefulness, and the ill-posed nature of the problem precludes a straightforward solution. A number of retrieval approaches have been investigated, including empirical techniques, coupling with numerical weather prediction models, and data analysis techniques such as regression. In this paper, the inversion coupled with imager (ICI) scheme is used to retrieve vertical temperature and moisture profiles from infrared and microwave brightness temperatures from a polar-orbiting satellite. The bias and root mean square (RMS) deviations were assessed for the winter and summer conditions over land and sea, separately, using the National Center for Environmental Prediction (NCEP) reanalysis data. The results showed the RMS error of temperature in the lower troposphere to be about 2 K. On the other hand, the RMS errors of the moisture profiles are found to be about 1 g kg-1. However, below 850 hPa the errors were of the order of about 3.5 K and 3 g kg-1 for the temperature and moisture profiles over the land and about 2.5 K and 2.0 g kg-1 over the sea. Two numerical experiments are designed, one control simulation without assimilation of observations, and another in which the advanced microwave sounding unit (AMSU) together with high-resolution infrared radiacion sounder (HIRS) retrieved temperature and moisture profiles are assimilated for the prediction of two tropical cyclones, which formed over the Bay of Bengal during 24 to 27 November 2002 and during 16 to 18 May 2004. The model run with assimilation of AMSU and HIRS could simulate the wind and thermodynamic structures associated with a tropical cyclone better than the control run. The spatial pattern of the precipitation simulated by the model with assimilation is in good agreement with the Tropical Rainfall Measuring Mission (TRMM) rainfall observations for the November 2002 cyclone case. The time series of minimum sea level pressure and maximum wind speed simulated by the model run with assimilation are closer to the corresponding observations when compared with the control simulation.

Relatively few studies have been performed about the onset, duration, and intensity of the canícula (midsummer drought) within central México in response to El Niño/Southern Oscillation (ENSO) events. The objective of our research is to assess the impact of the El Niño (EN) phase of ENSO upon air temperature (T), precipitation (PP), and drought index (DI = PP/T) during the canícula period. Daily air temperature and precipitation data from weather stations throughout central México are averaged for eight consecutive 10 (or 11)-day periods during the summers of 1960 through 1998. The data are grouped into seven climate regions according to specific precipitation criteria. Statistical comparisons between EN and neutral (N) years for the seven regions are made with pooled average T, PP and DI values from the summer. Results indicate that the EN phase significantly increases air temperatures within the wetter climate regions. The El Niño phase also increases summer precipitation within five of the regions, though not significantly. The added summer rainfall during El Niño phase does not reduce drought intensity with the exception of brief intervals within the wetter regions. Roughly, during EN and N years the canicula begins on July 11 and ends on August 31.

Tropospheric ozone is a secondary air pollutant, changes in the ambient content of which are affected by both, the emission rates of primary pollutants and the variability of meteorological conditions. In this paper, we use two multivariate statistical methods to analyze the impact of the meteorological conditions associated with pollutant transformation processes. First, we evaluated the variability of the spatial and temporal distribution of ozone precursor parameters by using discriminant analysis (DA) in locations close to the industrial area of Kladno (a city in the Czech Republic). Second, we interpreted the data set by using factor analysis (FA) to examine the differences between ozone formation processes in summer and in winter. To avoid temperature dependency between the variables, as well as to describe tropospheric washout processes, we used water vapour content rather than the more commonly employed relative humidity parameter. In this way, we were able to successfully determine and subsequently evaluate the various processes of ozone formation, together with the distribution of ozone precursors. High air temperature, radiation and low water content relate to summer pollution episodes, while radiation and wind speed prove to be the most important parameters during winter.  

This paper describes the rainfall climatology in Argentinean Patagonia and faces with rainfall trends. Gridded precipitation dataset from Delaware University is used as an alternative data and they seem to reflect the same patterns that the observed ones. The mean annual precipitation shows maximum amplitude in Patagonia, winter values greater than in summer in the northwest, especially in the west and over the Andes. Both, principal component analysis (PCA) applied to the monthly anomalous precipitations and linear annual rainfall trends, show positive trends in north and south of Patagonia, meanwhile precipitation tends to decrease in the western and central zone. An alternative nonlinear methodology, a piecewise linear function, is used to detect a number of breakpoints in order to identify the moments at which the tendency changes its behavior. Northeast of the Patagonia region and a small zone to the Southeast of Santa Cruz experienced a change in the annual tendencies of precipitation later to the decade of 1960. To the northwest, a vast region denotes a change in precipitation in the 1970 decade, whereas in the environment of the Peninsula of Valdez, the decade of 1990 is in which the change seems to predominate.

This study deals with the climatic differences between rural and urban areas over a two-year-period and three different climatic elements in the conditions of the city of Erzurum; and it was aimed to determine what factors may have affected these differences. It was found in the study that temperature difference between the areas was 1.7 ºC, mean relative humidity was 2.5% and rainfall was 4.8 mm/m2 (urban is wetter). The factors thought to be effective on these differences were surface structures, buildings, smoke prevalent in the urban area and snow cover. Consequently, it was suggested that, in order to obtain more favorable and healthy climatic conditions, green areas amount, which are now not effective in the city center, must be increased.

In the present study, a method is proposed for the ensemble forecasting of rainfall over the Indian monsoon region based on daily outputs of four operational numerical weather prediction (NWP) models in the short-range time scale (up to 48 hours). The method is applied to prepare 24 and 48 hours ensemble forecastings of rainfall in the test mode daily during the summer monsoon 2006, using the rainfall prediction of constituent models with the pre-assigned grid point weights. The prediction skill of the ensemble forecasts is examined against observations and corresponding outputs of each constituent model. The intercomparison reveals that the method is capable to improve the forecast by taking the strength of each constituent model. The method has the potential for operational application.  

An analysis based on the compilation of bibliographic information for the southwestern Gulf of México led to the establishment of an integrated oceanographic framework useful to assess the processes that take place at different spatial and temporal scales. Those scales are related to the survival of the Sistema Arrecifal Veracruzano (SAV). This study should help us understand the multidisciplinary approach necessary to understand the marine environment of the area. The information was analyzed considering two main dynamic scales: the basin and the coastal zone, both included in a conceptual model, which states that the circulation in the SAV is the result of the interaction between the different components of the circulation and atmospheric processes. Both processes influence the generation of gradients of scalar properties, which, in turn, influence the coral reef community of the SAV.