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

2021 ◽  
Author(s):  
Nicola Cortesi ◽  
Verónica Torralba ◽  
Llorenç Lledó ◽  
Andrea Manrique-Suñén ◽  
Nube Gonzalez-Reviriego ◽  
...  
Keyword(s):  
Seasonal Predictability ◽  
Weather Regimes

scholarly journals Seasonal predictability of Mediterranean weather regimes in the Copernicus C3S systems

2021 ◽  
Author(s):  
Ignazio Giuntoli ◽  
Federico Fabiano ◽  
Susanna Corti
Keyword(s):  
Mediterranean Region ◽  
Climate Models ◽  
Reanalysis Data ◽  
Seasonal Predictability ◽  
Economic Implications ◽  
Weather Regimes ◽  
Weather Patterns ◽  
The Mediterranean ◽  
Good Agreement

AbstractSeasonal predictions in the Mediterranean region have relevant socio-economic implications, especially in the context of a changing climate. To date, sources of predictability have not been sufficiently investigated at the seasonal scale in this region. To fill this gap, we explore sources of predictability using a weather regimes (WRs) framework. The role of WRs in influencing regional weather patterns in the climate state has generated interest in assessing the ability of climate models to reproduce them. We identify four Mediterranean WRs for the winter (DJF) season and explore their sources of predictability looking at teleconnections with sea surface temperature (SST). In particular, we assess how SST anomalies affect the WRs frequencies during winter focussing on the two WRs that are associated with the teleconnections in which the signal is more intense: the Meridional and the Anticyclonic regimes. These sources of predictability are sought in five state-of-the-art seasonal forecasting systems included in the Copernicus Climate Change Services (C3S) suite finding a weaker signal but an overall good agreement with reanalysis data. Finally, we assess the ability of the C3S models in reproducing the reanalysis data WRs frequencies finding that their moderate skill increases during ENSO intense years, indicating that this teleconnection is well reproduced by the models and yields improved predictability in the Mediterranean region.

scholarly journals Seasonal predictability of Mediterranean Weather Regimes in the Copernicus C3S Systems

2021 ◽  
Author(s):  
Ignazio Giuntoli ◽  
Federico Fabiano ◽  
Susanna Corti
Keyword(s):  
Mediterranean Region ◽  
Climate Models ◽  
Reanalysis Data ◽  
Seasonal Predictability ◽  
Economic Implications ◽  
Weather Regimes ◽  
Weather Patterns ◽  
The Mediterranean ◽  
Good Agreement

<p>Seasonal predictions in the Mediterranean region have relevant socio-economic implications, especially in the context of a changing climate. To date, sources of predictability have not been sufficiently investigated at the seasonal scale in this region. To fill this gap, we explore sources of predictability using a weather regimes (WRs) framework. The role of WRs in influencing regional weather patterns in the climate state has generated interest in assessing the ability of climate models to reproduce them.</p><p>We identify four Mediterranean WRs for the winter (DJF) season and explore their sources of predictability looking at teleconnections with sea surface<br>temperature (SST). In particular, we assess how SST anomalies affect the WRs frequencies during winter focussing on the two WRs that are associated with the teleconnections in which the signal is more intense: the Meridional and the Anticyclonic regimes . These sources of predictability are sought in five state-of-the-art seasonal forecasting systems included in the Copernicus Climate Change Services (C3S) suite finding a weaker signal but an overall good agreement with reanalysis data. Finally, we assess the ability of the C3S models in reproducing the reanalysis data WRs frequencies finding that their moderate skill improves during ENSO intense years, indicating that this teleconnection is well reproduced by the models and yields improved predictability in the Mediterranean region.</p>

Weather regimes in South East Asia: Sub-seasonal predictability of the regimes and the associated high impact weather  

2021 ◽  
Author(s):  
Paula Gonzalez ◽  
Emma Howard ◽  
Simon Thomas ◽  
Thomas Frame ◽  
Oscar Martinez-Alvarado ◽  
...  
Keyword(s):  
East Asia ◽  
Large Scale ◽  
High Impact ◽  
Lead Times ◽  
South East Asia ◽  
Synoptic Scale ◽  
Seasonal Predictability ◽  
Weather Regimes ◽  
Predictive Skill ◽  
High Impact Weather

<div> <p>This work considers the sub-seasonal predictability of two sets of weather regimes for South East Asia: a two-tiered assignment, that first considers large-scale patterns and then assigns synoptic-scale regimes, and a flat classification, which only considers the synoptic scale. In the two-tiered approach, the tier 1 large-scale regimes, which capture ENSO and seasonal variations, are each partitioned into South East Asia regional clusters that capture synoptic variability.   </p> </div><div> <p>The sub-seasonal predictability of both the standard and tiered regimes is assessed using UKMO GloSea5 hindcasts and forecasts for lead times of up to 5 weeks. We find that the GloSea5 system presents an accurate representation of the regimes’ climatology and a good level of skill for their assignment. Nonetheless, the predictability depends on the specific regimes and some significant forecast drifts are also identified. Additionally, the predictive skill of high impact precipitation events obtained statistically from the prediction of the regimes is assessed and compared with the probabilistic precipitation forecasts of the GloSea5 ensemble.    </p> </div><div> <p>A description of the regime classification methodology and their connections to seasonal and synoptic phenomena will be discussed in a separate presentation, titled “Weather regimes in South East Asia: connections with synoptic phenomena and high impact weather” and presented by Emma Howard. </p> </div>

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 Understanding the cold biases of CMIP5 models over China with weather regimes

2021 ◽  
Author(s):  
Wei Chen ◽  
Da-Bang Jiang ◽  
Xian-Mei Lang ◽  
Zhi-Ping Tian
Keyword(s):  
Cmip5 Models ◽  
Weather Regimes

scholarly journals Seasonal Predictability of the North Atlantic Oscillation and Zonal Mean Fields Associated with Stratospheric Influence in JMA/MRI-CPS2

SOLA ◽  
2017 ◽  
Vol 13 (0) ◽  
pp. 209-213 ◽  
Author(s):  
Naoaki Saito ◽  
Shuhei Maeda ◽  
Tosiyuki Nakaegawa ◽  
Yuhei Takaya ◽  
Yukiko Imada ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Seasonal Predictability ◽  
The North ◽  
Mean Fields ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Seasonality in the Cross Section of Stock Returns: The International Evidence

2010 ◽  
Vol 45 (5) ◽  
pp. 1133-1160 ◽  
Author(s):  
Steven L. Heston ◽  
Ronnie Sadka
Keyword(s):  
Stock Returns ◽  
Cross Section ◽  
Domestic Market ◽  
Trading Strategies ◽  
Global Risk ◽  
Seasonal Predictability ◽  
International Evidence ◽  
Local Risk ◽  
The Cross ◽  
Highly Correlated

AbstractThis paper studies seasonal predictability in the cross section of international stock returns. Stocks that outperform the domestic market in a particular month continue to outperform the domestic market in that same calendar month for up to 5 years. The pattern appears in Canada, Japan, and 12 European countries. Global trading strategies based on seasonal predictability outperform similar nonseasonal strategies by over 1% per month. Abnormal seasonal returns remain after controlling for size, beta, and value, using global or local risk factors. In addition, the strategies are not highly correlated across countries. This suggests they do not reflect return premiums for systematic global risk.

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