• Anonymous
    Anonymous, 2020/03/26 22:36

    test comment from A Robertson

  • s2s_wiki
    s2s_wiki, 2020/05/06 22:47

    The MJO-Teleconnection sub-project is launching a webinar series once a month on the last Thursday of the month. 

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  • s2s_wiki
    s2s_wiki, 2020/05/06 22:51

    Dear Colleagues,

    Please join us for the first webinar of the monthly series of webinars hosted by the WWRP/WCRP/S2S/MJO-Teleconnections sub-project. ​

    Date: Thursday, April 30, 2020, 10:30 am  |  (UTC-04:00) Eastern Time (US & Canada)  |  1 hr
    Title: On the Subseasonal-to-seasonal Variability of Extra-tropics
    Speaker: Cristiana Stan, George Mason University, USA

    Recent advancements in understanding the subseasonal-to-seasonal (S2S) variability outside of the tropics will be discussed. I will introduce the multi-channel singular spectral analysis (MSSA) method used to isolate the S2S variability in the extra-tropics, present the oscillatory modes dominating the extra-tropics on these time scales and their relationship with tropical and stratospheric variability, and discuss the implications of midlatitude oscillatory modes for the predictability at Week 3&4.

    The S2S variability of the extra-tropics is dominated by three propagating oscillations with broad-band spectra centered at 120, 45, and 28 days are found. The first oscillatory mode is referred to as the midlatitude seasonal oscillation (MLSO), and the other two are referred to as midlatitude intraseasonal oscillation 1 and 2 (MLISO 1 and MLISO2). When combined, the oscillations explain up to 30% of the natural variability of the extra-tropics on the intra-seasonal to seasonal time scales. These oscillations share some features with the circumglobal wave guide and in some phases of their lifecycles they project onto the canonical teleconnection patterns.

    MLSO and MLISO-1 are related to the intraseasonal convective activity of the tropics and MLISO-1 shows some connection with the stratospheric variability associated with QBO.

    When used as predictors in a simple linear regression model with 2-meter temperature as predictand, the mid-latitude oscillations extend the potential predictability of dependent variable to about 20 days. 

    To participate send and email to subseasonal_to_seasonal_prediction_mjo_tel

    Webinar Recording:

  • Anonymous
    Anonymous, 2020/05/22 03:16

    Dear Colleagues,

    Please join us for the May Webinar of the monthly series of webinars hosted by the WWRP/WCRP/S2S/MJO-Teleconnections sub-project. ​

    Date: Thursday, May 28, 2020, 10:30am | (UTC-04:00) Eastern Time (US & Canada) | 1hr
    Title: Non-normal optimal growth of the Pacific-North American pattern
    Speaker: Stephanie Henderson, University of Wisconsin-Madison, USA

    The Pacific-North American (PNA) pattern has been previously linked to tropical variability including the Madden-Julian Oscillation (MJO) and the El Niño-Southern Oscillation (ENSO), as well as internal extratropical variability.  However, many questions remain regarding how these various relationships act, both together and individually, to yield observed PNA variability.  The role of tropical heating and the extratropical circulation on PNA pattern growth is examined using linear inverse modeling (LIM).  Optimal PNA growth is found to occur via the non-normal interference between the modes strongly coupled to sea surface temperatures (SST), including ENSO, and the modes internal to the atmosphere, such as the MJO.  PNA growth beyond this interference is also examined through the development of an “internal atmospheric” LIM that excludes the modes strongly coupled to SST, such as ENSO, while retaining MJO variability.  Optimal PNA growth in the internal atmospheric LIM is driven by MJO Indian Ocean heating with suppressed heating over the tropical western Pacific, and a retrograding northeast Pacific streamfunction anomaly.  The separate contributions of tropical heating and the extratropical circulation on PNA growth are also investigated.

    Importantly, the non-normal PNA growth highlights the difficulty in partitioning PNA variance into contributions from different phenomena and should be considered in attribution studies.

    To participate send and email to subseasonal_to_seasonal_prediction_mjo_tel

  • s2s_wiki
    s2s_wiki, 2020/06/18 20:22

    Dear Colleagues,

    Please join us for the June webinar of the monthly series of webinars hosted by the WWRP/WCRP/S2S/MJO-Teleconnections sub-project. 

    Title: MJO Teleconnections to the Euro-Atlantic sector
    Speaker: Robert Lee, National Centre for Atmospheric Science and Department of Meteorology, University of Reading, UK

    The teleconnection from the Madden-Julian Oscillation (MJO) provides a source of subseasonal variability and predictability to the North Atlantic-European (NAE) region.
    The El Niño-Southern Oscillation (ENSO) modulates the seasonal mean state, through which the MJO and its teleconnection pattern propagates; however, its impact on this teleconnection to the NAE region has not been investigated. In this webinar I will present evidence of a robust dependence of the teleconnections from the MJO to NAE weather regimes on the phase of ENSO. I will demonstrate that the MJO to NAO+ regime tropospheric teleconnection is strongly enhanced during El Niño years, via enhanced Rossby wave activity, and inactive during La Niña. Conversely the MJO to NAO− regime stratospheric teleconnection is enhanced during La Niña years, and inactive during El Niño. This dependence on the background state has strong implications for subseasonal predictability, including interannual variations in subseasonal predictive skill.
    I will go on to show statistical analysis of the MJO-NAE teleconnections using a larger set of 29 patterns, known as the Grosswetterlagen (GWL), to represent the European weather. Since the GWL patterns are smaller in spatial scale, they capture more synoptic detail. These findings demonstrate how the MJO can modify the preferred evolution of the NAE atmospheric flow.

    To participate send and email to subseasonal_to_seasonal_prediction_mjo_tel. 

    Webinar recording:

  • Anonymous
    Anonymous, 2020/06/25 14:52

    Why does MJO follow almost exactly the SOI time series ?

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