Sanjo

You need to think about the meaning of "gridded data". A satellite sensor generates a direct observation for an entire pixel (but not precip or temp). It is possible to generate precipitation measurements for "pixels" using Doppler Radar but strictly speaking it does not measure precip. on the ground. All of this suggests that the "gridded data" for precip is obtained by interpolation from rain gage data perhaps as spatial averages, in that case you need to know what interpolation method was used and how it was used. Likewise temperature is usually observed at point locations and you only get gridded data by interpolation.

Finally what do you want the "gridded data" for, i.e. what will you use it for?

# Date: 27/04/2015

# Author: lihui luo ([email protected])

# This script mask netcdf file with time dimension through shape file

library(raster)

library(ncdf)

library(rgdal)

rm(list = ls()) # clear objects

graphics.off() # close graphics windows

# List all raster files

# Please insert your directory in quotation marks

data_dir

Hi Donald,

The gridded data were generated based on station data and its interpolation to other grids. I am using this data for analysing the past climate variability and other related analysis.

Hi Lihui,

Thank you for the script.

But I have the data in the .grd and .txt format. So which R package can be used for that?

install.packages('maptools') library(maptools)

test

Sanjo Jose,

The attached R script will help to extract temperature data(data format : .txt) and output format .txt.

Thank you Subash. Let me check it out.

Subash Yeggina thank you very much for your code. It is working. Can you help me to convert the .txt generated from your code to NetCDF file? So that it can be opened in ArcGIS or even in R. In NetCDF file we can apply bilinear interpolation to have data for any latitude and longitude within India by taking 4 grids adjoining the particular latitude and longitude.

Sanjo Jose can you please help me by providing the steps for using IMD data converter developed by @Kamal Pandey. I am trying to use it. But it is showing '

Something wrong with the input file'.

Bappa Das you can directly convert data sets using CDO in linux platform.

command : cdo -f nc import_binary XXXXXX.ctl output.nc

XXXXXX.ctl is meta data file in which grid info is present

Girish Patidar I tried using the command as you mentioned for extracting the IMD gridded data , but I'm getting error as could not open the file.

Sakila Saminathan what error you are getting ?

Girish Patidar the error which I get is "cdo import_binary (Abort): Could not open file: e:\ind1901_rfp25.grd"

Sakila Saminathan and Girish Patidar , I am getting the exact error in CDO. I think I have the correct CTL file.

Here is an executable program that you can use to extract IMD 0.25° rainfall and 1° temperature datasets. The details are provide in the instructions file. This is an easy method if you are looking to extract daily data to excel or text file. the link to the code is: https://github.com/sinannizar/IMD-Gridded-Rainfall-Extractor

Sinan Nizar, Thank you very much.

@Kamal Pandey sir the extractor is not functioning

Hi folks,

There is easy way to direct download precipitation data from IMD site along with visualization in Python.

A python package to download and handle binary grided data from India Meteorological Department (IMD)

Link:

https://pratiman-91.github.io/2020/10/05/IMDLIB.html

Hope so this will help.

Cheers...!

Avinash

Hi all,

If you wish to use the R codes, Here is the code from my git repository to extact rainfall for your region of interest

https://github.com/ysubash/imdrain

Thank You, Sinar Nizar Bhai..