Ocean-Atmosphere Interaction
description
Transcript of Ocean-Atmosphere Interaction
![Page 1: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/1.jpg)
Ocean-Atmosphere Interaction
![Page 2: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/2.jpg)
Review of last lecture
• Large spread in projected temperature change comes from uncertainties in climate feedbacks
• Main climate feedbacks for global warming: albedo, lapse rate, water vapor, cloud, aerosol, carbon cycle
• Feedback strength in climate models: cloud feedback causes the largest uncertainty
![Page 3: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/3.jpg)
Radiation
Cloud/precip
Shallow convection Boundary layer turbulence
Mesoscale convective system Tornado/Thunderstorm
Extratropical cycloneHeat waveTropical cyclone
Diurnal variation
Madden-Julian Oscillation Convectvely coupled waves
Monsoon
AMO/PDOENSOAO/AAO
Glacial cyclesGlobal warming
105yr102yr10yr1yr1mon1day1min1sec10-15sec
Global Climate SystemWhole globe
Half globe
103 km
102 km
1 km
1 mm
1 m
Global model grid
Regional model grid
Spatial Scale
Time Scale
Land-atmosphere interaction
Ocean-atmosphere interaction
Radiation feedback (T, q, cloud, aerosol, carbon)
Convection feedback
10-4 m Chemistry
![Page 4: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/4.jpg)
Key regions for ocean-atmosphere interaction
Indo-Pacific warm pool
Eastern Pacific cold tongue
North AtlanticNorth Pacific
![Page 5: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/5.jpg)
Tropical mean state: Precipitation
GPCP Annual Mean Precipitation for 1979-2005 (mm/day)
Inter-tropical convergence zone (ITCZ)
Strong rainfall (heating)
Weak rainfall
![Page 6: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/6.jpg)
Tropical mean State: Walker Circulation
• The SST contrast between warm pool and cold tongue leads to an atmospheric circulation cell oriented along the equator with rising motion in the west and sinking motion in the east, which is induced by
• Interacts with underlying Pacific Ocean with stronger upwelling (cooling) in the east, leading to a positive feedback.
![Page 7: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/7.jpg)
Theories of tropical mean climate: Ocean-atmosphere feedback mechanisms
SST gradient - trade wind (Bjerknes) feedback (e.g. Bjerknes 1969, Neelin and Dijkstra 1995; Pierrehumbert 1995; Sun and Liu 1996; Jin 1996; Clement et al. 1996; Liu 1997; Cai 2003)
SST - LHF feedback (e.g. Wallace 1992; Liu et al 1994; Zhang et al. 1995)
SST - SWF feedback (e.g. Ramanathan and Collins 1991)
![Page 8: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/8.jpg)
Blind men and an elephant
![Page 9: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/9.jpg)
Movie time!
Chasing El Nino
![Page 10: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/10.jpg)
El Nino/Southern Oscillation (ENSO): The 4-year oscillation
• El Nino: Very warm sea surface temperature over central and eastern tropical Pacific, which occurs every 3-7 years. The Walker Circulation becomes disrupted during El Niño events, which weakens upwelling in eastern Pacific.
• La Nina: the opposite condition to El Nino
• Southern Oscillation: The atmospheric oscillation associated with the El Nino-La Nina cycle.
• The whole phenomena is now called El Nino/Southern Oscillation (ENSO)
![Page 11: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/11.jpg)
Typical ENSO period is 3-7 years, but with significant irregularity
![Page 12: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/12.jpg)
Existing ENSO theories
(1) Slow coupled mode theory (Philander et al. 1984, Gill 1985, Hirst 1986, Neelin 1991, Jin and Neelin 1993, Wang and Weisberg 1996)
(2) Delayer oscillator theory (Suarez and Schopf 1988, Battisti and Hirst 1989)
(3) Advective-reflective oscillator theory (Picaut et al 1997)
(4) Western Pacific oscillator theory (Weisberg and Wang 1997)
(5) Recharge oscillator theory (Jin 1997a,b)
(6) Stochastic forcing theory (McWilliams and Gent 1978, Lau 1985, Penland and Sardeshmukh 1995, Blanke et al. 1997, Kleeman and Moore 1997, Eckert and Latif 1997)
![Page 13: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/13.jpg)
Blind men and an elephant
![Page 14: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/14.jpg)
The 1997-1998 El Nino event
![Page 15: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/15.jpg)
Atlantic Multi-decadal Oscillation (AMO)
• The Atlantic Multidecadal Oscillation (AMO) is a 60yr oscillation in water temperatures and is a major factor in the increase in Atlantic hurricane activity.
![Page 16: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/16.jpg)
Global SST anomaly for AMO warm phase
![Page 17: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/17.jpg)
AMO and thermohaline circulation
![Page 18: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/18.jpg)
An theory involving atmosphere-ocean-ice interactions (Dima and Lohmann 2007)
![Page 19: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/19.jpg)
Summary
• Mean state: The two basic regions of SST? Which region has stronger rainfall? What is the Walker circulation? Two types of ocean upwelling
• Mean state: ocean-atmosphere feedback
• ENSO: Which region has warm SST anomaly during El Nino? 4-year period.
• Existing ENSO theories
• AMO and thermohaline circulation
![Page 20: Ocean-Atmosphere Interaction](https://reader030.fdocuments.net/reader030/viewer/2022033021/56814d84550346895dbae455/html5/thumbnails/20.jpg)
Works cited• http://www.jpl.nasa.gov/images/earth/20100325/atlantic20
100325-full.jpg