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

This study assesses the medium-range flow-dependent forecast skill of Euro-Atlantic weather regimes: the positive and negative phases of the North Atlantic Oscillation (NAO+ and NAO−), Atlantic ridge (ATLR), and Euro-Atlantic blocking (EABL), for extended winters (November–March) in the periods 2006/2007–2013/2014 and 1985/1986–2013/2014 using The Interactive Grand Global Ensemble (TIGGE) and...

A major source of sub-seasonal predictability for the mid-latitudes during boreal winter and spring and austral spring is variability of the stratospheric polar vortex. While a number of studies have now demonstrated that surface predictability is enhanced during both sudden stratospheric warming (SSW) and strong vortex events, there has been little comparison of model performance beyond a...

Surface weather variability on subseasonal timescales influences energy production, demand, and prices. Improving the skill of subseasonal predictions of surface weather is thus of high interest for the energy industry. This is particularly the case for near-surface wind due to the ongoing shift toward more wind power generation. Anomalous states of the stratospheric polar vortex during winter...

Predictability of the MJO, especially the initiation and eastward propagation of the large-scale convection and precipitation over the Indian Ocean and West Pacific warm pool across the Maritime Continue, is extensively investigated using the S2S ensemble. The model forecasts are compared with the Large-scale Precipitation Tracking (LPT) of the MJP using the 20-years TRMM-GPM precipitation...

As a potential source of multiweek predictability, we investigate the MJO’s impact on temperature extremes during Austral spring. We find a significant MJO influence on weekly mean temperature extremes (defined here as exceeding the upper and lower quintiles) over southeastern Australia when the MJO is in phases 2, 3, and 6 and 7. During these phases, the occurrence of maximum and minimum...

The effect of the Madden-Julian Oscillation (MJO) on the Northern Hemisphere wintertime stratospheric polar vortex is evaluated in operational subseasonal forecasting models. Reforecasts which simulate stronger MJO-related convection in the Tropical West Pacific also simulate enhanced heat flux in the lowermost
stratosphere and a more realistic vortex evolution. The time scale on which vortex...

The natural variability of the extra-tropics is studied at seasonal and intra-seasonal time scales. Nonlinear oscillations in the extra-tropics are extracted from daily anomalies of 500-hPa geopotential height for the period 1979-2012 using a data-adaptive method. Three propagating oscillations with broad-band spectra centered at 120, 45, and 28 days are found. When combined, the oscillations...

Pentad forecast skill over the Northern polar region in boreal winter is evaluated for the subseasonal to seasonal prediction (S2S) systems from three operational centers: the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers for Environmental Prediction (NCEP) and Environment and Climate Change Canada (ECCC). The former two systems are running with air-sea...

The TIGGE database consists of medium-range ensemble forecasts from eleven global NWP centres up to 15 days ahead. It started in October 2006 and it has currently reached 3 PiB of data. The S2S database consists of real-time and reforecast outputs from eleven global models producing sub-seasonal to seasonal forecasts up to 60 days ahead. Although the S2S database was established only in 2015,...

CMA's latest progress in the development of S2S Numerical Model database Management and Services Including the following aspects (Xing Hu)：
1. Preprocessing of S2S model data. The original big data files sent by the ECMWF is received and disassembled by preprocessing to be easy for the users to obtain the download.
2. Convenient and flexible data retrieval. Provide online access based on HTTP...

The International Research Institute for Climate and Society Data Library (IRIDL) is a powerful and freely accessible online data repository and analysis web-service that allows a user to view, analyze, and download hundreds of terabytes of climate-related data (including sub-seasonal data) through a standard web browser in a computer or a smartphone. A wide variety of operations, from simple...

An overview of the methodologies for representing initial uncertainties and model uncertainties in the ECMWF ensemble forecasts will be given. Initial uncertainties are represented with perturbations from an ensemble of 4D-Vars with perturbed observations and with perturbations based on singular vectors. Model uncertainties are represented with the Stochastically Perturbed Parametrization...

Since January 2018 DWD runs a global ICON ensemble suite with 40 members and approx. 40km horizontal resolution including a grid refinement for Europe of 20km. Forecasts are generated at 00/12UTC up to +180h and at 06/18UTC up to +120h. To improve the boundary conditions for the COSMO-D2-EPS four additional runs take place at 03/09/15/21 with a limited forecast time of +30h. The ICON-EPS...

The demand for forecast information beyond week-2 has increased significantly in recent years. This information provides valuable guidance for various users who use it to guide public safety, quality of life, and business decisions that drive economic growth. Discussions of predictability, current numerical model capability and applications are greatly enhancing our understanding for...

The Navy Earth System Prediction Capability (ESPC) is a coupled global model consisting of the Navy Global Environmental Model (NAVGEM) atmospheric model coupled to the Global Ocean Forecast System (GOFS), which consists of the Hybrid Coordinate Ocean Model (HYCOM) and the Los Alamos Community Ice Code (CICE). The performance of a 15-member Navy ESPC ensemble during 2017 is compared to coupled...

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...

The primary variables forecast by the U.S. tropical cyclone (TC) forecast centers, National Hurricane Center (NHC) and Joint Typhoon Warning Center (JTWC), are TC track, intensity, and radius of gale-force winds. For all three variables the primary forecast guidance products used by the forecasters are multi-model ensemble mean or consensus forecasts derived using the forecasts from global...

Forecasting temperature and precipitation on subseasonal timescales beyond two weeks lead-time is at the limits of predictability and modeling capabilities. The NOAA Climate Prediction Center (CPC) relies on both dynamical and statistical models to make operational and experimental, above and below median, temperature and precipitation forecasts for weeks 3 and 4. Both statistical and...

We introduce isotonic distributional regression (IDR), a nonparametric technique for the generation of calibrated probabilistic forecasts from numerical weather prediction (NWP) model output. IDR learns calibrated predictive distributions directly from training data, subject to natural monotonicity constraints, without invoking any parametric distributional assumptions.

In a nutshell, IDR...

A Bayesian framework for postprocessing multi-ensemble weather forecasts

Clair Barnes (1), Richard E. Chandler (1) & Christopher M. Brierley (2)
(1) Department of Statistical Science, University College London
(2) Department of Geography, University College London

Ensemble weather forecasts often under-represent uncertainty, leading to overconfidence in their predictions. Multi-model...

Located in the tropical Southwest Pacific, New Caledonia is prone to heavy rainfall events that may be related either to tropical or to mid-latitude perturbations. Precipitation over New Caledonia should therefore exhibit some subseasonal predictability owing to large-scale drivers, such as ENSO and the Madden-Julian Oscillation. This study aims to assess the skill in predicting precipitation...

Subseasonal Prediction of European Summer Heat Waves in the S2S Hindcast Ensembles

Authors: Ole Wulff and Daniela Domeisen
Affiliation: ETH Zurich, Switzerland

Due to their devastating impact, the prediction of heat waves beyond the weather forecasting range is of great significance to society. The potential for successful subseasonal predictions of summer heat waves stems from e.g....

We utilize the Guan and Waliser (2015) atmospheric river (AR) detection algorithm and DeFlorio et al. (2018) AR activity forecast approach on three operational subseasonal forecast systems (ECMWF, NCEP, and ECCC) to predict AR activity over the eastern Pacific Ocean and western N. America, with a focus on subseasonal variations, and in particular the week-3 lead time. The predictand for these...

Many people living in East Africa are significantly exposed to risks arising from climate variability. Droughts and floods in the region are common; poor performance of the rainy season in 2011 and 2016 led to widescale threats to food security and flooding in 2018 led to significant impacts on human life.

The project ForPAc (Toward Forecast-Based Preparedness Action, funded by NERC & DFID)...

As a user of subseasonal weather forecasts we are particularly interested in quantifying and attributing drivers of enhanced sub seasonal predictability. Here we will discuss methods we have developed to address this question including various approaches to quantity both the signal but also systematic model errors in processes such as regime transitions and tropical-extratropical...

Weather and Climate information lies at the heart of managing agriculture. Decisions that need to be made on farm are wide-ranging from hourly spraying conditions to longer term crop choices or stocking management. Beyond the farm gate weather and climate influence shipping strategies and supply chains, insurance premiums and commodity markets. Australia’s CSIRO has invested in a Future...

Floods in the Alpine region can be destructive and lead to large losses. Many rivers and lakes in Switzerland, however, are regulated and flood damage can therefore be mitigated through an optimal management of lake levels and runoff. To support planning and prevention, high-quality forecasts of atmospheric flood precursors extending beyond short-range predictions are expected to be useful....

Considering lessons learned from experiences at seasonal timescale, this talk discusses some concrete S2S applications using both calibrated and uncalibrated forecasts from the S2S Database and the SubX project.

First, we illustrate how a Python interface for IRI’s Climate Predictability Tool —PyCPT— can be employed to assess skill and calibrate sub-seasonal forecasts in ways that are useful...

The S2S4E project aims to bring sub-seasonal to seasonal climate predictions to the renewable energy sector. Raw climate predictions come with a set of challenges which require the deployment of a climate service in order to produce valuable information for users. This involves the development of robust methodologies to calibrate predictions, a quality assessment, and the effective...

Accurate real-time monitoring and prediction of drought on a sub-seasonal timescale enhance our capability of drought risk assessment and management. This study investigated the feasibility of the sub-seasonal drought prediction using dynamical model outputs. To this aim, we adopted the Keetch-Byram Drought Index (KBDI) to estimate soil moisture deficits and used real-time and historical...

The skill of subseasonal to seasonal forecasts models is relatively high for Southeast Asia; however, uptake of such information by the disaster risk reduction community is still in its infancy. As part of the implementation of the ASEAN-UN Joint Strategic Plan of Action on Disaster Management (2016-2020), recommendations were made to build capacities for using S2S products at the timescales...

Telecommunication networks are integral part of secure and competitive societies where commercial enterprise and essential services depend on low-cost and reliable communications. In the UK, an estimated net economic contribution of £33bn/year (or 1.5% of GDP) is attributable to telecommunications infrastructure, however, as with many other aspects of infrastructure, the exposed nature of the...

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...

We introduce the “replicate Earth” ensemble interpretation framework, based on theoretically derived statistical relationships between ensembles of perfect models (replicate Earths) and observations. We transform an ensemble of (imperfect) climate projections into an ensemble whose mean and variance have the same statistical relationship to observations as an ensemble of replicate Earths. We...

Traditionally crop and other agronomic models are forced using an analogue year approach based on historical climate data. With the increasing skill and resolution of seasonal climate models, a model ensemble is now becoming a feasible option to directly force agronomic models and predict yields. However we have found that even when a climate model scores well on standard metrics (such as...

As part of the GCRF project “African Science for Weather Information and Forecasting” (African-SWIFT), this study assesses the sub-seasonal precipitation hindcast quality over Africa using three operational ensemble prediction systems (ECMWF, UKMO, and NCEP) from the S2S database. Deterministic forecast quality is quantified using different metrics, such as linear correlation and mean squared...

By utilizing operational forecast products from The International Grand Global Ensemble (TIGGE) during 2006 to 2015, the forecasting performances of European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP), Japan Meteorology Agency (JMA) and China Meteorological Administration (CMA) for the onset of North Atlantic Oscillation (NAO) events...

The past decades have witnessed radical change in the practice of weather forecasting, in that ensemble prediction systems have been implemented operationally. Despited their undisputed successes, ensemble forecasts remain subject to biases and dispersion errors, thereby calling for statistical postprocessing, to generate calibrated probabilistic forecasts from ensemble output.

Quantitative...

Data assimilation assumes unbiased observations and an unbiased forecast model and, hence, is expected to produce a zero-analysis increment on average. However, in practice, numerical weather prediction (NWP) and observations are all biased, resulting in non-zero average analysis increment. To the extent that variational observation bias correction successfully removes bias from the...

Accurate predictions of severe weather events are important for the society, economy, and environment in regions affected by such events. In the present study, the ensemble-based early warning products for severe weather events routinely available at the TIGGE museum (http://gpvjma.ccs.hpcc.jp/TIGGE/tigge_extreme_prob.html), are introduced. The early warning products are based on operational...

Weather and climate extreme events are of major concern for countries in Southeast Asia, with hydro-meteorological events making up a total of 85% of disasters in 2017 [1]. Drought severely impacts high risk countries like Cambodia, Lao People’s Democratic Republic, Myanmar and Vietnam. Through interactions with agricultural and the water management sector, sub-seasonal to seasonal forecasts...

The extratropical prediction skills of the subseasonal-to-seasonal (S2S) prediction models are evaluated by analyzing the nine models, which participated in the S2S prediction project, for the common reforecast period of 1999-2010. Based on mean squared skill score (MSSS) of geopotential height poleward of 30°, overall prediction skill and its inter-model spread are quantified to be 9.92 ±...

This study assessed subseasonal global precipitation hindcast quality from all Subseasonal to Seasonal (S2S) prediction project models. The deterministic forecast quality of weekly accumulated precipitation was verified using different metrics and hindcasts considering lead times up to 4 weeks. The correlation scores were found to be higher during the first week and dropped as lead time...

GMAO Sub/Seasonal prediction system (S2S) has recently been upgraded. A complete set (1981-2016) of 9-months hindcasts for the previous and current versions (S2S-1.0 and S2S-2.1 respectively) allows for the evaluation of the forecast skill and a study of various characteristics of the ensemble forecasts in particular. We compared the intra-seasonal and interannual SST variability of the two...

The quasi-biennial oscillation (QBO) refers to the mean zonal winds of the tropical stratosphere oscillating between westerlies and easterlies with a mean period of 28-29 months. The QBO affects the polar vortex, e.g., via the Holton-Tan effect. During boreal winters, the westerly (easterly) QBO often coincide with stronger (weaker) than average polar vorticity and warmer (colder) than average...

Southeast and Southern regions of South America (SA) are affected by teleconnection patterns as Pacific South America (PSA) and Southern Annular Mode (SAM). PSA shows a wavetrain pattern from tropical to extratropical atmosphere over South Pacific Ocean triggered by convection in the tropical Indian, Maritime Continent and tropical Pacific. The SAM has opposite atmospheric anomalies between...

Climate forecasts at subseasonal to seasonal (S2S) timescales have received little attention until recently, even though research focused on seasonal forecasting are already being developed for several decades. The S2S forecasts seek to fill a significant gap between short and long-term forecasts, and its applicability can be seen in several social and economic sectors. In this context the...

The intraseasonal oscillation (e.g., the MJO and the BSISO) is the major source of predictability of extreme weather in a S2S time scale (e.g., 3-4 weeks). Many authors examined the predictability of the MJO and the BSISO in subjectively selected months. Recently, Kikuchi et al. (2016) applied a method which can objectively determine which ISO mode is dominant in a given day to a cloud-system...

On the Dynamical Downscaling of Multi-model Ensemble Forecasts for Sub-seasonal Predictions of Extreme Weather Events

Manpreet Kaur, R. Phani, Sahai A. K., Susmitha J.,
Indian Institute of Tropical Meteorology, Pune, India 411008

Abstract:

The massive social-economic impacts of heavy precipitation events demand reliable prediction at requisite response-time window. The extreme rainfall...

Seasonal forecasting models are increasingly being used to forecast application-relevant aspects of upcoming climatic conditions, often summarised by climate indices. There is even the hope that for some cases, predictive skill of forecasts of such indices may exceed that of forecasts of the corresponding mean quantity. Here we analyse forecasts of two generalised indices derived from daily...

The large-scale extratropical circulation is dominated by Rossby wave activity along the upper-level midlatitude wave guide and jet stream. This activity often occurs in preferred quasi-stationary, persistent, and recurrent states, so-called weather regimes (e.g. Vautard, 1990). In the Atlantic-European region, weather regimes account for most of the atmospheric variability on sub-seasonal...

The optimal number of ensemble members for effective subseasonal-to-seasonal (S2S) ensemble predictions is explored. It turns out that the prediction skill increases with increasing the number of ensemble members, but the skill improvement which is defined by the increase of mean squared skill score (MSSS) against the theoretical maximum (or infinite ensemble size) is independent of the...

Electricity generation output forecasts for wind farms across Europe use NWP model output, such as that from the ECMWF. These forecasts influence decisions in the energy market, such as those that determine daily energy prices or the usage of thermal power generation plants. The predictive skill of power generation forecasts therefore directly impacts on the profitability of energy trading...

The present study evaluates the performance of an S2S model (called CMA: the China Meteorological Administration) in simulating RODs over West Africa. Using two ROD definitions, we compared the model ROD at six lead-time forecasts (10, 20, 30, 40, 50 and 60 days) with the observed ROD from satellite datasets, statistically quantify model capability to reproduce the inter-annual variability of...

The Japan Meteorological Agency (JMA) operates the Global Ensemble Prediction System (GEPS) to support issuance of Five-day Tropical Cyclone (TC) Forecasts, One-week Forecasts, Two-week Early Warning Information on Extreme Weather, and One-month Forecasts. In this study, we indicate the performance of JMA-GEPS prediction for the extremely warm days over Asia in spring 2018.
In February 2018,...

The aim of this work is evaluate the sub-seasonal prediction ability of the Brazilian Atmospheric Model (BAM), a general circulation model developed by Brazilian Center for Weather Forecast and Climate Studies (CPTEC in Portuguese). BAM is a spectral model with T126 horizontal resolution and 42 levels in the vertical. Hindcasts were generated for the extended austral summer period (November to...

A sub-seasonal to seasonal forecast system has been developed using the medium resolution version of the Beijing Climate Center Climate System Model (BCC-CSM1.2). Based on the retrospective forecasts of 60-day integrations by the model initiated from every 00,06,12,18 UTC cycle from 1994-2013, a comprehensive assessment of the prediction skill in global atmospheric circulations, especially the...

Understanding and predicting wet and dry spells is particularly important in West Africa where the population is highly vulnerable to severe weather events related to precipitation. Several recent events, in 2007 over the Sahel, or in 2009 in Burkina Faso, have illustrated the high impact of the wet spells. Dry spells have a high impact on crops and livestock, especially during the onset of...

The CNR-ISAC monthly forecasting system is calibrated through a fixed reforecast dataset made up of 5-member ensembles initialized every 5 days over a 30-year period (1981-2010). In this work, this reforecast dataset, available on the S2S database, is used to assess the capability of the system to predict categorical probabilities of above- and below-normal 2-m temperature events. The...

Hot temperatures and prolonged periods with large thermal discomfort can have tremendous socio-economic impacts. Besides temperature alone combined indices are frequently used as heat stress proxies as they better quantify the physiological impact of heat. They are primarily based on a combination of temperature and humidity, but can also include additional variables such as radiation and...

Reliable forecasts of summer rainfall in coastal northeast Australia can empower sugar cane growers to better manage nitrogen applications reducing damage to the Great Barrier Reef. This study aims to explore the dynamical systems that affect rainfall in the wet tropical sugar cane growing region in northeast Australia, where nitrogen losses pose the greatest ecological threat. We then...

The potential of early warning for high impact events, such as extreme temperature conditions, is explored using the S2S model data. At medium range, predictions for severe temperature conditions can be directly based on temperature forecast probabilities. At the extended range, we argue that the predictable signal for severe and persistent warm/cold spells is better exploited by the use of...

The predictability of the 1-4 week tropical cyclone (TC) forecasts in the western North Pacific is evaluated in this study. The CWB TC Tracker (Tsai et al. 2011; Wea. Forecasting) is utilized to objectively detect TCs in the 28-day ECMWF Subseasonal to Seasonal real-time forecasts during 2015-2017. Two types of the forecast evaluation methods are used: (i) categorical binary forecast...

Rossby wave packets (RWPs) are one of the dominating atmospheric phenomena which shape the midlatitude weather. A realistic representation of RWPs is essential for a skillful prediction of the day-to-day weather and weather extremes. Using an objective RWP tracking technique, this study verifies the representation of RWPs for all models in the Subseasonal to Seasonal Prediction Project...

Recent years have seen a rapid growth in the development of “climate services for energy” across Europe. There remains, however, only a relatively modest level of understanding of how meteorological skill in probabilistic numerical weather predictions transfers into skill in simulating the behaviour of a complex system such as a power network.

At S2S time-horizons (weeks to months), results...

ECMWF has been producing ensemble-based sub-seasonal forecasts since 2004. Sub-seasonal forecasts at ECMWF are based on 51-member ensemble integrations running twice a week for 46 days. An 11-member ensemble of re-forecasts covering the past 20 years is produced routinely to calibrate the real-time forecasts. This presentation will discuss its skill in predicting several sources of...

National Institute of Meteorological Science (NIMS)/Korea Meteorological Administration (KMA) has been operating Climate Prediction System since 2014 for long-range forecasting. The system is based on GloSea5GC2 that is fully coupled global climate model. GloSea5 consists of atmosphere (UM), ocean (NEMO), land surface (JULES), and sea ice (CICE) components through the coupler OASIS. The system...

This study analyzes the error characteristics of the Global Forecast System T574L64 (GFS) model over the South Asian region during the boreal summer season of 2012. We demonstrate that growth of forecast error with lead time behaves differently over land and ocean. Even though the magnitude of error is larger over land, error grows faster with lead time over the ocean. The increase in error...

The extended-range predictability of European surface weather variables is generally low because of unpredictable transitions in the large scale flow. Forecast skill also depends on the definition of the response variable and constitutes a trade-off between the threshold or extremity of the anomaly one wants to predict, the level of spatial and temporal aggregation and the desired lead-time....

The Taiwan Central Weather Bureau global forecast system (CWBGFS) has provided 45 days 20 ensemble member prediction on resolution T319L60 model since 1 July 2017. The ensemble perturbations are given by singular vectors which are calculated from northern and southern hemisphere (20N/S~80N/S) domain total energy norm separately. Moreover, the Stochastically Perturbed Parameterization Tendency...

Land initial conditions to initialise the ECMWF reforecasts used in Subseasonal-to-seasonal (S2S) operational since 2018 are based on the land surface scheme CHTESSEL (Carbon and Hydrology Tiled ECMWF scheme for surface exchanges over Land) forced with the meteorology provided by atmospheric reanalyses for generating the land surface initial conditions for the ECMWF S2S reforecast system as...

We introduce two websites displaying a variety of ensemble forecast products: the TIGGE (The International Grand Global Ensemble) and S2S (Subseasonal to Seasonal) Museums (http:// gpvjma.ccs.hpcc.jp/TIGGE/ and http:// gpvjma.ccs.hpcc.jp/S2S/).

The TIGGE Museum displays various products of 10 global medium-range ensemble (TIGGE) forecasts, originally provided by the WWRP THORPEX project to...

The National Center for Atmospheric Research (NCAR) Research Data Archive (RDA; https://rda.ucar.edu) provides open access to a large and diverse collection of meteorological and oceanographic observations, operational and reanalysis outputs, and remote sensing datasets to support atmospheric and geoscience research. The RDA contains greater than 600 dataset collections which support the...

The Weather Prediction Center (WPC) currently provides detailed weather forecasts out to day 7. There is intense demand and interest in extending daily weather forecasts to ten days. Extending daily forecasts out to day ten requires the development of a methodology to turn raw model guidance into consistent, actionable products and services for decision makers. To accomplish this, WPC’s...

The utility of sub-seasonal to seasonal forecast information for agricultural risk assessments
Matthew Young (1,2), Emily Black (1,2), Dagmawi Asfaw (2), Matt Brown (3), Ross Maidment (2)

(1) National Centre for Atmospheric Science, University of Reading, UK
(2) Department of Meteorology, University of Reading, UK
(3) Department of Atmospheric, Oceanic and Planetary Physics, University...

The growing use of weather-dependent renewable power is changing the way electricity systems operate. The traditional paradigm – where large power plants are managed to meet variations in electricity demand – is being replaced by a situation in which demand and supply are strongly influenced by weather. This has profound consequences for power systems where supply-demand balance must be...

Abstract
This study is inspired by the huge economic implications of rainfall onset in Nigeria. It accessed and evaluate, the skills of CMA, ECMWF and UKMO Sub-Seasonal to Seasonal (S2S) models in predicting monsoon onset, its variability, the global drivers modulating the variability and the Tele-connections of the drivers with the variability of the onset anomaly in Nigeria. All the models,...

While a connection between the El Ni˜no-Southern Oscillation (ENSO) and the Northern Hemisphere wintertime stratospheric polar vortex appears robust in observational studies focusing on the period before 1979 and in many modeling studies, the strength of this connection has weakened in the past few decades. In this study, the factors that have led to this decline are assessed by comparing...