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

2021 ◽  
Author(s):  
Vannia Jaqueline Aliaga Nestares ◽  
Diego Fernando Rodriguez Zimmermann ◽  
Nelson Quispe Gutiérrez
Keyword(s):  
Coastal Region ◽  
Heavy Rain ◽  
Intertropical Convergence Zone ◽  
Sea Surface ◽  
Mixing Ratio ◽  
Barotropic Instability ◽  
Surface Winds ◽  
Sea Level Pressure ◽  
Trade Winds ◽  
Peruvian Coast

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.

Evaluation of reanalysis and satellite-based sea surface winds using in situ measurements from Chinese Antarctic Expeditions

2013 ◽  
Vol 24 (3) ◽  
pp. 147
Author(s):  
Ming LI ◽  
Qinghua YANG ◽  
Jiechen ZHAO ◽  
Lin ZHANG ◽  
Chunhua LI ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Sea Surface ◽  
Surface Winds ◽  
Sea Surface Winds

scholarly journals Contrasting Impacts of Three Extreme El Niños on Double ITCZs over the Eastern Pacific Ocean

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 424
Author(s):  
Yinlan Chen ◽  
Li Yan ◽  
Gen Li ◽  
Jianjun Xu ◽  
Jingchao Long ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Intertropical Convergence Zone ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
Symmetric Structure ◽  
Double Itcz ◽  
Sst Warming

In the recent four decades, there were three record-breaking El Niño events: 1982/1983, 1997/1998, and 2015/2016 events. A double intertropical convergence zone (ITCZ) pattern distinctively emerges over the eastern Pacific Ocean during boreal spring. Based on reanalysis (ERA-Interim) during 1979–2018, this study examines how these three extreme El Niños modulate such double ITCZs. The 1982/1983 and 1997/1998 El Niños moved both northern and southern ITCZs equatorward to form an individual and broad equatorial ITCZ. In contrast, the regulation of 2015/2016 El Niño was unique with a strengthened southern ITCZ to form a symmetric double-ITCZ. The above differences can be attributed to the different meridional structures of sea surface temperatures (SSTs). For the 1982/1983 and 1997/1998 El Niños, there was a meridionally symmetric structure of SST warming with a maximum at the equator. While for 2015/2016 El Niño, there was a meridionally symmetric structure of SST warming with a minimum at the equator.

scholarly journals The Probability Distribution of Sea Surface Wind Speeds: Effects of Variable Surface Stratification and Boundary Layer Thickness

2010 ◽  
Vol 23 (19) ◽  
pp. 5151-5162 ◽  
Author(s):  
Adam Hugh Monahan
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Surface Wind ◽  
Sea Surface ◽  
Surface Winds ◽  
Free Atmosphere ◽  
Wind Speeds ◽  
Sea Surface Wind ◽  
Variable Surface

Abstract Air–sea exchanges of momentum, energy, and material substances of fundamental importance to the variability of the climate system are mediated by the character of the turbulence in the atmospheric and oceanic boundary layers. Sea surface winds influence, and are influenced by, these fluxes. The probability density function (pdf) of sea surface wind speeds p(w) is a mathematical object describing the variability of surface winds that arises from the physics of the turbulent atmospheric planetary boundary layer. Previous mechanistic models of the pdf of sea surface wind speeds have considered the momentum budget of an atmospheric layer of fixed thickness and neutral stratification. The present study extends this analysis, using an idealized model to consider the influence of boundary layer thickness variations and nonneutral surface stratification on p(w). It is found that surface stratification has little direct influence on p(w), while variations in boundary layer thickness bring the predictions of the model into closer agreement with the observations. Boundary layer thickness variability influences the shape of p(w) in two ways: through episodic downward mixing of momentum into the boundary layer from the free atmosphere and through modulation of the importance (relative to other tendencies) of turbulent momentum fluxes at the surface and the boundary layer top. It is shown that the second of these influences dominates over the first.

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