Theme D: Analysis and Prediction of Regional and Large-Scale Variability and Change

Theme Lead: Ronald Stewart (University of Manitoba)

Overview

Theme D uses the comprehensive measures of regional change developed in Theme A and models developed in Theme C to assess how, for example, changing large-scale atmospheric controls interact with regional Earth system processes in governing changes in climate variability and extremes. It addresses the key science questions: 1) what governs the observed trends and variability in large-scale aspects of the Earth system and how well are these factors and effects represented in current models, and 2) what are the projected regional scale effects of Earth system change on climate, land and water resources?

Work Package Descriptions

D1 Large/Regional-Scale Land Surface and Climate Controls

This work packages involves the assessment of large and synoptic scale atmospheric circulation patterns as they relate to observed temporal and spatial trends and variability (including extremes) in hydro-climate over the study region. The large-scale assessment analyzes well-known atmospheric/oceanic teleconnection patterns that have been shown to influence the hydro-climatology of the region. These include El Niño/Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) the Pacific North American (PNA) pattern, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO) and the Atlantic Multi-Decadal Oscillation (AMO). In addition, studies are undertaken to understand the mechanisms which link the regional water and energy response to large-scale forcings. This includes the role of the orographic barrier in amplifying the region’s climate sensitivity to upstream large-scale forcings. Statistical techniques and diagnostic studies are carried out to examine the coupled mode of variability between low-frequency forcings such as SST anomalies, large-scale circulation patterns and warm-season synoptic activities. Another focus is on precipitation, including the occurrence of precipitation extremes from droughts to heavy precipitation, regional and larger scale factors leading to such events, changing occurrence of winter precipitation, changes in the occurrence of extreme precipitation rates, and linkages with the large and regional scales forcing factors.

Description of Activities & Milestones:

D1.1 Large-scale controls over recent past climate (anticipated completion by April, 2015): Determine the large-scale conditions, including SST anomalies and large-scale oscillations, that have occurred, examine how the region's orographically-influenced circulations have varied, and relate both to observed regional change documented in A2.

D1.2 Determination of past changes in all aspects of precipitation (April, 2016): Determine the change in precipitation amount, phase and intensity, convection, droughts and heavy precipitation over the last few decades using a variety of datasets and relate these to the changing large- and regional-scale circulation. 

D1.3 Diagnosis of large-scale change and feedbacks (April, 2017): Use the large basin-scale models developed in C to diagnose causal effects of the observed changes in river flows, and to investigate the feedbacks that occur on the regional scale between the many surface and atmospheric variables.  

D2 Changing Climate, Changing Land Surface Systems, and Large-Scale Hydrology

This work package addresses the feedback effects of the changing land surface on regional climate using off-line MESH simulations (including the improved CLASS algorithms developed in Theme C). The widely varying, and changing surface leads to feedbacks acting to enhance and/or reduce large scale forcing factors. As well, the MESH models developed in Theme C will be used to investigate the linkage between the large-scale climate controls and land-atmosphere feedbacks on flow regimes in the major river basins of the Saskatchewan, Peace-Athabasca, and Mackenzie. A critical challenge is to explain historical variability in flow regimes, and identify sensitivity of the river systems to climate and land surface change.

Description of Activities:

D2.1 Assessment of large/regional circulations in models  (anticipated completion by April, 2015): Establish the degree to which historic GEM, WRF, NARCCAP and CMIP5 models have simulated the large-scale and regional-scale circulations examined in D1 and, as appropriate, understand reasons for inadequate capabilities.

D2.2 MESH/GEM sensitivity/feedback simulations using existing CLASS (April, 2016): Undertake regional scale MESH simulations using existing CLASS land surface schemes in a preliminary off-line analysis of the sensitivity of land-atmosphere feedbacks to cryospheric, hydrologic and terrestrial ecosystem change. 

D2.3 MESH development to include large-scale controls (April, 2016): Develop and test new MESH algorithms to represent a) water management controls on river flows, including reservoir and irrigation management, and b) land management change, for the Saskatchewan, Peace-Athabasca and Mackenzie River basins.

D2.4 GEM sensitivity/feedback simulations using improved CLASS  (April, 2017):  Undertake regional scale MESH simulations using improved CLASS/MESH schemes to analyze the sensitivity of land-atmosphere feedbacks to cryospheric, hydrologic and terrestrial ecosystem changes and land/water management. This builds on large scale model developments in Theme C.  

D3 Atmospheric Circulations, Temperature and Precipitation

Changes in the large-scale atmospheric circulation will be assessed from CMIP5 and other projections. Their subsequent effects on the continental synoptic activities and associated heat and moisture transports which affect critically regional temperature and precipitation responses will be assessed from the downscaled projections. The initial focus will be on projections of temperature, precipitation, and their variation. Key focal points will be on regional and local scale temperature changes and variations of prolonged summer hot periods, and extension of above freezing conditions. In terms of precipitation, the focus will be on the development of drought, heavy precipitation, extreme precipitation rates, as well as the changing phase of precipitation. Special attention will be placed on heavy precipitation events in the lee of the Rockies.

Description of Activities and Milestones:

D3.1 Establishment of large-scale controls in future climate (anticipated completion by April, 2017): Examine GEM, WRF, NARCCAP and CMIP5 projections to examine changes in large-scale conditions and regional-scale circulations over the next 10-30 years and relate these to anticipated temperature changes.

D3.2 Determination of role of regional circulations on future climate (April, 2018): The future occurrence and variability of circulations linked with orography, and those affecting storm tracks will be established. The role of such circulations in governing surface parameters, including temperature, will be determined.

D3.3 Determination of future changes in precipitation (April, 2018): Utilize appropriate projections from GEM, WRF, NARCCAP and CMIP 5 to examine future changes over the region in precipitation quantity, phase and intensity including drought as well as instances of concurrent heavy precipitation. In light of the 2013 Alberta flooding, special attention will be placed on heavy precipitation in the lee of the Rockies.

D3.4 Preliminary examination of future climates (April, 2018): Critical review of GEM, WRF, NARCCAP and CMIP5 projections for concurrent extremes, including drought persistence. Enhanced capability for future projections provided using expert analysis and spatial-temporal stochastic modelling.

D4 Water Resources, Cryosphere and Ecosystems

The projection results will be used to address regional scale effects on land and water resources, using the large-scale models developed in Theme B. This includes the change in river flows for the Saskatchewan, Peace-Athabasca and Mackenzie River Basins, and effects of climate change for specific ecosystems using the models developed in Theme A. We will determine whether future changes cross ‘tipping points’ in Earth system behaviour, leading to further extremes and dramatic system changes, such as deglaciation, permafrost disappearance and terrestrial ecosystem transition. Outputs from this analysis will thus be used to identify global climatological controls on broad regional water resource response, and hence to enable specific design, operational or policy development problems under climate change to be addressed in Theme D. To address this issue, specific analyses will be carried out utilizing future conditions along with threshold guidance on conditions needed to trigger a fundamental shift.

Description of Activities and Milestones:

D4.1 Climate scenario selection for impacts assessment (anticipated completion by April, 2018): Building on D2.1, select a sub-set of climate scenarios from GEM, WRF, NARCCAP and CMIP5 for impacts assessment, to scope the full range of future scenarios and assign associated levels of confidence.

D4.2 Determination of impacts on WECC observatories (April, 2018): Apply scenarios to WECC observatory and small/medium sized basins using fine- and meso-scale models and assess potential impacts on cryospheric, ecological and hydrological systems.

D4.3 Determination of potential impacts on major river systems (April, 2018): Apply scenarios to MESH models of the Saskatchewan, Peace-Athabasca and Mackenzie River basins and explore future river flow responses, including preliminary assessment of impacts of management options.

D4.4 Assessment of whether tipping points will occur (April, 2018): Synthesize results of D4.2 and D4.3 in conjunction with expert elicitation to undertake assessment of potential for tipping points to be reached in the next 10-30 years.