Latitudinal trends in O<SUB>3</SUB>, CO, CH<SUB>4</SUB> and SF<SUB>6</SUB> over the Indian Ocean during the INDOEX IFP-1999 ship cruise

Surface measurements of ozone (O3), carbon monoxide (CO), methane (CH4) and sulfur hexafluoride (SF6) were made over the Arabian Sea and the Indian Ocean during the INDOEX field experiment in January- March 1999 covering the latitude range from 17&#176;N to 20&#176;S. Observations show decreasing trends in all these trace gases from the Indian coastal region to the open Indian Ocean. Ozone with a lifetime of few days, shortest among the species presented here, shows large variations while SF6, which has relatively longer lifetime, shows smaller variations. Ozone also shows clearly the effect of ITCZ and its movement. These observations show higher ozone near the Indian coastal region in January 1999 than in March 1999 and also compared to the observed ozone during the INDOEX-1998 cruise. This is believed to be due to strong anti-cyclonic conditions in January 1999 bringing more polluted air from the Indian continent. A decrease in the latitudinal gradient in CH4 was observed in 1999 compared to that in 1998 in the same region, indicating slower growth rate in 1998-1999 period

Airborne Aerosol in Situ Measurements during TCAP: A Closure Study of Total Scattering

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively

Constraining cloud lifetime effects of aerosols using A‐Train satellite observations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95434/1/grl29404.pd

Observations of trace gases and aerosols over the Indian Ocean during the monsoon transition period

Characteristics of trace gases (O3, CO, CO2, CH4 and N2O) and aerosols (particle size of 2.5 micron) were studied over the Arabian Sea, equatorial Indian Ocean and southwest part of the Bay of Bengal during the monsoon transition period (October-November, 2004). Flow of pollutants is expected from south and southeast Asia during the monsoonal transition period due to the patterns of wind flow which are different from the monsoon period. This is the first detailed report on aerosols and trace gases during the sampled period as the earlier Bay of Bengal Experiment (BOBMEX), Arabian Sea Monsoon Experiment (ARMEX) and Indian Ocean Experiments (INDOEX) were during monsoon seasons. The significant observations during the transition period include: (i) low ozone concentration of the order of 5 ppbv around the equator, (ii) high concentrations of CO2, CH4 and N2O and (iii) variations in PM2.5 of 5-20&#956;g/m3

Variations of ozone in the marine boundary layer over the Arabian Sea and the Indian Ocean during the 1998 and 1999 INDOEX campaigns

Extensive measurements of surface ozone (O3) have been undertaken to study its transport from the continent to the marine region during the field cruises of Indian Ocean Experiment (INDOEX) in the winters of 1998 and 1999. The role of Intertropical Convergence Zone (ITCZ) in the distribution of O3 is investigated. These measurements show a large difference in ozone features during 1998 and 1999. Ozone mixing ratios, its latitudinal gradients, and amplitudes of diurnal variations are higher during INDOEX 1999 than in INDOEX 1998 over the Arabian Sea. The INDOEX 1999 period was characterized by many anticyclones and stronger inversions over the Indian region. The observed maximum latitudinal gradient and amplitude of diurnal variation are 7.5 ppbv lat-1 and 54%, respectively, during INDOEX 1999, which are more than the earlier levels observed over this region. There is almost no longitudinal gradient along the 20&#176;S latitudinal transect over the Indian Ocean. The marine type of diurnal variations observed in the regions where gradients in ozone are very small suggest that the theory recently given by de Laat and Lelieveld [2000] could not fully explain these variations. Using exponential decrease of ozone with latitude, we have estimated an e-fold time of 4.8 days for ozone, which is lower than that for aerosol (7 days) measured independently for this region. This indicates that in addition to mixing and deposition, which are common to both these species, chemical loss of ozone is also important over the marine environments of this region. Ozone levels over the Arabian Sea (~65 ppbv) are found to be more than four times the levels of ozone over the remote Indian Ocean (~14 ppbv), south of the ITCZ. These results suggest that anthropogenic activities in the Indian subcontinent can significantly affect its adjoining marine environments

Investigation of the Parameters Influencing Baseline Ozone in the Western United States: A Statistical Modeling Approach

Ground-level ozone (O3) is a key atmospheric gas that controls the oxidizing capacity of the atmosphere and has significant health and environmental implications. Due to ongoing reductions in the concentrations of O3 precursors, it is important to assess the variables influencing baseline O3 to inform pollution control strategies. This study uses a statistical model to characterize daily peak 8 h O3 concentrations at the Mount Bachelor Observatory (MBO), a rural mountaintop research station in central Oregon, from 2006–2020. The model was constrained by seven predictive variables: year, day-of-year, relative humidity (RH), aerosol scattering, carbon monoxide (CO), water vapor (WV) mixing ratio, and tropopause pressure. RH, aerosol scattering, CO, and WV mixing ratio were measured at MBO, and tropopause pressure was measured via satellite. For the full 15-year period, the model represents 61% of the variance in daily peak 8 h O3, and all predictive variables have a statistically significant (p 3 concentrations. Our results show that daily peak 8 h O3 concentrations at MBO are well-predicted by the model, thereby providing insight into what affects baseline O3 levels at a rural site on the west coast of North America

A Novel Analytical Approach for Optimal Integration of Renewable Energy Sources in Distribution Systems

The present research article focuses on an analytically based method for the optimal allocation and sizing of a renewable energy source (RES) capable of injecting both active and reactive powers in the distribution network. The placement of distributed generation (DG) in the distribution network reduces the magnitude of branch current in between the reference bus and the bus where DG is to be installed. Due to this, system power loss decreases significantly. The proposed method considers different levels of load in addition to peak load demand. The goal of the developed method is to minimize system losses by optimal DG allocations. In the proposed method, the optimum size of the DG is obtained on the basis of maximum loss saving criterion. For the execution of proposed method, only a base case load flow solution is required. The developed method has been tested on IEEE 69-bus and 33-bus radial distribution networks. On the basis of obtained results, it has been realized that the developed method is more capable of diminishing system energy losses