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In these charts composite MSLP is shown for anomalies in units of hPa are shown for El Niño (left) and La Niña (right), for Nov-Dec (ND, top) and Jan-Feb (JF, bottom).
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This method is further discussed in Molteni & Brookshaw 2023. |
Average effects
ENSO events tend to peak at the end of the calendar year; accordingly, impacts over Europe tend to be stronger in winter than at other times of year.
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Using the ENSO years selection approach outlined above (here with a choice between the period 1940-2022 and 1970-2022), typical effects on temperature and precipitation are illustrated, by displaying the number of years falling into the upper or lower tercile category of the distribution of the respective variable. Colours are only shown when the number of years is statistically significant. This concept and methodology is similar to that used in Davey et al. 2014.
These charts can be used to identify regions where, according to this analysis method, there is a statistically significant ENSO teleconnection for temperature or precipitation for each calendar month. Due to the variability seen within the postage stamp charts shown above for Europe, there is not a strong signature in the composites below.
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<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.1/jquery.min.js" integrity="sha512-aVKKRRi/Q/YV+4mjoKBsE4x3H+BkegoM/em46NNlCqNTmUYADjBbeNefNxYV7giUp0VxICtqdrbqU7iVaeZNXA==" crossorigin="anonymous" referrerpolicy="no-referrer"></script> <style> option:disabled { opacity: 0.4; } </style> <script> $(document).ready(function(){ var plotsBaseURL='https://confluence.ecmwf.int/download/attachments/373753650373753919/' var periods = [{key:'1940-2022', label:'1940-2022'}, {key:'1970-2022', label:'1970-2022'}] // populate selects var populate = function(vals,id,available){ $.each(vals, function(){ $('<option/>', {'value': this.key,'text': this.label}).appendTo('#'+id); }); } populate(periods,'sel_period'); // populate months function getMonthName(monthNumber) { const date = new Date(2001, monthNumber - 1, 1); return date.toLocaleString('en-GB', { month: 'long' }); } for (var i = 1; i < 13; i++) { $('<option />', {'value': i,'text': getMonthName(i) }).appendTo('#sel_month'); } //update functions var updateImage = function(){ var period = $('#sel_period').val(); var month = $('#sel_month').val(); var str_month = String(month).padStart(2, '0'); imgfname=period+'_t2m_ENSOneg_tsum_month'+str_month+'.png'; $('#t2m_nina').attr('src',plotsBaseURL+imgfname); imgfname=period+'_t2m_ENSOpos_tsum_month'+str_month+'.png'; $('#t2m_nino').attr('src',plotsBaseURL+imgfname); imgfname=period+'_tp_ENSOneg_tsum_month'+str_month+'.png'; $('#prec_nina').attr('src',plotsBaseURL+imgfname); imgfname=period+'_tp_ENSOpos_tsum_month'+str_month+'.png'; $('#prec_nino').attr('src',plotsBaseURL+imgfname); } updateImage(); $('#selectors select').on('change',function(e){ updateImage(); }) }) </script> <div id="selectors"> <label for="sel_month">Month: </label><select id="sel_month" ></select> <label for="sel_period">Reference period: </label><select id="sel_period"></select> <br> </div> <img id="t2m_nina" width="50%"/><img id="t2m_nino" width="50%"/><br/> <img id="prec_nina" width="50%"/><img id="prec_nino" width="50%"/><br/> |
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- Molteni, F., Brookshaw, A. Early- and late-winter ENSO teleconnections to the Euro-Atlantic region in state-of-the-art seasonal forecasting systems. Clim Dyn 61, 2673–2692 (2023). https://doi.org/10.1007/s00382-023-06698-7
- , , , et al. The ERA5 global reanalysis. Q J R Meteorol Soc. 2020; 146: 1999–2049. https://doi.org/10.1002/qj.3803
- Davey, M.K., Brookshaw, A. and Ineson, S., 2014. The probability of the impact of ENSO on precipitation and near-surface temperature. Climate Risk Management, 1, pp.5-24. https://doi.org/10.1016/j.crm.2013.12.002
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