Atmósfera (Journal)
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Analysis of the water balance under regional scenarios of climate change for arid zones of Colombia.
Get PDFThis workdiscusses in detail the parameters involved in water balance. The analysis is performed by considering the current conditions and climate change in a climatic zone that represents the arid regions of Colombia: The municipality of Uribia (desert) in the state of La Guajira. For this purpose, some climatological stations, which by their reported values of temperature and precipitation can be considered representative of the arid or desert climatic zones according to the Lang’s index (PCP/Tavg), were selected. Then, with historical temperature and precipitation values registered at the station of the area, the baseline was built and its behavior analyzed. The station data were obtained from the database of the Instituto de Hidrología, Meteorología y Estudios Ambientales (Institute of Hidrology, Meteorology and Environmental Studies) of Colombia. After estimating the baseline scenarios, the current water balance on the site was calculated by taking into account the original variables and including new parameters, if necessary, for the calculation of the simplified continuity equation. The analysis included parameters such as potential and actual evapotranspiration, moisture of soil, storage or recharge and their changes, water deficit and excess, runoff, periods of recharge, and water use. Anomalies in temperatures (ºC) and precipitation were calculated by taking into account the new climate scenarios “representative concentration pathways” for different periods (short- and long-term). With the anomalies identified, the baseline for the above-mentioned variables was adjusted. Again, the associated parameters were analyzed and discussed in the context of water balance. In climate change scenarios, the water balance projects a prospective exacerbation of desert conditions in the Uribia-Guajira region, since a decrease in the Lang’s index from its current value of 18.7 (desert) to 17.0 in 2050 and 14.5 in 2070 is expected, as a consequence of a decrease in precipitation (2.4 and 11.0%) and an increase in annual temperature of about 1.7 ºC with the HadGEM2-ES model for the period 2041-2060 and 3.7 ºC with the GFDL-CM3 model for the period 2061-2080. This can be verified by means of the Thornthwaite climate classification, which categorizes the area of study as an arid zone with limited and no excess of water. This deficit could lead to serious environmental consequences, social problems and a decline in the industrial and agricultural productivity of the zone
Sensitivity of pines in Mexico to temperature varies with age
Get PDFMexico 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
Analysis of the simulated global temperature using a simple energy balance stochastic model
Get PDFThis 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
THE ROLE OF LAND SURFACE SCHEMES IN THE REGIONAL CLIMATE MODEL (REGCM) FOR SEASONAL SCALE SIMULATIONS OVER WESTERN HIMALAYA
Get PDFClimate prediction over the Western Himalaya is a challenging task due to the highly variable altitude and orientation of orographic barriers. Surface characteristics also play a vital role in climate simulations and need appropriate representation in the models. In this study, two land surface parameterization schemes (LSPS), the Biosphere-Atmosphere Transfer Scheme (BATS) and the Common Land Model (CLM, version 3.5) in the regional climate model (RegCM, version 4) have been tested over the Himalayan region for nine distinct winter seasons in respect of seasonal precipitation (three years each for excess, normal and deficit). Reanalysis II data of the National Centers for Environmental Prediction (NCEP)/Department of Energy (DOE) have been used as initial and lateral boundary conditions for the RegCM model. In order to provide land surface boundary conditions in the RegCM model, geophysical parameters (10 min resolution) obtained from the United States Geophysical Survey were used. The performance of two LSPS (CLM and BATS) coupled with the RegCM is evaluated against gridded precipitation and surface temperature data sets from the India Meteorological Department (IMD). It is found that the simulated surface temperature and precipitation are better represented in the CLM scheme than in the BATS when compared with observations. Further, several statistical analysis such as bias, root mean square error (RMSE), spatial correlation coefficient (CC) and skill scores like the equitable threat score (ETS) and the probability of detection (POD) are estimated for evaluating RegCM simulations using both LSPS. Results indicate that the RMSE decreases and the CC increases with the use of the CLM compared to BATS. ETS and POD also indicate that the performance of the model is better with the CLM than with the BATS in simulating seasonal scale precipitation. Overall, results suggest that the performance of the RegCM coupled with the CLM scheme improves the model skill in predicting winter precipitation (by 15-25%) and temperature (by 10-20%) over the Western Himalaya.
Trend of total column ozone over Mexico from TOMS and OMI data (1978-2013)
Get PDFUsing satellite measurements from the Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) version 8, this work presents the total column ozone (TCO) trends over Mexico and, in particular, over the state of Zacatecas. Interannual variations and their statistical dispersion show a surprisingly systematic behavior. Yearly low values occur during December and January, while high values between April and May. A significant depletion of about 2.5% in TCO between 1978 and 1994 is derived from their statistical analysis, which also shows stabilization from 1996 to 2013. Although the depletion is merely significant, it is a sign that the studied regions, crossed by the Tropic of Cancer, have not escaped to the depletion of the ozone layer. The characterization described herein is important in terms of the correlation of TCO and ultraviolet radiation levels.En este trabajo se presentan las tendencias de 35 años de mediciones diarias de la columna total de ozono (TCO, por sus siglas en inglés) sobre la República Mexicana y en el estado de Zacatecas, y se describen las variaciones interanuales y su dispersión estadística. Para ello se utilizan mediciones satelitales de la TCO obtenidas con el espetrómetro para mapear ozono total (TOMS, por sus siglas en inglés) y el instrumento para el monitoreo del ozono (OMI, por sus sigas en inglés) versión 8. El comportamiento interanual, así como los niveles de dispersión de la TCO resultan sorprendentemente sistemáticos. A lo largo del año los valores más bajos ocurren en los meses de diciembre y enero, mientras que los más altos entre abril y mayo. Los análisis estadísticos realizados muestran que hubo un deterioro significativo del orden del 2.5% en la TCO entre 1978 y 1994, y que entre 1996 y 2013 hubo una estabilización. Aunque el deterioro es apenas significativo, es un indicio de que estas regiones de estudio, atravesadas por el Trópico de Cáncer, no han escapado al deterioro de la capa de ozono. La caracterización aquí descrita tiene importancia desde el punto de vista de monitoreo, pero sobre todo desde el punto de vista científico, por la correlación que existe entre el TCO y los niveles de radiación ultravioleta
PARAMETERIZATION OF NET RADIATION IN AN ARID CITY OF NORTHWESTERN MEXICO
Get PDFDuring the process of urbanization, different surface properties significantly alter the radiation balance. This paper attempts to quantify this balance over different surface types in an arid city of northwest Mexico over several days in August 2011. The albedo of each surface type, as well as local atmospheric properties such as the atmospheric clearness index (K0) and atmospheric emissivity (εatm), were estimated. The surfaces on which measurements were performed were asphalt, concrete, polystyrene painted with white elastomeric paint (PWEP), clay, and grass. It was found that, for a 24-h cycle of measurement, the highest average value of net radiation was for asphalt (146.1 Wm–2), and the lowest average value was for PWEP (33.6 Wm–2). Estimates of albedo values vary depending on the surface, whereas K0 and εatm are dependent on prevailing atmospheric conditions. From these measurements, preliminary statistical models of net radiation as a function of incoming solar radiation and net shortwave radiation were proposed. For each model, the coefficients of determination were higher than 0.97. We discuss the likely implications of the results found for the urban planning of the city.
SPATIAL, TEMPORAL AND SIZE DISTRIBUTION OF PARTICULATE MATTER AND ITS CHEMICAL CONSTITUENTS IN FAISALABAD, PAKISTAN
Get PDFSpatial and temporal variations in aerosol particulate matter (PM) were investigated for distribution over the four seasons of chemical constituents and particle size fractions in Faisalabad, Pakistan from June 2012 to April 2013. At nine sampling sites, four PM mass size fractions (total suspended particulates [TSP], PM10, PM4 and PM2.5) were monitored; simultaneously, TSP mass samples were collected on glass fiber filters using a high volume air sampler. TSP samples (144) were subjected to quantitative chemical analyses for determining trace elements (Pb, Cd, Ni, Zn, Cu, Fe) using atomic absorption spectroscopy, and water-soluble cations (Ca2+, Mg2+, Na+, K+, NH4+) and anions (Cl–, SO42– and NO3–) by ion chromatography. The highest PM mass concentrations were observed at industrial sites, while they were somewhat lower in major road intersections and lowest in the remote background site. It was also observed that PM mass concentrations were about two to 20 times higher than the standard limits of the World Health Organization and the US Environmental Protection Agency. Coarse particles (TSP, PM10 and PM4) were found to be highest during the summer, while relatively fine particles (PM2.5) were higher during the winter period. Concentrations of all size fractions were lowest during the monsoon sampling period at all sites. Concentrations of different elements and water-soluble ions also followed the similar temporal pattern as PM mass concentrations. The crustal elements Ca, Fe, Mg and Na were the largest contributors to TSP mass while elements of anthropogenic origin (Pb, Cd, Ni, Cu and Zn) had relatively lower concentrations and also showed a high spatial variation. Among the anions, sulfate (SO42–) was the predominant species contributing to 50-60% of the total anion concentration. It was found that rainfall, wind speed and relative humidity were the most important meteorological factors affecting PM concentrations. The evaluation of data presented in this paper will serve as a basis for future regional modeling and source apportionment.
Atmospheric energy conversion characteristics of heavy rainfall in Sindh during the 2011 monsoon
Get PDFSouth Asian monsoon occurs in most parts of the Indian subcontinent including Pakistan, India and Bangladesh during the period June to September of every year. These winds rich in moisture are forced to lift by the Himalayas causing extreme precipitation in different parts of the subcontinent, especially in Pakistan. The aim of this study is to explore the characteristics of atmospheric energy conversion and distribution during the heavy rainfall in Sindh, Pakistan for the period August-September 2011. The results show that when the energy value is greater than or equal to seven, the atmosphere jumps from stable to unstable. Under the influence of atmospheric circulations and terrain conditions, the kinetic energy is blocked by the mountains and is continuously converted into potential energy inside rainfall system. The peak phase of energy persisting for a considerable amount of time can lead to heavy rainfall. Moisture of this heavy rainfall mainly comes from the Arabian Sea and the Bay of Bengal
Winter frequency of western disturbances and precipitation indices over Himachal Pradesh, India: 1977-2007
Get PDFThe Himalayas have an important role in Indian weather and climate, since they control the western disturbances (WDs) during winter and the southwest monsoon during summer. During the winter months (December to March), westerly winds associated with WDs cause precipitation, sometimes along with heavy snowfall, extensive avalanches, etc., over Himachal Pradesh. Therefore, this study examined the temporal variability in the winter months frequency of WDs and various precipitation indices like wet days, rainy days, rather heavy and heavy precipitation days, and precipitation intensity during 1977 to 2007 over Himachal Pradesh. The study also examined synoptic features associated with intense WDs that caused heavy precipitation over the region during the same period. Analysis of data reveals a statistically significant (confidence level > 95%) decreasing trend in the frequency of WDs over this region. Since winter precipitation in Himachal Pradesh mainly occurs due to WDs, total winter precipitation and frequency of rather heavy and heavy precipitation days have decreased over the region. The analysis also shows a decrease of about 25% in heavy precipitation days and of 13% in total winter precipitation from their respective mean (from 1977 to 2007) over Himachal Pradesh
Inference of surface concentrations of nitrogen dioxide (NO2) in Colombia from tropospheric columns of the ozone measurement instrument (OMI)
Get PDFFor the first time, maps of surface concentration of nitrogen dioxide (NO2) are presented for the Colombian territory. NO2 surface concentrations for the year 2007 are inferred based on two sources of tropospheric NO2 column data: (1) a simulation using a three-dimensional global model (GEOS-Chem) and (2) measurements made by the ozone monitoring instrument (OMI) onboard the NASA Aura satellite. Results show monthly averages between 0.1 and 6 ppbv. We compare these inferred values to corrected ground measurements of NO2. We find correlation coefficients of up to 0.91 between the inferred data and the corrected observational data. A significant source of NO2 is biomass burning, which can be diagnosed by data of fire radiative power (FRP) from the Monitoring of Atmospheric Composition and Climate (MACC) reanalysis. We find a close relationship between high values of inferred NO2 surface concentrations and biomass burning for a large area which encompasses the departments of Caquetá, Meta, Guaviare, Vichada, and Putumayo.Por primera vez se presentan mapas de concentración superficial de dióxido de nitrógeno (NO2) para el territorio colombiano. Se infirieron concentraciones superficiales de NO2 para 2007 a partir de dos fuentes de datos de densidad de columna troposférica: 1) una simulación que utiliza el modelo global tridimensional GEOS-Chem y 2) mediciones realizadas por el instrumento de monitoreo del ozono (OMI, por sus siglas en inglés) instalado a bordo del satélite Aura de la NASA. Los resultados muestran valores mensuales promedio de 0.1 a 6 ppbv. Se compararon las concentraciones superficiales de NO2 inferidas con mediciones in situ corregidas y se encontraron coeficientes de correlación de hasta 0.91. Una fuente importante de NO2 es la quema de biomasa, la cual puede ser diagnosticada a partir de los datos de potencia radiativa de los fuegos provenientes del reanálisis para el monitoreo de la composición atmosférica y el clima (MACC, por sus siglas en ingés). Se encontró una fuerte relación entre altas concentraciones de NO2 inferidas y quema de biomasa para un área extensa que comprende los departamentos de Caquetá, Meta, Guaviare, Vichada y Putumayo