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Vulnerability assessment studies on climate change: a review of the research in Mexico
Get PDFVulnerability assessment studies on climate change are a substantial tool for the implementation of adaptation strategies that allow us to know what threats systems and their components (species, natural resources, populations, territories, among others) do face on climate change conditions, what actions are caused by them that increase their own vulnerability, and what strategies are implemented to reduce this vulnerability. The popularity of this research at the international level has caused different discussions about methods, components, and variables. How does the vulnerability to climate change have been assessed in Mexico? The objective of this article is to present a review of vulnerability assessment studies on climate change in Mexico, paying particular attention to study subjects, concepts, components, methodologies, tools, and applications. The method consisted of a systematic search and review of articles published on international databases (Scopus, Web of Science, Science Direct, and Scielo). A total of 57 articles were reviewed. The results identify knowledge gaps in research of vulnerability on climate change in Mexico. The conclusions can be used as a guide to understand the theoretical-conceptual framework of vulnerability and to conduct future research on subjects and areas which are less studied in Mexico
Simple statistical models of surface/atmosphere energy fluxes and their hysteresis in a desertic Mexican city (Mexicali)
No full textStatistical 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 México, 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 (R2) and the mean square error are used as indicators of the quality of models
Trends and variability of temperature and evaporation over the African continent: Relationships with precipitation
Get PDFThis study analyzes changes in the long-term (1901-2015) monthly values of potential evapotranspiration (PET), precipitation, and minimum (Tmin) and maximum (Tmax) temperatures across Africa to quantify trends and assess covariability between these climatic variables. Both warming and drying trends were observed across the continent. The 1979-2015 warming was stronger than that from 1901 to 1940. Some cooling occurred from 1941 to the mid-1970s. The 1901-2015 annual Tmax, Tmin, and PET averaged over Africa exhibited increasing or drying trends across the continent at rates of 0.18 ºC, 0.22 ºC, and 3.5 mm per decade, respectively. The 1961-1990 annual precipitation averaged over the whole continent showed that Africa experienced drying at a rate of about –28 mm per decade. When considering the period 1961-2015, the rate of precipitation decrease was about –8 mm per decade. From 1901 to 1915, areas around Lake Victoria in East Africa and along the western coastline south of the equator experienced wetting rates of up to 36 mm per decade. Significant (p < 0.01) warming trends occurred in Sudan, Southern and Northern Africa. Positive PET trends were significant (p < 0.01) in the warm Mediterranean climate, and the western part of South Africa. Long-term temperature increase and precipitation decrease across northern Africa possibly indicated the Sahara Desert expansion over time. Except in the warm desert climate, the continent exhibited high precipitation variability. Equatorial climate experienced low temperature and PET variability. The strongest coherence between precipitation and temperature existed at multiple scales (6-8 years). Correlations between precipitation and PET (or temperature) were mostly negative and weak (p > 0.01). Because the sensitivity of Tmin to local influences is higher than that of Tmax, areas with strong negative correlation were larger in coverage for Tmax than those of Tmin. These results call for planned measures to tackle food insecurity in sub-Saharan Africa
Evaluating reanalysis and satellite-based precipitation at regional scale: A case study in southern Mexico
Get PDFAccurate precipitation data is essential for any hydrometeorological study, particularly for calibration and simulation of hydrological models. In this paper, we evaluate the precipitation of two different reanalysis products (the ERA5 and GLDAS), and two satellite-based precipitation products (TRMM 3B42 and CHIRPS) over the La Sierra river basins in Southern Mexico, on regional and daily time scales, from 2008 to 2010. We compare the collocated gridded precipitation data against in-situ precipitation measurements in each gauge station, as well as the mean areal precipitation (MAP) over the catchments in the study area for the different products. The Pearson correlation coefficient, the root mean square error, and the multiplicative bias metrics suggest that CHIRPS and ERA5 are the highest quality precipitation products over the study area. CHIRPS performs better on the grid to point comparison, estimating better precipitation events from 10-50 mm, above 100 mm, and for all the values without threshold. ERA5 does better for precipitation from 0-10 and 50-100 mm. These two datasets also have better performance on representing the spatial rainfall variability according to the mean annual precipitation and MAP analysis, showing statistical values close to each other
Modeling photosynthetically active radiation: A review
Get PDFPhotosynthetically active radiation (PAR) is important in applications related to plant physiology or the carbon cycle. However, despite its importance, a global network for its measurement has not yet been established. This work consists of the revision of a series of works related to the development of empirical models for the estimation of PAR in places where it is not regularly measured, using for this purpose measurements of meteorological and radiation parameters available in weather stations. A list of the models developed, the study site, the results obtained, and the nomenclature used in each of them is made. The most common way to develop empirical estimation models is by studying spatio-temporal changes in the relationship between PAR and global solar radiation. Other estimation methods include the use of satellite-derived products such as MODIS-derived products and the use of artificial neural networks. Despite being more efficient for estimating PAR, the use of artificial neural networks is not as widespread because its use is more complex than the development of empirical models. The PAR to global solar radiation ratio reached its maximum in the summer months and the minimum in the winter months; in addition, the daily values per hour reached their maximum at sunrise and sunset, and their minimum around noon
Photochemical assessment monitoring stations program adapted for ozone precursors monitoring network in Mexico City
Get PDFThe purpose of this study is to select a number of stations from the existing Sistema de Monitoreo Atmosférico (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
Biomonitoring of atmospheric heavy metals pollution using dust deposited on date palm leaves in southwestern Iran
Get PDFHeavy 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 significant 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
Trends in temperature extremes in selected growing cities of Mexico under a non-stationary climate
Get PDFMexico is vulnerable to extreme climatic events; however, their impact is not uniform in all the country. This study presents an analysis of extreme temperatures in 12 Mexican cities, modeled under the assumption of a non-stationary climate. Temporal trends were estimated from an available climatological base of maximum and minimum temperatures with the non-parametric tests of Mann-Kendall and Sen’s slope method, and a generalized extreme value (GEV) distribution was used to model both temperatures. A likelihood ratio test and Akaike and Bayesian information criteria were used to evaluate the optimal model choice with incorporation of a covariate. Using the best model, return levels and confidence intervals for future scenarios were estimated. A trend towards urban warming was detected from both the non-parametric tests and the GEV distribution, although with heterogeneous behavior. In the series of the maximum temperatures, half of the cities analyzed were non-stationary, and of those, the city of Guadalajara, located in the center-west of the country had a negative trend. The trend for minimum temperatures was more uniform, as 90% of the cities were non-stationary with a positive trend, and only 10%, in an urban area to the east of the metropolitan area of the Valley of Mexico (Milpa Alta) and a coastal city of the Gulf of Mexico (Veracruz), showed stationary series. It is therefore concluded that return periods of thermal extremes estimated in a changing climate temporarily showed a significant variation, so statistical modeling must consider this behavior due to its importance for risk assessments and adaptation purposes
Diurnal, seasonal, and vertical distribution of carbon monoxide levels and their potential sources over a semi-arid region, India
Get PDFThe present study focuses on the investigation of both near-surface and vertical variability of carbon monoxide (CO) concentrations and their potential sources obtained from both in situ and satellite Measurements of Pollution in the Troposphere (MOPITT) over a semiarid region (Anantapur, India) from January 2016 to December 2017. The diurnal variation of CO shows sharp morning (07:00-09:00 LT) and evening (07:00-09:00 LT) peaks associated to local anthropogenic activities as well as the impact of the mixed layer height, and low concentrations during daytime (12:00-15:00 LT). The low levels during afternoon hours may be due to the increase of the mixed layer height and the decrease of anthropogenic sources. The seasonal mean CO showed no obvious variation, with highest levels observed in winter (329 ± 52 ppbv), followed by the pre-monsoon (327 ± 57 ppbv), post-monsoon (234 ± 36 ppbv) and monsoon (192 ± 22 ppbv). The high levels of CO during the winter are attributed to increased emissions from anthropogenic sources and a shallow mixed layer height. The vertical distribution of CO showed secondary peaks at high-pressure levels (300-200 hPa) during winter, pre-monsoon, and post-monsoon, which indicates CO transport from different source regions. These findings are reasonably confirmed through the air mass Concentrated Weighted Trajectory (CWT) analysis obtained from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. This study suggests that except for the monsoon, air masses transported from Indo-Gangetic Basin region also contribute to the enhancement of CO concentrations at the receptor site
Emission inventory point source visualization on Google Earth and integrated with HYSPLIT model (edited by Dr. Luisa Molina)
No full textEmissions inventories are fundamental tools in the management and research of air pollution, climate change, and other relevant areas of knowledge. This work shows how the Mexico national emissions inventory for criteria pollutants was transferred from an Excel file to a structured and standardized one based on Extensible Markup Language (XML), following the Keyhole Markup Language (KML) standard and the United States Environmental Protection Agency consolidated emissions reporting schema using a Python script (provided as supplementary material). We also show how once in the KML format, the results are compatible with Google Earth and any Geographic Information System (GIS) platforms. The KML format may also allow emissions inventory models to interoperate with Chemical Transport Models (CTM) that would be able to read/write XML files for research and public environmental management policy. As an example, we used Google Earth to engage the point source data and the dispersion of a hypothetical release for that point source modeled using the Hybrid Single Particle Lagrangian Integrated Trajectory developed by the National Oceanic and Atmospheric Administration (HYSPLIT-NOAA), whose outputs also can be displayed on Google Earth. Finally, the KML files outputs from the inventory and HYSPLIT-NOAA model can be visualized on any computer platform and mobile applications that incorporate Google Earth