Chapter 5 A Climate Overview of the Canadian Inland Seas

79 Chapter 5

A CLIMATE OVERVIEW OF THE CANADIAN INLAND SEAS

J.B.

MAXWELL

I NTRODUCTI0 N I n comparison w i t h most o t h e r lands around t h e globe a t t h e same l a t i t u d e i n the northern hemisphere, those i n t h e v i c i n i t y o f Hudson Bay and James Bay are abnormally cold. T h i s has been r e a l i z e d ever since Henry Hudson s a i l e d i n t o the bay t h a t bears h i s name w e l l over t h r e e c e n t u r i e s ago. He and subsequent explorers noted the cold, windswept and c l i m a t i c a l l y i n h o s p i t a b l e conditions t h a t predominate (Thompson, 1968). While weather observations had been taken systematically by f u r t r a d e r s a t a number o f posts during t h e eighteenth century, t h e frequent t r a n s f e r s o f personnel and t h e i n t e r m i t t e n t usage o f t h e posts themselves r e s u l t e d i n few records o f appreciable duration. It was n o t u n t i l C h u r c h i l l was opened i n 1931 as a terminus f o r a n o r t h e r n sea r o u t e t o t r a n s p o r t g r a i n and o t h e r goods through Hudson Bay and Hudson S t r a i t t o European markets t h a t a comprehensive network o f weather observing s t a t i o n s began t o develop. The need f o r wireless s t a t i o n s t o provide weather i n f o r m a t i o n and navigational assistance along the new r o u t e r e s u l t e d i n weather observing programs a t such locat i o n s as Chesterfield, Inukjuak (formerly P o r t Harrison), Coral Harbour and Nottingham Island. Soon a f t e r , observations a t Moosonee and Kuuj juarapik ( f o r merly Poste de l a Baleine and p r i o r t o t h a t Great Whale R i v e r ) began and they, along w i t h s h o r t e r periods o f data from Winisk and F o r t George, provide a knowledge o f the c l i m a t e o f t h e southern sections o f t h e I n l a n d Seas region. I n the north, around Foxe Basin, t h e development o f t h e D i s t a n t Early Warning (DEW) radar l i n e r e s u l t e d i n the establishment o f weather observing programs a t H a l l Beach, Rowley I s l a n d and Longstaff B l u f f i n t h e 1950's. Locations are i n d i c a t e d on Figure 5.1. I n t h e meantime, the passage o f ships p a r t i c u l a r l y through t h e waters o f northern Hudson Bay b u t a l s o i n the other areas o f t h e Foxe-Hudson-James region has provided a modest data s e t o f o f f s h o r e weather observations which allows comparison between coastal and o f f s h o r e c o n d i t i o n s during t h e navigat i o n season. A b r i e f program o f o f f s h o r e hydrocarbon e x p l o r a t i o n about 15 years ago a l s o provided some o f f s h o r e weather information; c u r r e n t l y , renewed i n t e r e s t i n t h e r e g i o n ' s hydrocarbon p o t e n t i a l and t h e probable necessity t o provide an improved weather f o r e c a s t i n g c a p a b i l i t y promise t o provide more.

80

HUDSON

BAY

Churchill

Kuujjuaq

MANITOBA

QUEBEC

/' / '

I'

f'

500

50"

70'

Figure 5.1.

Location map.

The discussion o f c l i m a t e t h a t f o l l o w s draws upon p a s t c l i m a t o l o g i e s prepared by Thornpson (19661, Archibald (19691, Danielson (1969) and Maxwell (1980, 1982). Data presented a r e taken from t h e 1951-80 normals p e r i o d where available. CLIMATE CONTROLS Radiation Regime The surface heat budget o f t h e Hudson Bay area was looked a t i n d e t a i l by Danielson (1969) and h i s comments remain v a l i d f o r t h e most p a r t . From May through August, s o l a r r a d i a t i o n dominates t h e heat budget d e s p i t e t h e r e s t r i c t i o n t h a t t h e h i g h surface albedo places on t o t a l income. With t h e presence o f warm a i r over t h e c o l d waters and f l o a t i n g ice, long-wave heat loss i s a t a minimum, so t h a t t h e highest mean d a i l y n e t r a d i a t i o n i s recorded during t h i s time. I n September, s o l a r h e a t i n g becomes l e s s important and longwave and t u r b u l e n t heat losses begin t o dominate so t h a t by January, n e t r a d i a t i o n i s a t a minimum w i t h mean d a i l y values near -2 Ml/mz. The long-wave losses t h a t continue through t h e w i n t e r a l l o w t h e i c e cover (which i s complete across the region) t o reach i t s maximum thickness i n A p r i l . A t t h a t time, solar r a d i a t i o n income increases sharply and n e t r a d i a t i o n values become posit i v e once again. Figure 5.2 i l l u s t r a t e s t h e s o l a r and n e t r a d i a t i o n regimes f o r l o c a t i o n s i n each o f James and Hudson Bay and Foxe Basin. H a l l Beach, located on the west coast o f t h e l a t t e r , shows t h e impact o f continuous n i g h t / continuous day on t h e incoming s o l a r r a d i a t i o n a maximum f o r t h e whole region received i n June, b u t none a t t h e h e i g h t o f winter.

-

Nature o f Imnediate and Adjacent Surfaces The bodies o f water themselves are e i t h e r characterized by i c e cover o r very c o l d surface waters. Generally, t h e January t o A p r i l p e r i o d experiences an i c e cover o f nearly 100 percent w i t h occasional leads, p a r t i c u l a r l y along the Hudson Bay coasts and near t h e Belcher Islands i n t h e southeast. From Ma.y t o mid-August, t h e i c e cover d i s s i p a t e s beginning w i t h t h e east and west coastal areas o f Hudson Bay, the south end o f James Bay and t h e area o f Foxe Basin t o the east o f H a l l Beach. I c e c l e a r i n g expands from these areas so t h a t by August, t h e remaining i c e l i e s i n t h e southwestern areas o f Hudson Ray and i n t h e northern and southern areas o f Foxe Basin. From then u n t i l early October, i c e c l e a r i n g i s complete over Hudson and James Bay and f r e quently so over Foxe Rasin. By mid-October, i c e cover s t a r t s t o reform i n the northwestern area o f Foxe Basin and around Southampton Island, and then generally spreads southwards. The impact o f t h i s regime i s such t h a t i n winter, t h e sea i c e cover causes t h e water bodies t o experience t h e same climate as t h e snow-covered tundra surrounding them. I n summer, t h e very c o l d waters l i m i t a i r temperatures i n the immediate coastal areas t o l i t t l e more than 5 t o 7°C h i g h e r than those o f t h e water i t s e l f . A l l o f the coastal lands around Foxe Basin and much o f those surroundi n g Hudson Bay are characterized by continuous permafrost. Patchy o r discon-

82 I

Solar Radiation

24

20

16

12 Mjlm2

a

4

0

-4

J

F

M

A

M

J

J

A

S

O

N

D

MONTH

Figure 5.2. Mean daily global solar and net radiation. tinuous permafrost can be found along the south and e a s t shores of Hudson Bay and around James Bay. The presence of permafrost has an important impact on the summer climate of the area particularly t o the west of Hudson Bay, f o r i t i s a t l e a s t p a r t i a l l y responsible f o r the water-logged s t a t e of the terrain. Water from melting snow or spring rains i s unable t o penetrate the frozen ground; instead i t simply collects i n puddles, small ponds and s h a l l m streams on the land. The r e s u l t i s a wet, swampy surface - evaporation from which consumes heat energy i n the summer which could otherwise be available t o increase a i r temperatures. Physical Geography In Canada, two of the major barriers t o large-scale a i r movement a r e the mountains of the western Cordillera and t o a l e s s e r extent the ranges on Raffin Island and northern Labrador. These tend t o r e s t r i c t o r modify the direct entry of a i r from e i t h e r the Pacific o r Atlantic Oceans respectively. Generally, the Foxe-Hudson-James region benefits i n t h i s regard; on the other hand, the region l i e s exposed t o outbreaks of cold a i r from the a r c t i c regions during a l l seasons and t o occasional intrusions of warm a i r from the s o u t h i n summer. The lack of major topographical features r i g h t i n the region means t h a t local climates are often dependent on variations i n t e r r a i n , vegetation and drainage. The western and southern coasts of Hudson Bay and nuch of James Bay's coastal stretches are generally a low coastal plain. Along eastern Hudson Ray, hmever, nuch of the land (both islands and mainland) r i s e s f i r s t

83 abruptly and then more g r a d u a l l y t o about 500 m w i t h lower a l t i t u d e s f u r t h e r east. Such c o n d i t i o n s r e s u l t i n a m o d i f i e d c l i m a t e on t h e leeward s i d e s o f t h e islands and inland. Around Foxe Basin, nuch o f t h e western and southern coasts have elevated l a n d masses w h i l e t h e e a s t e r n side, on B a f f i n I s l a n d , presents a l o w coastal p l a i n which g r a d u a l l y r i s e s inland. C i r c u l a t i o n and Weather Systems The u p p e r - a i r c i r c u l a t i o n c o n t r o l l i n g t h e movement o f weather systems over t h e I n l a n d Seas r e g i o n i s mainly r e l a t e d t o t h e l o w pressure v o r t e x which i s s i t u a t e d over n o r t h e r n B a f f i n I s l a n d i n winter, b u t which weakens and r e t r e a t s northward i n summer. As a r e s u l t , w i n t e r i s c h a r a c t e r i z e d by a genera l northwesterly t o w e s t e r l y f l o w over t h e western h a l f o f t h e r e g i o n and westerly t o southwesterly f l o w over t h e east. Low pressure systems u s u a l l y remain south o f t h e I n l a n d Seas, only a f f e c t i n g t h e r e g i o n when they recurve northward over Davis S t r a i t . I n so doing, they o f t e n induce s t r o n g n o r t h e r l y t o northwesterly s u r f a c e winds as they pass. D u r i n g summer, a g e n e r a l l y westerly f l o w over t h e e n t i r e r e g i o n e x i s t s , although much l e s s i n t e n s e than i n winter. Storms nw o f t e n move d i r e c t l y across Hudson Bay from t h e west a l l o w i n g warm, moisture-laden a i r from t h e south t o i n f l u e n c e t h e I n l a n d Seas (although a c t u a l surface a i r temperature c o n d i t i o n s a r e s t i l l u s u a l l y s t r o n g l y a f f e c t e d by t h e c o l d waters o f t h e r e g i o n ) . F i g u r e s 5.3 and 5.4 i l l u s t r a t e t h e frequency o f l o w pressure systems i n f l u e n c i n g t h e various areas o f t h e I n l a n d Seas region. SEASONS S i m i l a r t o most areas o f Canada's North, t h e I n l a n d Seas r e g i o n does not conform e x a c t l y t o t h e four-season p a t t e r n normally found i n southern Canada. Rearing t h i s i n mind, i t i s u s e f u l t o continue t o r e f e r t o t h e seasons o f autumn, w i n t e r , s p r i n g and summer f o r ease o f discussion. Autumn u s u a l l y l a s t s from e a r l y September through October and w i t h e a r l y w i n t e r (November t o mid-December) i s much t h e s t o r m i e s t time o f t h e year. During these months, c o l d a r c t i c a i r masses advance across t h e r e g i o n r e g u l a r l y i n 3 o r 4 day i n t e r v a l s w i t h t h e i r west-to-east paths moving p r o g r e s s i v e l y southward as t h e autumn days shorten and t h e u p p e r - a i r w e s t e r l i e s i n t e n s i f y . Large q u a n t i t i e s o f heat and m o i s t u r e a r e added t o t h e a r c t i c a i r masses as they pass from t h e c o l d lands over t h e s t i l l open waters o f Hudson and James Bays r e s u l t i n g i n cloudiness and snowfall p a r t i c u l a r l y along t h e eastern coasts. Generally, October and November (except November and December f o r southern Hudson Bay and James Bay) are t h e months o f g r e a t e s t snowfall, maxi-

mm cloudiness and s t r o n g e s t winds. Winter i s l o n g and cold. I n t h e n o r t h e r n h a l f o f t h e I n l a n d Seas region, i t l a s t s from November t o May; i n t h e southern h a l f , i t begins a l i t t l e l a t e r

and ends perhaps a month e a r l i e r . nnce w i n t e r does s e t in, however, t h e r e a r e b u t i n f r e q u e n t thaws, and temperatures l e s s than -15°C p e r s i s t f o r much o f t h e

Figure 5.3. Percentage frequency of occurrence o f cyclonic centres during December t o February. For example, the isoline enclosing the northeastern part o f Hudson Bay implies t h a t a cyclonic centre may be expected t o l i e within an area o f 400,000 km* centred on any point on t h a t line 6 percent of the time during December t o February.

Figure 5.4. Percentage frequency of occurrence of cyclonic centres during June t o August.

85

season. An important factor i s the conpletion of freeze-over of Hudson Bay i t s e l f by mid-December. Thereafter, aside from persistent shore leads and localized wind-induced patches of open water, Foxe Basin, Hudson Bay and James Bay display a uniform ice- and snow-covered surface much similar t o the surrounding snow-covered tundra areas. C1 oud, snowfall and temperature regimes show l i t t l e variation from west t o east. With the main storm tracks l y i n g t o the south, the region i s under the influence of a strong pressure gradient between the h i g h pressure of the Mackenzie-Keewatin areas t o the west and the low pressure of Baffin Bay-Davis S t r a i t t o the east. The r e s u l t i s f a i r l y strong winds throughout the winter. This, combined w i t h the cold tenperatures and the existing snow cover, r e s u l t s i n two of the best-known features of the region's climate - extreme wind c h i l l and severe blowing snow. The s p r i n g season i s a l a t e , cool one conpared t o spring further south. I t i s a short, transitional period extending from May t o June, characterized by rapidly lengthening hours of day1 i g h t , above-freezing temperatures and diminishing snow cover. Surface travel becomes extremely d i f f i c u l t due t o the runoff streams covering the tundra and the deteriorating i c e of the waterways themselves as well as the adjacent lakes and rivers. The remaining two months of the year, July and August, conprise the summer, normally a cool, cloudy season extending from the time the tundra i s finally c l e a r of snow and appreciable amounts of sea i c e have disappeared, until the f i r s t snow f l u r r i e s of autumn. During these months, the temperatures of the vast, cold water surfaces of the Inland Seas region contrast sharply w i t h those of the surface layer of the atmosphere, resulting i n extensive fog and cloud coverage both over the water and along the coasts, depending upon wind direction. TEMPERATURE W i t h the onset of autumn, outbreaks of cold a i r from the Arctic Basin

begin to drop mean daily a i r temperatures over the northern parts of the region below freezing. In October, values range from -10°C i n Foxe Basin t o -4°C along Hudson S t r a i t , -1 t o 0°C i n central Hudson Bay and +3"C over southern James Bay (Fig. 5.5A). As Hudson Bay remains open into early December, the moderating e f f e c t of the broad expanse of water i s increasingly f e l t along the leeward e a s t coasts relative t o conditions along the western side. In November, for example, mean daily temperatures along the eastern coastlines are i n the -5 t o -8°C range conpared w i t h -12 t o -18°C i n the west. Once ice covers Hudson Bay i n December, w i t h the exception of persistent shore leads, polynyas and wind-induced patches of open water kilometers from the shore, the surface becomes essentially the same as the snow-covered tundra surrounding i t w i t h the result t h a t variation i n the temperature regime from west t o east is modest. In January, mean daily temperatures vary from a low of -32°C i n the northwestern Hudson Bay area t o -28 t o -30°C over Foxe Basin, -25

86

Figure 5.5.

Mean daily tenperature ( " C ) .

87 t o -27'C over c e n t r a l Hudson S t r a i t , and -20 t o -22°C over James Bay (Fig. 5.58). By e a r l y spring, i n May, c o l d a i r s t i l l dominates the region, b u t i n a slow1.y receding wedge, as warm a i r reaches t h e southern c o a s t l i n e s w i t h i n creasing frequency. Mean d a i l y temperatures are i n t h e -5 t o -10°C range i n the north, b u t near f r e e z i n g i n the south (Fig. 5.5C). In summer, as Hudson Bay, James Bay, Hudson S t r a i t and sometimes Foxe Basin c l e a r o f ice, the r e l a t i v e coldness o f t h e water bodies r e l a t i v e t o the warmer a i r moving over them causes sharp temperature i n v e r s i o n s i n t h e lowest layers o f t h e atmosphere. The J u l y map shows pools o f surface a i r over Hudson Bay, Hudson S t r a i t and Foxe Basin d i s t i n c t l y c o o l e r than adjacent l a n d areas (Fig. 5.5D). Over-water temperatures i n J u l y are i n the 5 t o 7°C range w i t h coastal s t a t i o n s being warmer by about 2°C f o r Foxe Basin and Hudson S t r a i t and by about 5°C f o r c e n t r a l and southern Hudson Bay. James Bay i s t h e warmest area o f a l l , both over water and along t h e coasts, w i t h temperatures ranging from 12°C t o 15°C from n o r t h t o south. Extremes o f l o w temperature (which u s u a l l y occur i n January, b u t occas i o n a l l y i n February) are i n the -45 t o -50°C range over Hudson and James Bays. Over northern Hudson Bay and Foxe Basin, extremes a r e about 5°C colder. Along Hudson S t r a i t , the p r o x i m i t y o f warmer a i r t o t h e east keeps extreme lows from being below -45°C. It i s apparent then t h a t t h e r e g i o n ' s r e p u t a t i o n f o r severe c o l d does n o t r e s t on i t s extreme low temperatures f o r correspondi n g values are nuch lower, f o r instance, i n t h e Mackenzie and Yukon areas t o the west. Rather, c o l d c o n d i t i o n s t h a t p e r s i s t over prolonged periods and frequent, severe wind c h i l l a r e t h e s i g n i f i c a n t factors. Extreme maximum temperatures are i n the 30 t o 35°C range a t Hudson and James Bays coastal l o c a t i o n s (+37.8'C a t Moosonee i n t h e extreme south). Over the water i t s e l f , the values are probably 5 t o 10°C lower. I n t h e Foxe Basin and Hudson S t r a i t areas, corresponding values are i n t h e 20 t o 25°C range both over water and along the coast. Only along t h e southern coast o f Hudson S t r a i t are higher extremes found, as t h a t i s the only p a r t o f these areas t h a t can experience warm a i r unmodified by a t r a j e c t o r y over r e l a t i v e l y c o l d water. F i g u r e 5.6 shows mean and extreme temperatures f o r selected s t a t i o n s across the region. WIND

October and November (November and December i n t h e south) are t h e months o f highest monthly mean and extreme surface wind speed over t h e I n l a n d Seas region. During t h i s period, w i t h t h e shortening autumn days and annual southward i n t e n s i f i c a t i o n o f the upper-level wester1 ies, t h e r e i s a corresponding southward displacement o f t h e paths taken by t h e storm centres. S i t e s surrounding the various water bodies, b u t p a r t i c u l a r l y Hudson Bay, a r e q u i t e vulnerable t o strong winds because o f t h e i r exposure t o open sea on one s i d e and t r e e l e s s tundra on the other. Average surface wind speeds are 20 t o 25

88

Figure 5.6.

Mean and extreme temperatures.

km/h ( s l i g h t l y higher i n Hudson S t r a i t , s l i g h t l y lower around James Bay) w i t h extremes highest over Hudson S t r a i t and northern Hudson Bay (Table 5.1). Prev a i l i n g winds are generally northwesterly except i n the southeast where the l a s t remaining open-water surface i n Hudson Bay i s r e f l e c t e d by frequent easte r l y winds a t Kuujjuarapik (Fig. 5.7, 5.8). During t h e winter, most o f t h e bad weather t h a t occurs over t h e I n l a n d Seas e i t h e r r e s u l t s from temporary changes i n the d i r e c t i o n o f t h e upper-wind f l o w (which causes storms t h a t would normally pass t o t h e south t o d e v i a t e t o a more northeastward d i r e c t i o n t o a f f e c t Hudson Bay), from storms moving up t h e Labrador coast, o r from f l u c t u a t i o n s i n t h e normally s t r o n g g r a d i e n t between high pressure over Mackenzie-Keewatin and l o w pressure over Davis S t r a i t . I n t h e f i r s t two cases, clouds, sncw and wind may r e s u l t ; i n t h e other, mainly s t r o n g wind. I n Canada, Hudson Bay i s one o f t h e w i n d i e s t areas i n w i n t e r although as w i t h t h e temperature, i t i s a case o f p e r s i s t i n g condit i o n s r a t h e r than extremes. Most importantly, wind combines w i t h l o w temperat u r e and snow t o c r e a t e severe wind c h i l l and blowing snow events. With the a r r i v a l o f s p r i n g comes a gradual change i n t h e upper-wind p a t t e r n s and weakening o f t h e i r i n t e n s i t y . High pressure i s s t i l l dominant throughout most o f the I n l a n d Seas region and average surface wind speeds a r e generally lower than during t h e winter. The exceptions are along t h e Hudson

89

Model

(

i'

%calm

Figure 5.7.

January percentage frequency o f wind occurrence by d i r e c t i o n .

90

@

%calm

Figure 5.8.

July percentage frequency of wind occurrence by direction.

91 TABLE 5.1 Monthly and annual wind speed Station

Chesterfield Coral Harbour Hall Beach Resolution I s l a n d Cape Hopes Advance Inukjuak Kuujjuarapi k Moosonee Churchill

Mean wind speed (km/h) Maximum wind SDeed (km/h) Feb.

Apr.

Jun.

Aug.

Oct.

Dec.

Ann.

24.6 80 20.2 135 22.5 97 40.4 130 30.0 97 17.2 59 16.9

21.4 78 19.3 93 20.8 74 34.5 137 26.5 90 23.6 74 17.0 80 14.5 51 22.6 74

18.5 93 19.6 74 18.7 85 32.1 119 23.5 77 20.8 52 16.7 64 14.1 45 20.7 77

20.4 70 19.8 97 18.9 69 30.3 119 25.4 84 21.6 61 17.9 77 12.3 48 20.5 95

27.9 95 22.1 90 25.2 106 36.1 127 32.6 106 22.4 65 21.2 80 14.4 56 24.9 82

23.8 74 20.5 109 20.8 72 40.1 190 32.1 106 20.8 63 20.4 84 11.8 56 22.7 80

22.3 95 20.2 145 21.3 106 35.3 190 28.2 106 21.2 74 18.3 97 13.5 61 22.7

74

i2.2 60 24.1

1 1 6

Bay coastlines and i n Hudson S t r a i t where i n c r e a s i n g storm frequencies r e s u l t i n a secondary maximum ( d i s t i n c t from t h e primary autumn maximum) i n average wind speeds. I n c o n t r a s t t o t h e o t h e r seasons, surface winds i n summer can be q u i t e variable i n d i r e c t i o n since t h e l o w pressure areas t h a t a f f e c t t h e region complicate t h e i r patterns. They are generally t h e l i g h t e s t winds o f t h e year w i t h average values o f 15 t o 20 km/h except 5 km/h higher along Hudson S t r a i t . During t h e summer, wind i s most important i n terms o f i t s d i r e c t i o n a t coastal locations, where o f f - o r onshore flow c o n d i t i o n s can make tremendous d i f f e r ences i n the amount o f cloud and f o g experienced. Winds o f f t h e water can be q u i t e c h i l l y and uncomfortable i n J u l y w h i l e l a n d breezes o f t e n g i v e q u i t e warm weather. PRECIPITATION, CLOUD AND FOG The r e t u r n o f p r e v a i l i n g northwesterly winds i n t h e autumn d i c t a t e s the autumn cloudiness and snowfall t h a t occur. As a r c t i c a i r passes from the c o l d land over t h e r e l a t i v e l y warmer water, l a r g e q u a n t i t i e s o f heat and moisture are added t o i t r e s u l t i n g i n cloudiness and snowfall p a r t i c u l a r l y along t h e southeast coast. Generally, October and November (a month l a t e r i n t h e south) are the months o f greatest snowfall and maximum cloudiness. Annual snowfall t o t a l s range from 120 cm i n t h e n o r t h and 150 cm along Hudson S t r a i t t o 200 cm over Hudson Bay and up t o 250 cm i n the southeast (Table 5.2). Almost one-half o f these t o t a l s f a l l s during these 2 f a l l months, p a r t i c u l a r l y i n t h e l a t t e r area. September and October (and November i n t h e south) are cloudy months w i t h

92 TABLE 5.2 Mean monthly and annual r a i n f a l l and snowfall t o t a l s ~~

Station

Chesterfield Coral Harbour H a l l Beach Longstaff B l u f f Nottingham I s l a n d Resolution I s l a n d Cape Hopes Advance Inukjuak Kuujjuarapik Moosonee Churchill

~~

Mean r a i n f a l l (mm) Mean sncwfall (cm)

( t r = trace)

Feb.

Apr.

Jun.

Aug.

Oct.

0.0 4.5

0.4 11.5

9.2 0.0

14.4 0.1 11.5 0.0 10.7 0.0 11.8 0.0 10.5 0.2 12.1 1.9 13.3 5.2 22.1 21.4 21.2 2.0 22.3

17.9 5.1 18.5 8.1 10.5 6.2 5.7 7.9 14.4 10.7 16.3 3.7 25.5 7.1 31.1 3.7 51.7 4.8 77.9 0.8 39.9 3.5

38.6 0.2 44.2 0.3 39.1 1.8 34.2 2.2 38.1 0.6 94.9 3.3 45.7 0.2 64.9

9.4 24.3 11.3 26.7 0.3 21.5 0.5 28.3 6.8 30.8 11.8 22.6 9.0 19.2 24.4 22.0 46.3 27.3 60.2 14.5 15.4 29.3

tr

8.5 0.0 5.2 0.0 10.4 0.1 10.8 tr

14.2 0.0 8.7 0.3 24.2 1.8 30.0 0.1 14.6

tr

tr

94.0 0.0 79.2 0.0 58.3 0.0

Dec. tr

13.8 tr

10.8 0.0 9.2 tr

5.3 0.0 14.3 0.1 19.1 0.2 25.1 0.1 23.2 1.0 42.0 3.9 39.9 0.2 22.8

-

Ann.

145.5 112.5 141.4 131.9 99.5 121.3 89.3 120.4 136.3 149.8 272.6 130.0 146.2 151.9 246.3 144.2 401.3 241.2 501.5 239.3 221.1 195.5

most s t a t i o n s r e p o r t i n g more than 80 percent average cloudiness skies being overcast, generally w i t h l o w clouds, on t h r e e o u t o f f o u r days during t h e autumn season. A i r operations may be s e r i o u s l y hampered by poor v i s i b i l i t y i n snowstorms, and by turbulence and r a t h e r severe i c i n g i n t h e l o w - l y i n g clouds. While w i n t e r snowfall i s n o t as heavy as during autumn, t h e snowfall season i s long. Snw covers t h e ground up t o 280 days i n northern Foxe Basin, 260 days along Hudson S t r a i t and gradually diminishing southward over Hudson Bay t o l e s s than 200 days i n t h e extreme south (Fig. 5.9). The l a t t e r , being much c l o s e r t o the major storm tracks, receives considerably more snow i n w i n t e r than does the north. Over Foxe Basin and Hudson Bay, w i n t e r i s genera l l y the season o f l e a s t cloudiness w i t h most s t a t i o n s r e p o r t i n g average c l o u d cover o f l e s s than 50 percent. Again t h e c l o s e r p r o x i m i t y t o t h e storm t r a c k s r e s u l t s i n greater c l o u d along t h e southern coasts and over Hudson S t r a i t . Localized steam f o g occurs over Hudson Bay due t o p e r s i s t e n t shore leads and wind-induced patches o f open water. I n spring, some thawing o f t h e snow and i c e begins, causing an increase i n the frequency o f occurrence o f l o w - l y i n g clouds. A t most locations, average cloudiness i s about 80 percent. Fog begins t o become a serious problem a t coastal l o c a t i o n s as open leads enlarge and become more numerous over James and Hudson Bays and Hudson S t r a i t . The f i r s t appreciable amounts o f r a i n f a l l

---

93

occur i n May p a r t i c u l a r l y across James Bay and southern Hudson Bay. More northerly l o c a t i o n s do n o t see s i g n i f i c a n t amounts u n t i l June on t h e average.

I

'

I

I

I

I

I

I

I

I

I

I

I

Church ill

-3D9

1

I

I

-3D@

Moosonee

-=elm-

I

I

Kuujjuarapik lnukjuak

Cape Hopes Advance d ou n f;e ;Nottingham Island Longstaff Bluff Hall Beach

*

Coral Harbour mean

I

l

l

Figure 5.9.

Chesterfield I

I

I

I

1

I

I

I

I

I

1

I

1

1

I

Disappearance and formation dates o f continuous snow cover.

Summer p r e c i p i t a t i o n i s heavier than t h a t o f any other season, w i t h a possible exception o c c u r r i n g i n the south where monthly amounts are f a i r l y s i m i l a r from May r i g h t through November. During J u l y and August, p r e c i p i t a - . t i o n i s e n t i r e l y i n the form o f r a i n over James Bay and southern Hudson Bay. I n northern Hudson Bay, along Hudson S t r a i t and i n Foxe Basin, some snow o r freezing p r e c i p i t a t i o n i s possible, b u t r a i n f a l l dominates. Monthly r a i n f a l l amounts i n summer range from 35 t o 40 mm i n t h e n o r t h t o 50 t o 60 mm i n cent r a l areas t o 80 t o 90 nun around James Bay so t h a t t h e J u l y and August t o t a l s amount t o between one-quarter and one-third o f t h e annual p r e c i p i t a t i o n regardless o f the p a r t i c u l a r area. The c o l d waters o f t h e r e g i o n a c t as a s t a b i l i z i n g influence, tending t o i n h i b i t shower development i n summer; t h i s shows up p a r t i c u l a r l y i n t h e l o w thunderstorm frequency over t h e northern h a l f o f Hudson Bay, i n Hudson S t r a i t and Foxe Basin. From C h u r c h i l l south, monthly frequencies increase from l e s s than one up t o 3 o r 4 a t Moosonee, and i n d i v i d ual events can be severe. F r o n t a l and maritime i n f l u e n c e s combine t o maintain q u i t e high average cloudiness d u r i n g t h e summer, generally o c c u r r i n g 70 t o 80 percent o f the t i m e w i t h decreasing frequencies inland. Probably t h e most

94 noticeable f e a t u r e o f t h e cloud/fog regime i s the high frequency o f f o g which develops under t h e sharp temperature i n v e r s i o n r e s u l t i n g from t h e c o n t r a s t between the c o l d waters o f t h e region and t h e r e l a t i v e l y warmer a i r above i t (Table 5.3). With strengthening winds, the f o g does l i f t , b u t only t o form l o w - l y i n g clouds. Fog i n Hudson S t r a i t i s a p a r t i c u l a r concern t o shipping, s t a t i o n s along the S t r a i t having the greatest number o f days w i t h f o g during J u l y and August when shipping i s a t i t s peak. The frequency varies from over one day i n two a t Resolution I s l a n d i n t h e east t o one i n t h r e e a t Nottingham I s l a n d i n t h e west. Frequencies s i m i l a r t o t h e l a t t e r occur i n Foxe Basin and i n eastern and southern Hudson Bay. Lesser frequencies c h a r a c t e r i z e t h e west coasts o f Hudson Bay where o f f s h o r e winds dominate i n J u l y and August. TABLE 5.3 Frequency o f f o g occurrence Station

Chesterfield Coral Harbour H a l l Beach Longstaff B1 u f f N o t t i ngham I s l a n d Resolution I s l a n d Cape Hopes Advance Inukjuak Kuujjuarapik Moosonee Churchill

Mean number o f days w i t h f o g Feb.

Apr.

Jun.

Aug.

Oct.

Dec.

1

3

2 3 3 2 15 4

5 5 7 12 7 20 14 7 9

4

8

6 5 9 12 12 21 17 9 9 2 6

4 5 4 9 3 20 6 3 1 1 4

2 2 4 3 1 12 1 1 1 1 1

3 7 2 1 11 2

1 1 1 2

3 3 2

1

Ann.

42 44 68 83 47 196 85 46 45 17 48

COMBINED EFFECTS The combination o f strong winds, l o w temperatures and snowfall leads t o some o f the most severe events t h a t occur over t h e I n l a n d Seas region high wind c h i l l , blowing snow and blizzards. Wind c h i l l , which s i g n i f i e s an i n creased c o o l i n g e f f e c t r e s u l t i n g from low temperatures and strong winds occurr i n g together, i s a t o r near i t s most extreme f o r a l l o f Canada i n t h e western

-

Hudson Bay and adjacent l a n d areas. The h i g h e s t monthly wind c h i l l values a t Canadian weather s t a t i o n s occur a t Baker Lake and C h e s t e r f i e l d (Table 5.4) and i t i s d i f f i c u l t t o imagine much more p e n e t r a t i n g c o l d than t h a t a t C h u r c h i l l on January 25, 1957 when winds o f 80 km/h w i t h gusts t o 110 km/h acconpanied temperatures o f -36°C (Thompson, 1968). Generally, one can g a i n a good impression o f t h e s e v e r i t y o f t h e problem simply by considering t h e average wind speeds o f 20 t o 25 km/h t h a t occur across the region and t h e average January temperatures o f -25 t o -30°C. Such c o n d i t i o n s correspond t o a c o o l i n g r a t e o f near 2300 watts m r , a l e v e l a t which c o n d i t i o n s f o r outdoor t r a v e l such as walking become dangerous and exposed areas o f the face freeze i n l e s s than 1 minute f o r the average person.

95 TABLE 5.4 Wind-chi1 1 occurrence Station

Chesterfield Coral Harbour Hall Reach Longstaff B l u f f Nottingham I s l a n d Resolution I s l a n d Cape Hopes Advance Inukjuak Kuujjuarapi k Moosonee Churchill

Maximum c o o l i n g r a t e experienced (watts

m-2)

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

2770 2526 2717 2574 2204 2408 2170 2264 2091 2008 2523

2930 2742 2923 2839 2445 2557 2452 2563 2442 2336 2654

3118 2879 3189 2919 2617 2733 2796 2779 2690 2534 2936

3107 2999 3045 2975 2645 2941 2759 2599 2567 2365 2825

3019 2836 2929 2819 2624 2751 2642 2529 2463 2195 2780

2780 2637 2590 2551 2579 2522 2418 2242 2210 1889 2391

The c h i e f cause o f r e s t r i c t e d v i s i b i l i t y i n t h e region during t h e w i n t e r i s blowing snow. As w i n t e r snowfall i s u s u a l l y o f a f i n e powdery nature, i t i s easily picked up and blown along by the r e g i o n ' s s t r o n g winds. Table 5.5 gives the average number o f days w i t h blowing snow, i n d i c a t i n g t h a t the most f r e quent occurrence i s i n the northwestern Hudson Bay and Foxe Basin areas where one day i n t h r e e experiences blowing snow from November t o March. TABLE 5.5 Frequency o f blowing snow occurrence Station

Chesterfield Coral Harbour Hall Beach Longstaf f 61u f f Nottingham I s l a n d Resolution I s 1and Cape Hopes Advance Inukjuak Kuujjuarapi k Moosonee Churchi 11

*

Mean number o f days w i t h blowing snow Feb.

Aor.

Jun.

11 9 10 5 8 9 5 9 7 4 11

7 8 8 5 6 6 4 8 5 1 5

* 1 1 1

* 1

* * * * *

Aua.

Oct.

Dec.

Ann.

0 0

5 5 10 6 4 5 4 2 3

10 9 10 5 9 9

72 64 76 45 55 55 41 62 52 18 64

* *

0

*

0 0 0 0 0

*

4

7 11 10 3 10

less than 1

The combination o f strong winds, l w temperature and f a l l i n g snow i n i t s severest form i s c l a s s i f i e d as a b l i z z a r d , during which outdoor human o r animal a c t i v i t y i s rendered impossible. While actual f a l l i n g s n w may cease a f t e r perhaps 24 hours, continued blowing snow can e f f e c t i v e l y maintain b l i z zard-like conditions f o r a nuch longer period. The Foxe Basin-northwestern

96 Hudson Bay area i s most a f f e c t e d i n t h i s regard w i t h b l i z z a r d c o n d i t i o n s occ u r r i n g 5 t o 7 percent o f the time i n January and February. Lesser frequencies occur i n Hudson S t r a i t and i n t h e southern h a l f o f t h e region. SEA STATE Exact d e s c r i p t i o n o f the sea s t a t e o f the various waterways o f t h e I n l a n d Seas region during the navigation season i s d i f f i c u l t due t o the lack o f suff i c i e n t r e l i a b l e data on wave heights and periods. During t h e 1951-80 period, data c o l l e c t e d by ships-of-opportunity i n the western Hudson Bay area amount t o a t best about 300 t o t a l observations f o r a given month over t h e 30 years combined. Other areas have much less, p a r t i c u l a r l y southeastern Hudson Bay, James Bay and Foxe Basin. Table 5.6 shows observed wave h e i g h t and wave p e r i o d i n f o r m a t i o n summarized f o r various marine areas i n t h e region. The number o f observations i n d i c a t e d suggests c a u t i o n be exercised i n using t h e data.

TABLE 5.6 Summarized wave data Location

Northern Hudson Bay Southern Hudson Bay Hudson S t r a i t Foxe Basin

*

No. observations Median Maxi mum No. observations Median Maximum No. observations Median Maximum No. observations Median Maximum

Wave h e i g h t (m)

Wave p e r i o d (sec)

Aug.

Sep.

Aug.

Sep

270 0.9 5.6 41 1.5 3.7 162 0.7 8.0

308 1.0 8.0 29 1.1 4.5 134 0.9 6.0 42 0.7 2.6

230

27 1

*

-

5 10 41 6 8 149 5 10

*

-

-

22 127 35

. 5 10 5 8 5 10

5 8

= l e s s than 10 observations

During o f f s h o r e exploratory d r i l l i n g conducted i n t h e 1969-70 period, data c o l l e c t e d i n the southwestern area o f Hudson Bay using a ship-borne wave meter suggested a mean wave o f h e i g h t 0.7 t o 2.0 m w i t h p e r i o d 5 t o 6 seconds and a maximum observed swell o f 4.0 m, p e r i o d 8 seconds (EAG, 19841, w e l l w i t h i n t h e range o f values suggested by the ships-of-opportuni t y data. CLIMATE VARIABILITY AND CHANGE I n Canada as a whole, t h e 20th century instrumental r e c o r d shows a warmi n g t r e n d reaching i t s peak i n the 1940's t o e a r l y 1950's f o l l o w e d by c o o l i n g through t h e 1960's and i n t o t h e e a r l y 1970's. then a l e v e l l i n g - o f f w i t h a tendency towards warming again i n the l a t e 1970's and e a r l y 1980's. This i s g e n e r a l l y i n agreement w i t h t h e northern hemi spheric trend.

5

0

E 2

-5

3

w

f?0 )

Q

-10 Longstaff Bluff -1 5

-20'

20

1930

I

1940

1950

Year

1960

1970

,

1980

B 199

Figure 5.10. Mean annual ( s o l i d l i n e s ) and 5-year running mean (dashed l i n e s ) temperatures.

98 The Inland Seas region r e f l e c t s the trend f o r Canada as a whole quite closely. Figure 5.10, which shows mean annual tenperature trends a s well a s 5-year running means f o r a selection of s t a t i o n s covering the region, indicates, w i t h the exception of a couple of s t a t i o n s along Hudson S t r a i t where records end by 1970, a f a i r uniformity of pattern across the region. A warmi n g peak occurs i n the early 1950's and is following by cooling t o the early t o mid-l960's, a brief warming i n the l a t e 1960's, cooling again i n the early t o mid-1970's and warming thereafter. There are some differences i n the relat i v e strengths of the peaks and troughs, principally along southeastern Hudson Bay and James Bay where the magnitudes (as depicted by the 5-year r u n n i n g means) of the warm events of the l a t e 1960's and the present do not rival t h a t of the early 1950's. In the other areas, particularly i n western Hudson Bay (Churchill and Chesterfield), current temperatures are comparable t o those of the early 1950's. In terms of individual years, the year uniformly coldest across the region i n the past 50 years was 1972. No individual year was u n i formly warmest across the e n t i r e region. SUMMARY Despite the relative lack of observational data from over the water bodies themselves, a f a i r l y reliable picture of the region's climate has been b u i l t up over the past three decades. The i n s t a l l a t i o n of additional coastal stations or the increased monitoring of offshore conditions through s a t e l l i t e s or observing programs on ships or d r i l l i n g platforms would, of course, f i l l i n much detail i n the climate picture. In l i g h t of such programs' expense, however, increased s t u d y of local climates and particularly the development of relationships between conditions a t adjacent land and marine s i t e s a r e extremely useful. So too is the development of synthetic offshore climatologies for such variables as w i n d and waves, which can be derived from surface pressure data sets, f o r example. Perhaps more f r u i t f u l than any of these approaches i s the study of past climate. The Hudson and James Bay areas are quite rich i n proxy records derived from historical archives (Hudson's Bay Company) and dendrochronology. Wilson (1982, 19831, Ball and Kingsley (1984) and Ball (1985) have used such records w i t h promising levels of success. I t appears t h a t mch my be learned about the region's response t o climate change through the study of such past climate indicators. Improved understanding of this response will enable researchers t o develop more reliable scenarios of future climate under conditions such as increased concentrations of atmospheric carbon dioxide. Further research along these 1 ines i s certainly warranted.

REFERENCES Archibald, D.C., 1969. Intense storm tracks over Hudson Bay, the eastern Nova Scotia coast and the Grand Banks. The Ice Seminar, CIM Special, Vol. 8: 1-9.

99

Ball, T., 1985. A dramatic change i n the general circulation on the west coast of Hudson Bay i n 1760 AD: synoptic evidence based on h i s t o r i c records. In Climate Change in Canada 5 Critical Periods i n the Quaternary Climatic History of Northern North Pmerica, Syllogeus 55, National Museums of Canada, Ottawa, pp. 219-228. Ball, T. and Kingsley, R.A. 1984. Instrumental temperature records a t two s i t e s i n central Canada: 1768 t o 1910. Climatic Change, 6: 39-56. Oanielson, E.W. J r . , 1969. The surface heat budget of Hudson Bay. Marine Sciences Manu. Rep. No. 9, McGill Univ., Montreal, 196 pp. EAG (Environmental Applications Group, Ltd. 1 , 1984. Environmental Literature Review, Hudson Bay Offshore Petrolem Exploration. Prepared f o r Canadian Occidental Petroleum Ltd. Maxwell, J.B., 1980. The Climate of the Canadian Arctic Islands and Adjacent Waters. Vol. 1. Atmospheric Environment Service, C1 imatological Studies No. 30, 531 pp. Maxwell, J.B., 1982. The Climate of the Canadian Arctic Islands and Adjacent Waters. Vol. 2. Atmospheric Environment Service, C1 imatological Studies No. 30, 589 pp. Thompson, H.A., 1968. The Climate of Hudson and James Bay. In C.J. Beals (Editor), Science, History and Hudsbon Bay, The Queen's Printer, Ottawa. Wilson, C.V., 1982. The Summer Season along the East Coast of Hudson Bay during the Nineteenth Century. Part 1. Canadian Climate Centre Report No. 82-4, 266 pp. Wilson, C.V., 1983. The Summer Season along the East Coast of Hudson Bay d u r i n g the Nineteenth Century. Part 2. Canadian Climate Centre Report No. 83-9, 222 pp.

-

100

Surface currents (velocity cm/sec) for August-September.

(From Dunbar, 1951)