In this homework, you will analyze the future projections of precipitation from an ensemble of global climate models that participated in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). You will describe both the present-day climatology and future projections of precipitation from IPCC AR5 models and the robustness of the results across models.
a. This webpage
http://strega.ldeo.columbia.edu:81/CMIP5/.byScenario/.historical/.atmos/.mon/.pr/
and
http://strega.ldeo.columbia.edu:81/CMIP5/.byScenario/.rcp85/.atmos/.mon/.pr/
lists all of the available IPCC AR5 models, for the historical scenario and future RCP8.5 scenario, respectively.
· Choose 10 models (ensemble member r1i1p1) for your analysis.
1. ACCESS1-0:
Historical
Future
2. ACCESS1-3:
Historical
Future
3. BNU-ESM:
Historical
Future
4. CESM1-BGC:
Historical
Future
5. CMCC-CESM:
Historical
Future
6. CMCC-CM:
Historical
Future
7. CMCC-CMS:
Historical
Future
8. inmcm4:
Historical
Future
9. IPSL-CM5B-LR:
Historical
Future
10. NorESM1-ME:
Historical
Future
· Calculate and plot both the multi-model annual mean precipitation (in the unit of mm/day) in the present climate, and difference in multi-model annual mean precipitation between the long-term future climate and present climate, as a function of longitude and latitude. Here we can choose a 20-year average during 1986-2005 in the historical experiment to represent the present climate, and a 20-year average during 2081-2100 in the RCP8.5 experiment to represent the long-term future climate. Choose your own method to quantify model agreement (About the difference between future projection(rcp8.5) and historical) (e.g., define that the future projection has a high level of model agreement if 90% or more of models agree on the sign of change), and plot the model agreement within the same figure.
Hints: since models may not have the same horizontal resolution, you may want to regrid the model output to a common grid. To do that, you could use regrid_cmip5.m that is uploaded to Canvas.
b. Describe the features that you see in (a) for both the present-day climatology and future change.
c. Similar to (a) and (b), but repeat the analysis for the near-term future during 2046-2065. Discuss the differences you see between the near-term and long-term future projections of precipitation change
% This function will regrid lat/lon data from CMIP5 climate models to a
% common 1x1 degree grid.
% Inputs:
% x1: vector of model longitudes (degrees E)
% y1: vector of model latitudes (degrees N)
% z1: matrix of lat/lon data (dimensions length(x1) x length(y1))
% Outputs:
% x2: vector of regridded longitudes (degrees E)
% y2: vector of regridded latitudes (degrees N)
% z2: regridded lat/lon data (dimensions length(x2) x length(y2))
% Mike Previdi - 10/30/20
function [x2,y2,z2]=regrid_cmip5(x1,y1,z1)
for y=1:length(y1)
for x=1:length(x1)
lats2D(x,y)=y1(y);
lons2D(x,y)=x1(x);
end
end
x2=[0.5:359.5]';
y2=[-89.5:89.5]';
z2=griddata(double(lons2D),double(lats2D),double(z1),x2,y2','nearest')';
end