Transcript AMTV

The Study of Environmental Arctic
Change (SEARCH) and the Barrow
Cabled Observatory
Winter Lead Convection
Presentation at Science and Education Opportunities for an Arctic Cabled
Seafloor Observatory
February 7-8, 2005
Jamie Morison
Polar Science Center, University of Washington
[email protected]
SEARCH Motivation
The Arctic has been characterized in
recent decades by a complex of
significant, interrelated, pan-Arctic
changes (Unaami).
Examples
•
Decreased sea level atmospheric pressure,
•
Increased air temperature over most of the Arctic,
•
More cyclonic ocean circulation and rising coastal sea level,
•
Warmer Atlantic waters,
•
Reduced sea ice cover,
•
Warming of permafrost
•
The physical changes of Unaami impact ecosystems and society.
Complex of change appears related to a spin up of the Northern
Hemisphere atmospheric Polar Vortex.
Complex of Arctic change is a possible component of climate change.
Motivates a program of long-term observations, analysis, and
modeling
SEARCH Implementation
Eight SEARCH Activities Areas include:
- DTO: Distributed Terrestrial Observatories
- DMO: Distributed Marine Observatories
- LAO: Large-scale Atmospheric Observatories
- DQU: Detecting and Quantifying Unaami and Other Modes of Variability
- LGC: Linkages and Global Coupling
- ASR: Arctic System Reanalysis
- SEI: Social and Economic Interaction
- SOR: Social Response
Implementation Strategy at SEARCH Web site:
http://psc.apl.washington.edu/search/index.html
Current Activities at
http://psc.apl.washington.edu/search/Activities/activities.html
Distributed Terrestrial Observatories
Yenisey R
Russia
x
Ob R
x
x
x
x
Lena R
Tiksi
Abisko
x Kolyma R
Cherksiy
Nor
Svalbard
Arcic Ocean
x
x
Barrow
Yukon R
x
Toolik
x
Bonanza
x
Alert
x
Eureka
Alaska
Distributed Terrestrial
Observatories
Intensive Site
Resolute
x
x
Mackenzi e R
Intermediate Site
(e.g., ITEX, CEON)
x
Extensive Site
Canada
Greenland
Thule
x
Large-scale Atmospheric Observatories
Yenisey R
Russia
x
Ob R
x
x
x
Tiksi
x
Lena R
Abisko
x Kolyma R
Norway
Cherksiy
Svalbard
Svalbard
x
x
Barrow
Yukon R
x
Toolik
x
Bonanza
x
Alert
Alert
xEureka
Alaska
Greenland
Thule
Large-scale Atmospheric
Observatories
Major Weather Stations
Remote Sensing, e.g. TOVS
x
Resolute
x
GCOS
GCOS -- GTOS
GTOS
DTO Intensive Site
x
Mackenzi e R
DTO
Site
DTO IntermediateSites
x
Canada
DTO Extensive Site
IABP Drifting Buoys
Automated Drifting Stations
DMO: Distributed Marine Observatories
Make large-scale atmospheric, oceanographic,
sea ice and ecosystem observations in the
marine environment.
SEARCH Implementation Strategy available at
http://psc.apl.washington.edu/search/index.html
Distributed Marine Observatories
Ob R
Yenisey R
Russia
Lena R
Tiksi
45
44
Abisko
Kolyma R
4
46
13
3
31
Cherksiy
43
Norway
23
2
5
27
20
32
6
19
37
40
Svalbard
33
17
1
30
38
26
22
14
42
41
21
36
15
29
33
7
16
Yukon R
35
Barrow
8
Distributed Marine
Observatories
34
Alert
39
18
25
Eureka
9
IABP Drifti ng Bu oys
Oce an Pa thway Moori ngs
Cross Shelf Excha nge Mo oring s
Bas in Moo rings
Gateway Moo rings
Shel f Moori ngs & Surveys
Mackenzi e R
ASOF Hydro graph ic Sections
Clic Hydrogra phic Sectio ns
Othe r Section s
Au toma ted Dri ftin g Sta tion s
Upward L ookingSona rs
12
Greenland
Thule
11
10
Resolute
24
28
Canada
DMO Philosophy
Scales are pan-Arctic and decadal.
Therefore the DMO emphasis is on:
- Basin-wide coverage
- Long, relatively low res time-series
And because startup is urgent:
- Use of proven, existing technologies
So, what role can a high-tech, highbandwidth cabled observatory at
Barrow have in DMO?
Two DMO elements near Barrow:
• Ocean pathway moorings
• Cross shelf exchange moorings
Role for high-bandwidth, localized
measurements particularly in
• Cross shelf exchange mooring
function of DMO, and
• The Linkages and Global Coupling
(LGC) activity area
Processes in the shelf and slope
region are important to ventilation of
the deep ocean, e.g.
• Generation of eddies that move into the
basin
• Cross shelf exchange driven by
buoyancy flux in the Seasonal Ice Zone
(SIZ) and winter shore leads and
polynyas
These processes tend to be
intermittent and spatially variable.
AIDJEX Lead Experiment, 1974
Indication of cross-shelf exchange
Example of bottom boundary layer
generated by Barrow shore lead
(ALEX, 1974)
Consider buoyancy flux and cross
shelf exchange.
SHORE LEAD
WIND MOVES PACK ICE AWAY FROM
SHOREFAST ICE
SHELF BREAK
FRONT
+
HALINE CONVECTION
SHOREFAST ICE
Consider buoyancy flux and cross
shelf exchange.
These processes create density structure
parallel to shore and cross shore pressure
gradients, which drive alongshore currents.
So where does cross-shelf exchange occur?
In the surface and bottom boundary layers
where flow moves down pressure gradient.
How would we use the BCO to measure shelf processes?
Monitoring Winter Shelf Convection With the BCO
Instrumented ROV
Servicing Arrays
Turbulent Instrument
Cluster "Pods"
Iridium, Met Sensors
Homing Beacon
Shore Lead
Pack Ice
Fast Ice
ROV Hangar
AUV
Fr
on
t
AUV Hangar
AUV Nav
Xponders
Salinity
Profile
Fixed CT D, ABPR, ADCP, ULS
Bottom
Boundary
AUV Nav
Layer
Xponders
Convective Plume
Cable
Supercoolometer:
Seamore ROV
Optical Backscatter
SBE 39 T Probe
Water In
Heater
SBE-19+
Temperature & Conductivity
JAMSTEC UROV 7k
Remotely Operated
Vehicle
Battery Operated
Fiber Optic Link
KAIKO Hanger
UROV
TIC
QuickTime™ and a
DV/DVCPRO - NTSC decompressor
are needed to see this picture.
Van Mijen Fjord Instruments
SonTek Instrument Cluster
0.6 m
Ice
T-string
1m
SBE 04 conductivity
meter
SBE 03 thermometer
ROVCTD
SBE 07 microconductivity meter
SonTek
ADVOcean (5 MHz)
Miles McPhee Turbulent Inst Cluster
Autonomous Flux Buoy
Tim Stanton Flux Buoy
The Autonomous Microconductivity-Temperature Vehicle
(AMTV)
AMTV
QuickTime™ and a
DV/DVCPRO - NTSC decompressor
are needed to see this picture.
AMTV Results SHEBA Summer Lead Study, Day 219.9
Under Lead
Back Toward Ice
Warmer
Cooler
Fresher
S constant?
From Hayes Dissertation, 2003
Under Ice
Cooler &
T’ small
S constant &
S’ small
AMTV Turbulence on 219.9
S’ and T’ Vigorous Under Lead
Turbulence Significant Under Lead
From Hayes Dissertation, 2003
S’ and T’ Reduced Under Ice
Turbulence Enhanced
Under Ice? Lower Frequency
AMTV Turbulent Fluxes on 219.9, 1998 at SHEBA
Summer Lead
98 W m-2
1.7x10-5 kg m-2 s-1
144 W m-2
2.4x10-5 kg m-2 s-1
1.9x10-5
Substantial Turbulent Heat and Salt Flux in the Lead, Reduced Fluxes Under Ice
Turbulent Stress, u*=(t/r)1/2, Increased Under Ice
From Hayes Dissertation, 2003
Conclusions:
 The BCSO can play an important part in
SEARCH.
 Focus as an intensive observing point for
shelf-basin processes critical for the large
scale behaviour of the marine environment
The End