Lattice Wind Description and Characterization of Mexico City Local Wind Events in the 2001-2006 Period

Urban transformation and expansion in Mexico City continuously affect its urban morphology, and therefore the modes of wind circulation inside it and their occurrence probabilities. Knowledge on these topics is an important issue for urban planning and for other urban studies, such as air quality assessment. In this paper, using a lattice wind model at a meso- scale, we develop a simple description and characterization of Mexico City local wind events that occurred during the period 2001-2006, including an estimation of the occurrence probabilities. This region was modeled as a 2D lattice domain of identical cells, and wind conditions in each cell were described by four wind attributes: the horizontal velocity components, divergence, and vorticity. Models of one and four cells were applied to wind data furnished by the meteorological network of the city. Results include the following: Early morning: low intensity winds (75%) from N, NW, W and SW (75%), convergent (93%), with a slight predominance of cyclonic vorticity (54%). Morning and early afternoon: winds from N, NE and E (72%) with speeds from 0.5 to 3.5 m/s, slight prevailing of convergent winds (51%), and slight predominance of cyclonic vorticity (57%). Late afternoon and night: winds blowing from N, NW, and S (63%) with speeds from 1.5 to 3.5 m/s (66%), convergent (90%), and cyclonic (72%).