On the variability of the diurnal tide and coupling with planetary waves in the MLT over Cachoeira Paulista (22.7°S, 45°W)

Guharay, A.; Batista, P. P.; Clemesha, B. R.

doi:10.1016/j.jastp.2015.07.016

Cited by 14 publications

(14 citation statements)

References 54 publications

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“…Although variability of the diurnal, semidiurnal and terdiurnal tides from the same locations was reported by a few previous studies Fig. 11 Occurrence frequency of the vertical wavelength over the year for a zonal wind at CA, b meridional wind at CA, c zonal wind at CP, d meridional wind at CP, e zonal wind at SM and f meridional wind at SM (Batista et al 2004;Buriti et al 2008;Andrioli et al 2009;Guharay et al 2013Guharay et al , 2015, investigation of the QDT remained untouched so far. The QDT signature in the present study is found to be quite regular over the year with a weak seasonal variability although the amplitude is much smaller than the same of the diurnal, semidiurnal and terdiurnal components as shown by the past investigators from the same observational sites.…”

Section: Discussionmentioning

confidence: 55%

On the variability of the quarter-diurnal tide in the MLT over Brazilian low-latitude stations

Guharay

Batista

Buriti

et al. 2018

Earth Planets Space

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The characteristic features of the quarterdiurnal tide (QDT) in the mesosphere and lower thermosphere (MLT) are investigated using meteor radar observations from three low-latitude southern hemispheric stations, Sao Joao do Cariri (7.4°S, 36.5°W), Cachoeira Paulista (22.7°S, 45°W) and Santa Maria (29.7°S, 53.7°W) in 2005. The QDT shows consistent appearance with a weak enhancement during late summer and fall interval. The QDT amplitudes are found to be much smaller (< 3 m/s) than the longer period tidal components most of the times of the year consistent with the previous investigations carried out from various locations over the globe. The vertical wavelength is found to reach up to 80 km in the MLT maximizing in winter although most of the times it remains within 20 km. Therefore, based on the observed characteristics of the QDT, it is surmised that both the migrating and nonmigrating components are involved in manifestation of the QDT at present locations. Further detailed investigations are sought in connection with the important issues pertained to the actual excitation mechanisms and existing dominant QDT modes in the low-latitude MLT.

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Section: Discussionmentioning

confidence: 55%

On the variability of the quarter-diurnal tide in the MLT over Brazilian low-latitude stations

Guharay

Batista

Buriti

et al. 2018

Earth Planets Space

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“…A previous study by Lima et al (2006) from Cachoeira Paulista (22.7 • S, 45 • W) illustrated the inter-annual variability of the QSDW in the MLT with more than 5 years of horizontal wind data. The most recent studies by Guharay et al (2015a, b) from the same location reported significant modulation of the diurnal tide and quasi-2-day wave amplitude in the period of ∼ 16 days implying an important role of QSDW in controlling shorter period waves by modifying the mean background wind. In the present paper an attempt has been made to look into the latitudinal variability of the wave along with zonal propagation characteristics and its coupling with other planetary waves with shorter periodicities using meteor radar and reanalysis data from three Brazilian stations: Sao Joao do Cariri (CA, 7.4 • S, 36.5 • W), Cachoeira Paulista (CP), and Santa Maria (SM, 29.7 • S, 53.7 • W), which have remained untouched so far.…”

Section: A Guharay Et Al: Latitudinal Variability Of the Quasi-16-dmentioning

confidence: 83%

“…They also found clear signature of interaction between the newly generated secondary wave and QSDW. With long-term meteor wind observations over CP, Guharay et al (2015a, b) found predominate coupling of the QSDW with diurnal tide and quasi-2-day wave (QTDW) and subsequent variability in the wave amplitudes. In the present study the results of bispectra clearly reveal appreciable coupling between the QSDW and shorter period planetary waves.…”

Section: A Guharay Et Al: Latitudinal Variability Of the Quasi-16-dmentioning

confidence: 95%

Latitudinal variability of the quasi-16-day wave in the middle atmosphere over Brazilian stations

et al. 2016

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Abstract.A comparative study of the quasi-16-day wave (QSDW) in the middle atmosphere using meteor radar observations and reanalysis data from three Brazilian stations, Sao Joao do Cariri (7.4 • S, 36.5 • W) (CA), Cachoeira Paulista (22.7 • S, 45 • W) (CP), and Santa Maria (29.7 • S, 53.7 • W) (SM) has been carried out in the year 2005 to delineate its latitudinal variability characteristics. The broad spectral behavior around 16-day periodicity may indicate multiple modes of the concerned wave component. The wave amplitude shows a number of peaks over the year with the largest one in summer and winter in the case of mesosphere-lower thermosphere (MLT) and stratosphere, respectively. A potential coupling of the concerned wave with other short period planetary waves, especially at CA and CP is evinced. Although zonal propagation exhibits both eastward as well as westward waves there is a general preference of eastward waves at mid-latitude and westward waves at tropical latitudes. The prevailing westerly background wind in the middle atmosphere is conceived to favor the wave filtering of westward propagating Rossby waves at lower latitude.

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“…Thus a smoothing out of short-term data fluctuations is characteristic and ensures a good mapping of oscillations with longer periods. Overall the spectral leakage can be reduced by using numerical windowing methods (Harris, 1978). We define the absolute amplitude of the wave as the peak-to-peak filtered signal and the relative amplitude as relative to the time-averaged amount of water vapor measured at the respective pressure level.…”

Section: Quasi 2-day Wave Activitymentioning

confidence: 99%

Responses to all referee comments

Lainer¹

2018

Preprint

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A mesospheric water vapor data set obtained by the middle atmospheric water vapor radiometer (MIAWARA) close to Bern, Switzerland (46.88 • N, 7.46 • E) during October 2010 to September 2017 is investigated to study the long-term evolution and variability of quasi 2-day waves (Q2DWs). We present a climatological overview and an insight on the dynamical behavior of these waves with the occurring spectrum of periods as seen from a midlatitude observation site. Such a large and nearly continuous measurement data set as ours is rare and of high scientific value. The core results of our investigation indicate that the activity of the Q2DW manifests in burst-like events and is higher during winter months (November-February) than during summer months (May-August) for the altitude region of the mesosphere (up to 0.02 hPa in winter and up to 0.05 hPa in summer) accessible for the instrument. Single Q2DW events reach at most about 0.8 ppm in the H 2 O amplitudes. Further, monthly mean Q2DW amplitude spectra are presented and reveal a high-frequency variability between different months. A large fraction of identified Q2DW events (20 %) develop periods between 38 and 40 h. Further, we show the temporal evolution of monthly mean Q2DW oscillations continuously for all months and separated for single months over 7 years. The analysis of autobicoherence spectra gives evidence that Q2DWs are sometimes phase coupled to diurnal oscillations to a high degree and to waves with a period close to 18 h.

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On the variability of the diurnal tide and coupling with planetary waves in the MLT over Cachoeira Paulista (22.7°S, 45°W)

Cited by 14 publications

References 54 publications

On the variability of the quarter-diurnal tide in the MLT over Brazilian low-latitude stations

On the variability of the quarter-diurnal tide in the MLT over Brazilian low-latitude stations

Latitudinal variability of the quasi-16-day wave in the middle atmosphere over Brazilian stations

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