Workshop on energy flow through the climate system

29 September - 01 October 2015

MetOffice - Exeter - UK

Aims and Objectives

An overarching scientific challenge faced by the whole climate science community is related to achieving accuracy in estimating the storage and flows of energy throughout the climate system adequate for climate state and variability studies. To face this challenge, the workshop will bring together international scientists, including early-career researchers and scientists engaged in interdisciplinary climate research who are interested in the energy flows in the Earth’s System. In particular, the workshop is aiming to bring together experts from ocean and atmospheric reanalysis, air-sea fluxes, ocean heat content (OHC), climate models, atmospheric radiation and sea level. Thus, an important goal of our workshop is to foster collaboration between these different communities to expedite progress, and to build up a multi-disciplinary synergy community for climate research aiming to work on two different issues:

1. Quantify Earth’s energy imbalance, the ocean heat budget, and atmosphere-ocean turbulent and radiative heat fluxes, their observational uncertainty, and their variability for a range of time and space scales using different observing strategies (e.g. in-situ, satellite), reanalysis systems, and climate models.
2. Analyze the consistency between the satellite-based planetary heat balance and ocean heat storage estimates, using data sets and information products from global observing systems (remote sensing and in situ) and ocean reanalysis, and compare these results to outputs from climate models to obtain validation requirements (for model and observations).

Developing the knowledge, and observational capability, necessary to “track” the energy flows through the climate system is critical for better understanding relationships between climate forcing, response, variability and future changes. An ongoing accounting of where heat goes and its manifestations is a great need and has implications for interpreting the recent past and immediate future.

The workshop is organised by the CLIVAR CONCEPT-HEAT Research Focus and the CLIVAR Global Synthesis and Observations Panel (GSOP).

Agenda

The meeting agenda can be downloaded from here (version 11th September 2015).

Workshop presentations

K. von Schuckmann - Welcome and overview on CONCEPT-HEAT

K. Trenberth - Approaches to addressing the Earth’s energy imbalance

S. Kato - Surface radiation and energy budget

L. Yu - The Earth’s surface budget: Outcomes, uncertainties and drawbacks

T. L’Ecuyer - NASA NEWS energy budget perspectives

M. Mayer - Energy exchanges between the dynamic components of the climate system: atmosphere and ocean

M. Palmer - Ocean heat content and Earth’s energy imbalance: insights from climate models

C. Senior - Overview on CMIP6

Y. Kushnir - Decadal Climate Variability and Predictability

D. Smith - Earth's energy imbalance since 1960 in observations and CMIP5 models

M. Balmaseda - An overview on ORA-IP

P. Hyder - Improving understanding drivers of ocean-only ocean and coupled near surface ocean biases using a novel heat flux climatology

M. Valdivieso - Freshwater and heat transports from global ocean synthesis

R. Allan - Air-sea fluxes from atmospheric reanalysis

A. Storto - Accuracy of global ocean reanalyses

K. Haines - An overview on COST-EOS

S. Gulev - Assessing and improving surface flux products across space-time scales: implications for surface energy budget

C.-A. Clayson - Overview on Sea-Flux

S. Josey - Surface fluxes from in-situ observations and their use in models and parameterizations

M. Kubota - Results from inter-comparison of various turbulent heat fluxes

R. Buss de Souza - Air-sea fluxes in the Southern ocean: advancements and challenges

A. Bentamy - An overview on turbulent flux estimates: current progress and remaining challenges and the ESA-OHF project

N. Loeb - Radiation at the Top of the Atmosphere

A. Donohoe - Top of atmosphere radiative imbalance: forced trends versus internal variability

C. Domingues - A review of global ocean temperature observations: implications for ocean heat content estimates

B. King - Overview on the Argo program, its maintenance and future extensions

M. Cronin - The global ocean observing system: ways to complement Argo

K. von Schuckmann - The ocean’s role in Earth’s climate change and variability: what have we learned so far from Argo?

J. Gregory - Mechanisms of global and large-scale change ocean heat uptake on multidecadal and longer timescales

L. Cheng - An updated historical (1970-2014) upper ocean heat content estimate and the implication for the global energy budget

K. Trenberth - Climate sensitivity and feedbacks implied by TOA radiation versus temperatures

G. Johnson - Deep Ocean Warming & Earth’s Energy Budget: Observations & Plans

Workshop Organising Committee

• K. von Schuckmann (MIO, France)
• T. Lee (JPL, USA)
• K. Haines (University of Reading, UK)
• M. Palmer (MetOffice, UK)
• A. Alvera Azcarate (Université de Liège, Belgium)
• N. Caltabiano (CLIVAR IPO, China)

Scientific Steering Committee for CONCEPT-HEAT

• K. von Schuckmann (MIO, France) - co-chair
• K. Trenberth (NCAR, USA) - co-chair
• M. Palmer (MetOffice, UK)
• K. Haines (University of Reading, UK)
• C.-A. Clayson (WHOI, USA)
• C. Domingues (CSIRO, Australia)
• S. Gulev (IORAS, Russia)
• N. Loeb (NASA, USA)
• P.-P. Mathieu (ESA)
• R. Weller (WHOI, USA)
• M. Wild (ETH Zurich, Switzerland)
• Y. Xue (NOAA/NCEP, USA)

Workshop organisation

During the first two days, the workshop will be organized in four different sessions, which are aiming to centralize main outcomes at the forefront of climate science as well as to highlight main challenges. On the last day, 2 breakout sessions and a round table will be organized in order to foster collaboration and exchange between the different science communities.

Each session will be introduced by a keynote talk, which will be followed by several talks. Below a description of different sessions is introduced:

Session 1: The Earth’s energy budget

Each of the existing independent approaches (satellite measurements at TOA, in-situ observations and reanalysis outputs for ocean heat content, estimates of EEI from climate models) to determine values for energy flows in the Earth's system has its own advantages and drawbacks in terms of sampling capability and accuracy, leading to different estimates, and associated uncertainties. In addition different communities are involved in delivering these estimates and as yet these communities have not worked closely together to allow different assumptions to be compared and for some of the uncertainties to be reduced. Thus evaluating and reconciling the resulting budget imbalance is a key emerging research topic in climate science, which has the potential to bring different communities together to make a major contribution to reducing climate change uncertainties. Errors involved in deriving single components without a coupled context can accumulate and have major impacts on the accuracy of climate indicators, leading to large imbalances differences in estimates of Earth’s budgets and climate. Reconciling the different approaches remains a challenge. This session explores our capability to measure and understand the exchanges of energy in the Earth’s climate system, in particular in the quantification of the magnitude and spatial distribution of heating in the system, and will hence give the introduction and background to our workshop. The principal scientific question will be “What is the magnitude and the uncertainties of our estimates of Earth's energy imbalance (EEI), and how does it vary over time?”

Session 2: Energy flow as estimated from reanalyses and climate models

We need to further understand the role of resolution of climate models and reanalysis models in resolving natural climate variability and providing accurate error estimates, as well as to understand which are the relevant model physics and parameterizations that need further improvements. The combination of ocean models, atmospheric forcing fluxes and ocean observations via data assimilation methods has the potential to provide more accurate information than observation-only or model-only estimations. This session principally builds on the outcomes of the initiative ORA-IP, as well as from experts of COST-EOS dedicated to focus on main outcomes, achievements, and remaining challenges of estimating energy flows through (and storage) the climate system from this climate tool. Of particular focus will be outcomes for OHC. Addressing the energy budget in climate models is a powerful method for understanding future climate projections. A prerequisite thereby is an adequate representation of the energy budget in climate models, which requires a careful validation process and adequate reference datasets. This session is hence dedicated to address the following scientific question: “How can we improve validation requirements for and from coupled climate models to improve estimates of EEI?”

Session 3: Air-sea fluxes

Characterizing the uncertainty and biases in surface fluxes is essential to address scientific challenges related to the Earth Energy budget, energy flows and understanding the observed interannual to interdecadal variability superimposed on the centennial-scale warming of the global ocean surface. Quantifying sea surface heat fluxes to the required level of accuracy needed to support the various applications is a very challenging task. The present level of uncertainties in global ocean estimates of heat and moisture fluxes is not adequate for many applications, including global and regional mass and energy budget closure and variability on different time scales. This prevents understanding the mechanisms of ocean climate variability. Biases in surface fluxes lead to the systematic errors in climate models and preclude their efficient use in climate simulation. Without accurate estimates of surface fluxes it is impossible to engage predictive potential of the ocean into weather and climate prediction. Thus, improvements in all aspects of producing surface flux estimates, including parameterizations, measurement techniques and post-proecssing are required for further progress. This session will hence discuss “How can we better constrain the surface energy fluxes and their spatio-temporal variations at regional scale?”

Session 4: OHC and atmospheric radiation

Observed climate variations such as the current hiatus or unresolved inconsistencies of climate observations (e.g. “missing energy” in the climate system) underpin the need for fundamental research activities on the regional distribution of TOA and OHC (including vertical distribution), as well as their implication for their global estimates. Continued assessment and attribution studies of regional natural climate variability are essential to improve our estimates of global changes. There is also an urgent need to evaluate the relative importance of currently under-sampled regions of ocean heat content change (ice-covered ocean, marginal seas and deep ocean) and to understand how heat is transferred vertically. We have to evaluate how regional patterns change in time and if regional OHC tendency patterns can, along with other patterns e.g. regional sea level, be used to test/falsify model hypotheses. The use of physical budget constraints such as the global sea level budget are an important tool for this evaluation. In summary, this session will address the question: “How are TOA net radiation and ocean heating rate distributed in space and time?”

Meeting participants

Sponsors

The organisers would like to acknowledge the financial support for this workshop from the World Climate Research Programme (WCRP), US CLIVAR, and the US National Oceanic and Atmospheric Administration (NOAA). Organisers would also like to thank the UK Met Office for hosting the workshop.