Matlab TRMM_ 3b42 data format conversion (NC to TIF, with code)

[2021 year 4 month 21 Daily update ]
TRMM_3B42_Daily data 【TRMM (TMPA) Precipitation L3 1 day 0.25 degree x 0.25 degree V7 (TRMM_3B42_Daily)】 No transpose required ;
TRMM_3B42RT_Daily data 【TRMM (TMPA-RT) Near Real-Time Precipitation L3 1 day 0.25 degree x 0.25 degree V7 (TRMM_3B42RT_Daily)】 No transpose required ;
TRMM_3B42RT_3h data 【TRMM (TMPA-RT) Near Real-Time Precipitation L3 3 hour 0.25 degree x 0.25 degree V7 (TRMM_3B42RT)】 Need to transpose .
TRMM_3B42_3h The data of 【TRMM (TMPA) Rainfall Estimate L3 3 hour 0.25 degree x 0.25 degree V7 (TRMM_3B42)】 by HDF Format , This article only considers nc turn tif Format , Not for the moment HDF Format .
See the end of the article for the comparison of the three kinds of data .

[2021 year 7 month 14 Daily update ]
Update Refference = georasterref('RasterSize', size(preciSets), 'Lonlim', [-180 180], 'Latlim', [-50 50]) sentence , The code will adaptively set according to the longitude and latitude range of the data .
in addition ,TMPA-RT The latitude range of is [-60 60].

Source code ：

Refference = georasterref('RasterSize', size(preciSets), 'Lonlim', [-180 180], 'Latlim', [-50 50]);

Update code ：

Refference = georasterref('RasterSize', size(preciSets), ...
        'Lonlim', double([floor(min(lon(:))) ceil(max(lon(:)))]), ...
        'Latlim', double([floor(min(lat(:))) ceil(max(lat(:)))]) ...
    );

TRMM 3B42 The data goes to tif Format .TRMM Please refer to the blog for data download steps —TRMM Precipitation data download steps .

stay nc File transfer tif When you file , We often encounter the problem of image rotation , Encounter such problems often need to use rot90() Function transposes the data . But not all nc Data needs to be transposed , Before that, you need to judge the number of rows and columns and longitude and latitude of the data （lon and lat） The length of .

【TRMM_3B42RT_3h Transpose of data cannot be used rot90() function , Direct use B = A' that will do 】

In the reading nc File data （data） Part and longitude and latitude to judge . If data The partial array is A x B, and lat The length of is A,lon The length of is B when , There is no need to transpose , for example TRMM 3B42 Of nc4 Format data ,data Part of it is 400 x 1440,lat The length of is 400,lon The length of is 1440, There is no need to transpose ; Otherwise, you need to transpose .

Another problem is through georasterref() Function to set the geogrid data reference object （ class ） when , We need to pay attention to 'Lonlim' and 'Latlim' Value range of , The settings here need reference lon and lat. for example lon For the range of [-179.875 179.875],lat For the range of [-49.875 49.875] when ,‘Lonlim’ and ‘Latlim’ The setting of should be 'Lonlim', [-180 180], 'Latlim', [-50 50].

TRMM_3B42RT_3h The data goes to tif The reference code and results of format data are as follows ：

%%
clc;
clear;

%%
ncpath = 'D:\20200115\3B42RT.2013092200.7.nc4';
ncinf = ncinfo(ncpath);
preciSets = ncread(ncpath, 'precipitation');
preciSets = preciSets';
lon = ncread(ncpath, 'lon');
lat = ncread(ncpath, 'lat');
OutputPath = 'D:\20200115\3B42RT.2013092200.7.tif';
% Geogrid data reference object （ class ）
Refference = georasterref('RasterSize', size(preciSets), ...
        'Lonlim', double([floor(min(lon(:))) ceil(max(lon(:)))]), ...
        'Latlim', double([floor(min(lat(:))) ceil(max(lat(:)))]) ...
    );
% It's written in GeoTif Format % It's written in GeoTif Format 
geotiffwrite(OutputPath, preciSets, Refference);   

TRMM_3B42_Daily data / TRMM_3B42RT_Daily The data goes to tif The reference code and results of format data are as follows ：

%%
clc;
clear;

%%
ncpath = 'D:\20200115\3B42_Daily.20000823.7.nc4';
ncinf = ncinfo(ncpath);
preciSets = ncread(ncpath, 'precipitation');
lon = ncread(ncpath, 'lon');
lat = ncread(ncpath, 'lat');
OutputPath = 'D:\20200115\3B42_Daily.20000823.7.tif';
% Geogrid data reference object （ class ）
Refference = georasterref('RasterSize', size(preciSets), ...
        'Lonlim', double([floor(min(lon(:))) ceil(max(lon(:)))]), ...
        'Latlim', double([floor(min(lat(:))) ceil(max(lat(:)))]) ...
    );
% It's written in GeoTif Format % It's written in GeoTif Format 
geotiffwrite(OutputPath, preciSets, Refference);   

Supplementary comparison ：

The show is 2013 year 9 month 22 The data of , The reference figure is https://journals.ametsoc.org/view/journals/wcas/11/2/wcas-d-18-0053_1.xml Of Figure 1(a)

TRMM_3B42_Daily data , Unit is mm d^-1,DN The value range is [0, 332.7]：

TRMM_3B42RT_Daily data , Unit is mm d^-1,DN The value range is [0, 228.96]：

TRMM_3B42RT_3h（ Unit is mm hr^-1） Synthetic Daily data （3B42RT.2013092200.7.nc4 / 3B42RT.2013092203.7.nc4 / 3B42RT.2013092206.7.nc4 / 3B42RT.2013092209.7.nc4 / 3B42RT.2013092212.7.nc4 / 3B42RT.2013092215.7.nc4 / 3B42RT.2013092218.7.nc4 / 3B42RT.2013092221.7.nc4）,DN The value range is [-19.5, 92.49]（ multiply 3 After that is daily）：

in addition , TRMM_3B42RT_3h The data has a negative value .
3B42RT.2013092203.7.nc4 Express 2013 year 9 month 22 Japan 3 when ±1.5 Precipitation in an hour , Please refer to TRMM_3B42RT_3h Data home page .