Date post: | 04-Apr-2018 |
Category: |
Documents |
Upload: | andrew-revkin |
View: | 218 times |
Download: | 0 times |
of 11
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
1/11
CLI MSENS: Con st r a in in g t o t a lf eedback o f t he cl im a te sys temby ob ser va t i ons and m odels.
Ragnh i ld B iel t ved t Sk e ie
Terje Berntsen CICERO and University of OsloGunnar Myhre CICEROMagne Aldrin Norwegian Computer CenterMarit Holden Norwegian Computer Center
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
2/11
2
Cl im a t e sen si t i v i t y :The equ i l i b r i um change i n t he annua l m ean g loba l su r facet e m p e ra t u re f o l l o w i n g a d o u b l i n g o f t h e at m o sp h e r i c CO2concen t ra t i on .
IPCC 2007
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
3/11
3
Const r a i n i ng t he cl im at e
sens i t i v i t y
Bottom-up approach. Perturbing the
representations of the climate feedbacks inGCM models.
Observational based approach. Using
historical observations and simple climatemodels
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
4/11
4
Q = F - T
Q: Heat flux in the system
F: Radiative forcing
: Climate Feedback Parameter
At equilibrium: Q = 0, = F2xCO2/ T2xCO2eq
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
5/11
5
Det a i led RF ca lcu la t ion s:Tr oposph er ic ozon e and aer oso ls
Emissions
Oslo CTM2 model
RF-calculations
IPCC 2007
F
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
6/11
6
A sim p le cl im at e m odel :Energy balance model/Upwelling Diffusion Ocean
StructureofthemodelParametre:
Schlesinger et al. (1992)
Name Unit Value
Mixed layer depth m 60Vertical heat diffusivity cm /sec 0.634Polar parameter - 0.4Vertical velocity, upwelling rate m/yr 4.0Air-sea heat exchange parameter W/(m
2K) 16.0
Oceanic interhemispheric heat exchange coeff. W/(m K) 3.5Atmospheric interhemispheric heat exchange coeff. W/(m K) 0.0Climate sensitivity K/(Wm ) 0.8
Q
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
7/11
7
Observa t i ons
Surface temperature
Ocean heat content
Levitus, GRL 2009
T
IPCC 2007
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
8/11
8
St a t i st i ca l m ode l :
The data:
Surface temperature (3 data set, NH and SH averages).Ocean heat content
Additative bias/correction for baseline
SOI index, Account for El Nino.
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
9/11
9
St a t i st i ca l m ode l
Bayesian approach and a MCMC-algorithm:
1. Apriori distributions for parameters and input data.
2. Update your model with observations.
3. Get posteriori uncertainties for your model parametersand input data. One of them is the climate sensitivity!
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
10/11
10
IPCC 2007
7/29/2019 Norwegian Study Finds Limited Warming from Doubled Greenhouse Gases
11/11
11
W h at s n ew ?
Improved representation of the radiative
forcing history
Longer time period with observations