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The main goals of this session are to review the state of the science and research activity in sub-seasonal to multi-decadal prediction. In order to advance prediction at these ranges it is essential to develop a seamless approach that integrates all relevant weather and climate physical, dynamical, land surface and aerosol processes. The outcomes of this session will contribute to identify the important elements needed for the development and implementation of Earth-system monitoring and prediction systems.
The session will focus on the following multi-disciplinary issues relevant to the prediction problem:
- Coupled atmosphere-cryosphere-ocean-surface numerical prediction systems;
- Coupled data assimilation for initialization;
- Predictability, dynamical and physical process (e.g., MJO and organised tropical convection) studies addressing the prediction problem;
- Ensemble prediction systems (EPS); and
- Intercomparison of predictions at the interface of weather and climate made by numerical prediction systems with the help of field campaigns, re-analyses, in-situ and satellite observations.
Extreme weather and climate events, such as heat waves and droughts, heavy rainfall and associated flooding, extreme winds, marine storminess and associated coastal flooding enhanced by the ongoing sea level rise, are responsible for a disproportionately large part of climate-related damages and are thus of great concern to the impact community and stakeholders. Extremes are also one of the most important cross-cutting issues of the WCRP involving several core projects (GEWEX, CLIVAR and CliC) and are also of considerable interest to the IPCC. Papers are solicited on advancing understanding of extremes to:
- clearly articulate the notion of extremes;
- improve the monitoring and assessment of extremes;
- document and understand past and current changes in extremes;
- describe the physical mechanisms that cause extreme events; and
- predict likely changes in the frequency and intensity of extremes on timescales ranging from seasons to a century or more.
This session invites forward looking papers in all of these areas that will help the WCRP to develop a well articulated and focused program of research on extremes. Topics may stretch across a broad range of disciplines, including users in impacted communities, statisticians, climatologists, meteorologists, hydrologists and others.
One of the most societal-relevant objectives of the Earth Sciences is to understand the history and future evolution of sea level. One-tenth of the global population and 13% of the world’s urban population live in coastal areas that lie within just 10 m above sea level which covers only 2 % of the world’s land area. Global sea level rise is one of the well documented changes and has increased from a few centimeters/century over recent millennia to 2-3 centimeters/decade in recent decades. Regional changes in sea level, however, are not monotonous, and strongly deviate from the global mean in many regions. Prediction of future sea level changes at the regional scale is essential for coastal impact assessment, but has not been practical yet owing to large disagreements between climate model projections. An improved skill in regional sea level prediction requires an understanding of the underlying dynamical processes and advances concerning their representation in climate models.
A strong contribution to regional sea level variability is due to a number of major climate modes which are known to be connected to ocean dynamics. On interannual to decadal time scales, observed changes in regional sea level correspond largely to changes in upper-ocean heat and salt content, reflecting lateral (adiabatic) redistributions of thermocline water associated with the variability of wind-driven ocean circulation. On longer, multi-decadal time scales, changes in the thermo-haline forcing are expected to cause additional changes in water masses and in ocean overturning circulations. The consequences of shifts in large-scale ocean transport patterns would be many, ranging from effects on heat and fresh water fluxes on basin and global scales; ocean cycling of carbon, oxygen, nutrients and other key dissolved elements; and significant changes in regional sea level.
This session solicits papers that address observations, model studies and results from ocean synthesis that relate to past, present and future variability and change of global and regional sea level. A particular emphasis is on the causes, patterns, and impacts of ocean circulation variability and trends on interannual to centennial time scales. |
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Historical climate observations are of varying quality, from high resolution satellite data to a tin bucket thrown over the side of a ship. The problems associated with turning these observations into climate data records are formidable. New approaches and the reprocessing of historical records together with the recovery of old data and metadata give a more precise and longer view of past climate, as well as elucidating the uncertainties inherent in those data. Reprocessing satellite data to account for changes in orbits, satellites and calibration is essential. New and ongoing initiatives will provide the future observing systems that can better suit the needs of climate science, climate services and society. Reanalyses merge conventional and satellite observations with numerical modeling, providing value-added data sets including many physical fields not routinely or easily observed. These data have been widely used in climate and weather studies, but the model component and changing observing system exert a significant bias in the resulting data. Reanalyses hold promise for incorporating many components of the Earth climate system (land, ocean, atmosphere, cryosphere), yet many challenges remain in reducing the uncertainties to a level required to detect climate trends.
This session solicits papers that address techniques and progress in producing or reprocessing observational data sets to generate climate data records and monitor changes in the climate system. Papers are also solicited that focus on the development of reanalyses, as well as on new methodologies to improve them or to extend their scope for use in climate services and research. The session aims to highlight especially innovative techniques that advance the state-of-the-art in these areas.
This session will consider climate variability and predictability at regional scales, linkages between regional variability and global modes of the climate system and processes that affect regional variability and predictability at a wide range of time scales. Particular emphasis is given to the different monsoon circulation systems and their variability, including their role in the Earth’s climate, the physical mechanisms that operate, and progress towards understanding and exploiting their predictability. The Session will also focus on issues related to modeling of regional climate variability and change. Submission of abstracts summarizing how WCRP activities have contributed to improve our knowledge and understanding of these research areas is encouraged.
This session covers observations, theory and modeling of mesoscale and smaller-scale processes, which are typically parameterized in climate models, and the development of improved model representations of these processes. Examples include clouds and convection, direct and indirect aerosol effects, turbulence and gravity waves. Dynamical processes on large scales and other atmospheric processes will be also considered. Topics of interest include the impacts of smaller-scale processes on the larger scales and the importance of various processes to feedbacks within the climate system. |
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The CMIP5 model database is filling up rapidly with a diversity of climate modeling experiments, including decadal predictions, long-term projections, and experiments dedicated to diagnosing the role of various processes and feedbacks in the climate system. The broad user community strives to make the best use of existing simulations for research, education, and a multitude of other interests such as policy making and resource management. A comprehensive statement on the "reliability" of the climate model results is therefore mandatory.
This session calls for papers that aim at assessing this reliability by systematic confrontation of models and observations at multiple temporal and spatial scales. The focus of the session is on the development and application of diagnostics and metrics to assess the performance of individual and ensemble mean simulations related to, for example:
- Process-oriented evaluation of CMIP5 models
- Quantification of advances between CMIP3 and CMIP5 models (improvements due to advances in the physical climate and the consideration of new Earth system components)
- Analyses of the spatial and temporal scale at which these models are considered to be reliable
- The use of initial condition experiments in climate modeling (e.g., decadal predictions and the testing of climate models in short-term weather forecasts mode)
- Methods of generating ensembles or combining information from multiple models
- Relation of model performance to aspects of climate projections
- Confrontations with paleo-records helping to assess confidence in the ability of models to capture climate forcings and major feedbacks
- Exploitation of novel observations for advancing the assessment of model reliability
- Pursuit of the above with CMIP3 simulations, in cases where CMIP5 data are not yet available
This session will include studies on the identification and mechanisms for modes and regimes of large-scale variability in different climates. We will consider papers addressing past and future climates: among them are the Last Interglacial (LIG), the Last Glacial Maximum (LGM), the mid-Holocene (MH), present day, and future warm climates with CO2 concentrations two or four times higher than preindustrial values. Weekly to multi-decadal timescales are of interest. Examples of modes and regimes covered are global and regional hydrological regimes, the El Nino Southern Oscillation (ENSO), the Madden-Julian Oscillation (MJO), the Northern and Southern Annular Modes (NAM/SAM), and tropical and extratropical storm regimes.
We welcome papers on both physical and statistical analysis of these modes and regimes in different climates, using observations and model datasets. Of particular interest are studies on mechanisms driving these modes and regimes and their sensitivity to various external forcings across a range of climates with different mean states. Changes to these modes and regimes in different mean states, the roles of high latitude versus tropical forcing, the various mechanisms involved in polar amplification, the land-sea thermal and hydrological contrasts in the response to various forcings, the roles of the ocean, land, sea ice cover and ice-sheets in initiating and/or amplifying change are all topics of interest in this session
This session will cover the following topics: radiative forcing of climate arising from natural and anthropogenic factors; greenhouse gases and their warming potentials; aerosol effects on climate and aerosol-cloud interactions; solar influences on climate; land-use and land-cover interactions in the climate system; biogeochemistry and climate; role of chemistry in forcings and feedbacks on different timescales and in climate sensitivity; emissions, tropospheric chemistry, air quality and climate; cloud chemistry and precipitation; stratosphere-troposphere exchange; effect of greenhouse gases and ozone-depleting substances on the stratosphere; effect of ozone depletion/recovery on climate. |
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Land-atmosphere interactions may lead to climate predictability on a range of time scales, and it has been shown, at least in some regions, that land surface conditions, such as vegetation cover and soil moisture, are key to the added predictability. There have also been many changes in land cover and use over time leading to deforestation, afforestation, and the expansion of crop lands, urbanization, irrigation and fertilization. The magnitude of these changes has increased significantly in the last century. Thus, land use and land cover changes are recognized as one of global drivers of environmental change, and modern earth system models take into account these anthropogenic activities. As population increases, the impacts of these changes on the regional environment need to be studied all the more, including the complex interactions among the physical and biogeochemical aspects of the environment and social-ecological systems. Since the regions affected by the large-scale changes in land cover and land use are also those of high human populations, the research has particular significance for assessing the impacts of the climate change on society and environment. Papers addressing these aspects of the climate and Earth system sciences are sought.
Session B11: Cryosphere and Climate
(conveners: M. Serreze, V. Kattsov, M. Drinkwater)
The cryosphere, existing at all latitudes, represents the realm of frozen water in the form of snow, sea ice, glaciers, ice sheets and permafrost. While much attention has been paid to characterizing and understanding causes of recent change in the cryosphere, including reductions in Arctic sea ice extent, increased sea ice extent in Antarctica, the mass balance of the Greenland and Antarctic ice sheets, disintegration of large ice shelves, and warming and thawing of Arctic permafrost, the greater challenge that lies ahead is understanding the feedbacks between these changes and the rest of the climate system as well as projecting their impacts, both negative and positive, on ecosystems and society. This session encourages papers on: characterizing variability and cryospheric change on relevant time and space scales; process studies to refine our understanding of climate feedbacks involving surface albedo, ice dynamics, atmospheric and oceanic circulation, and the carbon and hydrologic cycles; and model simulations assessing the role of the cryosphere as a driver of climate variability and change from regional to global scales. Particular emphasis will be given to use of models and observations in evaluating of the societal consequences of these changes.
Uncertainty in future climate change projections limits the ability of policy makers to use such information to make decisions. Uncertainty arises from three sources: natural variability, model and scenario uncertainty. While natural variability contributes the largest share to the total uncertainty at short lead times up to a decade or so, scenario uncertainty dominates at long lead times of many decades. Model uncertainty is important at all lead times. A major cause of this uncertainty arises from our limited understanding of climate processes and feedbacks, be they physical, chemical or biological, at both global and regional scales and their interaction with large-scale modes of variability. A better understanding of the key mechanisms driving climate change, globally, at a regional level and for climate extremes is hence an urgent goal.
This session invites contributions on quantification and understanding of processes, mechanisms and feedbacks controlling anthropogenic climate change at a range of space and timescales and sensitivity of climate predictions to model formulation, numerics, and resolution. These may be associated with:
- atmospheric processes (e.g. clouds, aerosols, hydrological cycle, land surface, stratosphere),
- oceanic Processes (e.g. convection, mixing, ocean eddies, overturning circulation),
- cryospheric processes (e.g. snow, sea-ice, glaciers, permafrost, land-ice), and
- coupling with biogeochemical cycles (e.g. carbon, nitrogen, methane). |
