Oscar Peralta

Main Characteristics of Mexico City Local Wind Events during the MILAGRO 2006 Campaign within a Meso-β Scale Lattice Wind Modeling Approach

A characterization of local wind events in Mexico City, which occurred during MILAGRO campaign, was carried out within the framework of a lattice wind modeling approach at a meso-β scale. Mexico City was modeled as a 2D lattice domain with a given number of identical cells. Local wind conditions at any cell were described by a state variable defined by the spatial averages of wind attributes such as speed, direction, divergence, and vorticity. Full and partial densities of wind states were discussed under different conditions using two simple lattice wind models. We focus on the results obtained with the 1-cell lattice wind model and provide brief comments about preliminary results obtained with the 4-cell model. The 1-cell model allowed identifying the main patterns of the wind circulation in Mexico City throughout the study period (anabatic and katabatic winds, winds induced by the urban heat island, and winds with high possibilities for exchanging pollutants between Mexico City and the neighboring settlements, among others). The model showed that Mexico City wind divergence and vorticity disclose superposed oscillations whose most important periods were 24 and 12 hours, suggesting strong connections with the diurnal cycle of incoming solar radiation and the urban heat island.

Spatial variability of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the southern Gulf of Mexico

Environmental context Dimethylsulfide (DMS), the main biogenic sulfur compound in the atmosphere, is produced by the marine biosphere and plays an important role in the atmospheric sulfur cycle. This study recorded the spatial variability of DMS and dissolved and particulate dimethylsulfoniopropionate (DMSP) in the water column of the southern Gulf of Mexico. The results suggest that the spatial variability of DMS and DMSP is directly related to the hydrodynamics of the study area. Abstract The spatial variability of dimethylsulfide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd and DMSPp) was recorded in the southern Gulf of Mexico at three different depths (10, 30 and 60m) in January 2013. DMS and DMSP values were recorded through solid-phase microextraction coupled to gas chromatography. Average concentrations of DMS (2.8±1.5nM), DMSPd (1.7±0.9nM) and DMSPp (352±157nM) were significantly correlated with chlorophyll-a concentrations and the depth of the mixed layer. Vertical concentration profiles were similar, indicating a well-mixed water column with a thermocline at a depth of 50–100m. Average DMS sea-to-air flux was 5.0±1.7µmolm–2day–1. The greatest fluxes were recorded at the stations in the western region of the study area, owing to the combined effect of high DMS concentrations (3.7–7.21nM) and a high wind speed (4.4–6.8ms–1). The greatest concentrations were recorded at the stations nearest the coast. The distribution of DMS and DMSP was apparently related to the oceanic hydrodynamics.

Synergy between COSPEC observations and MODIS images in the monitoring of volcanic SO 2

Volcano monitoring is developed mainly with remote sensing techniques. In the case of SO2, it has been strongly used both surface techniques, such as COSPEC, and satellite techniques, such as MODIS. The two techniques differ in their measurement principle presenting advantages and disadvantages to each other. The purpose of this work is to show the synergy of both remote sensing methods in order to utilize information derived from these two techniques for continuous volcano monitoring. In this communication, we propose a methodology to correct any lag between COSPEC measurements and MODIS images at either time or space based on the wind speed and difference of the exact time of acquisition between the two techniques. The difference observed between COSPEC data and MODIS estimates is removed by using an exponential regression function derived from simultaneous observations using both sensors.

Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy Studies of Soot Particles Emitted from a Domestic Cook-stove

Household air pollution due to the use of biomass fuels in domestic cook stoves is a serious public health problem. It is estimated that two billion people use biomass fuel (wood, dung and fiber residues) as their primary energy source for domestic needs such as heating and cooking [1]. People who use these tools for food preparation are exposed to different kind of emissions, mainly soot originated by the inefficient combustion. Inhalation of soot causing serious adverse health effects in women and children, for this reason it is important to learn more about the nature of these particles. [2], [3], [4].

The carbon monoxide-elemental carbon link: A methodology for diagnosing and monitoring soot in urban areas

Abstract As the amount of soot and CO produced by combustion is proportional to the type of fuel that is used and the amount of available oxygen, it is likely that the soot-CO relationship can vary from city to city. In addition, the current measurements were made several kilometers distant and 1–2 hours of aging downwind of the primary sources. Since the mixing and dilution processes are different for gases and aerosols, the CO- σ a relationship may possibly depend upon the distance from emission sources, as well. The ability to estimate soot from CO measurements is highly promising, however, because of the ease of measuring CO compared to soot, the abundance of past CO measurements that could be analyzed with this relationship, and the potential for better monitoring of soot in the future.