1999-2005 DROUGHTOVER THE CANADIAN

PRAIRIESPRAIRIESIts Story

2005 DROUGHTOVER THE CANADIAN

PRAIRIESPRAIRIESIts Story

OBJECTIVE

• To understand how the drought was established, continued and ended

• To illustrate factors controlling the drought’s internal evolution

• To consider some of the many implications of • To consider some of the many implications of this research

• To outline needed, future research areas (we certainly can't do it all)

OBJECTIVE

To understand how the drought was established, continued and endedTo illustrate factors controlling the drought’s

To consider some of the many implications of To consider some of the many implications of

To outline needed, future research areas (we

GENERAL PERCEPTION

The general view for the formation of drought over the Canadian Prairies is the following:

• Sea surface temperature patterns over the • Sea surface temperature patterns over the Pacific Ocean in particular

• Associated, persistent atmospheric circulation• Descent, clear skies, and warm temperatures• Feedbacks allowing perpetuation of drought conditions

GENERAL PERCEPTION

The general view for the formation of drought over the Canadian Prairies is the

Sea surface temperature patterns over the Sea surface temperature patterns over the Pacific Ocean in particularAssociated, persistent atmospheric circulationDescent, clear skies, and warm temperaturesFeedbacks allowing perpetuation of drought

PRECIPITATION REDUCTION

There are many means of reducing precipitation.

Large scalesStorm track alterationReduced and altered types of cloudsAerosol effectsSub-cloud precipitation lossHigh cloud basesHigh cloud basesAltered surface evaporation...

Each of these occurred within the drought??

PRECIPITATION REDUCTION

There are many means of reducing precipitation.

So ...

Why did the drought occur?

What governed its structure?

How could it withstand the many large scale forcing How could it withstand the many large scale forcing changes?

How was it able to end?

Why did the drought occur?

What governed its structure?

How could it withstand the many large scale forcing How could it withstand the many large scale forcing

ARTICLE STRUCTURE

• The Drought• Large scale setting• Land area features• Feedbacks• Feedbacks• Means of sustained lack of precipitation• Anthropogenic factors• Implications• ...• Concluding Remarks

ARTICLE STRUCTURE

Means of sustained lack of precipitationAnthropogenic factors

SOME DROUGHT FEATURES• No 'clear, persistent' major ridging (this needs clarification)• Major troughing (spring 2002) and cooler temperatures• Associations with large-scale teleconnections not clear cut• Most persistent dry conditions along the Alberta• Rapid movement of the drought was linked with storms• General lack of spring precipitation (Phil to check)• autumn and summer also had reduction of precipitation and several

'strings' of low precipitation seasons occurred (2002 for example)• Cold springs/summers sometimes occurred• Cloud fraction close to normal conditions• Windy conditions were common (Bob Kochtubajda to check)• Windy conditions were common (Bob Kochtubajda to check)• Boundaries of wet and dry regions were linked with associated

atmospheric circulations• Autumn and/or winter precipitation and frozen surfaces• Virga common• Dust and smoke were common• Vegetation was critically affected over large areas of the region• River flows, pond levels, other surface water variables extremely low• Sub-surface water levels were extremely low in some locations

SOME DROUGHT FEATURESNo 'clear, persistent' major ridging (this needs clarification)Major troughing (spring 2002) and cooler temperatures

scale teleconnections not clear cutMost persistent dry conditions along the Alberta-Saskatchewan borderRapid movement of the drought was linked with stormsGeneral lack of spring precipitation (Phil to check)autumn and summer also had reduction of precipitation and several 'strings' of low precipitation seasons occurred (2002 for example)Cold springs/summers sometimes occurredCloud fraction close to normal conditionsWindy conditions were common (Bob Kochtubajda to check)Windy conditions were common (Bob Kochtubajda to check)Boundaries of wet and dry regions were linked with associated

Autumn and/or winter precipitation and frozen surfaces

Vegetation was critically affected over large areas of the regionRiver flows, pond levels, other surface water variables extremely low

surface water levels were extremely low in some locations

TEMPORAL EVOLUTIONThe temporal evolution over the entire drought period:

• 1999-2000: Initial regions of drought centred in west-central Alberta but south Alberta by 2000

• 2001: Largest extent and severity of the drought across agricultural regions of the Prairies

• 2002: Wet anomalies in so• 2002: Wet anomalies in sodrought to the north and east into central and southern Manitoba

• 2003: Intensifying drought in MB; AB and SK improved/recovered

• 2004/05: Widespread end to meteorological drought and reduction of hydrological drought

TEMPORAL EVOLUTIONThe temporal evolution over the entire drought period:

2000: Initial regions of drought centred in central Alberta but south Alberta by 2000

2001: Largest extent and severity of the drought across agricultural regions of the Prairies

southern Prairies and shift of southern Prairies and shift of drought to the north and east into central and

2003: Intensifying drought in MB; AB and SK

2004/05: Widespread end to meteorological drought and reduction of hydrological drought

KEY PERIODS

The drought can be broken down into three key periods???

• 1999 - beginning• 2001/02 - core• 2002/03 - shift to the north• 2002/03 - shift to the north• 2005 - mainly over

KEY PERIODS

The drought can be broken down into three key

shift to the northshift to the north

WATER AND ENERGY CYCLING

Many factors affect the cycling of water and energy during drought

WATER AND ENERGY CYCLING

Many factors affect the cycling of water and energy during drought

PDSI- Palmer Drought Severity Index

SPI- Standardized SPI- Standardized Precipitation Index

20022002

Drought … Not Too Hot

Precipitation

Summers of 2000, 2001 and 2002

Drought … Not Too Hot

Temperature

Summers of 2000, 2001 and 2002

MONTHS EXPERIENCING DROUGHT

MONTHS EXPERIENCING DROUGHT

September 1999 –December 2004

SPI ≤ - 0.5

SPI ≤ - 1.5

MONTHS OF DROUGHTMONTHS OF DROUGHT

SPI ≤ - 0.5

Number of Months:

September 1999 –December 2004

SST Anomalies

1999

SST Anomalies

SST Annual Anomalies

2004

CONTINENTAL SCALE

1999

2002

CONTINENTAL SCALE PATTERNS

2004

Summer 500 mb

CANADIAN PRAIRIES2002

CANADIAN PRAIRIES2002

Daily PrecipitationAmounts

ClimatologyLow precipitation events: 52% of total

Precipitation

Low precipitation event:< 10 mm

total

Sub-drought 2001-2002Low precipitation events: 60% of total

‘CORE’ OF DRYNESS

• Was there an ongoing ‘drought core?central and/or northern Alberta

• Dry?• Dry?• Descending air?

‘CORE’ OF DRYNESS

Was there an ongoing ‘drought core?central and/or northern Alberta

Monthly-Scale Precipitation GradientsScale Precipitation Gradients

VEGETATION

NDVI

Healthy vegetation

VEGETATION

July 11-20, 2002

NDVI

NDVI: Normalized DifferenceVegetation Index

Healthy vegetation

SPECIFIC FEEDBACKS ON THE NATURE OF DROUGHT

deep, dry boundary later so precipitation could not reach the surface

dry sub-cloud region enhances severity of precipitation event

degree of dryness affects features of lightning/convectiondegree of dryness affects features of lightning/convection

altered dryness affects evaporation ratesaltered dryness affects albedo ... so what?drought affects winds and then evaporation, dust??

and .... all these others

SPECIFIC FEEDBACKS ON THE NATURE OF DROUGHT

deep, dry boundary later so precipitation could not reach the

cloud region enhances severity of precipitation event

degree of dryness affects features of lightning/convectiondegree of dryness affects features of lightning/convection

altered dryness affects evaporation ratesaltered dryness affects albedo ... so what?drought affects winds and then evaporation, dust??

PHYSICS OF ‘EDGES

• Acting to perpetuate and/or eliminate the drought

• vegetation feedbacks• precipitation overhangs• precipitation overhangs• ascent/descent• ...

PHYSICS OF ‘EDGES’

Acting to perpetuate and/or eliminate the

vegetation feedbacksprecipitation overhangsprecipitation overhangs

How did cool temperatures in the summer affect the drought?

just 'less' evaporation or also impacts on vegetation and ... ???

or ...

How did cool temperatures in the summer affect the drought?

just 'less' evaporation or also impacts on vegetation and ... ???

WINTER EFFECTS

• What was the impact of the varying snowcover on the drought?

• Warm and cool winters had what effects on the drought?

• When did the freezing and thawing of the ground occur and • When did the freezing and thawing of the ground occur and how did the timing of these affect the drought?

• How did loss of precipitation thdrought?

• Did the occurrence of freezing rain and/or winter thaws and rain-on-snow have significant impacts on the drought?

WINTER EFFECTS

What was the impact of the varying snowcover on the

Warm and cool winters had what effects on the drought?

When did the freezing and thawing of the ground occur and When did the freezing and thawing of the ground occur and affect the drought?

through blowing snow affect the

Did the occurrence of freezing rain and/or winter thaws and snow have significant impacts on the drought?

• Annual snow cover duration (SCD) anomaly series computed over the Augustyear from the NOAA dataset show the 1999/2000 southern prairie snow cover season as the second shortest in the satellite record.

• Conditions rebounded to near normal for the remaining drought years.• Similar results were found for the northern prairies.

Snow Cover Duration

Southern prairie annual SCD anomalies from the NOAA snow chart record.The thick black line represents 5-yr moving average.Solid symbols denote the 1999-2005 drought period.

Annual snow cover duration (SCD) anomaly series computed over the August-July snow year from the NOAA dataset show the 1999/2000 southern prairie snow cover season as the

Conditions rebounded to near normal for the remaining drought years.Similar results were found for the northern prairies.

Snow Cover Duration

Southern prairie annual SCD anomalies from the NOAA snow chart record.yr moving average.

2005 drought period.

SURFACE/SUBIMPACTS

• What was the impact of the dryingmany ponds and sloughs?

• What was the impact of submoisture decreases?moisture decreases?

• ...

SURFACE/SUB-SURFACE IMPACTS

What was the impact of the drying-up of many ponds and sloughs?What was the impact of sub-surface moisture decreases?moisture decreases?

BREAK POINTS

• Major changes in drought features

• Specific examplesJune 2002June 2002spring 2005...

• What happened and why?

BREAK POINTS

Major changes in drought features

What happened and why?

ANTHROPOGENIC EFFECTS

• Atmosphere• Surface

• Were large and regionalglobal warming patterns?global warming patterns?

• Did the altered land surface and agricultural crops act to enhance or reduce the drought?

• ...

ANTHROPOGENIC EFFECTS

al forcings consistent with global warming patterns?global warming patterns?

altered land surface and agricultural act to enhance or reduce the drought?

FURTHER INSIGHT AND IMPLICATIONS

• Palliser triangle• Devil's Lake• River flows across provincial/national boundaries• Agriculture• Hydro development• Oil sands• Oil sands• Forestry• Future climate projections: water availability, extremes

Prairies, western Canada, all Canada, other regions• ...

FURTHER INSIGHT AND IMPLICATIONS

River flows across provincial/national boundaries

Future climate projections: water availability, extremesPrairies, western Canada, all Canada, other regions

Standardized Precipitation Index (SPI) for agricultural years with severe droughtStandardized Precipitation Index (SPI) for agricultural years

WHAT WE CANNOT DO

What can we not address?

WHAT WE CANNOT DO

CONCLUSIONSA major multi-year drought affected the Prairies (and other regions) over the 1999-2005 period.

Some features as expected but other features not

Great deal of structure in terms of precipitation, dryness ...

Large as well as small scale factors important

Modelling capability MUST account for smallissues.

Harbinger of future climate?

Implications for society

Next steps

CONCLUSIONSyear drought affected the Prairies (and other

2005 period.

Some features as expected but other features not

Great deal of structure in terms of precipitation, dryness ...

Large as well as small scale factors important

Modelling capability MUST account for small-scale