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PUTTING INTO ACTION THE REGCM4.6 REGIONAL CLIMATE MODEL FOR THE STUDY OF CLIMATE CHANGE, VARIABILITY AND MODELING OVER CENTRAL AMERICA AND MEXICO
Get PDFWhat: International experts and attendees from several countries of Central America, Mexico, the Caribbean (CAM), and South America (SA) met to discuss regional issues on climate variability and climate change to learn the use of the non-hydrostatic version of the International Center for Theoretical Physics (ICTP) RegCM4.6 model, and to establish a regional modeling scientific community for understanding the physics of climate processes and the generation of regional climate change scenarios.When: 14-18 November 2016.Where: Center for Geophysical Research (CIGEFI in Spanish) and School of Physics, University of Costa Rica (UCR), San José, Costa Rica
Day by day evolution of a vigorous two wave Saharan dust storm – Thermal and air quality impacts
Get PDFThis paper conducts a day-by-day analysis of an intense Saharan dust storm that struck Athens (Greece) during April 2008 and consisted of two main dust waves (the first from 10/04/2008 to 14/04/2008 and the second from 19/04/2008 to 22/04/2008). Daily satellite data (1º × 1º resolution) of aerosol optical depth (AOD) were used, in order to follow the course of two dust plumes originated in North Africa through the eastern Mediterranean. Ground based measurements of particle concentrations (PM10 and PM2.5) and meteorological parameters (wind speed, air temperature, relative humidity and visibility) were also studied. The time intervals before and after each dust wave were taken under consideration, aiming to identify the atmospheric circulation that generated the dust storm and also the clearing mechanisms that removed the African dust from the Athenian atmosphere. Backward air mass trajectories isolated the source of the two dust plumes over Libya and Tunisia, where extreme daily AOD values were recorded. The transportation of dust in the Greek region, during both dust waves, was associated with south westerlies airflows attributed to the advent of low pressure systems from the Atlantic. The impact of both dust waves in Athens was interrupted by the prevalence of a strong north westerlies air stream, which carried the particles eastwards through Turkey, Cyprus and the Middle East. During this dust event, air quality in Athens was severely downgraded, but no thermal discomfort has occurred, according to the estimation of a Pollution Index (PI) and a Discomfort Index (DI), respectively. A drop in visibility was also reported.
Sea breeze in the Colombian Caribbean coast
Get PDFCirculation of sea breeze is a well-known and important mesoscale system, boosted by different properties of reception and storage of solar heat between land and sea during one day, and its effect on waves, currents, and transport of atmospheric contaminants, among others, has been proven. The aim of this work is to characterize sea breeze in three coastal zones of the Colombian Caribbean, in the north of South America: Riohacha, Barranquilla, and Santa Marta, through the analysis of data from the Instituto de Hidrología, Meteorología y Estudios Ambientales (Hydrology, Meteorology and Environmental Studies Institute) of Colombia during the period 1981-2008, and a detail analysis in the city of Santa Marta with data from the station of the Jorge Tadeo Lozano University of Bogotá in the period January 1st to December 31, 2010. Gustavsson´s method was used to identify the marine breeze cycle, its duration, frequency, and hourly pattern; hodograph representation and spectral analysis were performed according to the periodogram modified by the Welch method. It was established that the marine breeze signal in the Colombian Caribbean coast is stronger during the dry season (December-March), when it reaches the highest gradients of sea-land temperature and with a predominantly diurnal component. In the city of Santa Marta and central Caribbean, the sea breeze is stronger and more defined compared to those of the cities of Riohacha at the northeast, and Barranquilla at the southwest, reaching an estimated medium value of 4 m s–1 in March, and minimum values of 2 m s–1 in August. In Barranquilla, the sea breeze signal reaches 2.5 m s–1, while in Riohacha it reaches 1.5 m s–1, both in the dry season (December-March). According to the results, the strong signal in the city of Santa Marta is related to the gradient of 3 ºC between the sea-land temperature in the dry season, while in Barranquilla is 1.2 ºC, and in Riohacha it is less than 1ºC. Despite having observed a sea-land temperature gradient close to 2.5 ºC in July in the city of Riohacha, the hodograph is not well defined, and the signal magnitude is not strong, which could be related to the presence of strong synoptic winds almost the whole year, the desert landscape of the zone, and its geographical position. This the first scientific work related to marine breeze in this region of the Caribbean, and its results constitute an important base for studying the effect that such breezes may have on the spectrum of waves, upwelling, and especially in the transport of contaminants, given that Santa Marta is one of the most important harbors of mineral coal in Colombia, and one of the main touristic destinations in the northern Colombian coast
Fog collection and its relationship with local meteorological variables in a semiarid zone in Chile
Get PDFIn semiarid and arid zones, fog is considered an important alternative water source. The Southeast Pacific anticyclone and the cold Humboldt Current that characterize the north of Chile promote the formation of stratocumulus along the coastline. The thermally induced winds move these clouds eastwards favoring the formation of fog in the high hills of the Coast Range. The goal of this work is to characterize the fog water collected by a standard fog collector and its relationship with local meteorological variables. We found that the collected water is seasonally dependent, larger in summer than in winter. The mean diurnal cycle in autumn, summer and winter presents two maxima, at the early morning and late afternoon, meanwhile in winter it presents smooth variations during the day. The wind regime was compatible with land-sea circulation. The monthly mean temperature reached the maximum value in March and the minimum value between July and September, whereas the mean monthly daily temperature amplitude was larger in winter than in summer. The minimum values of relative humidity were achieved in the winter months. The fog water collection varies from zero to a maximum value that increased with wind speed, and mainly occurred with SW and NE winds. The fog index (FI) was defined as the percentage of foggy-days per month for which the water collected is greater than one liter. We found that FI follows the same trend as the monthly collected water, and decreases with the mean monthly daily temperature amplitude
A first approach to evaluate the vulnerability of islands’ vertebrates to climate change in Mexico
Get PDFMexican islands are one of the most diverse territories in the world and consequently their conservation should be a national and international priority. Three main threats to islands’ diversity have been detected: invasive species, land use change and climate change. Most studies have been focused on invasive species and land use change. Actually, as far as we know, this work is the first approach to evaluate climate change impacts on the biodiversity of islands in Mexico. We had two main goals: to list the vertebrate species that have been registered in Mexican islands and to model the possible impacts of climate change in the distribution of islands’ vertebrates. To evaluate climate change impacts, we used the ecological niche modeling that relates geographic occurrences with environmental variables to create a bioclimatic profile that can be projected in other time and other geographic areas. In our results we obtained a list of species registered in Mexican islands that increased in more than twice the number of species acknowledged by the Mexican government and the ecological niche modeling of 54 vertebrate species. We found that the species list effort was very important, because knowing which species exist is the first step to preserve them. In terms of ecological niche modeling, we modeled mammals, reptiles and amphibians. From these three groups, reptiles were the group with greatest losses and more species in the top-ten vulnerable list. If we considered a no dispersion scenario, all evaluated species presented losses regarding their current potential distribution area. If the full dispersion scenario was taken into account, the net change value resulted positive for the majority of the species evaluated, consequently if no barriers exist and the dispersion ability is good enough, changes in climatic conditions might not be an important threat. However, this is not the case for most species evaluated. Areas with a higher number of species (richest areas) do show changes in the future with shifts to the east and north of the country. Finally, we could find significant differences between times and scenarios in terms of suitable area losses. Greatest losses can be found in the long term RCP 8.5 Wm–2 in comparison to the long term RCP 4.5 Wm–2, meaning that the direction that humanity takes in terms of climate change will have consequences on island biodiversity. In this work, we did not take into account the sea level rise, which is expected to have important impacts on islands species
Acid rain in a Mexican site on the coast of the Gulf of Mexico
Get PDFThe activities taking place along the coast of the Gulf of Mexico are of great economic importance; however, these activities are potential sources of acid rain precursors. Potentially sensitive receptors to acid deposition in the coastal region of the Gulf of Mexico are lakes, rivers, forests, soils and monuments of cultural heritage. The aim of this study was to evaluate the chemical composition, enrichment factors and trends of wet atmospheric deposition at La Mancha, Veracruz, from 2003 to 2014. The major ions, pH and conductivity were analyzed daily during rainy and dry seasons. The following value ranges of the annual volume weighted mean (VWM) were: pH: 4.78-5.40; SO42–: 16-32 μeq L–1; NO3–: 4-15 μeq L–1, among others. The principal findings were found: (1) acid rain has been present for more than a decade along the coast of the Gulf of Mexico; (2) the non-marine ions in decreasing order were: NO3–, NH4+, Ca+ and SO42–; (3) all of the ions were present in major concentrations during the dry season due to minimal precipitation; (4) in several cases, the value of the pH events was low during the rainy season due to the low presence of chemical species that could favor neutralization; (5) the VWM pH in wet deposition was in the range of 4.78 to 5.40 during the study period (2003-2014), and (6) a significant increasing trend for pH was observed during the entire study period, while an increasing trend occurred from 2003 to 2008 for SO42–, NO3–, K+ and Ca2+, which decreased until 2011 and then increased until 2014
Total ozone mass calculation to assess the global ozone behavior
Get PDFThis work presents an assessment of the global and hemispheric total ozone mass and its interannual variations, using the total number of daily satellite measurements from the Total Ozone Mapping Spectrometer (TOMS) version 8 and Ozone Monitoring Instrument (OMI) level 3. The mean total ozone mass was 3.1283 ± 0.1337 × 1012 kg from November 1978 to November 1979, and 2.9979 ± 0.0917 × 1012 kg from November 2004 to November 2005. The difference (1.3033 ± 0.3221 × 1011 kg) represents a 4.2 ± 0.3% decrease in 26 yrs (1.615 ± 0.113% per decade), around 3% corresponding to the Northern Hemisphere and 5% corresponding to the Southern Hemisphere; 1.2 and 2.0% per decade, respectively. Differences in total ozone mass trends between Northern and Southern hemispheres indicate a change in geographic ozone distribution in the Southern Hemisphere. A linear fit between November 1978 and November 1991 shows a global ozone decrease of 4.72 × 109 kg per year, representing a loss of 1.5% per decade. Additionally, we found a net interannual variation of 16% of the total quantity existing during the equinoxes, when the maximum annual total ozone mass is reached
State of air quality in twin cities of Pakistan: Islamabad and Rawalpindi
Get PDFAtmospheric pollution has emerged as a disaster in developing countries like Pakistan. The aim of this study was to observe and analyze the air quality status of the twin cities of Pakistan, Rawalpindi and Islamabad, with a combined population of 15 million. The concentration of criteria pollutants along with CO2 was measured at five different locations within these cities. Sampling was done for 24 h at each location using a mobile air quality monitoring lab. The overall concentrations of SO2, NOX and O3 were found to be within the permissible limits of the US-EPA standards and the National Environmental Quality Standards of Pakistan, with higher PM10 and CO2 concentrations at most locations. The highest concentrations of PM10 were observed at Saddar, Rawalpindi (184 µg m–3), while minimum values were observed at the Blue Area of Islamabad (121 µg m–3). The concentration of CO2 during the study period was found to be high in almost all locations, with Saddar, Rawalpindi, indicating the highest value (409 ppm). The concentrations of CO2 at the Blue Area and the National University of Science and Technology of Islamabad were observed to be as high as 385.3 and 246 ppm, respectively. The behavior of pollutants with different meteorological parameters was also studied. For source identification, backward air trajectories were also generated using the HYSPLIT model
Interpolation of paleoclimatology datasets
Get PDFPaleoclimatology data includes measures of the amount of carbon dioxide in the atmosphere and level and temperature of the oceans, among others. Recent records of climate change data were done at equidistant times; the different variables were typically measured at the same time to allow for association studies among them. However, there are no registered records of climate change data for thousands or millions of years ago. Scientists have had to device alternative ways of measuring these quantities. These methods are usually a result of indirect measurements, such as ice coring, where both the variable of interest and the time have to be estimated. As a result, paleoclimate data are a collection of time series where observations are unequally spaced. Here we review a Bayesian statistical method to produce equally spaced series and apply it to three paleoclimatology datasets that span from 300 million years ago to the present
Evidence of traffic-generated air pollution in Havana
Get PDFIn Havana, transport is blamed as a likely source of pollution issues, which is usually supported on arguments referring to a vehicle fleet mainly made of old cars (i.e., most models are American from the 1950s or Russian from the 1980s) with poor technical conditions. Most of the existing studies are based on measurements from passive samplers collected for 24 h, which may not be representative of conditions where pollutant concentrations (particles or gases) fluctuate or are not homogeneous, such as transport-related pollution. The goal of this paper is to explore the transport-generated pollution by examining short-time correlations between traffic flows, pollutant concentrations and meteorological parameters. To do that, statistical relationships among all variables were analyzed, which revealed that PM10, NO2 and SO2 concentration levels are influenced by vehicular traffic, mainly with low-speed winds blowing perpendicular to the street axis. Furthermore, southeast and northeast winds force drag pollutionfrom sources other than traffic. These conclusions depend on the specific conditions of the summer season at the measurement area. A more complete analysis could be conducted when more data becomes available for each season