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The geographical regions of northwestern Mexico consisting of the Pacific Ocean, the Baja California Peninsula with its mountain range along it, the Gulf of California, and the coastal zone with its Western Sierra Madre Mountain range, configure an alternation of water, land, water, land, all interacting with the atmosphere. It suggests investigating the cloud patterns, what clouds are most relevant in controlling radiation and the climate, and what type of cloud is associated with observed precipitation patterns in the region. The principal aim was to carry out a climatology of five types of clouds: cumulonimbus, cumulus, altostratus, stratocumulus and nimbostratus. The data set was obtained from the MODIS sensor, placed on the Aqua and Terra satellites, covering the period from 2001 to 2020. The results revealed that the precipitation distribution predominantly relates to the deep convective cloud pattern. A minor fraction of rain is associated with the nimbostratus cloud pattern. The pattern of the fraction of total coverage of the five types of clouds coincides very well with lower radiation values, demonstrating the regulatory role of clouds in the area's climatology. [ABSTRACT FROM AUTHOR]

A field study was carried out in the Metropolitan Area of Monterrey (MAM), the second most populated city in Mexico, characterized by increasing urbanization, high traffic density, and intense industrial activity. These characteristics commonly present high concentrations of air pollutants leading to the degradation of air quality. PM2.5 was analyzed for heavy metals at two urban sites located within the MAM (Juarez and San Bernabe) in order to determine sources, health risk, morphology, and elemental content during the COVID-19 pandemic (autumn 2020 and spring 2021). Twenty-four-hour samples of PM2.5 were collected at each site during 30-day periods using high-volume equipment. Gravimetric concentrations and 11 metals were measured (Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Ni, Cr, and Pb) by different analytical techniques (flame atomic absorption spectroscopy, graphite furnace atomic absorption spectroscopy, and inductively coupled plasma optical emission spectroscopy). Selected samples were analyzed by scanning electron microscopy-energy-disperse spectroscopy in order to characterize their morphology and elemental content. PM2.5 concentrations exceeded the Mexican standard and WHO guidelines in Juarez during spring 2021. Cu, Cd, and Co were highly enriched by anthropogenic sources, and Ni, K, Cr, and Pb had a moderate enrichment. Mg, Mn, and Ca were of crustal origin. Bivariate statistics and PCA confirmed that alkaline metals originated from crustal sources and that the main sources of trace metals included traffic emissions, resuspension from soil/road dust, steel industry, smelting, and non-exhaust emissions at both sites. Lifetime cancer risk coefficients did not exceed the permissible levels established by EPA and WHO, implying that local residents are not at risk of developing cancer. Non-carcinogenic risk coefficients revealed that there is a possible risk of suffering cardiovascular and respiratory diseases due to inhalation of cobalt at the study sites. [ABSTRACT FROM AUTHOR]

Tornadoes are violent and destructive natural phenomena that occur on a local scale in most regions around the world. Severe storms occasionally lead to the formation of mesocyclones, whose direction or sense of rotation is often determined by the Coriolis force, among other factors. In the Northern Hemisphere, more than 99% of all tornadoes rotate anticlockwise. The present research shows that, in topographically complex regions, tornadoes have a different probability of rotating clockwise or anticlockwise. Our ongoing research programme on tornadoes in Mexico has shown that the number of tornadoes is significantly higher than previously thought. About 40% of all tornadoes occur in the complex topographic region of the Trans-Mexican Volcanic Belt. Data collected (from Internet videos) on the rotation of tornadoes formed in this region showed that about 50% of them rotated in a clockwise direction, contradicting tornado statistics for most of North America. Time series of the helicity parameter showed that tornadoes formed in topographically complex areas exhibited different behaviours compared to those formed in plains that are related with supercell systems. [ABSTRACT FROM AUTHOR]

Many regions of the world suffer loss of vegetation and reduced air quality due to wildfires. Studies on aerosol emissions by wildfires often discuss the negative effects of atmospheric contaminants from a regional or mesoscale perspective. The occurrence of wildfires reveals that a high percentage takes place close to large urban areas. Very high concentration of pollutants and PM10 particulate matter reach urban zones and millions of inhabitants. These events of high pollutant concentrations are seasonally recurrent. There are many large urban areas in the world that often undergo severe air deterioration due to wildfires smoke. We document the extreme impact of wildfire that occurs in the Protected Area of Flora and Fauna La Primavera located in neighborhood of Guadalajara, a large urban zone in Mexico. The simultaneous emissions of aerosols by 60 wildfires were simulated and compared with observed data. The plume generated by the wildfires reached large areas of the central part of Mexico. The principal characteristics of smog emissions (CO, NO2, and PM10) over the urban area were acceptably reproduced. Observed and modeled CO, PM10, and NO2 data indicated that aerosol plumes generated by the wildfires increased notably the concentrations over the metropolitan zone of Guadalajara. [ABSTRACT FROM AUTHOR]

The phenomenon of wildfires became a global environmental problem which demands estimations of their CO2 emissions. Wildfires have deteriorated the air quality increasingly. Using available information on documented wildfires and a data set of satellite detected hot spots, total yearly emissions of CO2 in Mexico were estimated for the period 1999-2010. A map of the main vegetation groups was used to calculate total areas for every vegetation type. The yearly number of hot spots per vegetation type was calculated. Estimates of emitted CO2 in a wildfire were then accomplished by considering parameters such as: forest fuel load, vegetation type, burning efficiency, and mean burned area. The number of wildfires and total affected areas showed an annual variability. The yearly mean of affected area by a single wildfire varied between 0.2 and 0.3 km². The total affected area during the period 1999 to 2010 was 86800 km² which corresponds to 4.3% of the Mexican territory. Total CO2 emissions were approximately 112 Tg. The most affected vegetation types were forest and rainforest. [ABSTRACT FROM AUTHOR]

Abstract: Vertical mixing and biological processes in the Gulf of California were analyzed using calculated relative vorticity fields induced by the barotropic M2 tide and zooplankton biomass distribution. M2 tidal currents contribute significantly to the general circulation observed in the upper gulf. The results revealed zones with high vertical and horizontal values of relative vorticity in regions where temperature anomalies and water exchange take place. The horizontal component of the vorticity vector is considerable in areas of the upper gulf, where high vertical shear of the velocity was estimated. Patterns of the horizontal component of the vorticity, the Simpson–Hunter criterion and the chlorophyll concentration showed similarities. The interaction of tidal flow with the complex bathymetry is the main source of vorticity and mixing in the gulf. The vertical component of the relative vorticity reaches positive values in regions where cyclonic circulation has been reported. A total of 35 groups of zooplankton were identified in the gulf; Copepoda, Chaetognatha, and Euphausiacea were the three major groups. High zooplankton biomasses in the archipelago region of the gulf were associated with topographic effect, which induces strong shear velocities, creating vertical mixing and increasing the supply of nutrients to the surface layers, which in turn induces high chlorophyll concentration or phytoplankton and thereby supports the zooplankton biomass. The zooplankton biomass was closely related to high values of the horizontal component of relative vorticity. [Copyright &y& Elsevier]