V1003 Climate & SocietyHomework 4Due in Class: October 22, 2014
Part A:
In class we have been discussing ENSO; below is a graph and the corresponding table of values of the SOI (southern oscillation index) from 1960-1990. SOI is one way used to track ENSO activity. Note that the equation for SOI is:
SOI=(SLP at Tahiti- SLP at Darwin)/SD(SLP at Tahiti- SLP at Darwin)
Where SLP=sea level pressure and SD=standard deviation
a)Are El Nino years represented by a positive or negative SOI value?
b)Why is this? Explain how ENSO affects atmospheric pressure gradients
c)Based on this data, calculate the recurrence time of both El Nino and La Nina events (i.e. use the peak value and look at the average of how many years are between events). Please show your work.
Year / SOI / Year / SOI1961 / 0.4 / 1976 / -4.2
1962 / 5 / 1977 / -13.6
1963 / -6.7 / 1978 / 1
1964 / 9.7 / 1979 / -2.2
1965 / -15 / 1980 / -2.6
1966 / -0.1 / 1981 / 5.3
1967 / 2.5 / 1982 / -22.6
1968 / 2 / 1983 / 0.5
1969 / -5.7 / 1984 / -0.5
1970 / 8.5 / 1985 / -1.7
1971 / 10 / 1986 / -1.3
1972 / -11.5 / 1987 / -11.8
1973 / 14.3 / 1988 / 13
1974 / 6.8 / 1989 / 3.6
1975 / 18.6 / 1990 / -1.6
Part B:
1)Imagine you are a fisherman in Peru and an El Niño is forecast to begin this fall and into early next year (as it is!).
a) Should you expect a prosperous year; why or why not? (2 sentences or less)
b)How would your outlook differ if it were an La Niña year and why? (2 sentences or less).
c)Draw a sketch of the Pacific Ocean as you expect it to be in December 2014, indicating the ocean temperature gradients (where it is warm/cold), the Walker circulation, where convection/rain occurs and where it is dry, the thermocline slope, sea surface height, trade winds (are they stronger or weaker than normal?), and upwelling (same).
2)Imagine Aqua-World – a world with no land surface anywhere, but a planet the same size and rotation rate as Earth.
a)Would there be trade winds? Why/why not?
b)Would there be equatorial upwelling? Why/why not?
c)Would there be Walker circulation? Why/why not?
d)Would there be an ENSO oscillation? Why/why not?
e)Sketch this world showing trade winds, upwelling, and where the rain fall occurs.
1)Now imagine Wall-World, which is the same as Aqua-World except that it has two large narrow landmasses (say, 100 km wide, see black bar on figure below), east and west Waldonia, bracketing a large open expanse of ocean like the modern Pacific Ocean except a lot larger.
a)Would there be trade winds? Why/why not?
b)Would there be upwelling? Why/why not? Where
c)Would there be Walker circulation? Why/why not?
d)Would there be an ENSO oscillation? Why/why not?
e)Sketch this world showing trade winds, upwelling, and where the rainfall occurs.
WESTEAST
2)Now imagine that you are the Climate Prediction Specialist for Walldonia.
a)The citizensof east Walldoniawant to know if their rainfall will be constant year to year or if it will vary. What do you tell them?
b)Now they want you to tell them whether the interannual (that is, year to year) rainfall variability at east Walldonia will be longer or shorter period that the 4 year average ENSO period on Earth. What do you tell them?
c)Imagine now that you could put TWOreportingstations anywhere on Wall-world to measure and (automatically report back) any TWO of the following climate properties (SST, pressure, winds, rainfall, sea level) at any TWO stations. Where would you put the stations and why? What TWO properties would they measure and why?
d)What would these stations tell you that would be helpful for climate prediction in Walldonia?