M.S. Jiménez Anaya, A.T. Celada Murillo, and A. Salcido (Mexico)
Wind circulation patterns, Wind direction states, Mexico City.
The knowledge of the surface wind circulation events and its possible organization in patterns is an important issue not only in meteorology, but also because these events may reflect the changes in the urban morphology in the cities and help to understand how the winds distribute the air pollutants in urban settlements. In this paper we proposed a model wind direction state which reflects in a discrete and simplified way the main features of the complex spatial structure of the surface wind circulation events in the Mexico City Metropolitan Area (MCMA). This approach yields a very simple analysis tool which allows a qualitative and quantitative identification of the MCMA wind circulation patterns. The MCMA was divided in quadrants (NE, NW, SW, SE) with the Mexico City’s Zocalo at the origin. For each quadrant, an hourly mean wind direction sector (N, NE, E, SE, S, SW, W or NW) is determined from the meteorological data of the official air quality network stations located inside it, and the wind direction state of the MCMA (as defined by the wind direction sectors of the quadrants) can be expressed by means of a 4-digits octal number, at any time. Within this framework, we calculated the full and partial densities of states of wind direction of the MCMA for the year 2001. We discussed the results for the dry and rainy seasons, and also for daylight hours and nocturnal ones. Our qualitative results were found in agreement with the few wind direction patterns reported by other authors. This approach, however, may allow to identify many other features of the real structure of the wind field.
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