Friday, September 11, 2009

3 box model

I have extended my 2 box model to 3 boxes:

There is not much change in deep ocean temperature (about 0.05K from 1880 to now). However, it changes another 0.05K in just ten more years if forcing stays at the last (2003) value provided by GISS.

Wednesday, September 9, 2009

2 box model

Yet another 2 box climate model. Excel file model available here:

Click the image to see graph detail.

Since my model uses a different technique than some recently discussed fitting models, not all parameters may correspond, but this is what I use for heat capacities:
Co=400 MJ/(K-m^2) Heat capacity of ocean box (~100m well mixed depth)
Ca= 50 MJ/(K-m^2) (Comparable to Cs?) Heat capacity of atmosphere box (~3x higher than dry air, due to heat required to maintain constant RH?).

Most of the other fitting parameters are the heat conductivities between the boxes and outside (in W/(K-m^2)):
Gao = 3.0 atmosphere to ocean
Godo=0.22 ocean to deep ocean
Gsa =1.78 space to atmosphere (this corresponds to 2.25K climate sensitivity if CO2 doubling causes 4 W/m^2 forcing).

Other assumptions are:
Both space and deep ocean are heat sinks at -0.1 K from the GISS baseline
All forcing is applied to the atmosphere box.
The temperature to compare to GISS land-ocean data is a weighted average (Ta+2To)/3 based on area.

There are some additional comments in the spreadsheet itself.