Glacier Mass Balance Forecasting
NORTH CASCADE GLACIER CLIMATE PROJECT
Mauri S. Pelto, Director NCGCP
Nichols College, Dudley, MA 01571

Peltoms@nichols.edu

Glacier Mass Balance Basics North American Glacier Mass Balance Glacier Mass Balance Prediction Glacier Mass Balance Forecasting Global Glacier Mass Balance North Cascades Glacier Mass Balance
What is mass balance?
Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation (melting and sublimation). Climate change may cause variations in both temperature and snowfall, causing changes in mass balance. Changes in mass balance control a glacier's long term behavior.A glacier with a sustained negative balance is out of equilibrium and will retreat. A glacier with a sustained positive balance is out of equilibrium and will advance.

 Annual balance is the most sensitive annual  glacier climate indicator.  This sensitivity to climate indicates that climatic driving forces may allow forecasting of the mass balance.  A mass balance forecast is valuable as it identifies the amount of glacier runoff that will be produced, which in turn will be key to water management decisions. North Cascade glaciers annual balance has averaged -0.54 m/a of water equivalent from 1984-2006, a cumulative loss of over 12.4 m in glacier thickness or  20-40 % of their total volume since 1984 due to negative mass balances.  With more than twenty years of glaciers from ten different glaciers we have tested a forecasting tool for glacier mass balance.  The forecasting relies on monthly data for October - April to forecast mass balance for the hydrologic year which ends in October.  The forecast thus is given at the start of the melt season and provides an assessment of the amount of glacier runoff that will be generated.  We are also working on predictions of mass balance based simply on monthly climate data.   This years forecast issued May 1 is for negative glacier mass balance. Mass balance prediction.

Mass balance data set

A Paper on this subject has been published in the premiere issue of The Cryosphere, A European Geophysical Union Journal

Locations of glaciers, SNOTEL sites and weather stations used in this study. 

 

 Table 4.  The columns are respectively: Mean value of winter PDOW (October-April).  Winter ENSOW  (October-April).  Glacier net balance bn-SC from South Cascade Glacier 1960-2005. Glacier annual balance ba-NC for the 10 NCGCP glaciers (1984-2006).  The relative phase: positive, >0.2 (p), negative, <-0.2 (n) and equilibrium -0.2 to 0.2 for equilibrium (e), for PDOW, ENSOW indices and glacier net balance and annual balance (bn-ba) respectively.   The number of the rule utilized from section 5.  Lastly if the rule correctly yields the annual balance in terms of negative, equilibrium or positive it is noted by a yes, if not a no for both bn-ba . The rule is correct in 41 of 46 years for the South Cascade Glacier for which the model was designed.  The rule is correct in 20 of 23 years for the North Cascade Glacier Climate Project glaciers. 


 
 


 



 

Year

PDOW

ENSOW

bn-SC

Ba-NC

PDOW

ENSOW

bn-ba

Rule#

Result

1960

0.34

-0.17

-0.50

 

p

e

n

3

yes

1961

0.30

-0.23

-1.10

 

p

e

n

3

yes

1962

-1.64

-0.79

0.20

 

n

n

p

2

yes

1963

-0.62

-0.71

-1.30

 

n

n

n

2

no

1964

-0.83

0.41

1.20

 

n

p

p

4

no

1965

-0.63

-0.64

-0.17

 

n

n

e

2

yes

1966

-0.42

1.06

-1.03

 

n

p

n

4

yes

1967

-0.73

-0.52

-0.63

 

n

n

n

2

no

1968

-0.54

-0.68

0.01

 

n

n

e

2

yes

1969

-0.74

0.54

-0.73

 

n

p

n

4

yes

1970

0.78

0.34

-1.20

 

p

p

n

1

yes

1971

-1.44

-1.38

0.60

 

n

n

p

2

yes

1972

-1.56

-0.74

1.43

 

n

n

p

2

yes

1973

-0.27

1.41

-1.04

 

n

p

n

4

yes

1974

-1.10

-1.70

1.02

 

n

n

p

2

yes

1975

-0.45

-0.85

-0.05

 

n

n

e

2

yes

1976

-1.40

-1.55

0.95

 

n

n

p

2

yes

1977

1.05

0.49

-1.30

 

p

p

n

1

yes

1978

0.34

0.81

-0.38

 

p

p

n

1

yes

1979

-0.16

0.29

-1.56

 

e

e

n

6

yes

1980

0.70

0.75

-1.02

 

p

p

n

1

yes

1981

0.87

0.15

-0.84

 

p

e

n

3

yes

1982

0.31

-0.07

0.08

 

p

e

e

3

yes

1983

0.87

2.68

-0.77

 

p

p

n

1

yes

1984

1.38

-0.07

0.12

0.43

p

e

e-p

3

yes- yes

1985

0.73

-0.45

-1.20

-0.37

p

n

n-n

5

yes-yes

1986

0.91

-0.15

-0.61

-0.14

p

e

n-e

3

yes-yes

1987

1.78

1.29

-2.06

-0.63

p

p

n-n

1

yes-yes

1988

1.23

0.98

-1.34

0.07

p

p

n-e

1

yes-no

1989

-0.52

-1.16

-0.91

-0.22

n

n

n-n

2

no-no

1990

-0.30

0.26

-0.11

-0.44

n

e

e-n

2

yes-no

1991

-1.37

0.33

0.07

0.33

n

e

e-p

2

yes-yes

1992

0.40

1.61