combine spectrogram result in one figure

I have 20 min signal and would like to combine its sepectogram become one spectrogram consecutively. my idea is put index of each S, P, T value and then joining together in one array then using imagesc. But I don't know if this flow is effective, since I have to combine for each 20 minutes into a month.

I write part of coding but I don't know how to looping index for spectogram result.

Please help me.

%% SPECTROGRAM

clc, close all, clear all

set(0,'DefaultFigureWindowStyle','docked')

datafold =  uigetdir(pwd,'Select data Folder');
myfiles=dir([datafold '/*.DAT']);
N = length(myfiles) ;    % total number of files 
data = cell(N,1) 
for i = 1:N
    thisfile = myfiles(i).name ;
    y = importdata(thisfile);
    t=(0:length(y)-1)';
    Nspec=512;
    wspec=hamming(Nspec);
    Noverlap=Nspec/2;
    fs=100;
    [Si,Fi,Ti,P]=spectrogram(y,wspec,Noverlap,Nspec,fs,'xaxis');
%     nexttile
%     imagesc(T/60,F,10*log10(P));  
%     axis xy;
%     axesHandle.YLim = [0.1 10000];
%     colormap default;
%     cbar = colorbar;
%     cbar.Label.String = {'Intensity in dB'};
%     xlabel('Time (s)');
%     ylabel('Freqwency(Hz)');
%     title('Spectrogram with RemInsRes');
end