Sub-seasonal Forecast Skill for Weekly Mean Atmospheric Variability over the Northern Hemisphere in Winter and its Relationship to Mid-Latitude Teleconnections

2020 ◽  
Author(s):  
Akio Yamagami ◽  
Mio Matsueda
Keyword(s):  
Northern Hemisphere ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Atmospheric Variability

scholarly journals High-Resolution Global Climate Simulations with the ECMWF Model in Project Athena: Experimental Design, Model Climate, and Seasonal Forecast Skill

2012 ◽  
Vol 25 (9) ◽  
pp. 3155-3172 ◽  
Author(s):  
T. Jung ◽  
M. J. Miller ◽  
T. N. Palmer ◽  
P. Towers ◽  
N. Wedi ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Climate Models ◽  
Global Climate ◽  
Seasonal Forecast ◽  
Horizontal Resolution ◽  
Forecast Skill ◽  
Boreal Winter ◽  
Project Athena ◽  
The Tropics ◽  
Ecmwf Model

The sensitivity to the horizontal resolution of the climate, anthropogenic climate change, and seasonal predictive skill of the ECMWF model has been studied as part of Project Athena—an international collaboration formed to test the hypothesis that substantial progress in simulating and predicting climate can be achieved if mesoscale and subsynoptic atmospheric phenomena are more realistically represented in climate models. In this study the experiments carried out with the ECMWF model (atmosphere only) are described in detail. Here, the focus is on the tropics and the Northern Hemisphere extratropics during boreal winter. The resolutions considered in Project Athena for the ECMWF model are T159 (126 km), T511 (39 km), T1279 (16 km), and T2047 (10 km). It was found that increasing horizontal resolution improves the tropical precipitation, the tropical atmospheric circulation, the frequency of occurrence of Euro-Atlantic blocking, and the representation of extratropical cyclones in large parts of the Northern Hemisphere extratropics. All of these improvements come from the increase in resolution from T159 to T511 with relatively small changes for further resolution increases to T1279 and T2047, although it should be noted that results from this very highest resolution are from a previously untested model version. Problems in simulating the Madden–Julian oscillation remain unchanged for all resolutions tested. There is some evidence that increasing horizontal resolution to T1279 leads to moderate increases in seasonal forecast skill during boreal winter in the tropics and Northern Hemisphere extratropics. Sensitivity experiments are discussed, which helps to foster a better understanding of some of the resolution dependence found for the ECMWF model in Project Athena.

scholarly journals Assessing the robustness of multidecadal variability in Northern Hemisphere wintertime seasonal forecast skill

2020 ◽  
Vol 146 (733) ◽  
pp. 4055-4066 ◽  
Author(s):  
Christopher H. O'Reilly ◽  
Antje Weisheimer ◽  
David MacLeod ◽  
Daniel J. Befort ◽  
Tim Palmer
Keyword(s):  
Northern Hemisphere ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Multidecadal Variability

Variability in seasonal forecast skill of Northern Hemisphere winters over the twentieth century

2017 ◽  
Vol 44 (11) ◽  
pp. 5729-5738 ◽  
Author(s):  
Christopher H. O'Reilly ◽  
James Heatley ◽  
Dave MacLeod ◽  
Antje Weisheimer ◽  
Tim N. Palmer ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Northern Hemisphere ◽  
Seasonal Forecast ◽  
Forecast Skill

scholarly journals The northern hemisphere circumglobal teleconnection in a seasonal forecast model and its relationship to European summer forecast skill

2018 ◽  
Vol 52 (5-6) ◽  
pp. 3759-3771 ◽  
Author(s):  
Jonathan D. Beverley ◽  
Steven J. Woolnough ◽  
Laura H. Baker ◽  
Stephanie J. Johnson ◽  
Antje Weisheimer
Keyword(s):  
Northern Hemisphere ◽  
Forecast Model ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Circumglobal Teleconnection

scholarly journals Yearly evolution of Euro-Atlantic weather regimes and of their sub-seasonal predictability

2021 ◽  
Author(s):  
Nicola Cortesi ◽  
Verónica Torralba ◽  
Llorenó Lledó ◽  
Andrea Manrique-Suñén ◽  
Nube Gonzalez-Reviriego ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Winter Season ◽  
Skill Score ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Seasonal Forecasts ◽  
Sea Level Pressure ◽  
Weather Regimes ◽  
Start Dates ◽  
Weekly Frequency

AbstractIt is often assumed that weather regimes adequately characterize atmospheric circulation variability. However, regime classifications spanning many months and with a low number of regimes may not satisfy this assumption. The first aim of this study is to test such hypothesis for the Euro-Atlantic region. The second one is to extend the assessment of sub-seasonal forecast skill in predicting the frequencies of occurrence of the regimes beyond the winter season. Two regime classifications of four regimes each were obtained from sea level pressure anomalies clustered from October to March and from April to September respectively. Their spatial patterns were compared with those representing the annual cycle. Results highlight that the two regime classifications are able to reproduce most part of the patterns of the annual cycle, except during the transition weeks between the two periods, when patterns of the annual cycle resembling Atlantic Low regime are not also observed in any of the two classifications. Forecast skill of Atlantic Low was found to be similar to that of NAO+, the regime replacing Atlantic Low in the two classifications. Thus, although clustering yearly circulation data in two periods of 6 months each introduces a few deviations from the annual cycle of the regime patterns, it does not negatively affect sub-seasonal forecast skill. Beyond the winter season and the first ten forecast days, sub-seasonal forecasts of ECMWF are still able to achieve weekly frequency correlations of r = 0.5 for some regimes and start dates, including summer ones. ECMWF forecasts beat climatological forecasts in case of long-lasting regime events, and when measured by the fair continuous ranked probability skill score, but not when measured by the Brier skill score. Thus, more efforts have to be done yet in order to achieve minimum skill necessary to develop forecast products based on weather regimes outside winter season.

scholarly journals Hayashi spectra of the northern hemisphere mid-latitude atmospheric variability in the NCEP–NCAR and ECMWF reanalyses

2005 ◽  
Vol 25 (6) ◽  
pp. 639-652 ◽  
Author(s):  
Alessandro Dell’Aquila ◽  
Valerio Lucarini ◽  
Paolo M. Ruti ◽  
Sandro Calmanti
Keyword(s):  
Northern Hemisphere ◽  
Atmospheric Variability

Interannual Variations and Prediction of Spring Precipitation over China

2018 ◽  
Vol 31 (2) ◽  
pp. 655-670 ◽  
Author(s):  
YuJia You ◽  
Xiaojing Jia
Keyword(s):  
Regression Model ◽  
Yangtze River ◽  
Climate Models ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Interannual Variations ◽  
The Yangtze River ◽  
Spring Precipitation ◽  
Coupled Climate Models ◽  
Time Variations

The interannual variations and the prediction of the leading two empirical orthogonal function (EOF) modes of spring (April–May) precipitation over China for the period from 1951 to 2014 are investigated using both observational data and the seasonal forecast made by six coupled climate models. The leading EOF mode of spring precipitation over China (EOF1-prec) features a monosign pattern, with the maximum loading located over southern China. The ENSO-related tropical Pacific SST anomalies in the previous winter can serve as a precursor for EOF1-prec. The second EOF mode of spring precipitation (EOF2-prec) over China is characterized by a dipole structure, with one pole near the Yangtze River and the other one with opposite sign over the Pearl River delta. A North Atlantic sea surface temperature (SST) anomaly dipole in the preceding March is found contribute to the prec-EOF2 and can serve as its predictor. A physics-based empirical (P-E) model is then formulated using the two precursors revealed by the observational analysis to forecast the variations of EOF1-prec and EOF2-prec. Compared to coupled climate models, which have little skill in forecasting the time variations of the two EOF modes, this P-E model can significantly improve the forecast skill of their time variations. A linear regression model is further established using the time series forecast by the P-E model to forecast the spring precipitation over China. Results suggest that the seasonal forecast skill of the spring precipitation over southeastern China, especially over the Yangtze River area, can be significantly improved by the regression model.

scholarly journals Enhanced seasonal forecast skill following stratospheric sudden warmings

2013 ◽  
Vol 6 (2) ◽  
pp. 98-102 ◽  
Author(s):  
M. Sigmond ◽  
J. F. Scinocca ◽  
V. V. Kharin ◽  
T. G. Shepherd
Keyword(s):  
Seasonal Forecast ◽  
Forecast Skill ◽  
Stratospheric Sudden Warmings

On the Level and Origin of Seasonal Forecast Skill in Northern Europe

1998 ◽  
Vol 55 (1) ◽  
pp. 103-127 ◽  
Author(s):  
Åke Johansson ◽  
Anthony Barnston ◽  
Suranjana Saha ◽  
Huug van den Dool
Keyword(s):  
Seasonal Forecast ◽  
Forecast Skill ◽  
Northern Europe
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