yangxhcaf / ghcnd

Scripts used to process Global Historical Climatology Network Daily data.

GHCND

Scripts used to process Global Historical Climatology Network Daily (GHCND) data. GHCND data available at: https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/global-historical-climatology-network-ghcn

Matlab scripts used for processing GHCND data. Code requires customization and will not run 'as-is'. Several of the matlab scripts are dervied directly from, or modified from, the Matlab Spring Indices code package: https://www.mathworks.com/matlabcentral/fileexchange/54679-extended-spring-indices--si-x--code Ault et al. 2015.

Always happy to answer questions and I welcome helpful suggestions to improve the efficiency of the code. The snow-related code was written for a specific project (Protect Our Winters & REI, 2018 - https://www.rei.com/blog/snowsports/climate-change-threatens-11-3-billion-snowsports-industry-protect-our-winters-report-says) and is adaptable for multiple uses. The code is also being used to update the New Hampshire Climate Assessment Report using Localized Constructed Analogs (LOCA) data (Pierce et al. 2014).

contact: [email protected].

Files listed in order of use in my processeing & analysis.

(1a) mk_ghcnd.m

• processes metadata file from GHCND (ghcnd-stations.txt)

(1b) mk_ghcnd_inv.m

• processes inventory file from GHCND (ghcnd-inventory.txt)

(2) filterGHCND.m

• Screens and filters Global Historical Climatology Network Daily (GHCN-D)
• for station availability based on:
  • start year of record
  • end year of record
  • location (US states)
  • data availability (var = SNWD, SNOW, TMAX, TMIN, or PRCP)

(3) read_ghcnd_dly_file.m

• loads ghcnd station data
• used in GHCND_SNWD.m, below. Not meant to run as stand-alone
• from Matlab Spring Indices code package (Ault et al. 2015)

(4) GHCND_SNWD.m (same for GHCND_TMAX.m, GHCND_PRCP.m)

• loads Global Historical Climatology Network Daily files using the function "read_ghcnd_dly_file.m"
• Output is a state-level .mat file of daily station data meeting criteria defined in filterGHCND.m

(5) procSNWD.m (same for procTMAX_LOCA.m, procTMIN_LOCA.m, procPRPC_LOCA.m)

• loads state-level .mat files created using "GHCND_SNWD.m", which contain GHCND daily snow depth data (in mm), 2000-2016.
• The script then does the following:
  • calculates percent missing data per season or year
  • removes years or seasons missing % threshold of daily records
  • removes stations missing > 2 years of data (procSNWD.m only)
  • sums the number of days per winter (December through March) with snow depth greater than a user-defined threshold (>4" recommended; procSNWD.m only)
  • calculates the state average # of snow days per winter (procSNWD.m only)
  • ranks the winters from highest to lowest number of snow covered days (procSNWD.m only)
  • calculates a variety of metrics for TMAX, TMIN, and PRCP.

(6) writeGHCND_metadata.m

• writes metadata from GHNCD station list generated using filterGHCND.m into .csv file (for use in LOCA processing)