The aim of this work is to investigate the influence of the Madden - Julian Oscillation
(MJO) on turbulent elements of the Atmospheric Boundary Layer (ABL). The MJO was
identify on a time series of 30 years of outgoing long-wave radiation (OLR) and zonal
component of the wind (u). The turbulent parameters were studied through the
covariance and the correlation coefficient of a fast response data set collected on
Caxiuanã’s (Pa) micrometeorological tower. The difference between each phase of the
MJO was statistically analyzed with the t test of Student. The OLR and u data set results
shows that the MJO occurrence is linked to El Niño / Southern Oscillation (ENSO)
happening. The El Niño phase of an ENSO tends to diminish the chances of MJO case
to develops, the opposite situation is identify during an La Niña episode, when the MJO
is favored by the dynamics of the ongoing ENSO mechanism. If a MJO occurs during
an El Niño, it can change the temperature, wind velocity and the precipitation expected
for an El Niño year. The MJO’s phase analysis, for Belém, reveled a significant
difference on precipitation and maximum temperature between the active and inactive
phase, but for minimum temperature and wind module, this difference is little
significant. The turbulent kinematic fluxes, analyzed by scale on each phase of the
MJO, during three different periods of the day, were more distinct during the daytime
period, with high confidence levels, mostly on w’T’ and w’q’ fluxes. The day – night
transition and the night period were less different, with only a few scales showing more
than or exactly 95% of confidence during the transition, and with none scales reaching
the 95% mark during the night. Those results indicate that the diurnal convection is the
responsible mechanism for this differences, and as the MJO is like a big convective cell,
the local convection during its active phase is amplified, explaining the differences
found during the daytime period.
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