how i can separate just data sea from land area?

Hi

i need total precipitation in time series 1959-2022 in Sea but the area that i have included land too

i applied this but stiil there is data land

filename1='lpc1.nc';filename2='lpc2.nc';filename3='lpc3.nc';filename4='lpc4.nc';filename5='lpc5.nc';filename6='lpc6.nc';

filename7='lpc7.nc';filename8='lpc8.nc';filename9='lpc9.nc';filename10='lpc10.nc';filename11='lpc11.nc';filename12='lpc12.nc';

p1=ncread(filename1,'tp');p2=ncread(filename2,'tp');p3=ncread(filename3,'tp');p4=ncread(filename4,'tp');p5=ncread(filename5,'tp');p6=ncread(filename6,'tp');

p7=ncread(filename7,'tp');p8=ncread(filename8,'tp');p9=ncread(filename9,'tp');p10=ncread(filename10,'tp');p11=ncread(filename11,'tp');p12=ncread(filename12,'tp');

lats1 = double(ncread(filename1,'latitude'));lats2 = double(ncread(filename2,'latitude'));lats3 = double(ncread(filename3,'latitude'));

lats4 = double(ncread(filename4,'latitude'));lats5 = double(ncread(filename5,'latitude'));lats6 = double(ncread(filename6,'latitude'));

lats7 = double(ncread(filename7,'latitude'));lats8 = double(ncread(filename8,'latitude'));lats9 = double(ncread(filename9,'latitude'));

lats10 = double(ncread(filename10,'latitude'));lats11 = double(ncread(filename11,'latitude'));lats12 = double(ncread(filename12,'latitude'));

lons1 = double(ncread(filename1,'longitude'));lons2 = double(ncread(filename2,'longitude'));lons3 = double(ncread(filename3,'longitude'));

lons4 = double(ncread(filename4,'longitude'));lons5 = double(ncread(filename5,'longitude'));lons6 = double(ncread(filename6,'longitude'));

lons7 = double(ncread(filename7,'longitude'));lons8 = double(ncread(filename8,'longitude'));lons9 = double(ncread(filename9,'longitude'));

lons10 = double(ncread(filename10,'longitude'));lons11 = double(ncread(filename11,'longitude'));lons12 = double(ncread(filename12,'longitude'));

[llats1,llons1] = meshgrid(lats1,lons1);[llats2,llons2] = meshgrid(lats2,lons2);[llats3,llons3] = meshgrid(lats3,lons3);

[llats4,llons4] = meshgrid(lats4,lons4);[llats5,llons5] = meshgrid(lats5,lons5);[llats6,llons6] = meshgrid(lats6,lons6);

[llats7,llons7] = meshgrid(lats7,lons7);[llats8,llons8] = meshgrid(lats8,lons8);[llats9,llons9] = meshgrid(lats9,lons9);

[llats10,llons10] = meshgrid(lats10,lons10);[llats11,llons11] = meshgrid(lats11,lons11);[llats12,llons12] = meshgrid(lats12,lons12);

land1 = landmask(llats1,llons1);land2 = landmask(llats2,llons2);land3 = landmask(llats3,llons3);land4 = landmask(llats4,llons4);

land5 = landmask(llats5,llons5);land6 = landmask(llats6,llons6);land7 = landmask(llats7,llons7);land8 = landmask(llats8,llons8);

land9 = landmask(llats9,llons9);land10 = landmask(llats10,llons10);land11 = landmask(llats11,llons11);land12 = landmask(llats12,llons12);

p1(land1)=NaN;p2(land2)=NaN;p3(land3)=NaN;p4(land4)=NaN;p5(land5)=NaN;p6(land6)=NaN;p7(land7)=NaN;p8(land8)=NaN;p9(land9)=NaN;p10(land10)=NaN;p11(land11)=NaN;p12(land12)=NaN;

pmm1(:,1)= nansum(nansum(p1));pmm1(:,2)= nansum(nansum(p2));pmm1(:,3)= nansum(nansum(p3));pmm1(:,4)= nansum(nansum(p4));

pmm1(:,5)= nansum(nansum(p5));pmm1(:,6)= nansum(nansum(p6));pmm1(:,7)= nansum(nansum(p7));pmm1(:,8)= nansum(nansum(p8));

pmm1(:,9)= nansum(nansum(p9));pmm1(:,10)= nansum(nansum(p10));pmm1(:,11)= nansum(nansum(p11));pmm1(:,12)= nansum(nansum(p12));

dpmm(:,1)=((pmm1(:,1).*31)+(pmm1(:,2).*28)+(pmm1(:,3).*31)+(pmm1(:,4).*30)+(pmm1(:,5).*31)+(pmm1(:,6).*30)+(pmm1(:,7).*31)+(pmm1(:,8).*31)+(pmm1(:,9).*30)+(pmm1(:,10).*31)+(pmm1(:,11).*30)+(pmm1(:,12).*31))*1;

plot(year,dpmm,'ro-.', 'MarkerFaceColor','c','LineWidth',2), shg