Study of Snow Density Across Canada

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Study of Snow Density Across Canada

Williams, G. P.

NATIONAL RESEARCH COUNCIL CANADA

D i v i s i o n o f B u i l d i n g R e s e a r c h

A STUDY OF SI'JOW I)UlJ:II'P17 ACROSS CANADA

ANALYZED by

G.P. Williams

T h i s r e p o r t h a s b e e n p r e p a r e d f o r i n f o r m a t i o n a n d r e c o r d p u r p o s e s a n d i s n o t t o be r e f e r e n c e d it?

any

p u b l i c a t i o n . R e p o r t TJo.

104

o f t h e D i v i s i o n o f B u i l d i n g R e s e a r c h O t t a w a ~ u e u s t

1956

SUMMARY

T h i s r e p o r t a n a l y z e s t h e snotr r!ensi t y o b s e r v a t i o n s talcen a t s o l e c t e d s t a t i o n s a c r o s s Cana.('a u n d e r t h e a u s p i c e s o.f t h e 1 \ ? a t i o n a l R e s e a r c h C o u n c i l and ti1.e A s s o c i a t e Comfii.ttee on : ; o i l o.nd Sn7t.j Msc!lanics, I t was f o u n d t h n t snow c ! e n s i t y

i ' i s ? ; r i b u t i o n cdi axranis f o r e x p o s e d s t a - t i o n s a 9 p r o x i m a t e a normal d i s t r i b u t l o n , w h e r e a s t he i l i s t r i b u t i o n diz[;:rams v i i r i e d ; ~ ; t h i r ~ c ' i v i d . u a l s i t e s f o r s h e l t e r e d . s t a t l i o n s , An a n a l ~ r s i s of d e n s i t y c h a n g e s w i t h d e p t h and t i m e i n d i c a t e s t h a t t h e m a j o r d e n s i f i c a t i o n of snow t a k e s p l a c e i n t h e s u r f a c e 1 a . y c r s . :i';no:.r t ? e n s i f i c a t i o n b e l o w

6

i n c h e s o c c u r s a t a g r a d u a l r a t e - w h i c h I s approximei;ely t h e same f o r a l l s t a t i o n s . Piore d c - [ ; a i l e d s t u d i e s a r e needed. t o a n a l y s e f u l l y snow d e v s i t y d e ~ t h - t i r n e ch.anges.

A STUDY O F SNOW CENSITY ACROSS CANADA b y G.P. W i l l i a m s S i n c e 1 9 4 7 ciata on s e v e r a l :;now c h a r a c t e r i s l ; i c s h a v e b e e n o b t a i n e d fro:n s e l e c t e d s t a t i o n s a c r o s s Canada u n d e r t h e a u s p i c e s of t 9 e f l s s o c i a t e C o r n i t t e e on d o i l a n d Snow l'q7echanics and throup-h t h e c o - o p e r a t i o n o f t h e D i v i s i o n of B u i l d i n g Re- s e a r c h , l d a t i o n a l R e s e c r c h C o u n c i l a n d t h e I i ' i e t e o r o l o ~ i c a . l D i v i - s i o n , D e p a r t m e n t of T r s n s p o r t . Snow d e n s i t y was o n e of t h e c h a r a c t e r i s t i c s m e a s u r e d w i t h t h e s t a n d a r d N . 1 f . C . snow k i t

d e s c r i b e d i n a o a p e r by K l e i n , P o a r c e a n d Gold ( 1 ) . The snow o b s e r v a t i o n s w e r e t a k e n i n wooded a r e a s

p r o t e c t e d f r o m wind, and i n a r e a s where t h e snow c o v e r was

ex-

p o s e d t o w i n d a c t i o n . F i ~ u r e I shows t h e l o c a t i o n o f t h c snow s u r v e y s t a t i o n s a c r o s s Canada. The p u p n o s e o f t h i s r e p o r t i s t o a n a l y s e t h e snow d e n s i t y o b s e r v a t i o n s f r o m t h e s e s e l e c t e d

s t a t i o n s a c r o s s Canada.

To d a t e t % r r

have

'3een few s t u d i e s o f snow d e n s i t y on a r e y i o n a l b a s i s . liJork ( 2 ) d e s c r i b e d snow l a y e r d e n s i t y c h a n p e s a t a p a r t i c u l a r s i t e . Oda a n d Kudo

( 3 )

h a v e r e p o r t e d on d e n s i t y c h a n c e s a t a snow s t a t i o n i n J a p a n . D m i t r i e v a

( 4 )

h a s r e n o r t e d

on snow d e n s i t y on a r e g i o n a l b a s i s i n t h e U.S.S.R. b u t h i s f i n d i n g s d o n o t n e c e s s a r i l y a p p l y t o N o r t h F~rnerican c o n e i t i o n s . Gold

and P e a r c e

( 5 )

r e p o r t e d on snow c h a r a c t e r i s t i c s a c r o s s Canada i n 1 9 5 0 a n d i n c l u d e d some o b s e r v a t i o n s o n snow c ' o n s i t y . L i n c e

t h e i r r e p o r t was w r i t t e n , d a t a f o r f o u r more y e a r s have been c o l l e c t e d and a more d e t a i l e d s t u d y was w a r r a n t e d .

Snow D e n s i t y D i s t r i b u t i o n Curves

-

Snow d e n s i t y i s r e l a t e d t o a t m o s p h e r i c c o n d i t i o n s . Diamond and Lowry

( 6 )

o b t a i n e d a c o r r e l a t i o n between d e n s i t y o f newly C a l l e n snow anct t h e 700 m i l l i b a r t e m p e r a t u r e s . Bosso- l a s c o

( 7 )

r e l a t e d t h e d e n s i t y of newly f a l l e n snow t o t h e mean a i r t e m p e r a t u r e . D n i t r i e v a

( 4 )

h a s r e l a t e d snow d e n s i t y on t h e ground w i t h a i r temperal;ure and wind v e l o c i t y .

N i t h t h e wide v a r i a t i o n i n a t m o s p h e r i c W n d i t i o n s

a c r o s s Canada

i t

i s n o t s u r p r i a i n g t o f i n d a wide v a r i a t i o n i n snow d e n s i t y between d i f f e r e n t s t a t i o n s . F i g u r e 2 shows d e n s i t y r ' i s t r i b u t i o n d i a g r a m s f o r s h e l t e r e d and e x p o s e d s t a t i o n s .

D e n s i t y d a t a were t slcen from d e p t h s 0-36 i n c h e s d u r i n g months of c o n t i n u o u s snow cover.

T a b l e I shows c a l c u l a t e d v a l u e s o f mean, s t a n d a r d d e v i a t i o n , skewness and p e a k e d n e s s a s d e s c r i b e d by Hoe1 ( 9 ) .

These

v a l u e s a r e u s e f u l i n t h a t e i s t r i b u t i o n d i a g r a m s c a n be compared a r i t h m e t i c a l l y .

The rnean d e n s i t i e s a t Old G l o r y , R e s o l u t e and C h u r c h i l l a r e .369,

.356,

and .325 _{r e s p e c t i v e l y . A s snow d e n s i t y i s}

* a p p a r e n t l y i n c r e a s e d by c o l d t e m p e r a t u r e s and wind

(4),

i t

i s n o t s u r p r i s i n g t o f i n d t h e h i g h e s t d e n s i t y v a l u e s a t R e s o l u t e and C h u r c h i l l i n n o r t h e r n Canada and a t Old G l o r y Mountain s t a t i o n ( 7 0 0 0 f o o t l e v e l ) i n s o u t h e r n B r i t i s h Columbia. M e l t i n g t e m p e r a t u r e s d u r i n g t h e w i n t e r s e a s o n c a n a l s o

i n c r e a s e snow d e n s i t y a s e v i d e n c e d b y t h e c o n i p a r a t i v e l y h i g h mean of . 2 7 5 a t O t t a w a . The mean v a l u e s a t t h e r e s t cf t h e

s t a t i o n s r a n g e d f r o m a h i g h o f

2.79

a t !i':innipeg t o a low of .22!+ a t Edmonton. The s t n n c ? a r d d e v i a t i o n i s r ~ . e n e r a l l y h i g h e r a t s h e l t e r e d s t a t i o n s t h a n n t e x p o s e 6 s t a t i o n s . 'i'h.~ s t a n d a r d d e v i n t i o n i s n o t o n l y a me~~.si:re o f snow d e n s i t y v a r i a t i o n b u t i t i s a l s o p r o b a b l y a m e a s u r e of t h e v a r i a b i l i t y o f w i n t e r c l i m a t e . F o r e x e n p l . e , t h e s t a t i o n s i n E a s t e r n Canada

-

Goose Uay, I.Ia,riiwaki, i ~ ' o r e s t v i 1 l . e a n d Ottawa sh~ow a hi:;her s t a n d a r d d e v i a t i o n t h m

i n n o r t h e r n an(! v e s t e r n Canac7a. W i n n i p e g , hdmonton, R e s o l u t e , A k l a v i k and ' i d h i t e h o r s e h a v e a l m o s t e q u a l s t a n d a r d d - e v i a t i o n s .

The s k e w n e s s a n d p e a k e d n e s s v::.lue s o f t h e c!f s t r i b u - t i o n d i a g r a m s a t e x p o s e d s t a t i o n s i n d i c a t e n o r m a l d i s t r i b u t i o n s . The p e a k e d n e s s of a nor2mal d i s t r i b u t i o n e q u a l s 3.0, compared t o p e a k e d n e s s of

3.55,

3 . 5 0 , 3.32 a n d

3.15

f o r ' d i n n i p e g , i l k l a v i k , l ' i e s o l u t e a n d Edmonton r e s g e c i ; i v e l y . The slrewness of a n o r m a l c ' i s t r i b u t i o n c a n b e taken c q u a l t o z e r o w h i c h c o m p a r e s t o t h e v a l u e s o f sl.cewness f o u n d a t t h e s e s t a t i o n s . The v a l u e s of p e a k e d n e s s a n d s!tewness seem t o v a r y w i t h i n d i - v i d u a l s i t e s f o r s h e l t e r e d s t a t i o n s . U n f o r t u n a t e l y t h e r e w e r e n o t enough d a t a t o w a r r a n t C i s t r i b u t i o n c u r v e a n a l y s i s f o r S h i p s h a w , Shawbrid-ge, 2nd K a p u s k a s i n g

.

idhen i t i s c o n s i d e r e d t h a t t h e s e s i a t i o n s a r e s c a t - t e r e d a c r o s s R c o n t i n e n t , t h e p a t t e r n o f d e n s i t y d i s t r i b u t i o n d i a g r a m s i s r e m a r k a b l y s i m i l a r , e s p e c i a l l y f o p e x p o s e d s t a t i o n s .

It i s c o n s i d e r e d t ' a t most of t h e v a r i a t i o n i n d i s t r i b u t i o n c u r v e i n d i c e s can b e e x p l r i n e d by e i t h e r s i t e

o r

c l i m a t i c copclit i o n s . C o n v e r s e l y , i f s u f f i c i e n t ~ - ~ a t a were a v a i l a b l e , snow c l c n s i t : ~ c : i s t r i b u t i o n c1ia;frarns c o u l d p r o b a b l y s e r v e a s m i c r o - c l i m a t i c i n c ' i c a t o r s f o r s i t e s where no o t h e r d a t a were a v a i l a b l e . Snow D e n s i t y

-

Depth V a r i a t i o n

-

.- "

-

-"lost a ~ ~ t h o r s r e p o r t t h a t snow d e n s i t y d o e s n o t i n c r e a s e w i t h snow d e p t h . Work ( 2 ) r e p o r t e d t h a t snow d e n s i t y a t o r n e a r t h e s u r f a c e was e s s e n t i a l l y t h e sarne a s snow d e n s i t y w i t h i n a few i n c h e s of t h e b o t t o m of t h e snow p a c k . D m i t - r i e v a

(4.)

c o n c l u d e d t h a t no c o n s p i c u o u s i n f l u e n c e of d e p t h of c o v e r on snow d e n s i t y c o u l d be f a l n d . liucio

( 3 )

r e p o r t e d

1,113t i n t 5 e f i r s t w i n t e r of h i s s t u d i e s t 5 e r e w a s no d i s c e r -

n i b l e d i f f e r e n c e i n d e n s i t y w i t h d e p t h , b u t t h a t on a month by month b a s i s , some i n c r e a s e i n d e n s i t ; r w i t h clepth was e v i - 6 e n t . I t i s difficult t o compare r e p o r t s b e c a u s e t h e a u t h o r s a r e o f t e n comparing d i f f e r e n t s i t e s , d i f f e r e n t snow c o n d i t i o n s o r a r e n o t s n e c i f i c a s t o what snow d e p t h s a r e i n v o l v e d .

I n o r d e r t c i n v e s t i g a t e snow d e n s i t y d.epth changes, th.e a v e r a g e d e n s i t y a t v a r i o u s l a y e r i n t e r v a l s w ~ s p l o t t e d a s

shown on F i g .

3.

Each l i n e j o i n i n g t h e a v e r a g e d e n s i t y a t v a r i o u s l a y e r s shows t h e a v e r a g e d e n s i t g chanpe w i t h d e p t h a t a s t a t i o n f o r a w i n t e r s o a s o n

--

u s u a l l y from December t o I?arch. The l i n e s a r e s t a ~ g e r e d s o t h a t s e v e r a l s t a t i o n s

c o u l d b e : ~ u t on t h e snnie f l ~ u r e

.-

w i t h o u t t o o many c o n i ' u s i n , ? l i n e s . The avera,ge r l e n s i t y i n t h e 0-4 i n c h l a y e r i s shown a t e a c h s t a . t i o n f o r c o r n p a r a t i - v e p u r p o s e s . A t s h e l t e r e d s t a t l o n s d - e n s i t y i n c r e a s e s w i t 1 1 d e p t h (!own t o t h e 8 - t o - 1 2 - i n c h l a y e r . Below 1 2 i n c h e s t h e r e i s a s l i g h t i n c r e a s e w i t h d e p t h , i n d i c a t i n g t h a t snow d e n s i f i c a - t i o n o c c u r s l a r g e l y i n t h e f i r s t 1 2 i n c h e s o f snow. A t e x p o s e d s t a t i o n s t ' i e d e n s i f i c a t l o n o f snow i n t h e u n p e r l a y e r s i s n o t s o rnmked, and t!!o ;::enera1 t e n d e n c y i s f o r d . e n s i t y t o r e m a i n c o n s t : m t w i t h d e p t h . A p p a r e n t l y snow e x p o s e d t o w i n d a c t i o n w a s s o t h o r o u g h l y worked. o v e r t h a t n o c o n s i s t e n t d e p t h - d e n s i t y chnn,ye w a s d . e t e c t e d . F i g u r e

3

_{i s b a s e d o n a v e r a g e v a l u e s a.nd d o e s n o t} n e c e s s a r i l y d e p i c t d e n s i t y - d e p t h c h z n p e s f o r s p e c i f i c con- d i t i o n s . To i n v e s t i t g a t e ch.anges i n g r e a t e r d e t a i l , a s i n g l e d e n s i - t y r e a d i n g i n t h c

8-to

1 2 - i n c h - y e r h a s b e e n cornparaed w i t h t h e a v e r a g e d e n s i t y f r o m 1 2 - t

36

_{i n c h e s f o r p a r 2 t i c u l a r}

snow p r o f i l e s a s shown i n F i g .

Ic.

F i g u r e

4

shows t h a t a d e n s i t y r e a d i n g i n t h e 8 - t o 1 2 - i n c h l a y e r i s a good. i n d i c a t o r o f a v e r a g e snow d e n s i t y f r o m 1 2 t o

36

_{i n c h e s . A t s h e l t e r e d s t a t i o n s t h e d e n s i t y f r o m} 1 2 t o

36

_{i n c h e s i s o n t h e a v e r a g e . 0 5 5 g r e a t e r t h a n t h e snow} d e n s i t y i n th.e 8 - t o - 1 2 - i n c h l a - y e r , A t e x p o s e d s t a t i o n s t h e d e n s i t y f r o m 1 2 t o

36

_{i n c h e s i s o n t h e a v e r a g e . 0 1 2 l e s s t h a n}

the

d - e n s i t y i n t h e & t o . 1 2 i n c h l a y e r .

Snow D e n s i t y Time Changes

C l o s e l y l i n k e d w i t h snow d e n s i t g d e p t h c h a n g e s a r e snow d e n s i t g t i m e chan,ues. The g r a d u a l i n c r e a s e w i t h d e p t h a t s h e l t e r e d s t a t i o n s c o u l d b e due t o t h e f a c t t h a t snow a t g r e a t e r d e p t h s h a s had t i m e t o d e n s i f g r a t h e r t h a n t o any c o n n e c t i o n w i t h d e p t h o f o v e r b u r d e n . F i g u r e

5

i s a p l o t o f a v e r a g e m o n t h l y snow d e n s i t y r e a d i n ~ s talcen f r o r r 0 - t o 1 6 - i n c h d e p t h s . T h e r e i s c o n s i d e r - a b l e v a r i a t i o n b e t w e e n i n d i v i d u a l s t a t i o n s w i t h a g e n e r a l tend-ency t o w a r d a n i n c r e a s e i n d e n s i t g f r o m November t o j4arch. These a v e r a g e r e s u l t s d e p i c t a wide v a r i e t y of con- d i t i o n s and do n o t g i v e a s a t i s f a c t o r y p i c t u r e o f t h e ciensi- f i c a t i o n of snow w i t h tiye p a s s a g e o f t i m e .

I n o r d e r t o i n v e s t i e a t e d e n s i t y c h a n ~ e s o v e r a s h o r t e r n e r i o d , t h e a v e r a g e snow d e n s i t y f r o m

6

t o

36

i n c h e s was

n l o t t e d a c a i n s t t h e a v e r a g e snow d e n s i t y f r o m

6

t o 3 6 i n c h e s f o r t h e same p r o f i l e two weeks l a t e r . F 3 , ~ u r e

6

shows t h a t d e n s i t y i n c r e a s e s on t h e a v e r a g e +.020 o v e r a two-week p e r i o d d u r i n g December t o F e b r u a r y . T h i s i n c r e a s e i s c o r n p a r a b l e t o t h e 1 0 t o 1 2 p e r c e n t m o n t h l y i n c r e a s e r e p o r t e d b y W e i n b e r g

( 8 ) .

More r a p i d c h a n g e s i n snow d e n s i t y p r o b a b l y t a k e p l a c e d u r i n g s p r i n g m e l t

-

a p e r i o d which was n o t i n c l - u d e d i n t h i s s t u d y . C o n c l u s i o n s

-

Snow d e n s i t g d i s t r i b u t i o n d i a g r a m s a c r o s s Canada show a d e f i n i t e p a t t e r n . Mean d e n s i t y v a l u e s

ranee

f r o m a h i e h of

.369 a t Old G l o r y M o u n t a i n s t a t i o n t o a low o f

.?24

a t Edmonton. The s t a n d a r d d e v i a t i o n , slrewness and p e a k e d n e s s o f

c7,i s t r i b u t i o n d i a p r a m s a r e q u i t e s i m i l a r a t e x p o s e d s t a t i o n s ,

a n d i n d i c a t e n o r m a l c ' i s t r i b u t i o n s , Wle d i s t r i b u t i o n d i a g r a m s s5ow more v a r i a b i l i t y a t t h e s h e l t e r e d s t a t i o n s .

An ana1:;sis of d e n s i t y c h a n g e s w i t h d e p t h and t i n e shows t h a t t h e m a j o r d e n s i f i c a t i o n o f snow t a k e s n l a c e i n t h e f i r s t 0 t o 1 2 i n c h e s o f snow. T h i s a n a l y s i s shows t 5 a t snow d e n s i t y m e a s u r e d i n t h e 0 - t o 1 2 - i n c h l a y e r i s a r e a s o n a b l e i n d i c a t o r of snow d e n s i t y f r o m 1 2 t o 36 i n c h e s . Average d e n - s i t y i n t h e snow p a c k i n c r e a s e s a p p r o x i m a t e l y . 0 2 5 i n t h e 6 - t o 3 6 - i n c h l e v e l g u r i n g two r-reek p e r i o d s i n December, J a n u a r y a n d F e b r u a r y a t a l l s t a t i o n s . F l i r t h e r m o r e , d e t a i l e d o b s e r v a t i o n s ancl s t t ~ d i e s a r e n e e d e d t o o b t a i n s p e c i f i c r e l a t i o n s h i p s b e t w e e n d e n s i t y a n d c l i m a t e , b e t w e e n d e n s i t : : a n 4 s i t e e x > o s u r e , and t o a n a l y s e p r o p e r l y t h e c h a n g e s i n snow d e n s i t y i n

t

he s u r f a c e l a y e r s . -4c knowled gment

-

s

Tlie a u t h o r w i s h e s t o a c k n o w l e d g e t h e work o f t h e ob- s e r v e r s who, o v e r a p e r i o d o f y e a r s , metlsured snow d e n s i t y a t t h e d i f f e r e n t s t a t i o n s a c r o s s Canada, o f t e n u n d e r a d v e r s e wea- t h e r c o n ? . i t i o n s . T h i s r e p o r t would n o t have b e e n p o s s i b l e w i t h - o u t t h e i r c o - o p e r a t i o n a n d e f f o r t . The a u t h o r a l s o wisktes t o e x p r e s s h i s a p p r e c i a t i o n t o L,JrJ, Gold f o r g u i d e n c e i n p r e p a r i n g t h i s r e p o r t , a n d t o J. P e a r l f o r h e l p i n p r e p ~ r i n g and. a n a l y z i n g t h e d a t a .

R e f e r e n c e s

1. K l e i n . G . J.. D . C . P e a r c e and I,.C\i. C o l d , MetG?od o f m e a s u r - - i n g t h e s i g n i f i c a n t c h a r a c t e r i s t i c s o f a snow c o v e r , T e c h n i c a l ?:e-lorandm No. 1 0 , P L s s o c i o t e Comr:xittee on S o i l and Snow i.lechanics, N a t i o n a l l-iesoarch C o u n c i l , 1 9 5 0 .

2. SJork, R.A. Snow l a g e r d e n s i t y c h a n g e s

-

t r a n s a c t i o n s o f American G e o p h y s i c a l Union, v.29,

p.525-546,

1948.

3.

Oda, 'Toshio and ICiyoshi ICudo. P r o p e r t i e s of snow and i t s d c n s i t y

-

Snow, I c e a n d P e r m a f r o s t R e s e a r c h E s t a b - l i s h m e n t A b s t r a c t S I P 34-42, November 1 9 5 4 .

4.

D m i t r i e v a , l I , G . C a l c u l a t i o n of snow-cover d e n s i t y u s i n g m e t e o r o l o p i c a l d a t a . ( R a s c h e t p l o t n o s t i s n e z h n o g o p o k r o v a po m e t e o r o l o ~ i s c h e skim dannym) M c t e o r o l o - r t i i a i ~ i d r o l o q i i a , no. 2 , 1950. Snow, 1 c e a n d . P e r m a f r o s t RA'senrch E s t a b l i s h m e n t T r a n s l a t i o n No. 2 4 , J a n u a r y 1954.

5.

P e a r c e , D . C . and

L.W.

Gold. ?he C a n a d i a n snow s u r v e y 1947-50, T e c h n i c :7,1 I!e:;~orandum No. 2 1 , A:: s o c i a t e Committee on S o i l and Snow M e c h a n i c s , N a t i o n a l R e s o a r c h C o u n c i l , A u g u s t , 1 9 5 1 .

6.

Diamond, lvI., a n d 'ti.P. Lowry. C o r r e l a t i o n o f t h e d e n s i t y of new snow w i t h 700

mb

t e m p e r a t u r e , A u g u s t , 1 9 5 3 , Snow, I c e a n d P e r m a f r o s t R e s r a r c h E s t a b l i s h m e n t R e s o n r c h P a p e r No. 1.

7.

B o s s o l a s c o , 13. f a l l e n snow and air t e m n e r a t u r e , N a t u r e , Noye?:{, ?. 362-363, n u r u s t

1954.

8

Weinberg, 3 . P . Snow, r t n e , hail, i c e and g l a c i e r s , 2nd E d i t i o n , "ONTI", ~ ? ~ ~ / s N E G , INm, GRAD, LYeD, 2 LEDNIICI

.

9. H o e l , P a u l

G.

I n t r o d u c t i o n t o m a t h e m a t i c a l s t a t i s t i c s , J o h n ; d i l e y a n d S o n s I n c . , New York.

TABLE I S t a t i o n Exposed d i n n i p e g A k l a v i k R e s o l u t e O l d G l o r y Ottawa Ilo o s one e 'dhi t e h o r s e S h e l t e r e d F t . C h u r c h i l l Goose 3ay

CALCULATED VALUES FOR DENSITY DISTBLBUTION

DIAGRAMS SHOWN ON _FIGURE 2 .

PI e

an

S t a n d a r d Skewness P e a k e d n e s s

,/AH L A V r K /

.

7---

/

r - -

I I I / I L E G E N D : @ E X P O S E W S T A T I O N S H E L T E 9 E P STATION

M A P

S H O V I N G

T H L

L O C A T I O N S

of

SNOW

S U R V E Y

O B S E R V A T I O N

STAT1 O N S

-

I

OLD

G L O R Y

I

OOSL BAY

Y

1 2 3 4 5 6 7 8 91011 12 1 2 3 4 5 6 7 8 9 l O l l l 2 C L A S S 1 N T L G V A L C L A S S I N T L R V A L

E . X P O S E V

_STATIONS

_S

_{H E L T L R E V}

_STATIONS

L E G E N D : C L A S S

I

LIMITS =

0 - 0 0 5 ,

C L A S S 2 LIMITS=

-03

- * I 0 [ D E N S / T Y )

F I G U R L

2

S N O W _{V E - N S I T Y U I A G R A M S}

_{A T}

_SE.Ll5CTE.V

S T A T I O N S

A C q O S S C A N A V A . 0 2 9 7 7 - 2

SURFACE, _{I I I I 1 1 I I I I 1} - -172

-233

_-155

-233

_.I10

_{e l 8 8}

-142

_-130 a20 3 6 P

-

SHELTERED STATIONS

-

-

O

-

"5

'I0 D E d C / T Y 5 C A L &

.

I I 1 1 I I I I I I I _t S U R F A C E , I I I 1 I I I I I I I

i

-

-

-

-

-

EXPOSED

STATIONS

-

FIGURE

3 .

AVERAGE DENSITY- DEPTH CHANGES AT

X -

SHELTERED

STATIONS

I

I

I

2

- 3

-4

V E N S I T Y

8"-

12" L A Y W X

S T A T I O N S

F I G U R E ,

4

W E N S

I T Y

M E A S U R E M E N T S

AT

8"-

12"

LAYER

AS I N P I C A T O R

D E ~ J S I T ' Y FROM

12'-

36"

t

1 - 1 DENSlTY SCALE 0 so5 .I0 9284 '358 v) I:

z

0 w Irl MAR-

-

I- APR.

-

EXPOSED STATIONS I DENSITY SCALE 0

-05

-10

FIGURE

5 .

AVERAGE DENSITY T I M E CHANGES A T SELECTED

STATIONS ACROSS CANADA.

0-16 INCH. DEPTH.

SNOW DENSITY

(AVERAGE OF AT L E A S T

3 READINGS) AT L E A S T 1 2 ~ 0 ~

SNOW

,

NO MORE T H A N

3aM

OF SNOW.

F I G U R E 6

BI-WEEKLY C H A N G E S IN O V E R - A L L S N O W

,I 88

D E N S I T Y 6 - 3 6 . SHELTERED A N D E X P O S E D

S T A T I O N S , DECEMBER

.

J A N U A R Y A N D

FEBRUARY.