Factors controlling the interannual variations of MJO intensity

Deng, Lin; Li, Tim; Liu, Jia; Peng, Melinda S.

doi:10.1007/s13351-016-5113-3

Cited by 24 publications

(9 citation statements)

References 41 publications

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“…To investigate what factors determine the propagation pathway of these four modes, the background mean states are analyzed first ( Figure 5). Strong upward motion and positive mean moisture anomalies occur over the MC (Figure 5a,e), associated with the weak central equatorial Pacific cooling during the northeast mode years (Figure 5i), which can facilitate the ISO maintenance by transporting moist air upward to further trigger convections [44]. Thus, the BSISO can reach the WEP and WNP due to the weak change in mean state over the WEP and WNP regions.…”

Section: Different Background Characteristics Of the Four Propagationmentioning

confidence: 99%

Inter-Annual Variability of Boreal Summer Intra-Seasonal Oscillation Propagation from the Indian Ocean to the Western Pacific

2019

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The inter-annual variability of boreal summer intra-seasonal oscillation (BSISO) propagation from the Indian Ocean (IO) to the western Pacific (WP) is investigated for the boreal summers (May to September) of 1979–2018. It is shown that the interannual variability of BSISO mainly happens in its evolution, not in its strength over the IO. Here, we classify four distinctive modes for inter-annual variability of BSISO propagation: (i) northeast mode, propagating from the IO to the western equatorial Pacific (WEP) and the western North Pacific (WNP); (ii) north-only mode, only propagating to the WNP; (iii) east-only mode, only propagating to the WEP; and (iv) stationary mode, propagating to neither the WEP nor the WNP. It is found that the Maritime Continent (MC) and WEP are two key regions determining these four modes concerning mean state moisture and vertical motion. Associated with central equatorial Pacific cooling, the BSISO of northeast and north-only modes can reach the WP by passing over the MC due to positive mean moisture anomalies and upward mean motion anomalies over the MC. The strong negative mean moisture anomalies and downward mean motion anomalies over the WEP, related to strong central Pacific cooling, prevents the development of BSISO there, resulting in north-only mode. For the east-only and stationary modes associated with the central Pacific warming, their BSISO can hardly pass the MC due to negative mean moisture anomalies and downward mean motion anomalies. The positive mean moisture anomalies and upward mean motion anomalies over the WEP related to strong central Pacific warming, however, will reinitiate the BSISO in the WEP for the east-only mode.

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Section: Different Background Characteristics Of the Four Propagationmentioning

confidence: 99%

Inter-Annual Variability of Boreal Summer Intra-Seasonal Oscillation Propagation from the Indian Ocean to the Western Pacific

2019

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“…Significantly, the structures of the Intraseasonal Oscillations (ISO) in Central Africa are only discussed by few authors. More recently, [19] used one-Degree Daily Global Precipitation Climatology Project (1DD GPCP) higher resolution rainfall product to study the ISO patterns in CA, but they considered the whole area (15˚S -15˚N, 0˚N -50˚N) and did not take into account the contrast patterns between western and eastern parts of the region with different climate features. Fortunately, only [19] addressed this issue.…”

Section: Introductionmentioning

confidence: 99%

“…More recently, [19] used one-Degree Daily Global Precipitation Climatology Project (1DD GPCP) higher resolution rainfall product to study the ISO patterns in CA, but they considered the whole area (15˚S -15˚N, 0˚N -50˚N) and did not take into account the contrast patterns between western and eastern parts of the region with different climate features. Fortunately, only [19] addressed this issue. It was proved that there are two dominant frequency bands in the intraseasonal rainfall variability, 10 -25-day and 25 -70-day respectively, but they studied this difference in the intraseasonal oscillations only for 10 -25-day frequency band.…”

Section: Introductionmentioning

confidence: 99%

“…It was proved that there are two dominant frequency bands in the intraseasonal rainfall variability, 10 -25-day and 25 -70-day respectively, but they studied this difference in the intraseasonal oscillations only for 10 -25-day frequency band. So the present study is a continuity of the work done by [19], for the 25 -70-day frequency band. We use the same methods as [19] to assess the detailed spatial and temporal patterns of the leading modes of ISV of rainfall over the region, both throughout the year and from year to another.…”

Section: Introductionmentioning

confidence: 99%

“…So the present study is a continuity of the work done by [19], for the 25 -70-day frequency band. We use the same methods as [19] to assess the detailed spatial and temporal patterns of the leading modes of ISV of rainfall over the region, both throughout the year and from year to another.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the Differences in the Intraseasonal Rainfall Variability between Western and Eastern Central Africa: Case of 25 - 70-Day Oscillations

Tchakoutio¹,

Nzeukou²

2016

GEP

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The intraseasonal timescale is critical in Central Africa, because the resources of the region are highly rainfall dependent. In this paper, we use 1DD GPCP rainfall product to investigate the differences in the space-time structures of the 25-70-day intraseasonal variability of rainfall, over the Western Central Africa (WCA) and the Eastern Central Africa (ECA), with different climate features. The results of Empirical Orthogonal Functions (EOFs) analysis have shown that the amount of variance explained by the leading EOFs is greater in ECA (58.4%) than in WCA (49.8%). For both WCA and ECA, the power spectra of the Principal Components (PCs) peaked around 40 days, indicating a MJO signal. The seasonality of ISO is evident, but this seasonality is much noticeable in ECA where almost 80% of the total yearly ISO power occurs during November-April season, against only around 60% for WCA. Moreover, the lagged cross correlations computed between WCA and ECA PCs time series showed that most of the WCA PCs led ECA PCs time series with a timescale of 8-12 days, revealing that the eastward propagation could potentially be the relationship between WCA and ECA modes. The interannual variations in the ISO activity are weak in WCA, when compared with ECA where the signal exhibits larger interannual variations, quite linked with ENSO.

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Interdecadal variability of intensity of the Madden–Julian oscillation

Wang

Sun

2021

Atmospheric Science Letters

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The interdecadal variability of intensity of the Madden-Julian oscillation (MJO) during boreal winter was investigated based on two reanalysis datasets (NOAA 20CR and ERA-20C). Both the reanalysis datasets reveal statistically significant power spectrum peaks at 12-20-year periods. A composite analysis shows that during the active interdecadal phase, eastward propagating MJO activity was strengthened over the equatorial warm pool expanded from the Indian Ocean (IO) to the western Pacific (WP). The cause of the enhanced MJO variability was attributed to the interdecadal change of background mean precipitation in situ. A further diagnosis shows that the increase of the background precipitation over the Maritime Continent and the WP was attributed to interdecadal warm sea surface temperature (SST) anomalies in situ, whereas the increase of the precipitation over the IO resulted from the local convective instability due to the increase of wind induced surface evaporation and moisture. The strengthened background precipitation impacted the MJO strength through the increase of the interdecadal background moisture in the lower and middle troposphere induced by anomalous vertical moisture advection. K E Y W O R D S interdecadal variability, Madden-Julian oscillation, modulation of MJO strength by interdecadal background mean state

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Factors controlling the interannual variations of MJO intensity

Cited by 24 publications

References 41 publications

Inter-Annual Variability of Boreal Summer Intra-Seasonal Oscillation Propagation from the Indian Ocean to the Western Pacific

Inter-Annual Variability of Boreal Summer Intra-Seasonal Oscillation Propagation from the Indian Ocean to the Western Pacific

On the Differences in the Intraseasonal Rainfall Variability between Western and Eastern Central Africa: Case of 25 - 70-Day Oscillations

Interdecadal variability of intensity of the Madden–Julian oscillation

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