Atmósfera (Journal)
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Changes in the flooding area due to storm surge under climate change in an extensive wetland area in the southern Gulf of Mexico (edited by Dr. Christian Appendini)
No full textFloods caused by intense cold fronts and how they could change under different scenarios of sea level rise in the Terminos Lagoon, Mexico, are studied through the analysis of observations and numerical simulations. The numerical ocean model used is the Finite-Volume Community Ocean Model (FVCOM) of the Marine Ecosystem Dynamics Modeling Laboratory of the University of Massachusetts-Dartmouth, and the meteorological forcing comes from high-resolution simulations with the Weather Research and Forecasting model (WRF). The ocean simulations were carried out using unstructured meshes with the possibility of flooding and drying in their cells. Results of the numerical simulations were compared against observations. Considering the current mean sea level, an intense northern cold front event (or Norte) floods an area of 940 km2 that is currently covered by mangroves. This indicates that Nortes are important in the irrigation of extensive mangrove areas. Under scenarios of sea level rise of 0.25, 0.50 and 0.75 m the flooded areas increase by 297, 1062 and 2152 km2, representing a considerable increase in the areas flooded at Isla del Carmen. It is suggested to consider this situation in long-term planning
Is the energy balance in a tropical lowland rice paddy perfectly closed?
Get PDFA two-year (2015 and 2016) field experiment was carried out to study the surface energy budget and energy balance closure (EBC) in a tropical lowland rice paddy in Cuttack, India. Maintenance of a standing water layer in lowland irrigated rice ecosystem makes it unique and this strongly influences the surface energy balance which may alter the surface runoff, ground water storage, water cycle, surface energy budget, and possibly microclimate of the region. To study this, an experiment was conducted using eddy covariance system to measure the surface energy balance components during two cropping seasons (dry season, DS and wet season, WS) and two consecutive fallow periods (dry fallow, DF and wet fallow, WF). The rice was grown in puddled wet lands in DS and WS and the ground was left fallow (DF and WF) during the rest of the year. Results displayed that daily average latent heat flux at surface (LE) and at canopy height (LEc) dominated over sensible heat flux at surface (H) and canopy height (Hc), respectively due to the presence of water source coming from the standing water in the rice field. The EBC was evaluated by ordinary least square (OLS), energy balance ratio (EBR) and residual heat flux (RHF). In OLS, the slope ranged 0.38-0.89 (2015) and 0.28-0.99 (2016) during the study period. Average RHF was 10.3-12.0% higher in WS as compared to DS. It was concluded that the EBC estimated using RHF is the most suitable way to calculate closure for lowland rice paddy since it can distinguish different seasons distinctively, followed by OLS. Much variation was not observed in EBR after inclusion of storage terms (water, soil, photosynthesis, canopy) to the classical EBR
Investigating the performance of SWAT and IHACRES in simulation streamflow under different climatic regions in Iran
Get PDFIt is often reported that simpler models, due to their low parameter requirements, perform better than more complex models. To test this, the current study compared a simple rainfall-runoff model (IHACRES) with a complex watershed model (SWAT). Based on these two approaches, six models were developed for three climatically distinct (arid, semi-arid and semi-humid) watersheds in Iran. The coefficient of determination (R2) and the Nash-Sutcliffe model efficiency coefficient (NS) were calculated in each case. In arid, semi-arid, and semi-humid watersheds the SWAT model (R2 = 0.52, 0.68, 0.66; NS = 0.54, 0.63, 0.64, respectively) outperformed the IHACRES model (R2 = 0.37, 0.70, 0.57; NS = 0.22, 0.57, 0.56, respectively) for the same respective climate zones. Overall, SWAT performed better than IHACRES, although both models had acceptable performances in the semi-arid and semi-humid watersheds. In the arid watershed, the IHACRES model performed poorly compared to SWAT
Connection between sea surface temperature patterns and low level geopotential height in the South Atlantic Ocean (edited by Dr. Christian Appendini)
No full textThe aim of this work is to study the connection between sea surface temperature (SST) in the South Atlantic Ocean and the semi-permanent anticyclone. In order to do this, SST and geopotential height in 1000 hPa from the NCEP/NCAR reanalysis for the 1981-2016 period were used, with a spatial resolution of 2.5º × 2.5º and restricted to the domain 65º W-20º E, 50º S-0º to study the South Atlantic Ocean. Variability modes of the seasonal anomalies of both variables were calculated using the T mode of principal component analysis. In addition, to study the connection between both variables, the linear correlation between the temporal series of the eigenvectors of the different principal components of SST and geopotential height in 1000 hPa were calculated. Results showed that both in summer and spring, negative geopotential height anomalies to the south are associated with warmer SSTs in the central and north regions of the South Atlantic Ocean and cooler to the south. However, in autumn and winter, a lower than normal geopotential height in the southwestern region is connected to warmer SST anomalies in the south area and cooler in the center of the basin
Statistical analysis of building-induced turbulence at an airport
Get PDFBuilding-induced turbulence may affect aviation safety, e.g., when the aircraft is about to land at an airport. Observations of such flow have been conducted at the Hong Kong International Airport using short-range LIDAR (SRL). Statistical analysis of the radial velocity, namely, the longitudinal structure function, is described herein. It is found that the classical Kolmogorov theory for homogeneous turbulence applies to LIDAR observations of building-disrupted airflow. Some distinctive features of the turbulent flow are also discussed, notably velocity streaks and tiny anticyclones at the hectometer scale. The potential impact on a landing aircraft is examined and compared to flight data. The results in this paper could be useful for studying building-induced turbulence at other airports around the world
Seasonal precipitation in south-central Chile: Trends in extreme events since 1900
Get PDFWe study a regional precipitation time series built upon seven meteorological records from south-central Chile (SCC; 37º-42º S), which altogether cover the period 1900-2019. As a first objective, we investigated changes in the return period (RP) of dry (< P20) and wet (> P80) seasonal extreme events of precipitation (SEE) for each season. We observed a reduction in the RP of wet SEE during 1900-1950 in all seasons. Moreover, the dry SEE RP shows a reduction from 1950 to the present in all seasons. This phenomenon is noteworthy since 1900 for summer and winter, and since 1930 for autumn. Spring registers a constant RP value from 1990 onwards. As a second objective, we study possible relationships between seasonal precipitation variability and climate modes, such as the Southern Annular Mode (SAM) and the Tripole Index (TPI) of sea surface temperature (SST) over the Pacific Ocean. Summer and autumn precipitation showed a significant negative correlation with SAM activity at interannual and decadal scales, while winter and spring precipitation recorded a significant positive correlation with SST variability over multiple regions of the Pacific Ocean (including the tropics and New Zealand) and the Southern Ocean (Amundsen-Bellingshausen Sea). Finally, we confirm that SAM strongly modulates precipitation in SCC, especially in autumn, and that SEE variability in SCC is considerably associated with climate modes of tropical and extra-tropical origin
The role of the coastal oceans on the seasonal mean air temperature in Argentina (edited by Dr. Christian Appendini)
No full textThis work aimed to detect the influence of the sea surface temperature (SST) of coastal Atlantic and Pacific oceans on the seasonal mean air temperature in Argentina. The study region was delimited by 30-90º W and 20-60º S. Patterns of interannual variability of seasonal (summer and winter) SST were obtained through principal component analysis (PCA) in the T-mode. Linear correlations between time series derived from this method and the simultaneous mean air temperature series from weather stations were performed. Some of the variability modes obtained showed a relationship with mean air temperature over a large portion of Argentina. Lagged-by-one-season correlations were also made to assess the predictability of the mean temperature employing these modes. Results showed a reasonable degree of predictability in spring temperatures using winter SST variability modes, but for autumn temperatures no relationship was found
Spatial and temporal variability of sea breezes and synoptic influences over the surface wind field of the Yucatán Peninsula
Get PDFThe balance between synoptic and sea breeze atmospheric phenomena can profoundly influence atmospheric circulation in coastal regions. In this paper, a comprehensive study to understand the quasi-permanent patterns of such variability over the surface wind field of the Yucatán Peninsula is described. We performed a Complex Empirical Orthogonal Function (CEOF) analysis on 10 years (May 2007-May 2017) of modeled surface winds from the North American Mesoscale Forecast System (hereafter, NAM). High-pass/low-pass filtering was applied to the time series obtained from the CEOF analysis, to study the high and low-frequency temporal behavior that can be associated with the modes. Results show that for the period from October to March, cold fronts dominate in two different patterns (first two modes), which damp the local winds that show higher amplitude during the nighttime (land breezes) than during the daytime (sea breezes). By the end of this season, the influence of tropical systems, although smaller, is noticeable (third mode). From April to September the peninsula is dominated by sea breezes accentuated at the western shelf (first mode) while land breezes exhibit lesser dominance than sea breezes (third mode). In this period cold fronts and tropical systems (mode 2) exert milder influence over local winds. A distinctive phenomenon seen in the high frequencies of the second mode during this period is the occurrence of peninsula-wide sea breeze. The results of this work have important implications for atmospheric pollutant dispersion, wind wave generation and coastal erosion, among others
Air pollution and daily mortality in the Mexico City Metropolitan Area
Get PDFWe utilize a time-series semi-parametric Poisson regression approach, incorporating natural cubic splines for temperature, to study the short-term associations between PM10 and daily mortality due to cardiovascular, respiratory, and cardiorespiratory events for seven municipalities in Mexico City Metropolitan Area (2001-2013). Our results demonstrate that assessing seasonality, along with temperature variability, is vital in understanding the relationship between air pollution and mortality events. Additionally, our findings support the World Health Organization’s morbidity and mortality threshold for PM10 within the assessed municipalities. We were able to identify associations between different meteorological seasons and air pollutions effects on mortality. Lastly, we demonstrate that geographical differences are modulating the relationship between air pollutants and mortality for models with and without distributed lagged. Our findings highlight the need for policy-driven approaches that take into consideration the dynamics of meteorological influences and geographic variability in terms of mitigating future deleterious health impacts of air pollutants in facilitating mortality risk
Performance of the WRF model with different physical parameterizations in the precipitation simulation of the state of Puebla
Get PDFIn Mexico, intense rains generated by tropical cyclones, cold fronts, and mesoscale convective systems can cause floods and landslides, causing damage to social, service, economic and financial sectors, among others, leaving the population with fewer resources and in greater vulnerability. Given this scenario, disaster prevention has relevance in the civil protection agenda, which recognizes that it is essential to establish long-range strategies and programs focused on preventing and reducing their effects, beyond only paying attention to emergencies and disasters. The objective of this work is to evaluate the performance of the WRF model for the simulation of accumulated pluvial precipitation in 24 hours in the state of Puebla, considering 768 different combinations of physical parameters, compared to rain records of weather stations for the period from June 1 to August 20, 2017. In addition, as part of the research, optimal configurations are defined to obtain the best performance of the model at local and state levels