Are Tropical Cyclones Changing the Meridional Overturning Circulation?

Gino

• Heat Pump for MOC?

• Heat Pump for El Nino?

• MOC changed by TC?

OCEAN

GHG Warming

Wind Stress Increase

MORE MIXING

z

EQ NS

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Meridional TOA Net Radiation

MOCWind-Driven Lateral Gyres

Atmosphere; 50%

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

2 Mechanism for MOC

Isopycnal

Diapynal

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Net heating at this stage

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Net Mixed Layer Cooling

Surface heat flux 15%

Entrainment 85%

Price 1981

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Mixed at base of Mixed Layer

Rightward bias

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Ekman PumpingHeat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

- SSH: Ekman Pumping Cooling

+ SSH: Rightward Net Warming

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Heat Content Calculation

• Net Cooling (Mixed Layer)

• Net Warming (Total Column)

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Result

• Net Warming by TC : (Emanuel 01)

• Peak Poleward transport : (Macdonald and Wunsch 96)

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

• MOC required mixing (Munk and Wunsch 98)?

• TC induced MOC (Emanuel 01)?

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

TC-mixed-parcel Track

EQ

20N

El NinoEQ Undercurrent

PACIFIC OCEAN

TC Mixing

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

No TC mixing

Full Band TC mixing

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Increase CO2 Only

Increase CO2Increase Vertical Diffusivity 8 – 40 N & S

Preindustrial CO2

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Uvic Model (OGCM)

• Based on Modular Ocean Model• Initialized with Modern Climatology• No Dynamic Atmosphere• 3000 yr• Control Run: without TC mixing • Exp Run: TC mixing parameterization

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

• Subtropical Overturning Circulation dominates in 10N – 30N upper ocean

• TC Mixing effect confined in tropics!

Heat Pump for MOC? Heat Pump for El Nino? MOC changed by TC?

reference

• Emanuel 2001 Contribution of tropical cyclones to meridional heat transport by the oceans

• Fedorov 2009 Tropical cyclones and permanent El Niño in the early Pliocene epoch

• Sriver 2010 Climate response to tropical cyclone-induced ocean mixing in an Earth system model of intermediate complexity