[Probabilidad-Estadistica-Seminario] Seminario de Probabilidad y Estadística - Angel Segura (CURE, Universidad de la República)

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Seminario de Probabilidad y Estadística
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Título: "Characterization of daily profiles of wind patterns in a subtropical (34° S) coastal zone using polar coordinate reconstruction"

Expositor: Angel Segura (CURE, Universidad de la República)

Resumen:
 
Understanding wind patterns in the coastal regions are relevant for
oceanographic, infrastructure and ecological processes. Wind patterns are
vectorial quantities that require special mathematical treatment. Here, using an
algorithm based on a polar coordinate reconstruction based on a projection on
the euclidean space, we developed a novel algorithm to cluster daily wind
patterns. Wind intensity in knots and directions in degrees were measured every
5 minutes with a meteorological station located in the Southweastern Atlantic in
La Paloma harbour by the National Hydrographic and Oceanographic Service (SOHMA)
from 1st January 2021 to 2nd September 2023. We analyzed 220572 records of wind
data from 770 days. We projected directional data in the cylinder and estimated
dissimilarity among days for each 5-minutal wind measure and then we averaged
the dissimilarity between each pair of days. In doing so we estimated an average
daily distance matrix of wind patterns. Using the dissimilarity matrix, we
conducted a hierarchical cluster algorithm using the Ward metric as implemented
in the stats package under the hclust function using “ward.D2” method in R. We
selected ten groups characterizing daily profiles of wind patterns. North East
(NE) winds and South West (SW) winds were predominant with intensities ranging
from calm days (no wind) to a maximum of 44 knots in the passage of an
extratropical cyclone. Daily patterns showed variation: for example, one cluster
included the typical sea breeze regime, winds blowing from the North (N) in the
morning and intensifying in the afternoon and rotating to the NE. Another
cluster included the passage of a cold front (SW) in the noon, with the rotation
of wind from the N to the SW and intensifying. Another cluster with intense
winds from the South all day long were also common. The transition matrix showed
that two clusters persist from one day to another (~36 to 50% of times
respectively), two never repeat from one day to another and most of the clusters
(N=5) presented a ca. 20% of persistence. Results provide a detailed description
of wind patterns and to our knowledge the first implementation of the algorithm
for wind classification that allows to characterize wind profiles integrating
intensity and speed. Implications for oceanographic processes, biological,
sailing and coastal infrastructure and predictability of weather forecast are
discussed.
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Viernes 23/10 a las 10:30, La charla del viernes 23 será exclusivamente por zoom

Contacto: Laura Aspirot - laspirot en gmail.com
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https://salavirtual-
udelar.zoom.us/j/87033011104?pwd=qnKGw4syp4Izilf5QekV7Ama7oyjXZ.1


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