Glacier atmosphere interactions and hydrology: Peyto field experiment discoveries .

Glacier atmosphere interactions and hydrology:

Peyto field experiment discoveries.

D. Scott Munro

University of Toronto

base (2240 m) +

low (2183 m) +

middle (2461 m) +

high (2709 m) +

AWS Network

• ← Point process investigation: glacier atmosphere interactions and hydrology

• ← Distribution tools (DEM, trigonometry, parameterization)

• ← Distributed modelling and prediction

• ← Base AWS/RCM forcing

j

fi/s

EH*i/s r/s δM

L

QQLα1KP

j

qj

Snow reservoir

Ice reservoir

Ice & Snow meltSnow accumulation

Model – AWS Comparisons

-5

-4

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-1

0

1

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30 60 90 120 150 180 210 240 270 300 330 360

h(m

)

Day of Year

Low AWS - 2003

Model SR50 DenAdjSR50

-5

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-1

0

1

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30 60 90 120 150 180 210 240 270 300 330 360

h(m

)

Day of Year

Middle AWS - 2006

Model SR50 DenAdjSR50

fi

MrM

QAq

K

qqSq tMt )1(1

K~1.5 h

K~10.5 h

Hydrology

R² = 0.73

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

Mea

sure

d 71-

74q/

q 24

Model03-06 q/q24

0.0

0.5

1.0

1.5

2.0

8 12 16 20 24 4

q/q 2

4

Time ( h )

2008 2003-06 1971-74

0.0

0.5

1.0

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2.0

170 173 176 179 182 185 188 191 194 197 200 203 206 209 212 215 218 221 224 227 230 233 236 239 241

q/q 24

June to August Melt Period

03-06 Mean 71-74 Mean

0.0

0.5

1.0

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2.0

168 169 170 171 172 173 174 175 176 177

q/q 24

Early Melt Period

0.0

0.5

1.0

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232 233 234 235 236 237 238 239 240 241q/

q 24

Late Melt Period

Mϋller & Keeler 1969

K~11.25 h, ice; 100 h, snow

• Focusing on the sensible heat flux, QH, there are respectively to the right of the equal sign the gradient, eddy correlation (EC) and bulk transfer methods of obtaining the flux density:

• The key feature of the flow regime is a local wind speed maximum, close to the surface, through which heat should not flow because Du/Dz = 0, yet the bulk transfer approach seems to provide reasonable heat flux values, regardless of the measurement height used.

• Although EC measurements of QH below the local wind speed maximum seem to agree with bulk transfer estimates, less is known about EC measurements near to and above the level of maximum wind speed.

2

2222

ln''

o

SpppH

zz

TTukcTwc

z

T

z

uzkcQ

Glacier – Atmosphere Interaction

temperature

win

d

win

d

• Also to consider is the Oerlemans-Grisogono parameterization (OG) ......which is convenient for modelling, but contrary to classical thinking..... ......about the nature of the glacier atmospheric boundary-layer.𝑄𝐻= 𝜌𝑐𝑝൬𝐾𝑔𝑒𝑜 + 𝐾𝑘𝑎𝑡2 ൰ሺ𝑇ത− 𝑇𝑆ሻ

• If classical thinking is correct EC measurements of QH → 0 near the .....local wind speed maximum, but if OG is correct the QH measurements .....will show a step change across the level of maximum wind speed.

Experiment objectives:

B to A: B-L acceleration & cooling

B

A: B-L turbulent flow field, 1-6 m

Mobile EC

Fixed EC

~50 m

~ 650 m

6 m

4 m

2 m

1 m

6 m

4 m

2 m

1 m

A

Regional Wind ?

Glacier Wind

Glacier

Wind

Regional

Wind

Turbulent flow field, 1-6 m

Acceleration & cooling

0

1

2

3

4

5

6

0 5 10 15 20

Wind S peed (m s -1) T emperature (°C )

Hei

ght (

m)

A: Wind

B : Wind

A: T emp.

B : T emp.d z

Taking mean values, assuming no heat transfer across 4 m and correcting for adiabatic warming, expect 1 & 2 m TA< TB by ~2 °C.

On hydrology:• An electrical analogue to consider for supraglacial runoff is a

series resistance system that links the runoff potential of the melting ice surface to supraglacial stream discharge.

• In such a system resistance should increase with weathering crust development, decrease with decay, so a good test of this idea is to continuously measure short-term runoff from a supraglacial basin all summer to see if K depends on the weather.

On glacier-atmosphere interactions:• An electrical analogue to consider for boundary-layer heat

transfer to the glacier is a parallel resistance system that links the energy potential of the regional air mass to surface melt.

• One branch of such a system is the geostrophic flow, the other a katabatic flow that is subject to sporadic breakdown, thus explaining hot flash behaviour.

• This is supported by the 2008 eddy correlation data that suggest two turbulent transfer fields adjacent to the glacier surface, one of which extends above the level of the wind speed maximum.

Concluding with analogues:

Acknowledgements

CFCAS → IP3 Network Funding

Environment Canada → CRYSYS Program

NSERC → Discovery Grants

Natural Resources Canada → GSC-CGVMAN University of Toronto Mississauga