scholarly journals Variations in the Flow of the Global Atmosphere Associated with a Composite Convectively Coupled Oceanic Kelvin Wave

2010 ◽  
Vol 23 (15) ◽  
pp. 4192-4201 ◽  
Author(s):  
Paul E. Roundy ◽  
Lynn M. Gribble-Verhagen
Keyword(s):  
Southern Oscillation ◽  
Deep Convection ◽  
Composite Analysis ◽  
High Latitudes ◽  
Madden Julian Oscillation ◽  
Global Flow ◽  
Kelvin Wave ◽  
Coupled Mode ◽  
The Pacific ◽  
The Pacific Ocean

Abstract Kelvin waves in the Pacific Ocean occasionally develop and propagate eastward together with anomalies of deep convection and low-level westerly wind. This pattern suggests coupling between the oceanic waves and atmospheric convection. A simple composite analysis based on observed coupled events from October through April demonstrates that this apparent coupled mode is associated with significant large anomalies in the global flow that extend to high latitudes. These high-latitude anomalies are significantly larger than those that are linearly associated with the El Niño–Southern Oscillation (ENSO), and they evolve on time scales between those of the Madden–Julian oscillation and ENSO, potentially providing an opportunity for enhanced subseasonal predictability in the flow of the global atmosphere.

scholarly journals Analysis of Apparent Coupling between an Oceanic Kelvin Wave and Atmospheric Convection during the Winter of 1986/87

2010 ◽  
Vol 23 (23) ◽  
pp. 6352-6364 ◽  
Author(s):  
Lynn Gribble-Verhagen ◽  
Paul E. Roundy
Keyword(s):  
Deep Convection ◽  
High Amplitude ◽  
Sea Surface ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Atmospheric Convection ◽  
Convective Envelope ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Wind Bursts

Abstract This study analyzes the apparent coupling between an intraseasonal oceanic Kelvin wave in the Pacific Ocean and atmospheric moist deep convection for a particularly high-amplitude event during the winter of 1986/87. This wave was initiated initially by westerly wind bursts that developed in association with the Madden–Julian oscillation (MJO). After initiation by the MJO, the active convective anomaly slowed to roughly 1.5 m s−1, suggesting that the event became distinct from the MJO, which usually propagates at roughly 5–7 m s−1. This study demonstrates how surface winds, currents, SST anomalies, fluxes of sensible and latent heat across the sea surface, and atmospheric convection evolve throughout the event. Results suggest that the convective envelope and oceanic Kelvin wave are mutually beneficial and serve to prolong and enhance each other.

scholarly journals The Association of the Evolution of Intraseasonal Oscillations to ENSO Phase

2009 ◽  
Vol 22 (2) ◽  
pp. 381-395 ◽  
Author(s):  
Paul E. Roundy ◽  
Joseph R. Kravitz
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Kelvin Waves ◽  
Kelvin Wave ◽  
Weather Patterns ◽  
The Pacific ◽  
Intraseasonal Oscillations ◽  
The Pacific Ocean ◽  
Atmospheric Variations

Abstract The Pacific Ocean intraseasonal Kelvin wave is a leading oceanic mode that links intraseasonal tropical atmospheric variations with interannual variations in the coupled ocean–atmosphere system. This study considers the premise that these waves may evolve differently with their associated weather patterns during different phases of El Niño–Southern Oscillation (ENSO). If atmospheric and oceanic intraseasonal modes interact and evolve differently during various stages of ENSO, this result may provide useful information with regard to the role of these intraseasonal processes in ENSO evolution. This work utilizes signals of the oceanic Kelvin wave as a statistical basis for a simple composite averaging technique that is applied during different phases of ENSO to objectively analyze the evolution of oceanic and the associated portions of atmospheric intraseasonal oscillations. Results confirm the above premise and suggest that coupling between Kelvin waves and atmospheric convection evolves differently during different stages of ENSO. Further, intraseasonal zonal wind anomalies across the east Pacific timed with oceanic Kelvin waves are stronger during adjustment toward El Niño than during adjustment away from El Niño. These and other patterns in the composites suggest the possibility that systematic changes in the evolution of intraseasonal variations over the course of ENSO might feed back upon this interannual mode to influence the evolution of ENSO itself.

scholarly journals LINEARIZATION OF RELATIVE HUMIDITY OVER THE PACIFIC OCEAN ON THE EQUATORIAL LINE

2019 ◽  
Vol 16 (33) ◽  
pp. 630-640
Author(s):  
C. M. DÍEZ ◽  
C. J. SOLANO
Keyword(s):  
Pacific Ocean ◽  
Relative Humidity ◽  
Earth Science ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
East Side ◽  
The West ◽  
Enso Events ◽  
The Pacific ◽  
The Pacific Ocean

The atmosphere system is ruled by the interaction of many meteorological parameters, causing a dependency between them, i.e., moisture and temperature, both suitable in front of any anomaly, such as storms, hurricanes, El Niño-Southern Oscillation (ENSO) events. So, understanding perturbations of the variation of moistness along the time may provide an indicator of any oceanographic phenomenon. Annual relative humidity data around the Equatorial line of the Pacific Ocean were processed and analyzed to comprehend the time evolution of each dataset, appreciate anomalies, trends, histograms, and propose a way to predict anomalous episodes such ENSO events, observing abnormality of lag correlation coefficients between every pair of buoys. Datasets were taken from the Tropical Atmosphere Ocean / Triangle Trans-Ocean Network (TAO/TRITON) project, array directed by Pacific Environmental Laboratory (PMEL) of the National Oceanic and Atmospheric Administration (NOAA), and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). All the datasets were processed, and the code was elaborated by the author or adapted from Mathworks Inc. Even occurrences of relative humidity in the east side of the Pacific Ocean seem to oscillate harmonically, while occurrences in the west side, do not, because of the size of their amplitudes of oscillations. This fact can be seen in the histograms that show Peak shapes in the east side of the ocean, and Gaussians in the west; lag correlation functions show that no one pair of buoys synchronize fluctuations, but western buoys are affected in front of ENSO events, especially between 1997-98. Definitely, lag correlations in western buoys are determined to detect ENSO events.

Interannual Modality of Upper-Ocean Temperature: 4D Structure Revealed by Argo Data

2015 ◽  
Vol 28 (9) ◽  
pp. 3441-3452 ◽  
Author(s):  
Ge Chen ◽  
Hanou Chen
Keyword(s):  
Interannual Variability ◽  
Southern Oscillation ◽  
Hadley Circulation ◽  
Walker Circulation ◽  
Upper Ocean ◽  
Kelvin Wave ◽  
Argo Data ◽  
Sea Temperature ◽  
Equatorial Undercurrent ◽  
The Pacific

Abstract Using the newly available decade-long Argo data for the period 2004–13, a detailed study is carried out on deriving four-dimensional (4D) modality of sea temperature in the upper ocean with emphasis on its interannual variability in terms of amplitude, phase, and periodicity. Three principal modes with central periodicities at 19.2, 33.8, and 50.3 months have been identified, and their relationship with El Niño–Southern Oscillation (ENSO) is investigated, yielding a number of useful results and conclusions: 1) A striking tick-shaped pipe-like feature of interannual variability maxima, which is named the “Niño pipe” in this paper, has been revealed within the 10°S–10°N upper Pacific Ocean. 2) The pipe core extends downward from ~50 m at 130°E to ~250 m near the date line before tilting upward to the sea surface at about 275°E, coinciding nicely with the pathway of the Pacific equatorial undercurrent (EUC). 3) The double-peak zonal modality pattern of the Niño pipe in the upper Pacific is echoed in the subsurface Atlantic and Indian Oceans through Walker circulation, while its single-peak meridional modality pattern is mirrored in the subsurface North and South Pacific through Hadley circulation. 4) A coherent three-peak modal structure implies a strong coupling between sea level variability at the surface and sea temperature variability around the thermocline. Accumulating evidence suggests that Rossby/Kelvin wave dynamics in tandem with EUC-based thermocline dynamics are the main mechanisms of the three-mode Niño pipe in ENSO cycles.

scholarly journals The precipitation variability of the wet and dry season at the interannual and interdecadal scales over eastern China (1901–2016): the impacts of the Pacific Ocean

2021 ◽  
Vol 25 (3) ◽  
pp. 1467-1481
Author(s):  
Tao Gao ◽  
Fuqiang Cao ◽  
Li Dan ◽  
Ming Li ◽  
Xiang Gong ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Climate Variability ◽  
Southern Oscillation ◽  
Eastern China ◽  
Wavelet Coherence ◽  
Spatiotemporal Variability ◽  
Climatic Research Unit ◽  
Wet Season ◽  
The Pacific ◽  
The Pacific Ocean

Abstract. The spatiotemporal variability of rainfall in the dry (October–March) and wet (April–September) seasons over eastern China is examined from 1901–2016 based on the gridded rainfall dataset from the University of East Anglia Climatic Research Unit. Principal component analysis is employed to identify the dominant variability modes, wavelet coherence is utilized to investigate the spectral features of the leading modes of precipitation and their coherences with the large-scale modes of climate variability, and the Bayesian dynamical linear model is adopted to quantify the time-varying correlations between climate variability modes and rainfall in the dry and wet seasons. Results show that first and second principal components (PCs) account for 34.2 % (16.1 %) and 13.4 % (13.9 %) of the variance in the dry (wet) season, and their variations are roughly coincident with phase shifts of the El Niño–Southern Oscillation (ENSO) in both seasons. The anomalous moisture fluxes responsible for the occurrence of precipitation events in eastern China exhibit an asymmetry between high and light rainfall years in the dry (wet) season. The ENSO has a 4- to 8-year signal of the statistically positive (negative) association with rainfall during the dry (wet) season over eastern China. The statistically significant positive (negative) associations between the Pacific Decadal Oscillation (PDO) and precipitation are found with a 9- to 15-year (4- to 7-year) signal. The impacts of the PDO on rainfall in eastern China exhibit multiple timescales as compared to the ENSO episodes, while the PDO triggers a stronger effect on precipitation in the wet season than the dry half year. The interannual and interdecadal variations in rainfall over eastern China are substantially modulated by drivers originated from the Pacific Ocean. During the wet season, the ENSO exerted a gradually weakening effect on eastern China rainfall from 1901 to 2016, while the effects of the PDO decreased before the 1980s, and then shifted into increases after the 2000s. The finding provides a metric for assessing the capability of climate models and guidance of seasonal prediction.

scholarly journals On the validity of foraminifera-based ENSO reconstructions

2019 ◽  
Author(s):  
Brett Metcalfe ◽  
Bryan C. Lougheed ◽  
Claire Waelbroeck ◽  
Didier M. Roche
Keyword(s):  
Climate Models ◽  
Southern Oscillation ◽  
Planktonic Foraminifera ◽  
Regional Climate ◽  
Enso Cycle ◽  
Oxygen Isotope Ratios ◽  
The Pacific ◽  
Enso Dynamics ◽  
Temperature Signal ◽  
The Pacific Ocean

Abstract. A complete understanding of past El Niño-Southern Oscillation (ENSO) fluctuations is important for the future predictions of regional climate using climate models. Reconstructions of past ENSO dynamics use carbonate oxygen isotope ratios (δ18Oc) and trace metal geochemistry (Mg / Ca) recorded by planktonic foraminifera to reconstruct past spatiotemporal changes in upper ocean conditions. We investigate whether planktonic foraminifera-based proxies offer sufficient spatiotemporal continuity with which to reconstruct past ENSO dynamics. Concentrating upon the period of the instrumental record, we use the Foraminifera as Modelled Entities model to statistically test whether or not δ18Oc and the Temperature signal (Tc) in planktonic foraminifera directly records the ENSO cycle. Our results show that it is possible to use δ18Oc from foraminifera to disentangle the ENSO signal only in certain parts of the Pacific Ocean. Furthermore, a large proportion of these areas coincide with sea-floor regions exhibiting a low sedimentation rate and/or water depth below the carbonate compensation depth, thus precluding the extraction of a temporally valid palaeoclimate signal using long-standing palaeoceanographic methods.

Equatorial belt vapour measurements in the upper TTL under superpressure balloon during STRATEOLE 2 pre-campaign: tape recorder effect, role of waves and deep convection.

2021 ◽  
Author(s):  
Emmanuel Riviere ◽  
Mélanie Ghysels ◽  
Georges Durry ◽  
Jérémie Burgalat ◽  
Nadir Amarouche ◽  
...  
Keyword(s):  
Water Vapour ◽  
Lower Stratosphere ◽  
Deep Convection ◽  
Tape Recorder ◽  
Kelvin Wave ◽  
Water Vapour Content ◽  
The Pacific ◽  
Equatorial Belt ◽  
Local Water ◽  
Constant Altitude

<p>STRATEOLE 2 is a French-American project based on superpressure balloon borne measurements to study dynamics and processes in the TTL and the lower stratosphere of equatorial regions. One single flight of these balloons (of a duration of about 80 days) can make several turns of the Earth.</p><p>Here we present water vapour measurements by the Pico-SDLA infrared laser spectrometer on-board the TTL 2 gondola. The float altitude was of about 19 km during the technical campaign of STRATEOLE 2, providing measurements at the top of the TTL or the lower stratosphere. In this presentation, we analyse the tape recorder signal at a constant altitude during the 80 days of flight. We compute an anomaly of the <em>in situ</em> water vapour measurements with respect to a regional/temporal satellite-borne mean climatology from Aura MLS. It allows to analyse the local measurements by Pico-SDLA with respect to what is expected at a given position and a given time. The obtained contrast allows the positioning of observations with respect to local climatology and therefore, the identification of singular events responsible for modulation of the local water vapour content. Our analysis shows that a long wet anomaly above the Pacific Ocean is explained by the balloon “surfing” on a warm perturbation of a Kelvin wave. Concurrently, a dry anomaly is put to the fore over the Indian Ocean, associated to a packet of gravity waves cold perturbations. The balloon has flown twice above the Maritime Continent. For each passage, a short scale succession of dry and wet anomalies is shown, indicating a possible influence of local deep convection. This influence is studied further using satellite borne cloud top data.</p>

scholarly journals Observed Structure of Convectively Coupled Waves as a Function of Equivalent Depth: Kelvin Waves and the Madden–Julian Oscillation

2012 ◽  
Vol 69 (7) ◽  
pp. 2097-2106 ◽  
Author(s):  
Paul E. Roundy
Keyword(s):  
Shallow Water ◽  
Deep Convection ◽  
Longwave Radiation ◽  
Kelvin Waves ◽  
Water Model ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Easterly Wind ◽  
Equivalent Depth ◽  
Westerly Winds

Abstract The view that convectively coupled Kelvin waves and the Madden–Julian oscillation (MJO) are distinct modes is tested by regressing data from the Climate Forecast System Reanalysis against satellite outgoing longwave radiation data filtered for particular zonal wavenumbers and frequencies by wavelet analysis. Results confirm that nearly dry Kelvin waves have horizontal structures consistent with their equatorial beta-plane shallow-water-theory counterparts, with westerly winds collocated with the lower-tropospheric ridge, while the MJO and signals along Kelvin wave dispersion curves at low shallow-water-model equivalent depths are characterized by geopotential troughs extending westward from the region of lower-tropospheric easterly wind anomalies through the region of lower-tropospheric westerly winds collocated with deep convection. Results show that as equivalent depth decreases from that of the dry waves (concomitant with intensification of the associated convection), the ridge in the westerlies and the trough in the easterlies shift westward. The analysis therefore demonstrates a continuous field of intermediate structures between the two extremes, suggesting that Kelvin waves and the MJO are not dynamically distinct modes. Instead, signals consistent with Kelvin waves become more consistent with the MJO as the associated convection intensifies. This result depends little on zonal scale. Further analysis also shows how activity in synoptic-scale Kelvin waves characterized by particular phase speeds evolves with the planetary-scale MJO.

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