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An 8-year database of sea surface temperature (SST), 7 years of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color images, wind fields, and numerical model results are analyzed to identify regions and periods of coastal upwelling on the western and southern shelves of

RESUMENLa dinámica del Golfo de México (GoM) se asocia frecuentemente con la Corriente del Lazo y los remolinos que se desprenden de ésta, los cuales son altamente energéticos y ocasionan corrientes intensas que pueden penetrar varios cientos de metros en la columna de agua. Sin embargo, hay regiones en el GoM y periodos de tiempo en que el forzamiento atmosférico local juega un papel importante en su dinámica y termodinámica. La circulación en las plataformas, particularmente en la interna, es generada principalmente por viento y tiene estacionalidad, ya que cambia de dirección a lo largo del año y tiene algunos periodos de condiciones favorables para el afloramiento/hundimiento. La circulación generada por el viento se vincula con el transporte de aguas con diferentes características de temperatura y salinidad. La variabilidad interanual de la circulación en las plataformas está asociada con la variabilidad interanual de la circulación atmosférica. Se ha identificado que la variabilidad intraestacional de los patrones de viento modifica considerablemente la ocurrencia de afloramientos y hundimientos. Debido a la forma y tamaño del GoM, cuando la circulación en una plataforma ocurre en sentido horario, puede darse en sentido opuesto en otras plataformas. El ancho de las plataformas en el GoM es variable: la plataforma oeste de Florida, la de Texas-Louisiana y el Banco de Campeche miden más de 200 km, en tanto que las más angostas son las de Veracruz y Tabasco. Otra consecuencia de la fisiografía del GoM y el forzamiento del viento es el desarrollo de transportes perpendiculares a la plataforma en el sur de la Bahía de Campeche, el sur de la plataforma de Texas y al sureste del Mississippi, los cuales a su vez varían a lo largo del año. El GoM es afectado durante el otoño-invierno (desde septiembre hasta abril) por frentes fríos provenientes del noroeste de Estados Unidos, los cuales tienen asociados vientos fuertes, secos y fríos que mezclan sus aguas y generan intensos flujos de calor sensible y latente del mar hacia la atmósfera. Estos vientos también enfrían el GoM debido a la mezcla de aguas cálidas de la superficie con aguas subsuperficiales de menor temperatura. Durante el verano, los ciclones tropicales que cruzan el GoM afectan su circulación y los afloramientos costeros. ABSTRACTThe Loop Current and its shed eddies dominate the circulation and dynamics of the Gulf of Mexico (GoM) basin. Those eddies are strongly energetic and are the cause of intense currents that may penetrate several hundred meters deep. However, there are regions in the GoM and periods of time in which the local 318 J. Zavala-Hidalgo et al.atmospheric forcing plays an important role in its dynamics and thermodynamics. The circulation on the shelves, and particularly on the inner shelf, is mainly wind-driven with seasonality, changing direction during the year with periods of favorable upwelling/downwelling conditions. The wind-driven circulation is associated with the transport of waters with different temperature and salinity chara...

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In this paper evidence of anthropogenic influence over the warming of the 20th century is presented and the debate regarding the time-series properties of global temperatures is addressed in depth. The 20th century global temperature simulations produced for the Intergovernmental Panel on Climate Change’s Fourth Assessment Report and a set of the radiative forcing series used to drive them are analyzed using modern econometric techniques. Results show that both temperatures and radiative forcing series share similar time-series properties and a common nonlinear secular movement. This long-term co-movement is characterized by the existence of time-ordered breaks in the slope of their trend functions. The evidence presented in this paper suggests that while natural forcing factors may help explain the warming of the first part of the century, anthropogenic forcing has been its main driver since the 1970’s. In terms of Article 2 of the United Nations Framework Convention on Climate Change, significant anthropogenic interference with the climate system has already occurred and the current climate models are capable of accurately simulating the response of the climate system, even if it consists in a rapid or abrupt change, to changes in external forcing factors. This paper presents a new methodological approach for conducting time-series based attribution studies.

The climate in Mexico and Central America is influenced by the Pacific and the Atlantic oceanic basins and atmospheric conditions over continental North and South America. These factors and important ocean-atmosphere coupled processes make the region's climate a great challenge for global and regional climate modeling. We explore the benefits that coupled regional climate models may introduce in the representation of the regional climate with a set of coupled and uncoupled simulations forced by reanalysis and global model data. Uncoupled simulations tend to stay close to the large-scale patterns of the driving fields, particularly over the ocean, while over land they are modified by the regional atmospheric model physics and the improved orography representation. The regional coupled model adds to the reanalysis forcing the air-sea interaction, which is also better resolved than in the global model. Simulated fields are modified over the ocean, improving the representation of the key regional structures such as the Intertropical Convergence Zone and the Caribbean Low Level Jet. Higher resolution leads to improvements over land and in regions of intense air-sea interaction, e.g., off the coast of California. The coupled downscaling improves the representation of the Mid Summer Drought and the meridional rainfall distribution in southernmost Central America. Over the regions of humid climate, the coupling corrects the wet bias of the uncoupled runs and alleviates the dry bias of the driving model, yielding a rainfall seasonal cycle similar to that in the reanalysis-driven experiments.

Climate simulations for the North Atlantic and Europe for recent and future conditions simulated with the regionally coupled ROM model are analyzed and compared to the results from the MPI‐ESM. The ROM simulations also include a biogeochemistry and ocean tides. For recent climate conditions, ROM generally improves the simulations compared to the driving model MPI‐ESM. Reduced oceanic biases in the Northern Atlantic are found, as well as a better simulation of the atmospheric circulation, notably storm tracks and blocking. Regarding future climate projections for the 21st century following the RCP 4.5 and 8.5 scenarios, MPI‐ESM and ROM largely agree qualitatively on the climate change signal over Europe. However, many important differences are identified. For example, ROM shows an SST cooling in the Subpolar Gyre, which is not present in MPI‐ESM. Under the RCP8.5 scenario, ROM Arctic sea ice cover is thinner and reaches the seasonally ice‐free state by 2055, well before MPI‐ESM. This shows the decisive importance of higher ocean resolution and regional coupling for determining the regional responses to global warming trends. Regarding biogeochemistry, both ROM and MPI‐ESM simulate a widespread decline in winter nutrient concentration in the North Atlantic of up to ~35%. On the other hand, the phytoplankton spring bloom in the Arctic and in the North‐Western Atlantic starts earlier, and the yearly primary production is enhanced in the Arctic in the late 21st century. These results clearly demonstrate the added value of ROM to determine more detailed and more reliable climate projections at the regional scale.

The worldwide human population suffering from allergies continues to increase. Pollen grains are a major source of airborne allergens and significant cause of these diseases. Therefore, continuous monitoring of pollen grains released and transported in the air locally or regionally is required to determine the prevalence of various pollen types and identify intra-day and intraannual seasonal variations over time. In this study, we developed the first pollen calendar for Mexico City, which includes a large variety of taxa, many of which show a long Main Pollen Season which may last throughout the year. The analysis and comparison of daily, monthly and annual values showed that the occurrence and abundance of the main types of aeroallergenic pollen in the atmosphere were species of Fraxinus, Cupressaceae and Alnus, which occur during the periods from December through March, whereas airborne pollens of several species of Poaceae and Urticaceae occurred throughout the year. The variation in pollen concentration showed that the greatest intradiurnal variations occurred during the second half of the day. Regarding the relationship of pollen with bioclimatic factors, the increase in temperature favoured the presence of pollen in the air, whereas the increase in pluvial precipitation and relative humidity was associated with a decrease in airborne pollen. Large tracts of the Valley of Mexico have atmospheric conditions that are conducive to the accumulation of airborne particles, including pollen. Anomalous winds from the southeast dominated the surface wind variability during the first months of 2010. These patterns induced extreme values in wind convergence at the lower levels of the atmosphere, which resulted in high concentrations of pollen at our sampling site. We suggest that these conditions are related to the warm phase of the El Niño Southern Oscillation phenomenon (2009)(2010).