ODIAC Fossil Fuel CO₂ Emissions

Documentation of data transformation

This script was used to transform the ODIAC Fossil Fuel CO₂ Emissions dataset from GeoTIFF to Cloud Optimized GeoTIFF (COG) format for display in the Greenhouse Gas (GHG) Center.

import xarray
import re
import tempfile
import numpy as np
import boto3
import os
import gzip,shutil, wget
import s3fs
import hashlib
import json

session = boto3.session.Session()
s3_client = session.client("s3")
fs = s3fs.S3FileSystem()

data_dir = "data/"
dataset_name = "odiac-ffco2-monthgrid-v2024"
cog_data_bucket = "ghgc-data-store-develop"
cog_data_prefix= f"transformed_cogs/{dataset_name}"
cog_checksum_prefix= "checksum"

# Retrieve the checksum of raw files
checksum_dict ={}
for year in range(2000,2023):
    checksum_url = f"https://db.cger.nies.go.jp/nies_data/10.17595/20170411.001/odiac2024/1km_tiff/{year}/odiac2024_1km_checksum_{year}.md5.txt"
    response = requests.get(checksum_url)
    content = response.text
    tmp={}
    
    # Split the content into lines
    lines = content.splitlines()
    
    for line in lines:
        checksum, filename = line.split()
        tmp[filename[:-3]] = checksum
    checksum_dict.update(tmp)
checksum_dict = {k: v for k, v in checksum_dict.items() if k.endswith('.tif')}

def calculate_md5(file_path):
    """
    Calculate the MD5 hash of a file.

    Parameters:
    file_path (str): The path to the file.

    Returns:
    str: The MD5 hash of the file.
    """
    hash_md5 = hashlib.md5()
    with open(file_path, "rb") as f:
        for chunk in iter(lambda: f.read(4096), b""):
            hash_md5.update(chunk)
    return hash_md5.hexdigest()

#Code to download raw ODIAC data in your local machine

# Creating  a base directory for ODIAC data
if not os.path.exists(data_dir):
        os.makedirs(data_dir)

checksum_dict_local={}
# Download and unzip data for the years you want
for year in range(2000,2023):
    year_dir = os.path.join(data_dir, str(year))
    checksum_download_link = f"https://db.cger.nies.go.jp/nies_data/10.17595/20170411.001/odiac2024/1km_tiff/{year}/odiac2024_1km_checksum_{year}.md5.txt"
    wget.download(checksum_download_link, year_dir)
    # Make a subfolder for each year
    if not os.path.exists(year_dir):
        os.makedirs(year_dir)

    for month in range(1,13):
        month = f"{month:02d}"
        download_link = f"https://db.cger.nies.go.jp/nies_data/10.17595/20170411.001/odiac2024/1km_tiff/{year}/odiac2024_1km_excl_intl_{str(year)[-2:]}{month}.tif.gz"
        target_folder = f"{data_dir}/{year}/"
        fname = os.path.basename(download_link)
        target_path = os.path.join(target_folder, fname)

        # Download the file
        wget.download(download_link, target_path)

        # Unzip the file
        with gzip.open(target_path, 'rb') as f_in:
            with open(target_path[:-3], 'wb') as f_out:
                shutil.copyfileobj(f_in, f_out)
                
        # Calculate checksum of the .gz file 
        checksum_dict_local[target_path.split("/")[-1][:-3]]=calculate_md5(target_path)
        
        # Remove the zip file
        os.remove(target_path)
    

# check if the checksums match
checksum_dict_local == checksum_dict

# List of years you want to run the transformation on
fold_names=[str(i) for i in range(2000,2024)]

for fol_ in fold_names:
    names= os.listdir(f"{data_dir}{fol_}")
    names= [name for name in names if name.endswith('.tif')]
    print("For year: " ,fol_)
    for name in names:
        xds = xarray.open_dataarray(f"{data_dir}{fol_}/{name}")
        filename = name.split("/ ")[-1]
        filename_elements = re.split("[_ .]", filename)
        
        # Remove the extension
        filename_elements.pop()
        # Extract and insert date of generated COG into filename
        filename_elements[-1] = fol_ + filename_elements[-1][-2:]

        # Replace 0 values  with -9999
        xds = xds.where(xds!=0, -9999)
        xds.rio.set_spatial_dims("x", "y", inplace=True)
        xds.rio.write_nodata(-9999, inplace=True)
        xds.rio.write_crs("epsg:4326", inplace=True)

        cog_filename = "_".join(filename_elements)
        cog_filename = f"{cog_filename}.tif"

        # Write the cog file to s3 
        with tempfile.NamedTemporaryFile() as temp_file:
            xds.rio.to_raster(
                temp_file.name,
                driver="COG",
                compress="DEFLATE"
            )
            s3_client.upload_file(
                Filename=temp_file.name,
                Bucket=cog_data_bucket,
                Key=f"{cog_data_prefix}/{cog_filename}",
            )

        print(f"Generated and saved COG: {cog_filename}")

print("ODIAC COGs generation completed!!!")

# This block is used to calculate the SHA for each COG file and store in a JSON.

def get_all_s3_keys(bucket, model_name, ext):
    """Get a list of all keys in an S3 bucket."""
    keys = []

    kwargs = {"Bucket": bucket, "Prefix": f"{model_name}/"}
    while True:
        resp = s3_client.list_objects_v2(**kwargs)
        for obj in resp["Contents"]:
            if obj["Key"].endswith(ext) and "historical" not in obj["Key"]:
                keys.append(obj["Key"])

        try:
            kwargs["ContinuationToken"] = resp["NextContinuationToken"]
        except KeyError:
            break

    return keys

keys = get_all_s3_keys(cog_data_bucket, cog_data_prefix,".tif")


def compute_sha256(url):
    """Compute SHA-256 checksum for a given file."""
    sha256_hash = hashlib.sha256()
    with fs.open(url) as f:
        for byte_block in iter(lambda: f.read(4096), b""):
            sha256_hash.update(byte_block)
    return sha256_hash.hexdigest()

sha_mapping = {}
for key in keys:
    sha_mapping[key.split("/")[-1]]=compute_sha256(f"s3://{cog_data_bucket}/{key}")


json_data = json.dumps(sha_mapping, indent=4)
s3_client.put_object(Bucket=cog_data_bucket, Key=f"{cog_checksum_prefix}/{dataset_name}.json", Body=json_data)

print("Checksums created for ODIAC!!!")