Preprints
https://doi.org/10.5194/esd-2016-60
https://doi.org/10.5194/esd-2016-60
25 Nov 2016
 | 25 Nov 2016
Status: this discussion paper is a preprint. It has been under review for the journal Earth System Dynamics (ESD). The manuscript was not accepted for further review after discussion.

Seasonal forecast verification and application in times of change

Yoav Levi and Itzhak Carmona

Abstract. Seasonal forecast is being promoted as one of the climate services given to the public and decision makers also in the extra-tropics. However seasonal forecast is a scientific challenge. Rapid changes in climate and the socio-economic environment in the past 30 years introduce even a bigger challenge for the end-users of seasonal forecasts based on the past 30 years.

Decision makers should relay on a forecast only if they fully understand the forecast skill and the forecast will not be a completely erroneous.Therefore, the percentage of forecasts for above normal condition that realized to be below normal conditions and vice versa is measured straightforwardly by the "Fiasco score". To overcome the climate and socio-economic environment changes an attempt to relate the next seasonal forecast to the previous season forecast and observed values was tested.The findings indicate that ECMWF system-4 seasonal forecast skill for June-July-August (JJA) temperatures for the marine tropics is very promising as indicated by all the skill scores, including using the previous JJA forecast as the base for the next JJA season. However for the boreal summer temperatures forecast over land, the main source of the model predictability originates from the warming trend along the hindcast period. Over the Middle East and Mongolia removing the temperature trend eliminated the high forecast skill. Evaluation of the ability of the next season forecast to predict the changes relative to the previous year's season has shown a positive skill in some areas compared to the traditional 30 years based climatology after both forecasts and observed data were de-trend.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Yoav Levi and Itzhak Carmona
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Yoav Levi and Itzhak Carmona
Yoav Levi and Itzhak Carmona

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Short summary
Seasonal forecast is a scientific challenge drawing increase attention of both the scientific community and the decision makers. The manuscript deals with evaluation of seasonal forecasts skill taking into account the rapid changes in both climate and socio-economic development. An attempt to give a solution to overcome rapid changes may provide local stakeholders with a new way of using seasonal forecast.
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