Behavior of the ITCZ second band near the Peruvian coast during the 2017 coastal El Niño

Abstract

The behavior of the second band of the Intertropical Convergence Zone (ITCZ), near the Peruvian coast during early 2017, is studied, using precipitation, surface winds, sea surface temperature (SST) and atmospheric variables in different isobaric levels. The proposal of a daily index (Ia) to identify, opportunely, the formation of this band and the Lorenz energy terms in the region is also considered. This band was present from late January to early April 2017, associated with an anomalous dipole of sea level pressure between the east and west Oriental Equatorial Pacific, that configured anomalously northerly surface winds and relaxation of southeasterly trade winds near Peru. In medium levels, a zonally-oriented positive mixing ratio anomaly is observed in early March over the ITCZ’s second band, associated with heavy rain systems over the northern Peruvian coastal region. In the same period, positive anomalies of divergence in high tropospheric levels are observed. The daily Ia index allowed an effective detection of the ITCZ’s second band with 11 days prior the maximum coastal precipitation, and the Lorenz energy terms showed kinetic eddies energy (KE) peaks in January and February and a contribution of barotropic instability in equatorial regions.

Lagrangian Characterization of Surface Transport From the Equatorial Atlantic to the Caribbean Sea Using Climatological Lagrangian Coherent Structures and Self‐Organizing Maps

“…The particle's distribution and trajectories are associated with seasonal atmospheric variability. The periods of maximum particle accumulation coincide with the latitudinal displacement of the ITCZ (Aliaga Nestares et al, 2022;Haffke et al, 2016;Henke et al, 2012;Skliris et al, 2022), which gives rise to significant wind variability in the study area. When the ITCZ is in its southernmost location (∼3°N) from February to March, the wind intensifies in the Caribbean area, causing the particles to move toward the southern region of the Caribbean basin and on the NBC between October and January.…”

“…While the CLLJ can promote windage displacing particles toward the west, during its relaxation phase, the particle displacement into the CCC and the Panama‐Colombia Gyre could be expected. Finally, the trade winds' seasonality and the ITCZ's consequent latitudinal displacement (Aliaga Nestares et al., 2022; Haffke et al., 2016; Henke et al., 2012; Skliris et al., 2022) likely influence the currents and particularly the windage effect on particle transport.…”

Lagrangian characterization of surface transport from the Equatorial Atlantic to the Caribbean Sea using climatological Lagrangian Coherent Structures and Self-Organizing Maps

“…The particle's distribution and trajectories are associated with seasonal atmospheric variability. The periods of maximum particle accumulation coincide with the latitudinal displacement of the ITCZ (Aliaga Nestares et al, 2022;Haffke et al, 2016;Henke et al, 2012;Skliris et al, 2022), which gives rise to significant wind variability in the study area. When the ITCZ is in its southernmost location (~3 o N) from February to March, the wind intensifies in the Caribbean area, causing the particles to move towards the southern region of the Caribbean basin and on the NBC between October and January.…”

“…While the CLLJ can promote windage displacing particles towards the west, during its relaxation phase, the particle displacement into the CCC and the Panama-Colombia Gyre could be expected. Finally, the trade winds' seasonality and the ITCZ's consequent latitudinal displacement (Aliaga Nestares et al, 2022;Haffke et al, 2016;Henke et al, 2012;Skliris et al, 2022) likely influence the currents and particularly the windage effect on particle transport.…”

Caribbean Marine Heatwaves, Marine Cold Spells, and Co‐Occurrence of Bleaching Events

“…The Intertropical Convergence Zone (ITCZ) sits across the Caribbean at ∼11°N in July, and migrates south to ∼3°N in January. Due to the ITCZ latitudinal shift, winds over the Caribbean are stronger in January, February and March, and weaken in July and August (Aliaga Nestares et al., 2022; Haffke et al., 2016; Henke et al., 2012). Weaker/stronger winds are conducive of less/more evaporation or heat loss/gain from the ocean to the atmosphere (Fordyce et al., 2019).…”