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Mackenzie Basin
Climate-Hydrological System: MAGS Phase 2
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Executive Summary
The Global Energy and Water Cycle Experiment (GEWEX) is an international
effort developed by the World Climate Research Programme as a
coordinated group of activities aimed at improving our understanding
and prediction of the role that the water cycle plays in the climate
system. As a major contribution to GEWEX, the Canadian Mackenzie
GEWEX Study (MAGS) focuses on understanding and modelling the
flows of energy and water into and through the atmospheric and
hydrological systems of the Mackenzie River basin which yields
the largest North American source of fresh water discharge into
the Arctic Ocean. The Basin itself is subjected to wide climatic
fluctuations, and is currently experiencing a warming trend.
MAGS necessarily involves coordinated research into many atmospheric,
land surface and hydrological issues associated with cold climate
systems.
Substantial progress has already been made in Phase 1 of MAGS
on quantifying and understanding of key atmospheric and hydrological
processes affecting the water and energy cycles of the Basin.
Phase 2 is our final stage to gain and to demonstrate predictive
expertise to assess scientifically the effects of climatic variability
and climate change on the water and energy cycles and to apply
our knowledge to scientific, policy and economic issues in northwestern
Canada specifically and all of Canada in general. MAGS will encompass
the integration of the various physical processes into a unified
climate-hydrological framework to characterize and enhance understanding
of the cold climate system, particularly of the Mackenzie Basin
and areas with similar environments. Modelling will be performed
at different scales, from small catchment and individual events,
through the regional scale atmospheric and entire drainage systems,
to coupled modelling of the Mackenzie Basin as a unified atmospheric-hydrological
entity. Armed with the suite of models, appropriately tested
using data acquired from the field, from historical records and
from remote sensing platforms, we will use the models to analyze
the sensitivity of the system and its components to climatic forcings
and to study their effects on the water and energy cycles, including
spatial and temporal variability and extremes in climatic and
hydrological events. In collaboration with users, the models
will be applied for such purposes as improvement of weather prediction,
especially at high latitudes, operation of hydroelectric power
plants and providing scientific information to improve policy
making decisions.
The completion of Phase 2 (2001-2005) of MAGS is expected to benefit
not only the scientific community, but it will greatly assist
the government sector in making informed decisions, provide the
private sector with direct and indirect economic gains and enrich
the public with information and knowledge to better utilize their
resources and to enhance their environmental well-being. We will
leave major legacies. The records of scientific achievement will
include publications and models.
1. Overview of the Canadian GEWEX Programme
In 1988, the World Climate Research Program initiated the Global
Energy and Water Cycle Experiment (GEWEX) to improve our understanding
and prediction of the role played by the hydrological cycle in
the climate system. Several regional research activities cover
a wide range of climatic conditions, including the GEWEX Continental-Scale
International Project (GCIP), the Baltic Sea Experiment (BALTEX),
the GEWEX Asian Monsoon Experiment (GAME), the Large Scale Biosphere-Atmosphere
Experiment in Amazonia (LBA), and our Mackenzie GEWEX Study (MAGS).
Each must quantify the water vapour flux into and out of their
particular region, characterize the precipitation and evapotranspiration
fields, and handle runoff and discharge. Each must also work
with local water resource agencies to provide immediate benefits
of their activities, carrying out many diagnostic and model improvement
studies, and engaging user communities.
Canada, through its high latitude position, has a natural interest
and strong concern for cold climate processes. It is in this
area that Canada is expected to make a major contribution to the
understanding of the global energy and water cycles. The high
latitude environment has special effects on the climate and hydrology.
One major characteristic is the extreme seasonal radiation contrasts
due to the long days in summer and long hours of darkness in winter.
Low sun angle and high reflectance of snow surfaces lead to low
radiation receipt which is largely responsible for the intense
and persistent coldness. Atmospheric processes and air mass dynamics
are strongly influenced by the energy conditions (Stewart et al.
1998a). Water is subject to annual freeze-thaw, be it moisture
in the atmosphere, on the land and lake or underground. Snow,
ice, seasonal frost and permafrost are inseparable parts of the
landscape. All these phenomena affect the regime of water storage
and flow.
In 1994, Canada began its participation by undertaking the Mackenzie
GEWEX Study (MAGS), emphasizing the cold climate system and using
the Mackenzie Basin as the initial focal point of research. The
Mackenzie region is particularly suitable as a study site. It
is physiographically composed of three major zones: the mountainous
Cordilleran region in the west, the flat interior plains with
myriads of lakes and wetlands, and the rolling to rugged Canadian
Shield to the east where the glaciated Precambrian bedrock with
thin soil mantles favour a patchwork of lakes, wetlands and uplands.
Latitudinally, the Basin extends from the prairies of Alberta,
through the boreal and subarctic forests discontinuously underlain
by permafrost, to the continuous permafrost tundra zone along
the Beaufort Sea coast. The environments found in the Mackenzie
basin exist in many other parts of Canada and as such, they are
representative of areas beyond the confines of the study basin.
The overall goal of the Canadian research programme is to describe,
understand, model and predict the climate-hydrological system
and to apply our methodology and results to the high latitude
environment to address national and international issues. This
programme was and is envisaged to be a multi-year project, overlapping
with a large part of the international GEWEX time table.
The high latitude climate-hydrological system is complex but has
been little studied. The scarcity of data poses serious problems.
Extensive field studies are necessary to gain knowledge of the
processes by which water and energy flow into and through the
Mackenzie basin. These studies have constituted the primary research
effort in Phase 1 of our programme (abbreviated as MAGS-1). Modelling
offers an approach that would piece together results of these
process investigation. Current climate prediction models, however,
cannot adequately simulate water and energy flows in northern
regions and this has major implications for the prediction of
the ecological, economical and social impacts associated with
water resources. Phase 2 of our programme (abbreviated as MAGS-2)
addresses the modelling issue head-on. Our proposed studies
will ensure that our models properly account for all major components
of the physical system and that our unified knowledge and verified
models have the predictive capability to tackle water resource
problems in northern Canada.
Canada must have a strong, independent voice on water, one of
our most precious resources. Models to be developed in Phase
2 will improve the numerical prediction of climatic and hydrological
activities. The models will have significant applications at
various scales, from the operation of small hydroelectric power
dams to the prediction of Mackenzie river outflow to the Arctic
Ocean; from the analysis of local forest fire events to weather
forecasting on a regional scale. Interactions with concerned
groups dealing with water and related issues, initiated in MAGS-1,
will be pursued vigorously in Phase 2.
2. Goal of MAGS
The overall goals of the Canadian effort in the International
GEWEX Programme are (1) to understand and model the high-latitude
water and energy cycles that play roles in the climate system,
and (2) to improve our ability to assess the changes to Canada=s
water resources that arise from climate variability and anthropogenic
climate change. Building upon the achievements of phase 1,
and aiming at the attainment of the long term goals, the
tasks for Phase 2 are to:
(1) close the Mackenzie Basin water and energy balance at annual,
monthly or shorter time scales and at spatial scales ranging from
sub-basin to the entire catchment;
(2) develop and validate models that yield results within acceptable
error limits;
(3) 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;
(4) apply these models to address scientific, environmental
and water resource problems;
(5) transfer our models to similar environments in Canada and
in other areas of the GEWEX Continental Scale Experiments.
Thus, this second phase concentrates on the modelling, prediction
and application aspects of our long-term goal. By the end
of MAGS-2, we will (a) have an improved understanding of, and
ability to model, the response of energy and water cycles in the
Mackenzie Basin to climate variability and change, (b) be able
to characterize the impacts of its atmospheric and hydrological
processes and feedbacks on the regional and global climatic systems,
and (c) have the ability to apply our predictive capabilities
to climatic, water resource and environmental issues in the Mackenzie
Basin and other high latitude regions.
3. Achievements of Phase 1
Although there have been collaborative efforts prior to MAGS to
understand cold region processes (e.g. BOREAS, ACSYS, CRYSYS),
much remains insufficiently understood about many of the atmospheric
and hydrological processes and the interactions of these processes
as part of a unified system in a high latitude setting. Phase
1 of our Programme was designed to
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quantify the major processes affecting the water and energy
cycles of Mackenzie Basin
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assess the relative importance of various high latitude processes
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develop datasets for model parameterization and verification,
and
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develop a framework for coupling the models required to reproduce
the observed transport of moisture and energy into and through
the Basin on monthly and longer time scales.
We have made considerable progress towards completing these tasks.
The many achievements of Phase 1, described below, provides us
a solid foundation to launch MAGS-2.
3.1.1 Cold Climate Processes
Through MAGS-1, we gained considerable knowledge on the processes
occurring in high latitudes. The following section outlines the
major scientific questions, the achievements in addressing these
problems and the research questions that will lead to future investigations.
What are the important moisture sources for the Mackenzie?
Typically, about 400 mm of precipitation falls over the Basin
(Louie et al., 1999), approximately evenly divided between rain
and snow (Mekis and Hogg, 1999), but there is a large inter-annual
variability in these values. Through our studies (Lackmann and
Gyakum, 1996; Hudak and Young, 1999), we found that the moisture
mainly originates over the north Pacific Ocean, but the mountains
of the Western Cordilleras (Fig. 1) greatly reduce this moisture
flow into the area, leading to enhancements of precipitation over
the high elevations (Mackay et al., 1998; Misra et al., 1999).
These effects vary seasonally due to differences in large-scale
forcing and stability. Although we begin to appreciate some of
the important consequences of orography, much remains to be done
before these effects can be captured reliably by our models.
We also found that there are large year-to-year variations in
the strength of the Pacific moisture source; how this translates
into changes in the Basin=s
climate system is still uncertain. In most years, this advection
from outside of the basin dominates the atmospheric water budget
of the Basin, but summer periods can sometimes be linked with
net divergence, implying that local evapotranspiration is stronger
than advection (Smirnov and Moore, 1999; Cao et al., 1999; Liu
and Cho, 1999). There is considerable uncertainty in these estimates,
however; one contributing factor is that the large diurnal moisture
cycles are not being well re-produced in our models (Strong, 1997).
Further documentation of the moisture budget is needed and this
must address both the surface and sub-surface reservoirs and fluxes.
How do clouds affect the Basin's
climate system?
The Mackenzie Basin generally occupies a very cloudy region, with
estimated basin-fractional cloud coverage being approximately
50% (Isaac and Stuart, 1996; Stewart et al., 1998b). We found
that clouds are commonly associated with cyclonic storms that
pass over the region (Hanesiak et al., 1997; Szeto et al., 1997;
Stewart et al., 1998b; Asuma et al., 1998). These systems are
greatly disrupted by the orographic barrier, and the occurrence
of lee cyclogenesis on the eastern flank of the barrier is associated
with this process (Lackmann and Gyakum, 1996; Lackmann et al.,
1998). During the summer, we noted a substantial amount of convection,
often in the form of thunderstorms (Kochtubajda et al., 1999).
These storms, under dry conditions, initiate many devastating
forest fires within the basin (Kochtubajda et al., 1999). Clouds
significantly affect the climate, not only through their cutback
on surface radiation but also by their augmentation of precipitation,
with impacts on evaporation and snowmelt. One example is delay
of the initiation of snowmelt in northern areas due to cloudiness,
affecting the timing and magnitude of melt. Dry sub-cloud conditions
also affect climate by reducing the efficiency of converting water
vapour to precipitation. For example, Burford and Stewart (1998)
estimated that, in the autumn, half of the ice produced at cloud
base does not reach the surface.
How well is surface radiation accounted for?
Direct surface observations are inadequate to evaluate the reliability
of the radiation fields generated by the project's
atmospheric models, but satellite measurements and special surface
measurements are being used to deduce the surface solar radiation
budget ( Masuda et al., 1995) and to evaluate the fields generated
by the atmospheric models (Leighton et al., 1999). However, this
task is far from complete and will be pursued further in MAGS-2.
How important are winter processes to the atmosphere and to
surface hydrology?
Existing atmospheric and hydrological models assume that the snowfall,
once accumulated on the ground, is subject to little change over
the winter. However, field studies in Phase 1 showed that blowing
snow causes the loss of up to 30% of the total winter snowfall
due to sublimation both in tundra (Pomeroy et al., 1997) and in
boreal forest environments (Pomeroy et al., 1998a). This limits
the snow available for runoff, but provides an important vapour
source to the atmosphere. Predictive equations for these processes
compare favourably with field measurements (Pomeroy et al., 1998b;
1997), thus allowing the estimation of snow cover amount and distribution
over a grid or drainage basin. The developed model components
are now available for incorporation into land surface schemes,
though Dery and Taylor (1996) have suggested theoretical limitations
in our understanding of blowing snow. Ongoing work aims at bridging
such discrepancies between observations and theory, as well as
testing improved techniques in MAGS models.
How should heterogeneous land surfaces be accounted for in
large scale models?
Large horizontal gradients in the boundary layer characteristics
occur because of the variable terrain, land cover and vegetation
in the Basin. During MAGS-1, special measurements of the boundary
layer were made by ground-based instrumentation and by aircraft
to improve the representation of boundary layer processes in
large scale models. In the snow-covered period, heat advection
from the bare ground to snow patches increases the local melt
rates in both tundra (Marsh et al., 1997) and forested environments
(Woo and Giesbrecht, 1999). We developed algorithms simulate
this effect (Marsh et al., 1997, Pomeroy et al., 1998b) and they
are available for incorporation into land surface models. During
the snow-free period, our field observations demonstrated significant
variations in evapotranspiration efficiency for different landscape
types (Rouse, 1999), and the role of surface wetness in controlling
energy partitioning. The presence of lakes further complicates
the land surface schemes. Rouse (1999) showed that during a >normal
year, evaporation is minimal in the autumn period, yet for an
above-average warm summer, such as that in the1998 El Niño
episode, the fall evaporation season is extended by several weeks.
Progress is being made to improve the representation of all these
processes in our models (e.g. Xu and Taylor, 1997a,b; Neumann
and Marsh, 1998). Given the complexities of the hydrological
processes due to heterogeneity of the land surface, further research
in MAGS-2 is needed to characterize the sub-grid scale variability
in the models.
How do surface processes control water delivery to streams
in permafrost and Shield regions?
Zhao and Gray (1998) have shown that the infiltration of meltwater
is greatly retarded by frozen mineral soils. However, the presence
of an organic layer, which is common in the Mackenzie Basin, greatly
enhances infiltration (Carey and Woo, 1998) and facilitates slope
runoff through preferential pathways (Quinton and Marsh, 1998).
In discontinuous permafrost zones, Carey and Woo (1999) found
that some slopes do not yield water to streamflow. In areas with
extensive wetlands, conventional field work is extremely difficult
and stable isotope techniques were used to estimate the relative
importance of groundwater versus wetland storage (Gibson and Prowse,
1998). The Precambrian Canadian Shield is dominated by exposed
bedrock which have traditionally been considered to be impervious.
Our recent work has shown that the presence of many fissures
and cracks significantly increases the bedrock capacity to store
and transmit water as baseflow (Spence, 1999). Incorporation
of these processes into hydrological models is crucial to the
improvement of runoff prediction. The Shield region also has
numerous lakes which also affect the regional water balance due
to their storage capacity and enhancement of evaporation, both
of which substantially delay and limit streamflow responses to
snowmelt and rainfall events (Spence et al.,1999). Much work
remains to advance our understanding of the hydrology of bedrocks
and lakes.
3.1.2 Insights into the Mackenzie Energy and Water System
We have obtained an understanding of the internal circulation
of moisture and heat within the Mackenzie Basin and we have started
to improve our knowledge of its atmospheric and hydrological linkages
with areas outside the Basin (Lackmann and Gyakum, 1996). In
winter, the region experiences a great deal of heat loss, generating
cold air that spreads southward while the upper level cyclones
propagate towards eastern Canada. In summer, local evaporation
is a major moisture source and convective clouds redistribute
this atmospheric moisture (Szeto et al., 1999). In general, there
is strong evidence that climatic anomalies are amplified in the
Basin during winter, but are reduced in summer (Cao et al., 1999).
Our basin-scale studies have just begun and understanding the
basin system as a whole remains a task for MAGS-2. The land surface
has large diversity in hydrological environments due to large
contrasts in topography, vegetation, soil, rock outcrop and frost
distribution, and the presence of myriads of lakes and large areas
of wetlands. Superimposed on these features is the seasonal presence
of snow and ice which adds complexity to the energy and water
fluxes at the near surface zone. Through our process studies
reported in Section 3.1.1, MAGS-2 is in a position to comprehend
the dynamics of the whole atmospheric-hydrological system.
3.1.3 Database Development and Access
The MAGS-1 data strategy comprised a three-phased approach to
obtain information for process studies, model initialization and
validation: (1) compile available data from operational networks,
satellite, radar and research basins, (2) augment long-term observations,
and (3) carry out the following enhanced measurement over the
15-month (1998-99) Canadian GEWEX Enhanced Study (CAGES): soundings,
discharge, radar, aircraft and tower flux measurements, hillslope
runoff, and additional surface stations. Examples of the resulting
data sets include:
Surface observations: CAGES enhanced discharge estimates
during the ice-cover/breakup periods for the Mackenzie River and
major tributaries are available, as are surface meteorological
measurements for typical vegetation covers, and surface sensible
and latent heat fluxes for the research basins. In addition,
basin-wide monthly precipitation and temperature gridded datasets
(50 km grid squares) for the 1950-97 period are available.
Remote sensing (satellite): AVHRR images have been used
to develop data sets of land and water surface temperatures at
1-km resolution over the Basin, and also combined with ScaRaB
data to provide radiation maps during CAGES. SSM/I EASE-Grid
microwave radiometer images have been used to develop snow water
equivalent (SWE) for the basin and snow cover and lake ice characteristics
for Great Slave and Great Bear Lakes for the years 1987-99.
Aircraft and radar: Sensible and latent heat flux data
sets are available from aircraft measurements of the dynamic evolution
of surface-atmosphere fluxes of sensible and latent heat during
and following snow-melt, and for the snow-free period. A radar-based
precipitation accumulation product is available for Environment
Canada=s operational
radars in the southern Mackenzie Basin, while the IPIX radar was
used to provide data sets on the detailed kinematic description
(e.g. vertical structure, wind fields) of the cloud systems in
central Mackenzie Basin.
Data Management: A Data Management System was established
in MAGS-1 to maintain, describe, and promote accessibility and
distribution of the data sets necessary to meet the MAGS objectives.
These goals are being met through: (1) the availability of data
and information on the World-Wide Web, including archived and
real time data from the enhanced surface stations, and access
to over 300 pages of information describing the objectives, background,
status, and clients for the project, and (2) the production of
specialized data products. These data are being archived in a
series of CD-ROMS. In addition, the CMC have been archiving enhanced
global model data since October 1 1995. All these MAGS-1 data
sets are a legacy from Phase1 and will be used in model development
and validation in Phase 2.
3.1.4 Developing a Coupled Model Framework
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Besides the atmospheric and hydrological models for specific
processes, we contribute to the development of the Canadian Regional
and Global Climate Models and to the Canadian numerical weather
prediction models: MC2 and GEM (Global Environment Multiscale).
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A major contribution is the coupling of land surface and hydrological
process modules to the above, helping to capture the roles played
by natural variability of land surfaces and thus to improve the
closure of the large scale water budget in the atmospheric models.
A combined WATFLOOD-CLASS model offers the appropriate framework
for this task and, as they evolve based on process study results,
allows the magnitudes of the various components of the water cycle
to be represented correctly.
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The proof-of-concept for the coupled system was demonstrated
in MAGS-1. Tests with the prototype code have increased confidence
in the ability of these models to simulate the present reality
and ultimately to simulate the future. Development of a formal
operational framework is proposed for MAGS-2.
3.2 Relationship with MAGS-2
Phase 1 research has placed emphasis on gaining knowledge of the
physical processes that govern the atmospheric and hydrological
systems. This knowledge will be employed toward furthering model
development, testing and application. Insights into the Mackenzie
water and energy system provide an increased understanding of
the internal cycling of moisture and heat and its relation to
synoptic weather patterns, the linkages of the water and energy
balance to extra-basin processes, the amplification of cold climatic
anomalies in winter and the inefficiency of the basin in converting
atmospheric vapour to precipitation. Ongoing research will enhance
our understanding of the role played by the natural variability
of land surfaces in the hydrological cycle; provide an initial
coupling of atmospheric, land surface and hydrological models;
and demonstrate that coupled models can yield the correct magnitudes
for water cycling in the basin.
4. MAGS-2 Scientific Issues
To reach the goals stated in section 2 (understanding and modelling
the high latitude energy and water cycles and their responses
to climate variability and change), the primary issue to be considered
by MAGS-2 is to determine how the Mackenzie River Basin operates
both in situ and in the context of its role in the global
climate system. This is to be achieved by a combination of modelling,
prediction, and analyses, using the best-available data and models.
One of the principal products of this research will be an improved
analysis and modelling system so that responses of the atmospheric-hydrological
system to climate variability and climate change in the Mackenzie
Basin can be predicted and understood. Such knowledge and predictive
capabilities will allow us to answer a variety of scientific and
operational questions.
Process Integration Scaling
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MODELLING
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Prediction Application Enriched scientific insight
4.1 Phase 2 Research Activities
MAGS-2 will follow several overlapping themes of investigation
(labelled I to V below) to address major scientific questions
which can be expressed in terms of eleven research objectives.
The following sections elaborate upon the scientific investigations
to be conducted.
4.1.1 Theme I: Integration of Knowledge of the Physical Processes
Integrating the processes studied, both in Phases 1 and 2, into
a group of MAGS models will be a crucial step that provides understanding
of the cold climate processes as one unified system. This
integration and understanding will strongly augment Canadian expertise
in tackling atmospheric and hydrological issues in the Mackenzie
Basin and in other areas with similar environments.
Objective 1: To extend the process studies to encompass
the important physical processes not comprehensively covered in
Phase 1.
Several major processes important for the achievement of MAGS
goals were not comprehensively studied in Phase 1 due to limited
funding. These will be investigated to complete the process studies
required to improve the linked models. Topics include orographic
precipitation, convective processes, diurnal water vapour variations,
evaporation, blowing snow, overall contribution of lakes to water
and energy balance, basin storage, groundwater, river ice formation
and breakup effects on water level and river flow and channel
storage.
Objective 2: To consolidate knowledge of the atmospheric-hydrological
system of the Mackenzie Basin in a unified framework.
Facets of atmospheric research and components of hydrological
studies will be consolidated into a form appropriate for inclusion
in the MAGS models. This will be achieved through collaborative
investigations, frequent discussions and increased use of mini-workshops
among research groups and collaboration with the modelling groups
to ensure that the algorithms developed are incorporated into
the appropriate MAGS models.
4.1.2 Theme II: Scaling of Data and Processes to Harmonize
Temporal and Spatial Resolutions
Scaling refers to the linkage or transfer of information across
temporal and spatial scales. Energy and moisture fluxes occur
at many natural scales but data are seldom collected at the scale
required by the models, thus they have to be adjusted appropriately
(e.g. field observations made at local sites need upscaling to
match investigations at large basin scales; products of many climate
models, generated at the scale of tens to hundreds of kilometres,
need downscaling for use in the study of energy and water fluxes
at local and small basin levels).
Objective 3: To develop appropriate physically based
techniques for parameterization.
Scientific investigations of atmospheric and hydrological phenomena
will be carried out at different scales, ranging from local to
regional levels. Both downscaling and upscaling are needed to
bring the data to common resolutions in time and spatial intervals
that befit scientific studies at the scales required. Parameters
will be derived for models at different scales based on physically
sound approaches. To obtain distributed data and parameters at
required scales, remote sensing (especially taking advantage of
the upcoming generation of sensors) and ground-level measurements
will provide information that can be extended to cover the large
but data-sparse areas; spatial statistics and Geographic Information
Systems will enable the synthesis and interpolation of data obtained
from point observations.
Objective 4: To bridge the temporal and spatial scales
from local to regional levels of modelling.
Physical processes which are important at the local scale (e.g.
local advection of energy and moisture) may be unimportant when
averaged over a large area while large scale processes may not
be easily disaggregated to the sub-grid level to provide sufficient
resolution for local scale investigations (e.g. convective cells
which influence local rainfall). Various approaches will be used
to model the processes to bridge the information hiatus between
scales (e.g. hydrological investigations, Group Response Units
are used to characterize the processes of local zones within a
large drainage basin). In addition, high resolution models provide
synthetic datasets from which parameters will be derived for large-scale
models; outputs of water and energy fluxes from models at different
scales and for the same area will be compared to ensure that scaling
is carried out appropriately.
4.1.3 Theme III: Model Development and Evaluation
Models provide a tool to test sensitivities and to predict the
response of the system to external disturbances imposed by human-induced
or natural forces. To account for the highly diversified Mackenzie
Basin environment, synoptic-scale and meso-scale modelling must
cover a large range of terrain types and must simulate the seasonality
of the environmental variables (e.g. winter as distinct from summer
activities). Coupled models will be developed for the Mackenzie
Basin atmospheric-hydrological system.
Objective 5: To enhance, and develop as appropriate,
a hierarchy of models based on knowledge of the processes, to
enable the evaluation of how individual processes or phenomena
affect the atmospheric and hydrologic systems.
Models will include those tested and developed in MAGS-1, as well
as new models as required. Through linkages with Themes I and
II, these models will be updated to include the latest process
and scaling results. The models to be employed encompass a variety
of phenomena and cover a range of scales. Details regarding the
models are provided in Section 5.2. Major projects that contribute
to this objective will utilize the Canadian Regional Climate Model
(CRCM); the Mesoscale Community Model (MC2); the Global Environmental
Multiscale (GEM); the Canadian Land Surface Scheme or CLASS, and
WATFLOOD; and various process-based hydrological and river ice
models.
Objective 6: To improve coupled models developed in
MAGS-1 to assess the overall behaviour of the Mackenzie system.
Large-scale hydrologic modelling will make use of the WATFLOOD
model which calculates the horizontal transfer at the land surface
with physics that is easily adapted to atmospheric models. CLASS,
a sophisticated soil-vegetation-atmosphere transfer scheme that
explicitly resolves the energy and water budgets, will provide
the interface. The coupled model developed in MAGS-1, called WATFLOOD/CLASS,
will continue to be modified to reflect northern conditions, and
then linked with the atmospheric models such as MC2 and CRCM.
This coupled model will be an important final product of MAGS
capable of representing the climate-scale water and energy system.
Objective 7: To evaluate model performance using field,
historical and remote sensing data.
Data collected during the 1998-99 CAGES water year, 1994-95 water
year, observations during other water years, and through remote
sensing will provide the requisite information for the validation
of the above noted models at a variety of scales and for a variety
of processes. For large scale and coupled models, criteria for
the assessment of model performance will be established, one of
which will be the analyzed fields from the GEM model and another
the streamflow data from the Mackenzie and the experimental basins
of MAGS-1.
4.1.4 Theme IV: Prediction and Analysis of the Climate-hydrological
System
Incomplete knowledge of the physical system and data scarcity
have prevented accurately assessment of the water balance of large
basins such as the Mackenzie. The system also subjected to short
term climatic variability due to teleconnections with El Niño
events and long term changes, notably climatic warming. Prediction
of the responses of the climate-hydrological system remains quantitatively
inadequate, though these system responses have important implications
for the cold environment such as permafrost melt or alterations
of the streamflow regimes. MAGS-2 will produce the tools and
the knowledge required to perform this important task.
Objective 8: To close the water budget for the Mackenzie
hydro-climatic system at a variety of scales.
The water budget of the Mackenzie will be closed at a variety
of scales, using the improved models described in section 4.1.3.
The target years will be the 94/95 and 98/99 water years and
the international Coordinated Enhanced Observing Period (CEOP)
of 2001-02 when another data set will be acquired. At the small
scale, realistic simulation of the hydro-climatic system will
close the water balances of drainage basins with permafrost, lakes,
wetlands, tundra, forests and other attributes typical of the
Mackenzie landscape. At the regional scale, we will attempt water
budget closure for the entire Basin. These studies will use a
range of model products, remote sensing, and observations, to
determine the relative importance of local vs external factors
in controlling the water cycle of the Mackenzie region.
Objective 9: To assess the local and regional responses
to external forcing under climate variability and climate change,
including the feedbacks and sensitivity of the various elements
of the atmospheric-hydrological system.
The models developed will be calibrated with historical data and
then subjected to external forcing to simulate climate variations
and changes in climate based on scenarios depicted by the General
Climate Models and other climatic time series. Our predictive
capability will range over temporal and spatial scales and will
be applied to various atmospheric-hydrological processes, including:
episodic and local events to precipitation on a regional scale,
ice jam flooding, seasonal and inter-annual regional variability
of droughts or lake storage changes, changes in snow cover, streamflow
and lake evaporation. The responses of components of the atmospheric-hydrological
system to perturbations will be studied through statistical analyses
of correlation structures, time and spatial series and extreme
event occurrences.
4.1.5 Theme V: Applications of Predictive Capability
Capability for applying our research findings and methodology
to problems relevant to our partner institutions has strong scientific
merit and practical value; collaboration with our partners will
extend our outreach effort. It is also important to apply the
predictive capability to regions outside of the Mackenzie to demonstrate
the generality of our modelling tools and to satisfy the scientific
obligation of MAGS to international GEWEX.
Objective 10: To interact with users in the application
of the knowledge, the observational capability and the modelling
prowess to address water and climate related problems of importance
to the industries and to the governments.
A variety of modelling application activities is planned to provide
benefits to the user communities:
Table 1. Major themes and objectives of MAGS-2
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Themes
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Objectives
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Theme I:
PROCESS STUDIES AND INTEGRATION
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(1) Extend process studies
(2) Integrate process studies to produce a unified atmostpheric-hydrological framework
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Theme II:
SCALING OF DATA AND PROCESSES
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(3) Parameterization techniques
(4) Bridge temporal and spatial scales
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Theme III:
MODEL DEVELOPMENT AND EVALUATION
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(5) Develop a hierarchy of models
(6) Improve coupled models
(7) Evaluate model performance
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Theme IV:
PREDICTION AND ANALYSES
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(8) Close the water budgets
(9) Assess responses to climate forcings
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Theme V:
APPLICATIONS AND MODEL TRANSFER
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(10) Application to problems
(11) Transfer of information and models
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-
will include addressing the regional influences on the global
weather and climate (e.g. cold air generation in winter).
-
We will assess climatic control on northern river discharge
which significantly influences the Arctic Ocean circulation, a
topic of particular importance to oceanographers.
-
We will co-operate with industrial users to tackle water
resource management problems by providing hydrometeorological
expertise on seasonal snow, ice regimes, lakes and water supplies
for use in the management of water for consumption, flood control
and forecasting, hydro-power production, northern river transport
and ecological demands. The likelihood, severity and spatial
extent of extreme events (e.g. severe weather, floods and droughts),
lightning will be examined as essential elements of our application
strategy because of their importance to the northern communities.
- We will contribute scientific advice
to governments in their decision making process, such as water
licensing and other regulation issues. We expect to participate
in scientific discussions on inter-basin water transfer from northern
basins, a subject that is attracting increasing interest.
Objective 11: To transfer the information and models
to other areas to extend the benefit to national and international
bodies.
Applications of our capabilities over regions other than the Mackenzie
Basin will directly benefit Canada as well as contributing to
the global initiative. Suitable candidates include (1) the Saskatchewan
River Basin where, for at least one full year, our model capabilities
will be assessed in this water-sensitive area. (2) other continental-scale
experiments under GHP. One strategy of GHP is to develop diagnostic
and modelling capability for various regions around the world,
notably northern Europe through BALTEX and over the Lena River
basin through GAME-Siberia. This will take advantage of CEOP,
in association with other GEWEX organizations.
5. Modelling Strategy and Computation Capabilities
To realize the objectives of MAGS, a hierarchy of models, ranging
from small scale catchment to a variety of large domain atmospheric,
land surface and hydrologic models must be used. Canadian models
will largely be used but, to ensure transferability over the world
as a contribution to the GEWEX Hydrometeorology Panel, use in
the future will also be made of models from other countries.
The Canadian models can also be applied to other areas of the
world, which will facilitate evaluating the transferability of
the MAGS algorithms to other regions.
Models to be employed encompass a variety of phenomena and cover
a range of scales. Small basin hydrological models with permafrost,
snow, lake and wetland components will be developed in order
to test methods for modelling sub-grid square variability. A
concerted effort will be pursued to improve climate modelling
through the Canadian Regional Climate Model (CRCM) with its GCM
physics package. Through the use of the CRCM, features of the
water and energy cycles of the Mackenzie Basin can be assessed.
Fine scale (down to 1 km) features of the atmosphere and surface
will be simulated with non-hydrostatic models such as the Mesoscale
Community Model (MC2) which can address, for example, water budgets,
and interactions between many surface and atmospheric factors.
Our researchers will interact with the Canadian Meteorological
Centre (CMC) to assimilate fields of atmospheric and surface parameters
using its operational Global Environmental Multiscale (GEM) model
which uses a variable resolution strategy for limited area modeling
to produce forecasts valid over North America for a 48-h period.
For surface hydrological research, the coupled WATFLOOD/CLASS
model will continue to be modified to reflect northern conditions,
merged with the atmospheric models and the then version will be
fully tested. One of the final products will be the Canadian
Regional Climate Model (CRCM) coupled to CLASS and WATFLOOD to
replicate the Basin=s
climate-scale water and energy cycles. The Canadian models developed
should also be transferrable to other areas of the world.
Data collected during the 1998-99 CAGES water year, data to be
gathered in the 2001-02 period of CEOP, observations made in the
field and through remote sensing will provide the requisite information
for the validation of models of various scales. For large scale
and coupled models, model performance will be assessed by comparing
modelled results with the analyzed fields from the GEM model,
and with the streamflow data obtained from the Mackenzie and the
test basins.
The assessment of some of the model products will be facilitated
through the use of a common analysis system, referred to as IDPro,
which is based upon IDL software, and has been developed within
the Climate Research Branch of the AES to allow efficient display
and analysis of model and/or observational products on a PC=s
or on workstations.
6. TimeTable
MAGS-2 will span five years to ensure a stage by stage completion
of the sequence of overlapping tasks. The proposed activities
and their accompanying milestones are realistic (Table 2):
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Years 1-3: Carry out integration of processes to enable a
good understanding of the high latitude climate-hydrological system
and to provide information for modelling.
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Years 1-4: Improve and complete a suite of process models
and coupled models, properly scaled and verified for operation.
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Years 4-5: Apply our models and accumulated knowledge to
prediction studies and evaluate our model outputs.
7. Summarizing Comments
The Canadian GEWEX programme is at an important crossroad.
MAGS,
within GHP, has progressed rapidly over the last few years, and
we are now poised at a position to reap major benefits. In Phase
2, we will not only improve our scientific knowledge on the atmospheric-hydrological
system of high latitudes, but will also apply our capabilities
to address real-life problems associated with the climate and
water resources. We have, in the past several years, built a
strong team and a structure to conduct network research. We propose
to capitalize on this momentum, enlarge our teamwork and strengthen
our effort in MAGS-2, so that our scientific and practical visions
can be realized.
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