Ocean meridional overturning circulation (MOC)/ thermohaline
    circulation (THC) 

Lecture notes:
THC:
https://courses.seas.harvard.edu/climate/eli/Courses/EPS131/Sources/07-THC/3-notes-THC-Stommel-model.pdf

Saddle node: page 47 in:
https://courses.seas.harvard.edu/climate/eli/Courses/APM203/Sources/lectures/lecture_02_bif1d1.pdf

Hopf: P 26-26 in:
https://courses.seas.harvard.edu/climate/eli/Courses/APM203/Sources/lectures/lecture_07_bif2d3.pdf

    Motivation:
	 Temperature, salinity, and THC slides from EPS131 first lecture
         from EPS131/Sources/07-THC: 
           1a-THC-belt.jpeg
     	   1c-THC-cfc-animation-horizontal.gif
     	   1d-THC-cfc-animation-vertical.mpg
     	   1e-YouTube - The Day After Tomorrow.webloc
     	   1g-Surface_air-T_deviations-from-zonal-mean-Rahmstrof.jpg

    Stommel 1961 model, bifurcations, multiple equilibria, hysteresis
        (from EPS131: 3-notes-THC-Stommel-model.pdf
 	 1h-vellinga-wood-THC-collapse-Hadley-model.pdf
 	 4b-Rahmstorf-et-al-2005-Stommel-bifurcation-GCM-intercomparison.pdf
         6c-THC-in-global-warming-Bryden_etal_2005.pdf)
	 saddle-node bifurcation and hysteresis

    THC variability
	Motivation: 
           present day and past climate variability 
           (from EPS131: 2a-rapid_transports2.png
           little ice age and abrupt climate change slides from
   	   EPS-131-lecture-01-intro-2-phys-oceanogr.pptx) 
	Excitation of an oscillatory mode:
   	   Figs 3,4 from Tziperman-Toggweiler-Feliks-Bryan-1994.pdf  
           and Hopf bifurcation notes
	Non-normal transient growth, 
	   introduction, writing PDE in matrix form, optimal i.c.
	   non normal excitation of THC variability
           (slides #2,3,5,6,7,9 from nonormal_THC_short.pdf)
	   Time permitting: stochastic optimals (Tziperman-Ioannou
	      2002, section 4, eqns 11-14)