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Universidad Nacional Agraria La Molina (2020)

Patrones océano - atmosféricos y teleconexiones asociadas a las sequías meteorológicas extremas en la Sierra Sur del Perú

Sulca Paredes, Breat Sheylla

Titre : Patrones océano - atmosféricos y teleconexiones asociadas a las sequías meteorológicas extremas en la Sierra Sur del Perú

Auteur : Sulca Paredes, Breat Sheylla

Université de soutenance : Universidad Nacional Agraria La Molina

Grade : Ingeniero Meteorólogo 2020

Résumé
The ocean-atmospheric mechanisms and teleconnections connected to extreme meteorological droughts during the southern summer (january-march) in the southern highlands of Peru (SSP) were studied through the calculation of the standardized precipitation anomaly to categorize extreme dry events, use of spatio-temporal correlations to identify climate variability and teleconnections and finally the oceanic-atmospheric pattern was determined through the analysis of tropospheric dynamics analysis based on information from conventional SENAMHI meteorological stations, climate information from ERA5 reanalysis and ERSST sea surface temperature data in the period 1980 - 2019. Extremely dry events in the SSP were identified in the summers of the years 1983, 1990 and 1992 presenting a deficit higher than 46 percent of the normal average. On the other hand, in the evaluation of the climatic variability associated with the precipitations in the SSP in the period 1980-2019, it was found that the teleconnection indices NIÑO3, NIÑO4, NIÑO3.4, C, IOS and ONI presented a strong significant correlation. At the spatial analysis, the sea surface temperature (SST) over the North Pacific Ocean (northeast direction) together with the area of the South Pacific Convergence Zone, Equatorial Central Pacific Ocean showed a strong association with field of study. The oceanic-atmospheric pattern was associated with an anomalous increase of SST in the central-eastern Pacific Ocean by up to +3ºC. This heat source promoted an enhanced intensification of westerly winds in the lower troposphere (850 hPa), also induced a dipole of two anticyclonic circulations over the central equatorial Pacific at 200 hPa, in the medium levels (500 hPa) was observed a dorsal configured on the SSP. In the same way, the modification of the structure of the Walker circulation generated a subsident branch over the Amazon basin and the tropical Atlantic Ocean, while the Hadley circulation presented a descendent structure between 20ºS-40ºS, ten degrees further north of its climatic position. At regional level, there was evidence of atmospheric stability, convergence in the upper and divergence in lower troposphere and low content of humidity anomalies in the SSP.

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Page publiée le 7 novembre 2022