The Mackenzie GEWEX Study: A Contribution to Cold Region Atmospheric and Hydrologic Sciences -- The Mackenzie Climate System: A Synthesis of MAGS Atmospheric Research -- Climatological Analysis of the Mackenzie River Basin Anticyclones: Structure, Evolution and Interannual Variability -- Variability of Cold-Season Temperatures in the Mackenzie Basin -- Extreme Winter Warming over the Mackenzie Basin: Observations and Causes -- Water Vapor Fluxes over the Canadian Prairies and the Mackenzie River Basin -- Moisture Sources for Extreme Rainfall Events over the Mackenzie River Basin -- Precipitation Recycling in the Mackenzie and Three Other Major River Basins -- On the Cloud and Precipitating Systems over the Mackenzie Basin -- The Relationship between Monthly Precipitation and Elevation in the Alberta Foothills during the Foothills Orographic Precipitation Experiment -- On Predicting Maximum Snowfall -- Estimating Snow Water Equivalent in Northern Regions from Satellite Passive Microwave Data -- Mackenzie Basin Snow Cover: Variability and Trends from Conventional Data, Satellite Remote Sensing, and Canadian Regional Climate Model Simulations -- Recent Studies on the Climatology and Modeling of Blowing Snow in the Mackenzie River Basin -- On Blowing Snow and Sublimation in the Mackenzie River Basin -- Assessing Water and Energy Budgets for the Mackenzie River Basin -- Characteristics of the Moisture Flux Convergence over the Mackenzie River Basin for the 1990-2000 Wateryears -- The Influence of Lakes on the Regional Energy and Water Balance of the Central Mackenzie River Basin -- Mapping of Surface Albedo over Mackenzie River Basin from Satellite Observations -- Comparison of Solar Radiation Budgets in the Mackenzie River Basin from Satellite Observations and a Regional Climate Model -- Wildfire Aerosol and Cloud Radiative Forcing in the Mackenzie River Basin from Satellite Observations -- The Nature and Impacts of Thunderstorms in a Northern Climate -- Forest Fires and Climate Change in the Northwest Territories -- The Impact of CLASS in MAGS Monthly Ensemble Predictions -- The MAGS Regional Climate Modeling System: CRCM-MAGS -- Synopsis of Hydrologic Research under MAGS. ThegeographyofCanadamakesitoneofthebestlocationsintheworld for cold regionatmosphericand hydrologic studies:its high latitudeand high mountains,proximity to oceans in theArcticand cold temperate zones,a broadassemblage of landscapeand vegetation,and numerous lakesand rivers.Foryears,Canadians have conducted research on cold regions,either individually or in small groups, thusaccumulating rich experienceandample expertisein the farNorth.Creation of theGlobal EnergyandWaterCycleExperiment(GEWEX),undertheauspicesofthe WorldClimateResearchProgram,providedanexternalimpetusforlar- scale collaborative research. Canada responded to this initiativeby creatingtheMackenzieGEWEXStudyorMAGSthatfocusedonthecold region.ItwasrecognizedattheearlystageofMAGSthattheatmosphere andthehydrospherearestronglylinked.Aconcertedeffortofatmospheric andhydrologicscientistsisbeneficial,ifnotessential,toasuccessfullarge research program.In thisregards,investigation conducted bya groupof scientistsandengineersofMAGSwasentirelyrelevantandtimely.This study,carriedoutbetween1994and2005,hadtheresearchobjectivesof (1)understandingandmodelingthehigh-latitudeenergyandwatercycles that playroles in the climate system,and (2)improving ourability to assess the changestoCanada ?swaterresourcesthatarisefrom climate variabilityandanthropogenicclimatechange. So vast a world region that isunderthe influence of intense and persistent coldness cannot be covered by a contingent of Canadian researchersoveradecadaltimehorizon.TheMackenzieRiverBasinand its vicinity in northwestern Canada, occupying an area of about two millionsquarekilometers,wasadoptedasthepreferredresearchlocation. It offersa wideassemblage of environments, including mountainsand plains,tundraandforests,lakesandwetlands,andwinterslandscapesof snow, ice and frost. Its climatic continentality is accompanied by pronounced external influences,notably from the Pacific Ocean. The Mackenzie area presents a diversity of atmospheric and hydrologic conditionswiththeirattendantresearchproblemstochallengetheMAGS investigators. With increasing pressureofdevelopment, the previously neglected northernareas in many circumpolar nations havecome to the fore.The coldregionwithitspermafrost,snowandicethataresensitivetoclimate v warming,andwithitsecosystemthatisvulnerabletodisturbances,must be developed in a considered fashion toenable environmental sustainability.Information needstobegatheredand sound knowledge should be available for proper planning and operationalpurposes. Furthermore, the cold region isacknowledged to be highlysensitive to variationsandchangesintheclimate.Theeffectsofitsatmosphericand hydrologicfeedbackextendwellbeyondtheconfinesofthehighlatitudes to influence the globalmovements of waterand energy.Therearelarge uncertaintiesregarding howthe cold region respondsto the impetus of changesimposedbynatureandhuman.Progressincoldclimateresearch wouldcontributetoimprovedunderstandingofhowthesystembehaves, henceenablingbetterpreparationforandappropriateadaptationtothese changes. MAGSattempted toincreaseour knowledge of the North. All its projectsplacedanexplicitorimplicitemphasisonimprovingthecurrent understanding of the cold regionatmosphericand hydrologic processes.