Showing papers in "Atmosfera in 2016"
TL;DR: In this article, the concentration levels and sources of heavy metals contamination were studied in road dust samples collected from various locations including four different activity areas: industrial, highways, residential and mixed use in Delhi, India.
Abstract: Air pollution has been considered one of the major environmental challenges because of its effect on ecosystems and human health. The concentration levels and sources of heavy metals contamination were studied in road dust samples collected from various locations including four different activity areas: industrial, highways, residential and mixed use in Delhi, India. Metal content in road dust was analyzed by inductively coupled plasma atomic emission spectroscopy. The results showed high concentration levels of Ni, Cr and Pb in industrial areas. Pearson’s correlations coupled with principal component analysis revealed that Cd, Cr, Ni and Pb are associated with industrial sources whereas Zn and Cu are mainly contributed by vehicular traffic. Road dust contamination was assessed by various methods: degree of contamination, potential ecological index and pollution index. Contamination factor analysis showed that road dust samples are significantly contaminated by Zn and Pb. The potential ecological indices indicated high contamination of Cd and moderate contamination of Pb in road dust, but low contamination of Cr, Cu, Ni and Zn. The pollution index of most of the metals was higher than 1, indicating deterioration of road dust quality of Delhi city due to anthropogenic emissions. The degree of contamination, the potential ecological index and the integrated pollution index reveal that road dust from industrial, mixed use and highway areas are highly contaminated by heavy metals. The road dust from the residential area is also contaminated considerably. Evaluations by various methods indicated that all assessment methods are important for environmental quality evaluation.
83 citations
TL;DR: In this paper, the authors compared the performance of the CHIRPS v.2 satellite-derived rainfall product with the measurement data from the gauge data from 1981-2007 interval and categorical metrics for assessing rain detection skills.
Abstract: Satellite-derived rainfall products are useful for both drought and environmental monitoring, and they also allow for tackling the problem of sparse, unevenly distributed and erratic rain gauge observations provided their accuracy is well known. Venezuela is a country highly vulnerable to extreme weather events such as extensive droughts and flash floods; therefore, an understanding of the strengths and weaknesses of satellite-based rainfall products is useful for the planning of water resources. Using numerical metrics in order to evaluate performance, monthly rainfall estimates, from the Climate Hazards Group InfraRed Precipitation and Stations (CHIRPS v.2) product, are compared to gauge data from the 1981-2007 interval and categorical metrics for assessing rain-detection skills. The analysis was performed considering different rainfall categories, seasonality, and spatial context. The results show that the satellite product CHIRPS v.2 overestimates (underestimates) low (high) monthly rainfall values; although on the majority of numerical metrics of skill shows a good performance. This product, on the other hand, achieves better performance during the rainy season (April-September), significantly overestimating, however, the rainfall-events frequency. The product also shows best overall performance over flat and open regions (e.g., Los Llanos), where precipitation is influenced by the Intertropical Convergence Zone activity and local convective systems.
75 citations
TL;DR: In this paper, the main objectives of the study were to determine the concentrations and the sources of heavy metals including Zn, Cu, Pb, Fe, Ni, Cr, Co, and Mn, and the contamination levels of metals in the dust of Bushehr (an urban area) and Assaluyeh (an industrial area) located in the province of Iran.
Abstract: Heavy metals in dust are causing health problems in humans and other organisms. The main objectives of this study were to determine (1) the concentrations and the sources of heavy metals including Zn, Cu, Pb, Fe, Ni, Cr, Co and Mn, and (2) the contamination levels of metals in the dust of Bushehr (an urban area) and Assaluyeh (an industrial area) located in the province of Bushehr, southwestern Iran. Also, the transect between the two cities was investigated as a non-urban area. Fifty dust samples deposited on date palm leaves and 50 surface soil samples were collected. The mean concentrations of heavy metals in dust from the three areas were found to be higher than those of the nearby soils except for Co in Assaluyeh and Pb in Bushehr. Zn, Cu and Pb concentrations in dust samples from industrial and urban areas were higher than those in samples taken from the non-urban area. The results indicated minimal pollution levels of Mn, Fe and Cr, minimal to moderate levels of Co, moderate levels of Ni, moderate to significant levels of Cu, significant levels of Zn, and signi fi cant to very high levels of Pb in dust. The two main sources of different heavy metals in atmospheric dust deposited on date palm leaves were identified based on principal component analysis, cluster analysis and correlation analysis. Zn, Cu, and Pb seem to have anthropogenicsources, whereas Fe, Ni, Cr, Co, and Mn in atmospheric dust presumably derive from non-anthropogenic sources.In general, the implementation of environmental standards and improvement of the public transportation system are required to reduce the hazardous pollutants released into the atmosphere.
56 citations
TL;DR: In this paper, the authors presented a drought index modeling approach based on large-scale climate indices by using the adaptive neuro-fuzzy inference system (ANFIS), the M5P model tree and the multilayer perceptron (MLP).
Abstract: Climate modeling and prediction is important in water resources management, especially in arid and semi-arid regions that frequently suffer further from water shortages. The Maharlu-Bakhtegan basin, with an area of 31 000 km 2 is a semi-arid and arid region located in southwestern Iran. Therefore, precipitation and water shortage in this area have many problems. This study presents a drought index modeling approach based on large-scale climate indices by using the adaptive neuro-fuzzy inference system (ANFIS), the M5P model tree and the multilayer perceptron (MLP). First, most of the climate signals were determined from 25 climate signals using factor analysis, and subsequently, the standardized precipitation index (SPI) was predicted one to 12 months in advance with ANFIS, the M5P model tree and MLP. The evaluation of the models performance by error parameters and Taylor diagrams demonstrated that performance of the MLP is better than the other models. The results also revealed that the accuracy of prediction increased considerably by using climate indices of the previous month ( t – 1) (RMSE = 0.802, ME = –0.002 and PBIAS = –0.47).
50 citations
TL;DR: In this article, the authors evaluated the climate change projected by the end of the 21st century under the SRES A2 emission scenario over southern South America using the regional model MM5.
Abstract: Atmosfera 29(1), 35-60 (2016) This work focuses on evaluating the climate change projected by the end of the 21st century under the SRES A2 emission scenario over southern South America using the regional model MM5. The model projects: (i) an increase of precipitation over central Argentina, Uruguay and southern Brazil during summer and fall; (ii) a decrease in precipitation over most of the study domain during winter and spring; (iii) an important decrease in precipitation over central and southern Chile, through the year. In general, the projected temperature increase depends on the season and the examined area; particularly, it is highest over tropical and subtropical latitudes in spring and over high latitudes in summer. The MM5 model projects: (i) an increase of the interannual precipitation variability of precipitation over central Argentina and Uruguay regardless the season; (ii) a slight decrease in interannual temperature variability over large extents of Argentina for summer and winter; (iii) a slight increase in interannual temperature variability at transition seasons; with highest values over central Chile in autumn and over north central Argentina in spring. From the reliability assessment of regional climate projections, it can be concluded that signal-to-noise ratio is high for temperature and low for precipitation. Therefore, the MM5 model is a useful tool in the generation of regional climate change scenarios of high resolution over southern South America, particularly for temperature, and is a starting point to perform studies related to impacts of climate change.
45 citations
TL;DR: In this article, high-resolution simulations are conducted with triple nested domains having a horizontal resolution of 27, 9 and 3 km, as well as 27 vertical levels by using the 1. 1o NCEP Final Analysis meteorological fields for initial and boundary conditions.
Abstract: Mesoscale atmospheric circulations play an important role in the transport of air pollution and local air quality issues. The planetary boundary layer (PBL), the thermo-dynamical structure and the flow field play an important role in air pollution dispersion. Hence, the PBL parameters over Nagpur, India are simulated using the ARW v. 3.6.1 mesoscale model. High-resolution simulations are conducted with triple nested domains having a horizontal resolution of 27, 9 and 3 km, as well as 27 vertical levels by using the 1 . 1o NCEP Final Analysis meteorological fields for initial and boundary conditions. Eight fair-weather days in winter and summer (January and April 2009) with no significant synoptic activity were chosen for the study. Sensitivity experiments of the ARW model were conducted with two non-local (Yonsei University [YSU], and Asymmetric Convective Model v. 2 [ACM2]) and three local turbulence kinetic energy (TKE) closure (Mellor-Yamada Nakanishi and Niino Level 2.5 PBL [MYNN2], Mellor-Yamada-Janjic [MYJ], and quasi-normal scale elimination [QNSE]) turbulence diffusion parameterizations, to study the evolution of PBL parameters and the thermodynamical structure during the study period. After validation of the simulated parameters with the available in-situ data, it was revealed that the non-local PBL scheme YSU, followed by local scheme MYNN2, could able to capture the characteristic variations of surface meteorological variables and the thermodynamical structure of the atmosphere. The present results suggest that the PBL schemes, namely YSU and MYNN2, performed better in representing the boundary-layer parameters and are useful for air pollution dispersion studies.
44 citations
TL;DR: In this paper, the authors investigate the sensitivity of the Loop Current and LCE detachments to three different mechanisms deemed to be relevant to their behavior: a) suppression of Caribbean vorticity perturbations entering the GoM; b ) smoothness of the topography, and c ) suppression of a deep canyon on the eastern Campeche Bank.
Abstract: The dynamics of the Loop Current (LC) and the release of its anticyclonic eddy (Loop Current eddy, LCE) are some of the most important features of the circulation in the Gulf of Mexico (GoM) and key aspects to gauge the validity of numerical simulations. Using a numerical model, we investigate the sensitivity of the LC and LCE detachments to three different mechanisms deemed to be relevant to their behavior: a ) suppression of Caribbean vorticity perturbations entering the GoM; b ) smoothness of the topography, and c ) suppression of a deep canyon on the eastern Campeche Bank. The main results of these experiments in comparison to a reference run considered to be the more realistic one are: a. Suppression of Caribbean eddies reduces the number of LCE separations, but they are not the principal mechanism that triggers the separations. Locally generated instabilities over the northeastern Campeche Bank and the LC northward extension, appear to be the controlling factors. b. Smoothing the topography generates a wider and less intense LC and reduces the energy exchange terms related to flow instabilities. Nevertheless, the number of LCE separations is similar to the reference experiment. Extension of the LC controls the shedding that, in this case, tends to occur in the summer-fall season, when the LC is more extended, and the Yucatan transport abruptly weakens after its seasonal maximum. c. Removing the deep canyon in the eastern Campeche Bank, makes the LC extension more stable and reduces the number of LCE separations. The canyon appears to play an important role in spinning up cyclones generated over the LC eastern front that finally leads to an LCE release. The seasonal distribution of LCE separations in the experiments does not appear to be controlled by the strength of the barotropic and baroclinic instability source terms. Instead, a necessary but not sufficient condition for LCE separations is that the LC extends beyond 24o N. Our results indicate that caution should be exercised when interpreting LC statistics from a single numerical configuration.
20 citations
TL;DR: In this article, the concentrations of PM10 were measured both indoors and outdoors at 10 roadside residential buildings in Phitsanulok, Thailand during the dry and wet seasons of 2014.
Abstract: The concentrations of PM10 were measured both indoors and outdoors at 10 roadside residential buildings in Phitsanulok, Thailand during the dry and wet seasons of 2014. Seven trace metals (Zn, Fe, Pb, Cd, Ni, Cu and Cr) were also analysed in PM10. The monthly average concentrations of indoor and outdoor PM10 were 41.5 to 105.3 μg m–3 and 95.2 to 145.1 μg m–3, respectively. PM10 concentrations were significantly higher during the dry season compared to the wet season. The indoor/outdoor (I/O) ratios were less than one indicating that the particulate matter originates from the outdoor environment. Overall, the average concentrations of heavy metals in PM10 ranged from 0.2 to 2.7 μg m–3 and 0.5 to 7.1 μg m–3 for the indoor and outdoor environments, respectively. A strong positive correlation in indoor PM10 was found between Zn and Cu, Zn and Ni, and Cu and Ni. Zn and Ni, Pb and Cu, Cu and Ni, Cd and Ni, and Zn and Cu showed strong positive correlations in the outdoor environment. The enrichment factors of Zn, Cu, Pb, Cr and Ni were less than one suggesting that the metals in indoor PM10 have originated from crustal materials. For the health risk assessment, Cr was found to have the highest excess cancer risk in an evaluation using an Integrated Risk Information System.
19 citations
TL;DR: The results could help land managers to develop criteria related to forest management regarding P. cooperi by finding that the effects of rising temperatures during the previous winter are age-dependent; that is, maximum and minimum temperatures have opposite effects on the subsequent tree growth.
Abstract: Mexico has an abundance of Pinus species with P. cooperi as a dominant tree species of great ecological importance. In this study, we compared the climate sensitivity of P. cooperi trees of two age classes growing in the Sierra Madre Occidental: younger (< 80 years) and older (≥ 80 years) trees. A regional curve standardization (RCS) of growth ring width was developed for these two age classes. Our statistical analysis showed that annual tree growth was similar between the two age classes in absolute values of tree-ring widths. However, we found that the effects of rising temperatures during the previous winter are age-dependent; that is, maximum and minimum temperatures have opposite effects on the subsequent tree growth. Warming winter maximum temperatures have negative effects on radial growth, which are stronger in younger trees, whilst minimum winter temperatures enhance the growth. However, no difference in radial growth was observed between the two age classes based on precipitation. In climate change scenarios, an increase in temperature would affect younger trees of P. cooperi more than older trees. These effects of increased temperature may lead to a decrease in the growth and subsequent death of the trees. These results could help land managers to develop criteria related to forest management regarding P. cooperi.
18 citations
TL;DR: In this paper, the authors analyzed trends of high values of tropospheric ozone over Mexico City based on data corresponding to the years 2001-2014, and used Bayesian methods to estimate simultaneously a zonal and an overall time-trend parameter along with the shape and scale parameters of the generalized extreme value distribution.
Abstract: We analyze trends of high values of tropospheric ozone over Mexico City based on data corresponding to the years 2001-2014. The data consists of monthly maxima ozone concentrations based on 29 monitoring stations. Due to the large presence of missing data, we consider the monthly maxima based on five well identified geographical zones. We assess time trends based on a statistical model that assumes that these observations follow an extreme value distribution, where the location parameter changes in time accordingly to a regression model. In addition, we use Bayesian methods to estimate simultaneously a zonal and an overall time-trend parameter along with the shape and scale parameters of the Generalized Extreme Value distribution. We compare our results to a model that is based on a normal distribution. Our analyses show some evidence of decaying ozone levels for the monthly maxima during the period of study.
18 citations
TL;DR: In this article, a cloud shield stratification method based on different techniques arranged in a several layers approach of different convective features, aiming to stratify a cloud cover, is proposed.
Abstract: Moisture and instability, along with a triggering mechanism, are the main keys of deep convective storms initiation and evolution. Satellite data can provide indirect measurements of instability and moisture of a wide area in short periods of time. This paper studies the use of an objective method based on a blended use of multiple satellite-based convection estimation techniques. This method is based on different techniques arranged in a several layers approach of different convective features, aiming to stratify a cloud shield. Meteosat Second Generation (MSG) infrared (IR) 10.8 μm and water vapor (WV) 6.2 μm channels are explored together with tropopause temperature information provided by a numerical model. Threshold, brightness temperature differences (BTD), and time trends are applied to the information available resulting in a five layers product, highlighting areas of different convective activities. This cloud shield stratification method showed a great ability to better evaluate strong convection when compared with simpler techniques such as IR false color, and was especially useful to better identify the strongest convective cell in a large area with several convective outbreaks. A validation analysis was conducted using radar and lightning data, showing that this approach is very helpful in distinguishing very strong cases from weaker ones by pointing out subtle convective patterns only present in severe storms. Also, small changes in storm evolution were more pronounced in the method output. Besides some uncertainties that were observed, likely due to the large viewing angle, techniques derived from MSG spectral bands displayed good accuracy in studying large convective systems in the South America southern region.
TL;DR: In this paper, an instrument based on the Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique was designed and constructed to measure scattered sunlight in the UV-visible region at different elevation angles.
Abstract: An instrument based on the Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique was designed and constructed to measure scattered sunlight in the UV-visible region at different elevation angles. Slant column densities (SCDs) of specific gas absorbers such as nitrogen dioxide (NO 2 ) and formaldehyde (HCHO) are derived from the measured spectra. In this contribution, the technical characteristics and performance of the instruments, their deployment in a newly formed observational network within the metropolitan area of Mexico City, and some results of the retrieved NO 2 and HCHO SCDs are presented. These measurements provide more insight on the vertical and spatial distribution of these key atmospheric pollutants and their temporal variability, which also serve as a basis for present and future satellite validation studies.
TL;DR: In this article, the authors presented an ozone precursors monitoring network with continuous measurements for future trustful studies on air quality for ozone, considering the atmospheric chemistry and photochemical modeling for the design control strategies appropriate for the particular conditions of Mexico City.
Abstract: The purpose of this study is to select a number of stations from the existing Sistema de Monitoreo Atmosferico (Atmospheric Monitoring System, SIMAT) of Mexico City to serve as an equivalent to the Photochemical Assessment Monitoring Stations according to the US-EPA criteria, in order to improve the study of urban ozone occurrence. The results indicate that four existing SIMAT stations meet the criteria to form such network. The relevance of this study is to present an ozone precursors monitoring network with continuous measurements for future trustful studies on air quality for ozone, considering the atmospheric chemistry and photochemical modeling for the design control strategies appropriate for the particular conditions of Mexico City.
TL;DR: In this article, the authors evaluate the quality of high-resolution weather forecasts from the Weather Research and Forecasting (WRF) numerical weather prediction model at two horizontal resolutions (3 and 1 km).
Abstract: The aim of this paper is to evaluate the quality of high-resolution weather forecasts from the Weather Research and Forecasting (WRF) numerical weather prediction model. The lateral and boundary conditions were obtained from the numerical output of the Consortium for Small-scale Modeling (COSMO) model at 7 km horizontal resolution. The WRF model was run for January and July 2013 at two horizontal resolutions (3 and 1 km). The numerical forecasts of the WRF model were evaluated using different statistical scores for 2 m temperature and 10 m wind speed. Results showed a tendency of the WRF model to overestimate the values of the analyzed parameters in comparison to observations.
TL;DR: In this paper, high resolution data of horizontal winds profiles (zonal and meridional) in the lower troposphere, derived from a UHF wind profiler at a tropical Indian station, Pune (18 o 32' N, 73 o 51' E, 559 masl) during a 3-yr period (June 2003-May 2006) has been utilized to study seasonal and intra-seasonal variability of winds.
Abstract: High resolution data of horizontal winds profiles (zonal and meridional) in the lower troposphere, derived from a UHF wind profiler at a tropical Indian station, Pune (18 o 32’ N, 73 o 51’ E, 559 masl) during a 3-yr period (June 2003-May 2006) has been utilized to study seasonal and intra-seasonal variability of winds. Winds display a systematic seasonal evolution with behavior opposite in phase in the two altitude regimes below and above a height of 4-5 km. In the lower region, during the southwest monsoon months (June to September) winds are predominantly westerly with a peak in the 1.5-3.0 km range indicating the occurrence of the monsoon low-level jet (MLLJ). Soon after September, winds in this height region change from westerly to easterly and these easterlies continue in winter months (December to February). Above a height of 4 km, westerlies are observed during post-monsoon (October to November) and winter periods. The MLLJ is observed to be strong during normal/good monsoon years. On a day-to-day scale during southwest monsoon months, winds exhibit considerable intra-seasonal variability and periods of strong MLLJ seem to be associated with occurrence of spells of rainfall over the region.
TL;DR: In this article, a methodology to discover patterns in observed climatologic data, particularly temperatures and rainfall, in subnational political division units using an automatic classification algorithm (a decision tree produced by the C4.5 algorithm).
Abstract: This article proposes a methodology to discover patterns in observed climatologic data, particularly temperatures and rainfall, in subnational political division units using an automatic classification algorithm (a decision tree produced by the C4.5 algorithm). Thus, the patterns represent classification trees, assuming that: (1) every political division unit contains at least one climatological station, and (2) the recording periods of the stations are relatively similar in duration and in their initial and ending years. A series of classification models are produced by using different subsets from an experimental dataset. This dataset contains information from 3606 climatological stations in Mexico with recording periods whose durations, initial and ending years are diverse. The target (dependent) variable in all these models is the name of the political unit (i.e., the state). The predictors are 36 monthly features per each climatological station: 12 features corresponding to a minimum temperature, 12 to a maximum temperature, and 12 to cumulative rainfall. The altitude feature is also used as one of the predictors, in addition to the other 36; however, it is used only to quantify its additional contribution to the modelling. The results show that classification trees are effective models for describing and representing non-trivial patterns to characterize the political division units based on their monthly temperatures and rainfalls. One of the remarkable findings is that the cumulative rainfall of May is the feature with highest discrimination capability to the characterization task, which is consistent with the theoretical background on Mexican climatology. In addition, classification trees offer higher expressivity to non-experts in machine learning.
TL;DR: In this paper, the secondary velocities developed as an effect of the union of two water currents, based on data acquired from Doppler acoustic recorders, were analyzed.
Abstract: Fluid dynamics has the purpose of understanding the movement of liquids and gases by functions that describe the distribution of velocities. Some natural phenomena that present these functions are hurricanes, generated by pressure differences; cyclones, developed by the horizontal temperature gradient; and eddies, associated with a hydrostatic pressure gradient. In the particular case of eddies, they generate the so-called secondary velocities, which are flows formed by the presence of unequal forces between a hydrostatic pressure gradient and centrifugal forces, or by shear stresses at the joining of two flows. In addition, this phenomenon is observed in tornados, where the centrifugal force is greater in the upper layer and decreases towards the bottom, whereas the pressure gradient moves from a high to a low pressure; while in rivers it is detected particularly in bends or joins. Understanding the development of secondary currents is important for the reason that flow behavior is a function of the magnitude of these currents; hence their characterization is fundamental. The objective of this study was to obtain the secondary velocities developed as an effect of the union of two water currents, based on data acquired from Doppler acoustic recorders. A second objective was to draw the secondary velocities and to show the rotation flow
TL;DR: In this article, a new approach based on a combined simulation of the annual peak and mean flows was proposed to reduce the uncertainty in estimating the design flow when few data are available.
Abstract: The design flow is the basis for planning and designing different hydraulic works. The precision in estimated flows is important when analyzing the feasibility of such structures because the value directly influences the evaluation of the failure effects. However, due to flow variability, the precision of the estimate is drastically reduced when small samples are used in a conventional flood frequency analysis (FFA). This paper proposes a new approach based on a combined simulation of the annual peak and mean flows. The method was evaluated by considering 10-, 20-, 30-, 40- and 50-yr subsamples obtained from 13 gauging stations located in the Susquehanna River basin. The results were compared with those obtained by FFA and the regional station-year method. This new approach can reduce the uncertainty in estimating the design flow when few data are available.
TL;DR: In the days before and during the 2014 FIFA World Cup at the major landmarks of Rio de Janeiro, Brazil, air samples were collected and analyzed following Method TO-15 (US-EPA).
Abstract: Air samples were collected in the days before and during the 2014 FIFA World Cup at the major landmarks of Rio de Janeiro, Brazil. Samples were collected and analysed following Method TO-15 (US-EPA). Isoprene was selected as a marker of biogenic emissions, and benzene and toluene were selected as markers of anthropogenic emissions, primarily vehicular emissions. The isoprene, benzene, and toluene concentrations ranged from 0.39 to 2.32 µg m –3 , 2.27 to 10.16 µg m –3 , and 5.21 to 21.83 µg m –3 , respectively. The kinetic and mechanistic reactivities of these compounds were also calculated to estimate the actual contribution of these compounds to atmospheric oxidant formation. The benzene and toluene concentrations indicated that greener areas of the city are strongly affected by urban emissions. Levels of isoprene were similar to those previously determined in other areas with vegetation.
TL;DR: In this article, the authors analyzed the effects of vehicular traffic and its effects on air quality on the surroundings of provincial route No. 7 between the cities of Neuquen and Centenario.
Abstract: Vehicle traffic and its effects on air quality were analyzed on the surroundings of provincial route No. 7 between the cities of Neuquen and Centenario. Concentration levels of carbon monoxide, nitrogen oxides and sulfur dioxide were estimated for a period of five years (2005-2009) through regular data of traffic flow, considering average speeds per sector, the characteristics of vehicles in circulation and meteorological data. Calculations were made by applying CALINE, a line source Gaussian dispersion model developed for predicting pollution levels near highways and arterial streets. In the cases analyzed within the area of study, critical concentrations of gases did not exceed the limits established by Argentinean regulations nor current international standards. The results describe the impacts on receptors located near the route in areas that comprise both industrial and agricultural activities. The route analyzed presents high vehicular traffic with more than 14 000 vehicles traveling daily during 2007. Within a five-yr period, daily traffic increased by 12%. The study revealed that the highest concentration of gases occurred during the winter season in morning hours, when vehicles decreased their velocity at a toll area. This situation may have been modified in behalf of air quality due to the removal of the toll station.
TL;DR: In this article, the contribution of studied plants to the carbon cycle of an ecosystem located within an urban area, and the relationship of environmental variables such as temperature, density photosynthetic photon flux and relative humidity in the capture or emission of CO 2.
Abstract: Capture and emission of carbon dioxide of three species ( Buddleia cordata , Senecio praecox and Echeveria gibbiflora ) in the Reserva Ecologica del Pedregal de San Angel (Ecological Reserve of the Pedregal de San Angel), were estimated. CO 2 sampling was carried out in 2010 during the dry (February, March, April and November) and rainy seasons (July to October). On the dry season B. cordata and S. praecox captured 16.14 and 3.25 kg CO 2 , respectively, whereas E. gibbiflora emitted 45.76 kg CO 2 . In the rainy season the exchange of CO 2 was different for the three species. In the dry season, the photosynthetic rate was 22 pmol CO 2 m –2 s –1 for B. cordata, 27 pmolCO 2 m –2 s –1 for S. praecox and 29 pmolCO 2 m –2 s –1 for E. gibbiflora. In the rainy season they were 6, 5.25 and 3 pmol CO 2 m –2 s –1 , respectively. In addition, MODIS data were used to estimate the normalized difference vegetation index (NDVI), indicating that the intensity of greenery at the site increased during the rainy months. This paper explains the contribution of studied plants to the carbon cycle of an ecosystem located within an urban area, and the relationship of environmental variables such as temperature, density photosynthetic photon flux and relative humidity in the capture or emission of CO 2 . This work provides valuable information about the carbon cycle dynamics on urban ecosystems, which can be useful in future studies for climate change mitigation.
TL;DR: In this paper, the response of the simulated global temperature variability to additive and multiplicative stochastic parameterizations of heat fluxes, along with a description of the long-term variability in terms of simple autoregressive processes was studied.
Abstract: This work presents a study of the response of the simulated global temperature variability to additive and multiplicative stochastic parameterizations of heat fluxes, along with a description of the long-term variability in terms of simple autoregressive processes. The Earth’s global temperature was simulated using a globally averaged energy balance climate model coupled to a thermodynamic ocean model. It was found that simple autoregressive processes explain the temperature variability in the case of additive parameterizations; whereas in the case of multiplicative parameterizations, the description of the temperature variability would involve higher order autoregressive processes, suggesting the presence of complex feedback mechanisms originated by the multiplicative forcing. Also, it was found that multiplicative parameterizations produced a rich structure that emulates closely observed climate processes. Finally, a new approach to describe the stability in the steady state of a general one-dimensional stochastic system, through its potential function, was proposed. From an analytical expression of the potential function, further insight into the description of a stochastic system was provided.
TL;DR: An analysis of meteorological terminal aviation routine weather reports (METAR) generated at the “Ernesto Esguerra Cubides” (EEC) aerodrome (Tres Esquinas Airbase) is shown in this paper.
Abstract: An analysis of meteorological terminal aviation routine weather reports (METAR) generated at the “Ernesto Esguerra Cubides” (EEC) aerodrome (Tres Esquinas Airbase) is shown. The aerodrome is located in the municipality of Solano in the Colombian Amazonia. Reports covering the period January 1, 2009 to December 31, 2012 helped to identify and analyze the characteristics of the occurrence of fog events at the EEC aerodrome. The results show that fog is a frequent meteorological phenomenon at the EEC aerodrome: on average, one in five days of the study period had at least one report of fog. At the EEC, fog is the mete orological phenomenon that causes the most weather-related aerodrome closures; it caused 45.26% of the closures of the EEC aerodrome. The high percentage of episodes of fog with calm wind (95%) and its high occurrence between 22:00 and 08:00 LT suggest that fog at the EEC aerodrome is basically radiative-type. Fog appears in every month of the year. In addition, three episodes of dense fog over the EEC aerodrome were analyzed from METAR and aviation special weather reports (SPECI), images from the GOES-13 satellite, NOAA surface analysis charts and radio soundings made at the EEC aerodrome. The analysis of this information allowed us to establish the weather conditions in which three fog events were presented.
TL;DR: In this paper, statistical models for surface-atmosphere energy balance components (net radiation, sensible heat, and soil-stored heat) as functions of global radiation are proposed and the hysteresis pattern in the proposed models between the global radiation and net radiation was found during summer at suburban and urban sites, which seems to be originated by atmospheric moisture introduced by artificial irrigation and the thermal inertia of land cover.
Abstract: Statistical models for surface-atmosphere energy balance components (net radiation, sensible heat, and soil-stored heat) as functions of global radiation are proposed. This study was carried out during three seasons (winter, spring, and summer) in Mexicali, an arid city of northwest Mexico, by means of representative measurement campaigns of three types of land use in the study zone: urban, rural (desert), and farmed suburban. The hysteresis pattern in the proposed models between the global radiation and net radiation was found during summer at suburban and urban sites, which seems to be originated by atmospheric moisture introduced by artificial irrigation and the thermal inertia of land cover. The coefficient of determination ( R 2 ) and the mean square error are used as indicators of the quality of models.