Temperature contour surface plot

Hi,

I am trying to generate a 'simple' temperature map of the surface of the ocean for an specific region. However, all I get is a latitudinal gradient with no variations across longitudes (see figure). The data comes in three columns: latitude, longitude and temperature.

My code so far:

woa18SST=csvread('woa18_SST_5deg.csv',2,0,[2,0,40507,2]);
woa18SST=array2table(woa18SST,'VariableNames',{'Lat','Lon','SST'});
area1=woa18SST(woa18SST.Lat>=-30,:);
area1=area1(area1.Lat<=30,:);

figure
ax=worldmap([-30 30],[120 200])
load coastlines
surfm(area1.Lat, area1.Lon, area1.SST);
land = shaperead('landareas', 'UseGeoCoords', true);
geoshow(ax, land, 'FaceColor', [0.8 0.7 0.5])
tightmap;

Answer 1

[Juan]

So in case this might be useful for anyone I managed to solve this myself. My new code uses netCDF data rather than the threee column csv file. Iam sure is not pretty but seems to work OK.

%annual average surface temperature map for the western tropical pacific using data from the WORLD OCEAN ATLAS 2018 https://www.nodc.noaa.gov/OC5/woa18/woa18data.html
%%Define variables
clc; clear all ;
ncfile = 'woa18_decav_t00_04.nc' ; %loads temperature file
long = ncread(ncfile,'lon') ;nx = length(long) ;%obtains longiturdes and their size
lat = ncread(ncfile,'lat') ; ny = length(lat) ; %obtains latitudes and their size
time = ncread(ncfile,'time') ; nt = length(time) ; %reads the time variable and obtains its size
sst = ncread(ncfile,'t_an') ; %gets sea surface temperature value
[X,Y] = meshgrid(long,lat) ; % transform longitudes and latitudes into a grid of lon long x lat dimension
%% in case salinty wants to be used
ncfileS = 'woa18_decav_s00_04.nc' ; %loads salinity file
sal = ncread(ncfileS,'s_an'); %defines salinity variable
%%generates map
figure('Color','white'); %creates figure
ax=worldmap([-30 30],[130 -120]) % loads world map with the limits for the western tropical pacific
setm(ax,'mapprojection','mercator','Origin', [0 180 0]) %changes projection and changes origin reference for coordinates
levels=[18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34]; % creates levels for contours
geoshow(double(Y),double(X),sst','DisplayType','texturemap') %creates surface map of temperature
cb = contourcbar('peer',ax,'Location','southoutside'); %creates colorbar
caxis([15 35]) %defines limits for colorbar
colormap(jet) %sets color scheme
  set(get(cb,'XLabel'),'String','SST (^oC)') %title for color bar
  set(cb,'Position',[0.23 0.2417 0.5750 0.0335]) %adjust location and size of color bar
levels=[28]; %sets level for contour defining the Western Pacific Warm Pool
geoshow(double(Y),double(X),sst','DisplayType','contour','LevelList',levels,'LineColor','black') %plots temperature contour defining the western Pacific Warm Pool
land = shaperead('landareas.shp', 'UseGeoCoords', true); %define land areas
geoshow(land, 'FaceColor', [0 0 0]) % plots land areas in black

and here is the final product.

[Diana Berriel Bueno]

Thanks! It was very useful

[Ashfaq Ahmed]

Hi @Juan! Thank you for this answer. It helped me a lot to understand the general process. However, when I try to plot a sea surface temperature within a small geographical location, say,

geolimits([41.25 41.75],[-71.45 -71.20])

I don't get any result using your algorithm. This is my .mat file (attached). Can you kindly give me an advice on this? Thank you again for your time.