Intraseasonal modulation of spring‐strong wind events associated with convection in northeastern Argentina

SALIO, PAOLA; ALVAREZ, MARIANO S.; ALVAREZ, MARIANO S.; OTERO, FEDERICO; OTERO, FEDERICO; VERA, CAROLINA; VERA, CAROLINA; SALIO, PAOLA

INTERNATIONAL JOURNAL OF CLIMATOLOGY

JOHN WILEY & SONS LTD

Año: 2019 vol. 39 p. 5228 - 5240

0899-8418

The relationship between intraseasonal variability (IS; 10?90 days) and days whichregistered convection-associated strong surface wind events (CSSWE) over northeasternArgentina (NEA) was studied. The climatological behaviour of these strongwind events showed a higher duration and occurrence in austral spring. CSSWEwere categorized as a function of the wet and dry phases of the spring-seasonintraseasonal (spring-SIS) index, which describes the activity of the leading patternof IS-filtered outgoing longwave radiation (IS-OLR) during that season in easternSouth America. A modulation of the IS variability over localized and mesoscalephenomena as the CSSWE was found, showing significant peaks of wind variabilityin that timescale, and especially the submonthly timescale. The CSSWE werecategorized according to the phases of the spring-SIS pattern and most of themoccurred before or during a wet phase, especially for the longer CSSWE. Moreover,the detection of CSSWE days during and before a dry phase was scarce.Rossby wave trains were observed to organize the circulation on intraseasonaltimescales that configure regional cyclonic anomalies in such way that favours thedevelopment of CSSWE, promoting mid-level ascents over NEA and northerlyadvection of humidity to the region. Together with the composites of IS-OLRanomalies and the spectra of wind velocity, they support the fact that the higherfrequencyIS variability is the primary influence for the development of CSSWE.