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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - PROCEED (PROCess-based sEamless development of useful Earth system predictions over lanD)

Teaser

Summary

Predictability of climate at seasonal and longer time scales stems from the interaction of the atmosphere with slowly varying components of the climate system such as the ocean and the land surface. However, much of the improvement so far has been obtained over ocean. In contrast, the lack of observations to constrain the model complexity over land has determined the development of different prediction systems for different time scales, which is believed to considerably limit the current level of performance and usefulness of predictions. While benefit from daily verification, the models that are developed for short time-scales (Weather to seasonal climate predictions) include only that part of the surface and near-surface variability for which observations are available and that can be suitably modelled/initialized in order to positively contribute to the forecasts (verification-based approach). Therefore, to limit prediction errors, short time-scale models do not include those processes related to vegetation and their seasonal, interannual and sub-grid variability. On the other hand, for the interannual and longer time scales, the Earth system models used for climate variability/change research contain comprehensive soil-vegetation-atmosphere-transfer schemes that are intended to represent as many processes as possible, even those that are still poorly constrained or understood (process-based approach).
Because energy supply, demand and infrastructures are strongly affected by climate, energy sector has been recently included as a priority area in the Global Framework for Climate Services. Since most of the applications of climate predictions would serve energy, social and economic interests that are land-based, there is an urgent need to improve probability forecasts over land.
Objectives:
-Develop novel observational constraints to understand and improve modeling of land-climate interactions and feedbacks.
-Understand the land limitations that are affecting current prediction models across scales.
-Enhance Earth System predictions across scales by obtaining a practicable seamless development of verifiable land surface processes.
-Exploit performance/usefulness of improved Earth System predictions over land to provide valuable information to end-users in the energy sector.

Work performed

New generation satellite data products over land have been collected and used in order to develop observational constraints on the processes driving vegetation and surface-albedo interaction with atmosphere; the new observational constraints have been subsequently applied for the verification and process-based improvement of the land modeling.
The verification-based approach has been applied to evaluate the performance and limitations of the latest version of the operational ECMWF seasonal prediction system (SEAS5) that has been fundamental to drive subsequent process-based modeling developments. The sensitivity to the following key processes has been verified by performing a set of retrospective forecasts and potential predictability experiments:
-Interactive vegetation/land cover: the formulation prescribing constant vegetation coverage is replaced by a modified model version that allows vegetation/land cover fractional coverage to realistically change over time.
-Interactive surface albedo: the parameterization prescribing time-invariant blended albedo for each grid point, has been replaced with an interactive albedo scheme.
The knowledge from the verification-based and the process-based approaches has finally driven the seamless development of an improved land modeling across time scales in the European Community Earth system model (EC-Earth) and in the world-leading ECMWF seasonal prediction system.
Creating and exploiting an international network of collaborations, a comprehensive evaluation of the improved climate predictions has been performed in terms of skill, probabilistic quality and potential economic value for end users in the energy sector. Furthermore, a novel approach (index of opportunity) has been proposed to evaluate how the latest developments in seasonal climate forecasts can provide a useful prediction for the photovoltaic power production over European regions.
A considerable scientific production is being accomplished as an outcome of the activities in PROCEED. Other than the four peer-reviewed papers already published at the end of the project, there is one paper under revision, two under submission and other four in preparation for submission. Furthermore, 17 contributions/seminars has been presented in international converences/workshops or internationally established advanced schools, of which 4 Invited contributions.
The dissemination of news and results of PROCEED has been performed in a timely manner and with frequent updates as planned on the project web page.

Final results

An unprecedented combination of observational land data for the recent historical period has been exploited to better understand and model land-atmosphere interactions. For the first time, the different signatures of surface albedo feedback over Northern Hemisphere land warming was quantified over the recent historical period, providing guidance for the validation and improvement of the land models. Accordingly, the unprecedented observational data was used to develop and realistically constrain new interactive parameterizations of the vegetation cover and of the land albedo. A novel parameterization of the soil albedo dependence on soil moisture has been as well implemented and included in the latest version of EC-Earth. The improved representation of land surface processes that demonstrated to improve prediction skill has been included in a seamless way in SEAS5. It is shown for the first time consistent enhancement across scales of climate simulation and prediction due to a more realistic representation of land-vegetation processes. The improvement is consistently large over boreal winter middle-to-high latitudes due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Here the improved representation of land surface-vegetation tends to correct the winter warm biases, improves the climate change sensitivity as well as the skill of forecasts at seasonal time-scales. Remarkably, the improved coupling operated by the new interactive parameterizations introduces significant improvements of the prediction of 2m temperature and rainfall over transitional land surface hot spots (i.e. North American Great Plains, Nordeste Brazil and South East Asia).
The results in PROCEED are considerably impacting the end-users community. It is demonstrated for the first time the useful application of seasonal climate prediction for energy demand forecasting, with significantly increased potential economical value compared with state-of-the-art (i.e. using only climatological information from past observations). Therefore, PROCEED is fostering more efficient policy and operation of the power grid at the National and European level. In this respect, a novel approach (index of opportunity) has been proposed to evaluate the usefulness of seasonal climate forecasts for the average photovoltaic power production. The index of opportunity computed across European regions indeed indicates that seasonal forecasts can provide some potential benefits during both winter and summer seasons in different parts of Europe.