Workshop on Predictability, dynamics and applications research using the TIGGE and S2S ensembles

Receiver Operating Characteristic (ROC) curves

Tilmann Gneiting, Peter Vogel, and Eva-Maria Walz

Heidelberg Institute for Theoretical Studies and Karlsruhe Institute of Technology, Germany

Relative or Receiver Operating Characteristic (ROC) curves are used in a very wide range of settings where covariates, features, markers, or probability forecasts for binary events are to be evaluated. In...

Caio A. S. Coelho, Mári A. F. Firpo, Felipe M. de Andrade

Affiliation:
Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE)

We propose a verification framework for South American sub-seasonal (weekly accumulated) precipitation predictions produced one to four weeks in advance. The proposed framework assesses both hindcast and near real...

Global 2-meter temperature analyses in 2018 from ECMWF, JMA, and the UK Met Office were downloaded for 2018 from the TIGGE database. Using the multi-model analysis mean as a surrogate for truth, the daily spreads were decomposed into an estimate of the systematic error component (from time-mean differences between analyses) and a random component (the perturbation magnitude with respect to...

Current status on the use of TIGGE/Global ensembles in tropical cyclone (TC) research and operational forecasts is presented. First, the current status on the use of global ensembles in TC track, intensity and genesis forecasting at operational tropical cyclone forecasting centres over the world is presented based on a questionnaire survey conducted by the World Meteorological Organization...

Sub-seasonal time scales lie in the middle of the range of "seamless" prediction that spans from deterministic instantaneous weather prediction to the probabilistic time-averaged conditions of seasonal weather forecasts. However, attaining true seamlessness across these disparate types of forecasts is not easy. We propose a flexible approach to model validation that blends day-to-day weather...

In this study, we analyze the reason for low prediction skill in extended-range precipitation forecasts over the US west coast during boreal winter from the NCEP Climate Forecast System version 2 (CFSv2). Our assessment focuses on whether low skill is due to the biases in CFSv2 or is consistent with the possibility of low inherent predictability over that region. The analysis is based on...

We use S2S multi-model ensemble forecasts of circulation regimes to assess the changes in the probability of storminess over Europe and the US in the sub-seasonal forecast range.
The existence of preferred planetary scale flow structures (circulation regimes) in the Pacific - North American (PNA) and Euro-Atlantic (EA) sectors on sub-seasonal time scales has been well validated in the...

On sub-seasonal time scales the large-scale extratropical circulation often has a better predictability than surface weather at a specific location and time. However, classical ensemble forecast products focussing on the ensemble mean and spread are often indistinguishable from the underlying model climatology. Therefore novel approaches are needed to reveal the predictable components of the...

With retreating sea ice and increasing human activities comes a growing need for reliable sea ice forecasts up to months ahead. We exploit the subseasonal-to-seasonal (S2S) prediction database and provide a thorough assessment of the skill of operational forecast systems in predicting the location of the Arctic and Antarctic sea ice edges on these time scales. We find large differences in...

In September 2014, a devastating flood wrought havoc in the Indian state of Jammu and Kashmir and adjoining areas of the Pakistan. The very heavy rainfall during last stage of monsoon has resulted in a devastating flood which caused an estimated death toll well above 2000 peoples over the region. After a disaster on this scale and its associated implications in various sectors, the question...

Accurate forecasting of sub-seasonal to seasonal (S2S) variations in rainfall can help mitigate hydrological hazards throughout the tropics. It is therefore essential to analyse the skill of contemporary S2S forecasts systems and investigate whether there are windows of opportunity within which these systems may be more skilful, based on the regional- or large-scale atmospheric circulation. As...

Sudden Stratospheric Warmings (SSWs) are significant source of enhanced sub-seasonal predictability but whether this source is untapped in operational models remains an open question. Here we report on the prediction of the SSW on 12 February 2018, its dynamical precursors, and surface climate impacts by an ensemble of dynamical forecast models. The ensemble forecast from 1 February predicted...

Understanding the variations in the strength of the Madden-Julian Oscillation events as they propagate across the Indo-Pacific Maritime Continent (MC) has been an important challenge. In this study a method of estimating moisture sources associated with sustenance of MJO strength directly from precipitation observation is introduced. The method is used to show the existence of slow eastward...