Download presentation
Presentation is loading. Please wait.
Published byReginald Harrington Modified over 9 years ago
1
Potential temperature ( o C, Levitus 1994) Surface Global zonal mean
2
Salinity (psu, Levitus 1994) Surface Global zonal mean
3
Evaporation – precipitation
4
Density as function of temp, salinity and pressure max density freezing point ρ–1000 kg m –3
5
Potential density ( -1000 kg m –3, Levitus 1994) Surface Global zonal mean
6
Mixed layer depth
7
Seasonal variation of mixed layer depth
8
World ocean currents Map shows vertically averaged currents around the world oceans
9
Western boundary currents: Gulf Stream Benjamin Franklin’s map (Richardson, Science1980) SST satellite image, from U. Miami RSMAS
10
Surface wind (NCEP, m/s) January July
11
Ekman spiral
12
Coastal upwelling due to Ekman transport
13
Observed asymmetry of gyres what one might expect what one observes westerlies trades
14
Annual mean Ekman pumping (m/year)
15
Friction in western boundary current
16
World ocean overturning and heat transport Results from a numerical model (Boccaletti et. al 2005) mass flux (Sv) heat flux (PW) Eq40N80N40S80S
17
Atlantic salinity and flow
18
The Great Conveyor Belt
19
Ocean heat transport by basin
20
Lumpkin and Speer (2007) The present perception of Southern Ocean overturning: it makes global the global thermohaline circulation possible Speer et al., 2000; Sloyan and Rintoul, 2001ab
21
Warm sources have to be deeper than cold ones: The Sandström’s theorem Mixing is crucial: A scenario with a surface buoyancy forcing of NADW upwelling is problematic NADWFormationNADWConsumption Mixing No THC Intense THC
22
“[…] understanding the physics related to the spatial and temporal distribution of mixing is one of the most important research frontiers in physical oceanography.” Huang (2004) Mixing is crucial: Different scenarios for the NADW upwelling a) Pushing by deepwater formation b) Pulling by deep mixing c) Pulling by wind stress & surface waves
23
A simple model of the thermohaline circulation = flow strength, proportional to density difference , adim. constants temperature difference salinity difference
24
Multiple equilibria
25
Change in surface temperature 30 years after thermohaline shutdown
26
Tropical Pacific sea-surface temperature
27
Equatorial temperature cross section
28
Equatorial currents Surface Meridional cross section Equatorial undercurrent
29
Driving the undercurrent
30
Water parcel trajectories
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.