The Mackenzie GEWEX Study

Transcription

1 The Mackenzie GEWEX Study Philip Marsh National Hydrology Research Centre, Saskatoon, SK, Canada

2 Background Mackenzie GEWEX Study (MAGS) was a study of the hydro-climatology of the Mackenzie River Basin (MRB) The MRB is the largest river basin in Canada and it has a broad impact on both the weather of North America and on the Arctic Ocean 1.8 million Km 2

3 Approximate MAGS Time Line Publication of the MAGS Books (18 years after the first GEWEX Workshop) NSERC Research Network Grant for MAGS Phase II. Successful. NSERC Research Network Grant for MAGS Phase I. Successful. NSERC Collaborative Special Project Program Grant. Not successful. NSERC Collaborative Special Project and Program Grant. Not successful. Canadian GEWEX Secretariat formed at NHRC in Saskatoon Env. Canada Green Plan Funding for MAGS activities First Canadian GEWEX Workshop

4 Overall Goals of MAGS II: To understand and model the high-latitude energy and water cycles that play roles in the climate system, and To improve our ability to assess the changes to Canada s water resources that arise from climate variability and anthropogenic climate change. MAGS made a distinct decision to limit the focus to energy and water cycles, and to not include related biogeochemistry or policy issues for example, and human impacts could be ignored.

5 The resulting Tasks for MAGS II were: close the water and energy balance at annual, monthly or shorter time scales and at spatial scales ranging from sub-basin to the entire catchment; develop and validate models that yield results within acceptable error limits; Use observations and models to describe and understand the flows of energy and water through the Mackenzie region under the present range of climate variability and climate change; Apply these models to address scientific, environmental and water resource problems; Transfer our models to similar environments in Canada and in other areas of the GEWEX Continental Scale Experiments

6 MAGS Research Strategy 1. Standardize background information 2. Observe the water and energy cycle at a range of scales 3. Develop basin-scale representations of the water and energy cycles based upon observations and data assimilation techniques 4.Carry out critical process studies 5.Develop atmosphere-surface-hydrology modelling capability 6.Assess the ability of our regional climate model to replicate the water and energy cycles when driven by observed large scale forcing and improve the model until it replicate these cycles 7.Develop the capability for seasonal prediction of Basin water resources with the use of predicted large scale fields 8.Understand the climate system and its possible alteration through anthropogenic effects

7 MAGS data and models: Operational observing network: weather, upper air, discharge Dedicated Field observations: network of approx. 15 sites across the basin, including: research basins, lake sites, upward pointing radar, aircraft flux observations, and river ice observations Numerical weather prediction model output with dedicated MAGS archive Canadian Regional Climate Model Mackenzie version WATCLASS hydrologic and landsurface model Remote sensing products, including: passive microwave, AVHRR, SPOT, MODIS, and ScaRaB for example This integration of field studies, models and remote sensing was very successful

8 MAGS Organization Science Team This organization structure was generally successful - the International Advisory Panel was especially helpfully - As was the Users Advisory Group - Annual workshops that brought the MAGS science community together, and other special focus meetings were extremely useful in developing the team work needed to carry out MAGS. This was essential since MAGS covered such a broad range of disciplines and many scientists have little understanding of each others disciplines International GEWEX - Links to International GEWEX were key for a variety of reasons, and full participation of Canadians in GEWEX SSG & GHP are essential

9 Data Archiving A significant effort was made to develop common data sets, including: observational network data, and gridded products research basins special aircraft and radar observations archiving data from the operational Numerical Prediction Models In general, insufficient funds and other resources were put into the development of an integrated data base. This is very hard to do (but maybe getting easier with modern technology?), but is essential and should not be underfunded, or funded at the expense of the science component of the program.

10 Mix of EC & NSERC Funding Govt. Researchers Env. Canada Abase funding Env. Canada Green Plan Funding University Researchers NSERC Research Network Grant for MAGS Phase II. NSERC Research Network Grant for MAGS Phase I. EC funding during early phases The combined science program was reviewed and approved by the MAGS Science Committee, and recommendations for integration made

11 Funding issues The MAGS program was carried out as an integrated Government- University research program, but the funding was not integrated, but was often in two pots of funds. This created various funding issues, As a result, it was difficult for the Science Committee to properly distribute funds to the highest priority science issues, Another funding issue resulted from the fact that annual project funding levels were set early in the funding program. As a result, the program was not sufficiently flexible to deal with changes needed as the program developed. Recommendation: GEWEX SRB should have an integrated research program, with both Govt. and University scientists and organizations, and it should have a budget that is available to fund the best science at an appropriate level, regardless of which organization they are in. There will be organizational inertia against this approach.

12 Funding levels NSERC (MAGS II) approximately $5 million over 5 years 15 Principal investigators Training: approx. 20+ PDFs and 40+ graduate students Environment Canada Green Plan approx. $3 million Rest of MAGS variable levels, but typically less than during Green Plan Approximately 17 Principal investigators Numerous PDFs and graduate students Other Govt Departments

13 MAGS Results Mackenzie GEWEX STUDY (MAGS) 2007

14 Process based studies Focused on cold regions processes: - river ice and ice jam flooding - snow interception, accumulation and melt - permafrost and active layer thaw - large lakes - flow connectivity in lake-stream systems - groundwater was not considered, but some GRACE observations compared to modelled A major component of MAGS was to ensure that these process based results were used to improve various hydrologic models. MAGS was reasonably successful in this, but in the future additional resources should be provided to ensure that process based studies are used to improve models.

15 Gridded Hydro-climate Products Mackay et al., 2008 Mean Precipitaiton Considerable effort in MAGS was used to understand the hydroclimatology of the basin using a combination of gridded observations and models. This was reasonably successful and provided the first basin wide understanding of the MRB hydro-climatology

16 Gridded Hydro-climate Products Mean P-E, DeltaS, and R Mackay et al., 2008 Total runoff A significant portion of flow to the Mackenzie R. originates in the mtn headwaters to the west of the river. This makes modelling of flows a challenge. Similar issues will occur with the SRB.

17 Moisture recycling Annual moisture recycling was considered through the use of observations and modelling. This showed it was surprisingly high for such a northern basin. This would obviously be a key aspect of understanding the SRB. - Annual: Recycling is strongest in the Amazon at 30%, and the ratios for the Mackenzie, Lena and Mississippi basins are within values between 23 and 25%. - Cold Season: Apart from the Amazon, the ratios exhibit strong seasonal variability with very low values during the cold season - Warm season: Close to or more than half of the summer precipitation in the downwind regions of all the test basins is derived from local evaporation. Szeto et al., 2008

18 Closing the MRB Water Budget Assuming negligible long-term changes in the atmospheric and surface water storage (i.e., MC ~ P E ~ N), water budget closure is traditionally assessed by the balance between the average atmospheric moisture flux convergence and observed runoff. With this definition, the regional water budget for the MRB is closed within 6% (ERA-40/NARR) 8% (CMC) and 10% CRCM of the observed runoff using the moisture flux convergence Szeto et al., 2008

19 Some failures: One of the main goals of MAGS was: To improve our ability to assess the changes to Canada s water resources that arise from climate variability and anthropogenic climate change Although MAGS was successful on the first of these, to assess climate variability MAGS did not make sufficient progress on using Regional Climate Models to assess changes to the water resources due to anthropogenic climate change.

20 Conclusion MAGS made significant contributions to our understanding of such northern areas: MRB water budget can be closed within 10% 25% of annual precipitation comes from local evaporation Over 50% in the summer Mtn headwaters dominate total flow MRB has warmed over the last 50 years Spring breakup is occurring earlier Annual flow is not increasing, BUT large errors in breakup flows are likely Integrated atmospheric/hydrology/hydraulic models developed and validated BUT Little ability at the moment to estimate the effect of the Mackenzie Delta on flows of water, sediment and nutrients to the Beaufort Sea

21 Conclusion The major MAGS legacy includes: the development of Canadian expertise to carry out such large basin hydroclimatic studies in Canada. IP3 and DRI have built upon this legacy. Pre-MAGS the hydrologic and atmospheric research communities in Canada we separated and did not interact. Today, many in these research communities know each other, have experience working together, and understand each others language and biases The development of a range of models needed to carry out such studies, including Small scale process based hydrologic models (ie CRHM) Land surface models (i.e. CLASS) Larger scale hydrologic models linked with land surface models (MESH) Methods to link these models with various atmospheric models Various Atmospheric Models (i.e. GEM, RCM)