Observations of Wind
in Nares Strait
There is incidental
evidence that winds
are strong …
but how strong?
And why?
Observations of
surface wind are
very sparse
3 November 2006
01:06 UTC
Numerical simulation demonstrates that wind along the
strait increases with end-to-end sea-level pressure drop
High terrain in northern Canada & Greenland can facilitate a
close juxtaposition of disparate SLP anomalies – here 41 mb
3 November 2006
00:00 UTC
Surface weather has been
routinely observed by field
teams operating from PCSP
camps along Nares Strait
Atkinson, D.E., B. Alt and K. Gajewski. 2000.
A new database of High Arctic climate data from
Polar Continental Shelf Project archives.
Bull. Amer. Meteor. Soc. 81(11), 2621-2629.
83 N
8 2N
Lincoln Bay
Beaufort Lakes
Fort Conger
8 1N
Carl Ritter Bay
Lafayette Bay
Camp April 2005
80N
Scoresby Bay
Dobbin Bay
79N
PCSP Camps, Nares Strait
Pim Island
Cape Herschel
68W
72W
60W
64W
76W
7 8N
Lincoln Bay: 1974
Beaufort Lakes: 1981
Fort Conger: 1977-1979, 1981-1982
Carl Ritter Bay: 1978
Scoresby Bay: 1983
Dobbin Bay: 1985
Pim Island: 1990
Cape Herschel: 1974-1989
56W
1974-1990
Primarily during late
spring & summer
Only 2x per day
300
200
Maximum 19 m/s
Rare above 15 m/s
100
Number of data
Lincoln Bay: 1974
Beaufort Lakes: 1981
Fort Conger: 1977-1979, 1981-1982
Carl Ritter Bay: 1978
Scoresby Bay: 1983
Dobbin Bay: 1985
Pim Island: 1990
Cape Herschel: 1974-1989
Atkinson, D.E., B. Alt and K. Gajewski. 2000.
A new database of High Arctic climate data from
Polar Continental Shelf Project archives.
Bull. Amer. Meteor. Soc. 81(11), 2621-2629.
0
0.15
PCSP Camps, Nares Strait
160
120
80
0
40
0.05
Number of data
0.10
200
1974 1976 1978 1980 1982 1984 1986 1988 1990
1-Apr
1-May
1-Jun
1-Jul
1-Aug
0.00
Relative frequency of occurrence
0.20
400
But no extreme winds were reported
0
5
10
15
20
Wind Speed (kt)
25
30
35
40
31-Aug
Perhaps lack
of strong
winds reflects
indolence?
The only other observations
were made by 19th century
explorers at several overwintering sites
83 N
Alert
8 2N
Fort Conger
Hall Land
Polaris Bay
8 1N
Hall Expedition, Polaris Bay
November 1871 – August 1871
Lafayette Bay
Camp April 2005
80N
Hall Expedition, Life Boat Cove
November 1872 – May 1873
68W
72W
60W
56W
7 8N
64W
24x per day
Polaris House
76W
Lady Franklin Bay Expedition
Fort Conger (Greely during IPY)
August 1881 – July 1883
79N
360
270
40
90
180
Speed (m/s)
10
20
30
0
0
1-Dec-71
7
1-Jan-72
6
1-Feb-72
8
1-Apr-72
3
1-May-72
270
Wind at Polaris Bay
1871 - 1872
Hourly average
90th percentile
Direction
2
1-Jul-72
2
1-Aug-72
0
6 November 1871 to 31 August 1872
Wind topped 20 m/s once or twice
per week, especially during the
winter months
1-Sep-72
0
1-Jun-72
Speed on the hour (m/s)
10
20
30
40
3
50
0
90
180
Speed (m/s)
10
20
30
0
1-May-72
5
1-Mar-72
360
7
40
1-Nov-71
0
10
20
30
40
Hourly mean speed (m/s)
50
The maximum hourly speed was about 35 m/s (68 kt)
… but stronger winds were missed for operational reasons
0.16
0
<=5
315 >5 - 15
45
Fraction of data
0.08
0.12
>15 - 25
>25
270
20%
90
30%
Speed histogram was
strongly skewed
< 5 m/s for 65% of
the time
> 20 m/s for 5%
0.04
10%
135
0.00
225
180
10
20
30
Hourly average speed (m/s)
40
0
0.16
0
Speed (m/s)
315
45
Fraction of data
0.08
0.12
Median
Maximum
270
0.04
0
0.00
225
10
20
30
Speed on the hour (m/s)
40
20
30
135
180
0
10
Strongest & most
common winds blew
along the strait
90
40
Polaris Bay
6 November 1871
to 31 August 1872
0
Most of the net atmospheric displacement occurred during
winter
15-Nov
15-Dec
-10,000
30-Nov
30-Dec
29-Jan
14-Jan
-20,000
28-Feb
14-Mar
28-Apr
-30,000
29-Mar
13-Apr
12-Jun
28-May
13-May
12-Jul
27-Jul
-40,000
North (km)
13-Feb
-50,000
6 November 1881
to
31 August 1882
27-Jun
11-Aug
26-Aug
-40,000
-30,000
-20,000
East (km)
-10,000
0
90
5
0
0
1-Oct-81
1-Nov-81
1-Dec-81
1-Jan-82
1-Feb-82
1-Jun-82
1-Jul-82
1-Aug-82
1-Dec-82
1-Jan-83
1-Feb-83
1-Jun-83
1-Jul-83
1-Aug-83
360
1-Sep-81
270
20
1-Aug-81
1-Apr-82
1-May-82
360
1-Mar-82
1-Oct-82
1-Nov-82
360
1-Sep-82
90
180
Speed (m/s)
10
15
5
1-Feb-83
0
0
Wind topped 20 m/s
only twice in 2 years
270
20
1-Aug-82
0
0
5
90
180
Speed (m/s)
10
15
270
20
1-Feb-82
0
0
5
90
180
Speed (m/s)
10
15
15 August 1881
to 31 July 1883
180
Speed (m/s)
10
15
270
20
360
Wind speed at Fort Conger, Discovery Harbour
1-Mar-83
1-Apr-83
1-May-83
The strongest winds were aligned with Nares Strait
0
Direction histogram reflects
local terrain
Speed histogram is strongly
skewed
< 5 m/s for 95% of the time
<=5
315 >5 - 10
>10 - 15
>15
45
270
10%
225
20%
90
30%
135
Discovery Harbour
180
15 August 1881
to 31 July 1883
0.16
0
Speed (m/s)
Median
Fraction of data
0.08
0.12
315 Maximum
45
270
10
20
0.04
0
0.00
225
0
10
20
30
Hourly average speed (m/s)
40
135
180
90
30
1-Jan-73
1-Feb-73
1-Apr-73
1-May-73
270
1 November 1872
to 31 May 1873
1-Aug-73
Wind topped 20 m/s infrequently,
but low wind speed was uncommon
1-Sep-73
0
1-Jul-73
Speed on the hour (m/s)
10
20
1-Jun-73
30
0
90
180
Speed (m/s)
20
10
0
1-May-73
1-Mar-73
360
1-Dec-72
30
1-Nov-72
0
0
90
180
Speed (m/s)
20
10
270
30
360
Wind speed at Polaris House, Life Boat Cove
0
10
20
Hourly mean speed (m/s)
30
The wind regime was dominated by north-easterlies from
Kane Basin
0.20
0
Fraction of data
0.10
0.15
<=5
315 >5 - 15
>15 - 25
>25
45
90
20% 40% 60% 80%
Average wind speed
is high
0.05
270
135
0.00
225
Speed histogram is
bi-modal
180
10
20
30
Hourly average speed (m/s)
40
0
0.40
0
Speed (m/s)
315
45
Fraction of data
0.20
0.30
Median
Maximum
270
0.10
0
0.00
225
10
20
30
Speed on the hour (m/s)
40
10
20
30
135
180
0
Strongest winds
blow along the strait
90
40
Polaris House
1 November 1872
to 31 May 1873
Histograms of along-channel airflow suggests two regimes
of wind
1200
Atmospheric modeling
has revealed strong
correlation between
along-strait airflow &
SLP difference.
Samelson et al. (2006)
1000
Wind Along Channel
1871-1872
-0.5 m/s Mean
2.0 m/s Stnd dev'n
800
600
400
-7.0 m/s Mean
10.0 m/s Stnd dev'n
200
0
-45
1) Light winds dominate
to a degree varying with
season & site
-35
-25
-15
-5
5
15
Hourly average speed (m/s)
25
35
45
250
3.10 mb Mean
7.33 mb Stnd dev'n
200
Pressure Drop Along Channel
2005-06
150
2) Occasional
very Carey Islands
100
Alert minus
strong winds follow the
50
Strait
0
25
20
15
10
5
0
-5
Pressure difference (mb)
-10
-15
-20
-25
These observations suggest an important role for
boundary-layer stability
The incidence of light wind at Polaris Bay was much higher than the likely incidence
of weak along-channel pressure gradient
This suggests a non-linear response of surface wind to pressure forcing
The most likely cause of non-linearity under weak forcing is stable stratification of the
atmospheric boundary layer
This prevalent condition is known as the Polar Inversion. Potential temperature may
increase by 20°C in the lowest 300 m of the atmosphere
Contributing factors are atmospheric subsidence (adiabatic heating), cloud-free skies,
strong long-wave radiative heat loss from the high emissivity snow-surface & weak
insolation
The resulting stratification in potential density suppresses turbulence generated by
shear in airflow near the ground
In consequence, momentum is not mixed down to the surface and ground-level wind
remains light
Strong boundary-layer stratification decouples
airflow aloft from surface friction (for a while)
Air flow through Nares Strait is not subject to geostrophic
control on a synoptic scale
Suppression of boundary-layer turbulence permits continued
acceleration of airflow aloft
Acceleration continues until shear production of TKE via freestream instability (e.g. KH) overcomes buoyancy suppression
The atmospheric boundary then becomes turbulent, first
intermittently and then explosively as eddies bring high-speed
air to the surface
20
10
… and with a composite of windstorms
measured at Polaris Bay during the
winter of 1871-1872
0
Speed (m/s)
30
40
The implied sudden onset of extreme wind from calm is
consistent with events at Lafayette Bay in April 2005
-9
-6
-3
0
3
Elapsed time (hours)
6
9
12
Factors influencing the Polar Inversion affect the
wind climate of Nares Strait
Snow cover (through surface emissivity)
Cloudiness (through down-welling long wave radiation)
Solar season
Lateral & vertical (viz. subsidence) advection of warm air aloft
Nares Strait may harbour a unique wind regime, by virtue of:
Its great length (550 km)
Its high relief (2000-3000 m)
Its strong boundary-layer stratification (Polar Inversion)
Its lack of a diurnal cycle in B-L stratification in winter