Other CTT estimation options

[zmoon]

@qlawton is exploring the methods in Christensen and Driver (2021) (section 3.1). It would be cool for us to provide some other options for OLR -> CTT. Could also provide some Tb -> CTT options instead of assuming same.

[zmoon]

Another option: Yang and Slingo (2001) (OLR <-> "window Tb")

[zmoon]

There is one we are using in the DYAMOND comparison (same as mentioned in the previous comment):

TAMS/examples/dyamond/lib.py

Lines 313 to 322 in 4f3d6bf

	# Yang and Sligo (2001)
	# Given by Zhe
	a = 1.228
	b = -1.106e-3
	tf = (ds["olr"] / sigma) ** 0.25
	ds["tb"] = (-a + np.sqrt(a**2 + 4 * b * tf)) / (2 * b)
	ds["tb"].attrs.update(
	long_name="brightness temperature",
	units="K",
	)