1. Sea breeze raw data can be downloaded from the NOAA website in the United States
https://www.ncei.noaa.gov/data/blended-global-sea-surface-wind-products/access/winds/daily/
2. Taking the daily data in 2018 as an example, the program code for downloading sea breeze raw data using terminal commands is as follows.
for string in uv20180114rt.nc uv20180115rt.nc uv20180116rt.nc uv20180117rt.nc uv20180118rt.nc uv20180119rt.nc uv20180120rt.nc uv20180121rt.nc uv2018 0122rt.nc uv20180123rt.nc uv20180124rt.nc uv20180125rt.nc uv20180126rt.nc uv20180127rt.nc uv20180128rt. nc uv20180129rt.nc uv20180130rt.nc uv20180131rt.nc uv20180201rt.nc uv20180202rt.nc uv20180203rt.nc uv20180204rt.nc uv20180205rt.nc uv20180206 rt.nc uv20180207rt.nc uv20180208rt.nc uv20180209rt.nc uv20180210rt.nc uv20180211rt.nc uv20180212rt.nc uv20180213rt.nc uv20180214rt .nc uv20180215rt.nc uv20180216rt.nc uv20180217rt.nc uv20180218rt.nc uv20180219rt.nc uv20180220rt.nc uv20180221rt.nc uv20180222rt.nc uv201802 23rt.nc uv20180224rt.nc uv20180225rt.nc uv20180226rt.nc uv20180227rt.nc uv20180228rt.nc uv20180301rt.nc uv20180302rt.nc uv20180303rt.nc uv20180304rt.nc uv20180305rt.nc uv20180306rt.nc uv20180307rt.nc uv20180308rt.nc uv20180309rt.nc uv20180310rt.nc uv20180311rt. nc uv20180312rt.nc uv20180313rt.nc uv20180314rt.nc uv20180315rt.nc uv20180316rt.nc uv20180317rt.nc uv20180318rt.nc uv20180319rt. nc uv20180320rt.nc uv20180321rt.nc uv20180322rt.nc uv20180323rt.nc uv20180324rt.nc uv20180325rt.nc uv20180326rt.nc uv20180327rt.nc uv20180328 rt.nc uv20180329rt.nc uv20180330rt.nc uv20180331rt.nc uv20180401rt.nc uv20180402rt.nc uv20180403rt.nc uv20180404rt.nc uv20180405rt .nc uv20180406rt.nc uv20180407rt.nc uv20180408rt.nc uv20180409rt.nc uv20180410rt.nc uv20180411rt.nc uv20180412rt.nc uv20180413rt.nc uv201804 14rt.nc uv20180415rt.nc uv20180416rt.nc uv20180417rt.nc uv20180418rt.nc uv20180419rt.nc uv20180420rt.nc uv20180421rt.nc uv20180422rt.nc uv20180423rt.nc uv20180424rt.nc uv20180425rt.nc uv20180426rt.nc uv20180427rt.nc uv20180428rt.nc uv20180429rt.nc uv20180430rt. nc uv20180501rt.nc uv20180502rt.nc uv20180503rt.nc uv20180504rt.nc uv20180505rt.nc uv20180506rt.nc uv20180507rt.nc uv20180508rt. nc uv20180509rt.nc uv20180510rt.nc uv20180511rt.nc uv20180512rt.nc uv20180513rt.nc uv20180514rt.nc uv20180515rt.nc uv20180516rt.nc uv20180517 rt.nc uv20180518rt.nc uv20180519rt.nc uv20180520rt.nc uv20180521rt.nc uv20180522rt.nc uv20180523rt.nc uv20180524rt.nc uv20180525rt .nc uv20180526rt.nc uv20180527rt.nc uv20180528rt.nc uv20180529rt.nc uv20180530rt.nc uv20180531rt.nc uv20180601rt.nc uv20180602rt.nc uv201806 03rt.nc uv20180604rt.nc uv20180605rt.nc uv20180606rt.nc uv20180607rt.nc uv20180608rt.nc uv20180609rt.nc uv20180610rt.nc uv20180611rt.nc uv20180612rt.nc uv20180613rt.nc uv20180614rt.nc uv20180615rt.nc uv20180616rt.nc uv20180617rt.nc uv20180618rt.nc uv20180619rt. nc uv20180620rt.nc uv20180621rt.nc uv20180622rt.nc uv20180623rt.nc uv20180624rt.nc uv20180625rt.nc uv20180626rt.nc uv20180627rt. nc uv20180628rt.nc uv20180629rt.nc uv20180630rt.nc uv20180701rt.nc uv20180702rt.nc uv20180703rt.nc uv20180704rt.nc uv20180705rt.nc uv20180706 rt.nc uv20180707rt.nc uv20180708rt.nc uv20180709rt.nc uv20180710rt.nc uv20180711rt.nc uv20180712rt.nc uv20180713rt.nc uv20180714rt .nc uv20180715rt.nc uv20180716rt.nc uv20180717rt.nc uv20180718rt.nc uv20180719rt.nc uv20180720rt.nc uv20180721rt.nc uv20180722rt.nc uv201807 23rt.nc uv20180724rt.nc uv20180725rt.nc uv20180726rt.nc uv20180727rt.nc uv20180728rt.nc uv20180729rt.nc uv20180730rt.nc uv20180731rt.nc uv20180801rt.nc uv20180802rt.nc uv20180803rt.nc uv20180804rt.nc uv20180805rt.nc uv20180806rt.nc uv20180807rt.nc uv20180808rt. nc uv20180809rt.nc uv20180810rt.nc uv20180811rt.nc uv20180812rt.nc uv20180813rt.nc uv20180814rt.nc uv20180815rt.nc uv20180816rt. nc uv20180817rt.nc uv20180818rt.nc uv20180819rt.nc uv20180820rt.nc uv20180821rt.nc uv20180822rt.nc uv20180823rt.nc uv20180824rt.nc uv20180825 rt.nc uv20180826rt.nc uv20180827rt.nc uv20180828rt.nc uv20180829rt.nc uv20180830rt.nc uv20180831rt.nc uv20180901rt.nc uv20180902rt .nc uv20180903rt.nc uv20180904rt.nc uv20180905rt.nc uv20180906rt.nc uv20180907rt.nc uv20180908rt.nc uv20180909rt.nc uv20180910rt.nc uv201809 11rt.nc uv20180912rt.nc uv20180913rt.nc uv20180914rt.nc uv20180915rt.nc uv20180916rt.nc uv20180917rt.nc uv20180918rt.nc uv20180919rt.nc uv20180920rt.nc uv20180921rt.nc uv20180922rt.nc uv20180923rt.nc uv20180924rt.nc uv20180925rt.nc uv20180926rt.nc uv20180927rt. nc uv20180928rt.nc uv20180929rt.nc uv20180930rt.nc uv20181001rt.nc uv20181002rt.nc uv20181003rt.nc uv20181004rt.nc uv20181005rt. nc uv20181006rt.nc uv20181007rt.nc uv20181008rt.nc uv20181009rt.nc ;do curl https://www.ncei.noaa.gov/data/blended-global-sea-surface-wind-products/access/winds/daily/2018/$string --output $string done
3. Replace uv20180114rt.nc uv20180115rt.nc… uv20181009rt.nc and the corresponding URLs in the above command with the names of other data in the website to download other data files.
4. The matlab program used to decode .nc files and perform preprocessing.
close all;
clear all;
clc;
% Find all files in the folder in the format '.nc', the file information is stored in the structure WindFileLists, and then loop through WindFileLists
WindFileLists=dir(fullfile('/Users/zlh/Downloads/Wind','*.nc'));
% Read the loop variable value
N=length(WindFileLists); %Use 'length()' function to read the length of the structure
% Write the main program of the loop body
M1=[];M2=[];M3=[];M4=[];M5=[];M6=[];
M7=[];M8=[];M9=[];M10=[];M11=[];M12=[];
for i=1:N
strWindFileName=WindFileLists(i).name;
ncid = netcdf.open(strWindFileName); %Open netCDF data file (read-only mode)
varid1 = netcdf.inqVarID(ncid,'u'); % Get the ID of variable u in the file
varid2 = netcdf.inqVarID(ncid,'v');
varid3 = netcdf.inqVarID(ncid,'w');
varid4 = netcdf.inqVarID(ncid,'lon');
varid5 = netcdf.inqVarID(ncid,'lat');
u = netcdf.getVar(ncid,varid1); %Get the value of the variable
v = netcdf.getVar(ncid,varid2);
w = netcdf.getVar(ncid,varid3);
lon = netcdf.getVar(ncid,varid4);
lat = netcdf.getVar(ncid,varid5);
netcdf.close(ncid); %Close netCDF data file
a = find(lon==122);% Query the wind data located at (31°N, 122°E). The sampling height is 10m at the current time.
b = find(lat==31);
% Use '' as the character to split the data, and the result is a cell array
s=split(strWindFileName,'');
% Take the element s{8,9} in the array, first convert it into a string char and then convert it into a number str2num
wd1 = str2num(char(s{8})); % month
wd2 = str2num(char(s{9}));
mm=wd1*10 + wd2;
switch mod(mm,12) %classify all data according to the month of each year
case 1
M1=[M1;u(a,b) v(a,b) w(a,b)];
case 2
M2=[M2;u(a,b) v(a,b) w(a,b)];
case 3
M3=[M3;u(a,b) v(a,b) w(a,b)];
case 4
M4=[M4;u(a,b) v(a,b) w(a,b)];
case 5
M5=[M5;u(a,b) v(a,b) w(a,b)];
case 6
M6=[M6;u(a,b) v(a,b) w(a,b)];
case 7
M7=[M7;u(a,b) v(a,b) w(a,b)];
case 8
M8=[M8;u(a,b) v(a,b) w(a,b)];
case 9
M9=[M9;u(a,b) v(a,b) w(a,b)];
case 10
M10=[M10;u(a,b) v(a,b) w(a,b)];
case 11
M11=[M11;u(a,b) v(a,b) w(a,b)];
case 0
M12=[M12;u(a,b) v(a,b) w(a,b)];
end
end
M=[M1;M2;M3;M4;M5;M6;M7;M8;M9;M10;M11;M12];
l=[size(M1,1) size(M2,1) size(M3,1) size(M4,1) size(M5,1) size(M6,1) size(M7,1) size(M8,1 ) size(M9,1) size(M10,1) size(M11,1) size(M12,1)];
Ml=[];
for j=1:size(l,2)
Ml=[Ml sum(l(1:j))];
end
% Display the netCDF data source content in the command line window
ncdisp(strWindFileName)
info=ncinfo(strWindFileName)
5. Visualize the preprocessed data and collect statistics on the monthly changes in sea breeze in the target sea area.
Mu=[];
Mv=[];
Mw=[];
for k = 0:11
if k==0
u1 = M(1:Ml(1),1);
u1(u1<-9990) = [];
v1 = M(1:Ml(1),2);
v1(v1<-9990) = [];
w1 = M(1:Ml(1),3);
w1(w1<-9990) = [];
else
u1 = M(Ml(k) + 1:Ml(k + 1),1);
u1(u1<-9990) = [];
v1 = M(Ml(k) + 1:Ml(k + 1),2);
v1(v1<-9990) = [];
w1 = M(Ml(k) + 1:Ml(k + 1),3);
w1(w1<-9990) = [];
end
u111=max(u1); % max value
v111=max(v1);
w111=max(w1);
u112=min(u1); % min value
v112=min(v1);
w112=min(w1);
if u111>abs(u112)
u11=u111;
else
u11=u112;
end
if v111>abs(v112)
v11=v111;
else
v11=v112;
end
if w111>abs(w112)
w11=w111;
else
w11=w112;
end
u12=mode(u1); % mode number
v12=mode(v1);
w12=mode(w1);
u13=mean(u1); % mean number
v13=mean(v1);
w13=mean(w1);
Mu = [Mu;u11,u12,u13];
Mv = [Mv;v11,v12,v13];
Mw = [Mw;w11,w12,w13];
end
figure()
subplot(331)
bar3(Mu(:,1))
view(35,30)
xlabel('u');ylabel('month');zlabel('m/s');
title("max velocity of u","FontSize",10)
subplot(332)
bar3(Mu(:,2))
view(35,30)
xlabel('u');ylabel('month');zlabel('m/s');
title("mode velocity of u","FontSize",10)
subplot(333)
bar3(Mu(:,3))
view(35,30)
xlabel('u');ylabel('month');zlabel('m/s');
title("mean velocity of u","FontSize",10)
subplot(334)
bar3(Mv(:,1))
view(35,30)
xlabel('v');ylabel('month');zlabel('m/s');
title("max velocity of v","FontSize",10)
subplot(335)
bar3(Mv(:,2))
view(35,30)
xlabel('v');ylabel('month');zlabel('m/s');
title("mode velocity of v","FontSize",10)
subplot(336)
bar3(Mv(:,3))
view(35,30)
xlabel('v');ylabel('month');zlabel('m/s');
title("mean velocity of v","FontSize",10)
subplot(337)
bar3(Mw(:,1))
view(35,30)
xlabel('w');ylabel('month');zlabel('m/s');
title("max velocity of w","FontSize",10)
subplot(338)
bar3(Mw(:,2))
view(35,30)
xlabel('w');ylabel('month');zlabel('m/s');
title("mode velocity of w","FontSize",10)
subplot(339)
bar3(Mw(:,3))
view(35,30)
xlabel('w');ylabel('month');zlabel('m/s');
title("mean velocity of w","FontSize",10)
6. Calculate the distribution pattern of sea breeze in the target sea area during the entire time period.
Wdu=M(:,1);% eastward wind speed
Wdv=M(:,2);%Northward wind speed
Wdw=M(:,3);% combined wind speed
Wuv=atan(Wdu./Wdv);%The angle between the wind direction and the north direction
Wdu(Wdu<-9990)=[];
Wdv(Wdv<-9990)=[];
Wdw(Wdw<-9990)=[];
Wuv(Wuv<-9990)=[];
Wdu=roundn(Wdu,-1);
Wdv=roundn(Wdv,-1);
Wdw=roundn(Wdw,-1);
Wuv=roundn(Wuv,-1);
Wdu1 = tabulate(Wdu);% counts the frequency of elements in the array (x)
Wdu2 = array2table(Wdu1, 'VariableNames', ...
{'Value','Count','Percent'});%Convert array into table
Wdv1 = tabulate(Wdv);% counts the frequency of elements in the array (x)
Wdv2 = array2table(Wdv1, 'VariableNames', ...
{'Value','Count','Percent'});%Convert array into table
Wdw1 = tabulate(Wdw);% counts the frequency of elements in the array (x)
Wdw2 = array2table(Wdw1, 'VariableNames', ...
{'Value','Count','Percent'});%Convert array into table
Wuv1 = tabulate(Wuv);% counts the frequency of elements in the array (x)
Wuv2 = array2table(Wuv1, 'VariableNames', ...
{'Value','Count','Percent'});%Convert array into table
figure()
% subplot(1,3,1)
% bar(Wdu2.Value,Wdu2.Count);
% xlabel("Velocity(m/s)");ylabel("Count")
% title("Eastward Velocity of Wind")
% subplot(1,3,2)
% bar(Wdv2.Value,Wdv2.Count);
% xlabel("Velocity(m/s)");ylabel("Count")
% title("Northward Velocity of Wind")
% subplot(1,3,3)
subplot(121)
bar(Wdw2.Value,Wdw2.Count);
xlabel("Velocity (m/s)");ylabel("Count")
title("Compound Velocity of Wind")
% subplot(1,3,4)
% bar(Wuv2.Value,Wuv2.Count);
% xlabel("Degree(rad)");ylabel("Count")
% title("Wind Direction To North")
% figure()
subplot(122)
[f,xi]=ksdensity(Wdw);
plot(xi,f,'r*');
hold on
[mu,sigma]= normfit(Wdw,0.05)
% [mu,sigma,muci,sigmaci]= normfit(data,a);
% data: original data
% a: Confidence
% mu: mean
% sigma: standard deviation
% muci:mean in the interval 1-a
% sigmaci: standard deviation within the interval 1-a
TJ=ones(100,1);
LTJ=length(TJ);
N0=normrnd(mu,sigma,1,LTJ);
[f1,xi1]=ksdensity(N0);
plot(xi1,f1,'b-o');
hold off
xlabel('Velocity (m/s)')
ylabel('Density')
legend('Raw','Fit')
title("Raw data & amp; Probability density function")
txt = { ['Miu_{MW} = ' num2str(mu)]; ['Sigma_{MW} = ' num2str(sigma)] };
text(xi(60),f(60) + 0.12,txt)
7. Save and process important sea breeze data
%The matrix that needs to be saved
data7=[Mu,Mv,Mw];
% row name
row={'m1';'m2';'m3';'m4';'m5';'m6';'m7';'m8' ;'m9';'m10';'m11';'m12'};
% column name
col={'data7','max_u','mode_u','mean_u','max_v','mode_v','mean_v','max_w' ,'mode_w','mean_w'};
%Generate table, generated by columns
result=table(row,data7(:,1),data7(:,2),data7(:,3),data7(:,4),data7(:,5),data7(:,6),data7( :,7),data7(:,8),data7(:,9),'VariableNames',col);
%Save form
writetable(result, 'data7.csv');
% bar(Wdu2.Value,Wdu2.Count);
% title("Eastward Velocity of Wind")
% bar(Wdv2.Value,Wdv2.Count);
% title("Northward Velocity of Wind")
% bar(Wdw2.Value,Wdw2.Count);
% title("Compound Velocity of Wind")
LEu=length(Wdu2.Value);
LNv=length(Wdv2.Value);
LCw=length(Wdw2.Value);
Lmax=max([LEu,LNv,LCw]);
Eu=[[Wdu2.Value;zeros(Lmax-LEu,1)],[Wdu2.Count;zeros(Lmax-LEu,1)]];
Nv=[[Wdv2.Value;zeros(Lmax-LNv,1)],[Wdv2.Count;zeros(Lmax-LNv,1)]];
Cw=[[Wdw2.Value;zeros(Lmax-LCw,1)],[Wdw2.Count;zeros(Lmax-LCw,1)]];
data8=[Eu,Nv,Cw];
csvwrite('data8.csv',data8);
8. This is what batch acquisition, decoding and preprocessing, statistics and storage of sea breeze data look like.
Interested friends are welcome to communicate and make corrections.