FB-WS2011_Howarth

Irish Sea Ferry – some results
John Howarth
Chris Balfour
www.pol.ac.uk
Measurements (real time)
Numerical models
Web site – http://coastobs.pol.ac.uk
Irish Sea Observatory
Integrated measurements
Measurements to test
models
Variety of space and
time scales
Some real time
Long time series
In situ time series
Sites A and B
Spatial survey
HF Radar
Ferry
Satellite (weekly
composite)
Glider
Liverpool Seaways, Birkenhead - Belfast
Norfolk Line / Norse Merchant / DFDS
December 2003 – January 2011
CTD – SeaBird SeaCat SBE / FSI
Turbidity – Sea Point + wiper
Fluorimeter – Chelsea Minitracka II
Oxygen – Aanderaa optode
Intake 3m below surface
Sample interval – 10 seconds
Data transmission – Orbcomm – 15 mins
Wiper on turbidity sensor
Isolation valve
7 hour crossing, 230 km
there and back daily
Water depths (m)
55
150
150
53.8
54.5
100
53.6
100
54
53.4
53.5
50
50
53.2
0
-6
-5.5
-5
-4.5
-4
-3.5
-3
0
53
-6
-5
-4
-3
0
-20
m
-40
-60
-80
-100
-120
98% within 5 km of tracks
-6
-5
W
-4
-3
Tides
Mean spring tidal current (m s-1)
2
54.5
1.5
54
1
53.5
0.5
53
-1
Mean spring surface maximum amplitude (m s )
-6
-5
-4
-3
53.8
53.6
53.4
53.2
53
2
1.5
1
0.5
-6
-5
-4
-3
Irish Sea
Number of days temperature
stratified in a year
Dublin
Birkenhead
Salinity
Dublin-Birkenhead
Salinity
Birkenhead-Dublin
Average salinity
36
33
34
32
Salinity
Salinity
31
32
30
30
29
28
26
28
-6
-5.5
-5
-4.5
-4
Longitude ( W)
-3.5
27
-3.5
-3.4
-3.3
-3.2
Longitude ( W)
-3.1
Eastern end expanded
Red westbound; blue eastbound
Constant 4.75 mins; 1.6 miles (sea chest)
Salinity correction per crossing 0.009
(Before valve installed
0.019)
SmartBuoy Comparison
Temperature ( C)
Salinity
34
33
SmartBuoy
SmartBuoy
15
10
5
32
31
30
5
10
Ferry
15
20
29
30
31
32
Ferry
Temperature
Correlation coefficient
0.998
Mean difference
0.16
Standard deviation of difference
0.23
33
34
Salinity
0.91
-0.00
0.27
Temperature – seasonal cycle
11.7
7
Mean
11.6
Amplitude
6
11.4
C
C
11.5
5
11.3
4
11.2
Dublin
-6
-5
-4
3
-3
0.98
-6
Birkenhead
-5.5
-5
-4.5
-4
-3
260
September
250
Days
0.96
0.94
240
230
0.92
0.9
-3.5
220
r2
-6
-5.5
-5
-4.5
August
-4
-3.5
-3
210
Phase
-6
-5
-4
-3
Amplitude of temperature seasonal cycle:
relation with water depth
0
6
-20
5
-40
m
C
7
4
-60
3
-6
-5.5
-5
-4.5
-4
-3.5
-3
-80
0
-100
3
-20
m
-40
-60
4
54.5
5
C
6
7
54
-80
53.5
-100
53
-120
-6
-5
W
-4
-3
52.5
-6.5
-6
-5.5
-5
-4.5
-4
-3.5
-3
-2.5
Salinity – seasonal cycle
2
36
34
Amplitude
1.5
32
1
30
0.5
28
26
Mean
-6
-5.5
-5
0.35
-4.5
-4
-3.5
0
-3
-5.5
-5
-4.5
-4
-3.5
-3
400
r2
0.3
-6
December
350
0.25
Days
0.2
0.15
300
250
0.1
200
0.05
0
-6
-5.5
-5
-4.5
-4
-3.5
-3
150
Phase
-6
-5
-4
June
-3
Salinity variability
Maximum salinity per crossing
-4
-4.5
35
2009
-5
W
34.8
34.6
-5.5
34.4
-6
-6.5
2200
34.2
2600
2800
3000
3200
54.5
34
33.8
33.6
2200
2400
54
2400
2600
2800
Days
3000
3200
53.5
53
52.5
-6.5
-6
-5.5
-5
-4.5
-4
-3.5
-3
-2.5
20
Near shore gradients
Mersey Bar
Mouth of Mersey
Difference
C
10
Correlation
Temperature 0.96
Salinity
0.42
54.5
15
5
0
-5
2200
35
2400
2600
2800
3000
3200
30
54
25
20
53.5
2009
15
53
10
5
52.5
-6.5
-6
-5.5
-5
-4.5
-4
-3.5
-3
-2.5 0
2200
2400
2600
2800
3000
3200
Spring – neap cycle at SmartBuoy site
Salinity
33
Red – leaving of Liverpool
Green – arriving
Blue - SmartBuoy
32.5
32
Liverpool tide gauge
10
31.5
8
Days
m
3140 3142 3144 3146 3148 3150 3152 3154
6
4
2
0
3140 3142 3144 3146 3148 3150 3152 3154
Turbidity
25
FTU
20
4-25 November 2010
15
10
25
20
0
-6
-5.5
-5
-4.5
W
-4
-3.5
Ferry (FTU)
5
-3
-1
Mean spring surface maximum amplitude (m s )
53.8
53.6
53.4
53.2
53
2
1.5
1
0.5
-6
-5
-4
-3
15
10
5
0
0
10
20
SmartBuoy (FTU)
r=0.67
30
Summary
East-west differences – time / distance constant
Seasonal cycle
Temperature variability
Salinity variability
Nearshore gradients
Effect of Spring-Neap cycle
Liverpool Seaways, Birkenhead - Belfast
Salinity
Norfolk Line / Norse Merchant / DFDS
December 2003 – January 2011
CTD – SeaBird SeaCat SBE / FSI
Turbidity – Sea Point + wiper
Fluorimeter – Chelsea Minitracka II
Oxygen – Aanderaa optode
Intake 3m below surface
Sample interval – 10 seconds
Data transmission – Orbcomm
Wiper
Isolation valve
54.5
54
53.5
7 hour crossing there and back daily
53
52.5
-6.5
-6
-5.5
-5
-4.5
-4
-3.5
-3
-2.5