Multitemporal analysis with statistical models: influence of the atmospheric condition on urban concentrations of particulate matter

This paper shows a multitemporal analysis with autoregressive integrated moving average models of the influence of atmospheric condition on concentrations of particulate matter ≤ 10 µm in Bogotá city, Colombia. Information was collected from six monitoring stations distributed throughout the city. The study period was nine years. Autoregressive component of the models suggests that urban areas with greater atmospheric instability show a lower hourly persistence of particulate matter (one hour) compared to urban areas with lower atmospheric instability (two hours). Moving average component of the models hints those urban areas with greater atmospheric instability show greater hourly variability in particulate matter concentrations (5-10 hours). The models also suggest that a high degree of air pollution decreases the temporal influence of the atmospheric condition on particulate matter concentrations; in this case, the temporal behavior of particulate matter possibly depends on the urban emission sources of this pollutant rather than on the existing atmospheric condition. This study is relevant to deepen the knowledge in relation to the following aspects of atmospheric physics: The use of statistical models for the time series analysis of atmospheric condition, and the analysis by statistical models of the influence of atmospheric condition on air pollutant concentrations.

Air pollution climatology of Cochin for pollution management and abatement planning

The prevailing atmospheric condition is very important in determining the dispersion and dilution and thereby the resulting concentration of air pollutants, While high wind speed and stability conditions in general favour good inhaling of air pollutants conditions like inversion and calm winds cause for the build up of pollutants. In order to understand the different favourable and unfavourable conditions, some of the atmospheric aspects of air pollution are studied for the industrial city Cochin, situated on the west coast of India. Being a coastal city the frequency of occurrence of inversions and isothermal is not very high. Low values of mixing heights are observed in the southwest parts of the city during early morning hours, The study of spatial variation of mixing heights has revealed for the first time, that a single value of mixing height at the normal point of observation cannot be taken as a representative value for the whole city.

Robust mixed H2/H∞ fuzzy tracking control of photovoltaic system subject to asymmetric actuator saturation

This paper focuses on mixed [Formula: see text] fuzzy maximum power point tracking (MPPT) of photovoltaic (PV) system under asymmetric saturation and variations in climatic conditions. To maximize the power from the PV panel array, the DC–DC boost converter is controlled by its duty ratio which is practically saturated between 0 and 1. MPPT based on conventional control presents the problems of oscillations around maximum power point (MPP) and divergence under rapid climatic changes. In order to attenuate the effect of atmospheric condition variation and take into account asymmetric saturation of the duty ratio, we propose a novel robust saturated controller based on both [Formula: see text] performances and Takagi-Sugeno (T-S) representation of PV-boost nonlinear system. Within this approach, the nonlinear PV-boost system and its reference are first described by T-S fuzzy models. Second, the saturation effect is represented by a polytopic model. Then, a fuzzy integral state feedback controller is designed to achieve stable MPPT control. Based on Lyapunov function, the mixed [Formula: see text] stabilization conditions are derived in terms of linear matrix inequalities (LMIs). The optimization of the attraction domain of closed-loop system is solved as a convex optimization problem in LMI terms. Finally, the efficiency of the proposed controller under irradiance and temperature variations is demonstrated through the simulation results. The comparison with some existing controllers shows an improvement of MPPT control performance in terms of power extraction.

Numerical Behaviour of Primary Air Flow Field of a Swirl Injector Under High Pressure and High Temperature Condition

Injector plays pivotal role to meet better combustion performances requirements in terms of combustion efficiency, flame stability, ignition, lower emissions etc. In a multi-swirler injector, the primary swirler mainly dictates the airflow field inside and some extend outside the injector. Present CFD studies have been attempted to characterize the flow field of a swirl injector consisting of conical nozzle fitted with single radial swirler at its upstream. Studies are performed at high pressure and high temperature resulting to high density (increased by around 9 times compared to atmospheric condition) and its impact on the flow field in terms of location of energetic zones useful for fuel atomization. Since direct effect of increase in density lead to increase in turbulence which is helpful for mixing and atomization, this study is helpful to capture the same. Embedded LES based hybrid model has been used where the computational domain divided into 3 zones which are seamlessly connected by capturing the interface fluid dynamics. In LES zone, both the time and spatial scales have been resolved by suitably refining the grids. Analysis is carried out with CFL no. around 2, fixed time step of 1 micro second. The analysis is reasonably able to capture various unsteadiness (PVC, CTRZ, frequencies etc. useful for the atomization of the liquid fuel) which are not available beforehand.

Development of solar photovoltaic model for wide range of operating conditions

Assorted climatic conditions such as irradiation, temperature and shading due to clouds, trees, buildings, communication towers etc. has an unavoidable impact on the output of solar photovoltaic (PV) system. This creates a need for the analytical performance study of solar PV system in changing atmospheric condition in order to design and install an optimized solar PV system for both, stand alone and grid connected. The present work shows the developed PV model in MATLAB codes and simulation is done under varying climate conditions showing change in irradiation and temperature using different arrangements of PV system. PV parameters are obtained in different setup and I-V and P-V characteristics of the developed model of the PV modules are analyzed. A comparative study of the parameters obtained is quite beneficial for an optimized design of the PV system under different atmospheric conditions.

North China Plain as a hot spot of ozone pollution exacerbated by extreme high temperatures

A large population in China has been increasingly exposed to both severe ozone (O3) pollution and extreme heat under global warming. Here, the spatiotemporal characteristics of coupled extremes in surface O3 and heat (OPCs) over China are investigated using surface observations, a process-based chemical transport model (GEOS-Chem), and multi-model simulations from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). North China Plain (NCP, 37–41° N; 114–120° E) is identified as a hot spot of OPCs, where more than half of the O3 pollution days are accompanied by high temperature extremes. OPCs over NCP exceed 40 days during 2014–2019, exhibiting an increasing trend. Both O3 concentrations and temperatures are elevated during OPCs compared to O3 pollution days occurring individually (OPIs). Therefore, OPCs impose more severe health impacts to human than OPIs, but the stronger health effects are mainly driven by the higher temperatures. GEOS-Chem simulations further reveal that enhanced chemical production resulting from hot and stable atmospheric condition under anomalous weather pattern primarily contributes to the exacerbated O3 levels during OPCs. In the future, CMIP6 projections suggest increased occurrences of OPCs over NCP in the middle of this century, but by the end of this century, OPCs may decrease or increase depending on the pollutant emission scenarios. However, for all future scenarios, extreme high temperature will play an increasingly important role in modulating O3 pollution in a warming climate.

PREFACE

The seasonal atmospheric condition over the Maritime Continent is mainly driven by the Asian-Australian Monsoon. Precipitation over the Maritime Continent is highly influenced by the intra-seasonal Madden-Julian Oscillation (MJO), also highly affected by the El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole Mode (IOD). At an interannual time scale the Maritime Continent is also crossed by Indonesia Through Flow (ITF), as the artery connecting Tropical Pacific and Indian Oceans, and acting as a crucial link of the ocean general circulation that affects not only properties of these two oceans but also global climate. This complex mixture of land and sea interaction, with various atmospheric and oceanic phenomena within, makes the Maritime Continent as a unique, enigmatic and challenging area for scientific endeavor on tropical meteorology and atmospheric sciences. Various observations and research have been coordinated, campaigned, and conducted to better understand the atmospheric and oceanic condition over the tropics, especially the Maritime Continent. Many scientific discoveries have been found to enrich the knowledge of atmospheric science on the tropics, from the International Winter Monsoon Experiment in 1978, TOGA COARE in 1993, HARIMAU that ended in 2010, to CINDY/DYNAMO in 2011. The recent Year of Maritime Continent (YMC) during 2017 - 2020 aimed to improve understanding and prediction local multi-scale variability of the Maritime Continent weather-climate system and its global impact through observations and modelling exercises, was the state-of-art for such coordinated research on the tropics. As a part of YMC program, BMKG will also be involved in Measurements and Modelling of the Indonesian Throughflow International Experiment (MINTIE) which is collaborative research among countries including Indonesia BMKG and being led by Columbia University during 2019 – 2024. LIST OF Committee, Steering Committee, Organizing Committee Leader, Leader, Secretariat & Public Relations, Treasure, Event are available in this pdf.

A Competitive Study on MPPT Techniques Employed in Solar PV Systems

Integration of maximum power point tracking (MPPT) with photovoltaic (PV) systems is a necessity to track and deliver maximum power available. This paper focuses on comparing the tracking efficiencies of Perturb and Observation method (P&O), Incremental Conductance (IC) and Fuzzy-Logic System based MPPT technique. Change in atmospheric condition such as varying irradiance causes the output power to continuously vary over time. IC as well as P&O based MPPT techniques exhibit poor dynamic responses and so operating points keeps fluctuating. Variation in solar irradiance over a day at constant temperature is given as input to the solar PV module. The algorithm used here implements tracking over the period of a day. All the simulation study are implemented with the use of MATLAB/SIMULINK.

American Elegy, Reflux

This is a meditation on bad air as a defining bodily, temporal, political, and atmospheric condition of the twenty-first-century American Dream. In 2020, the novel viral respiratory illness COVID-19 stole the final breaths of nearly 350,000 Americans (and severely damaged the lungs of many, many more). George Floyd and Daniel Prude, unarmed and Black, were suffocated by the police in Minneapolis, Minnesota, and Rochester, New York, respectively. Protesters marching in the streets for racial justice were tear-gassed under milky skies. Wildfires raged up and down the West Coast of the United States, thickening the air in the mountains, in the valleys, in the woods, in the cities, with particulate matter. And doctors found a malignant mass in the right lung of this author’s mother. This essay uses the double meaning of aspiration (to inhale and to dream) to trace the myriad ways our collective breathing is central to, and curtailed by, the American Aspiration. Grounded through the breath, it traces the deep entanglements of global pandemic, climate change, state violence, and lung cancer, and their combined social, political, and environmental implications for Americans’ collective flourishing, or collective strangulation. Carried on the polar jet stream from rural Oregon, to the streets of Minneapolis and Rochester, to the tobacco plantations of the American South, it is a rhetorical exercise in breathless grief, in having the wind knocked out, in going up in smoke.