本代碼可實現(xiàn)下載、讀取、可視化Ocean nino Index(ONI)。

% Ocean_nino_Index(ONI)_from_ERSSTv5

% data from https://origin.cpc.ncep.noaa.gov/data/indices/

% Seasonal ERSSTv5 (centered base periods) "Oceanic Ni?o Index" or

% the 3-month running average in Ni?o 3.4 (5oNorth-5oSouth) (170-120oWest))

% Data (Oceanic Nino Index):

% https://origin.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt

% Jia-Shun Wang

% Email: wjs@hrbeu.edu.cn / wjs@outlook.at

% Personal Academic Website: https://jia-shun.wang

% 2022.09.18 in First Institute of Oceanography(FIO)

clear;close;clc

%% 0 download timeseries

filename='oni.ascii.txt';

url=['https://origin.cpc.ncep.noaa.gov/data/indices/',filename];

format shortG

Index_table=readtable(url,'FileType','text');

% save it to the local disk.

output_path='data/Climate Timeseries/';

writetable(Index_table,[output_path,filename,'.xlsx']);

%% 1 read data

filename='oni.ascii.txt';

target_data=['data/Climate Timeseries/',filename,'.xlsx'];

Timeseries_table=readtable(target_data);

start_year=1950;end_year=2022;

start_raws=find(Timeseries_table.YR==start_year);

start_raw=start_raws(1);

end_raws=find(Timeseries_table.YR==end_year);

end_raw=end_raws(end);

Timeseries_table(end_raw+1:end,:)=[];%remove the year after end-year first

Timeseries_table(1:start_raw-1,:)=[];%remove the year before start-year

Timeseries_length=length(Timeseries_table.TOTAL);

%% 2 plot line graph

figure('name','Ocean_nino_Index(ONI)','color','w')

figure_Y=Timeseries_table.TOTAL;

plot(figure_Y)

set(gca,'xtick',1:5*12:Timeseries_length,...

? ?'xticklabel',start_year:5:end_year,'fontsize',15)%5 years=60 months

grid on

xlabel('Time(year)')

ylabel('Ocean Ni?o Index(ONI)')

title('the 3-month running average in Ni?o 3.4')

%% 3 ?plot phase graph

x0=1:Timeseries_length;

x=1:0.001:Timeseries_length;

y0=zeros(size(x));

figure_Y=Timeseries_table.ANOM;

y=interp1(x0,figure_Y,x);

figure('name','nino-color','color','w')

plot(x,y0,'k','linewidth',1.5)

hold on

iip=find(y>=0);

xp=x(iip);yp=y(iip);

iin=find(y<0);

xn=x(iin);yn=y(iin);

fill([xp,xp(end),xp(1)],[yp,0,0],'r')

fill([xn,xn(end),xn(1)],[yn,0,0],'b')

set(gca,'xtick',1:5*12:Timeseries_length,...

'xticklabel',start_year:5:end_year,'fontsize',15)%5 years=60 months

grid on

xlabel('Time(year)')

ylabel('Ocean Ni?o Index(ONI)')

title('the 3-month running average in Ni?o 3.4')