Comparison of the PACRAIN Database to the Global Historical Climatology Network Data Set

The Pacific Rainfall Program (PACRAIN) at the University of Oklahoma maintains a comprehensive online database of tropical Pacific rainfall observations. The database includes data from several sources, including PACRAIN's Schools of the Pacific Rainfall Climate Experiment and external sources such as the National Climatic Data Center (NCDC) and the National Institute of Water and Atmospheric Research (NIWA). Data from NCDC make up the bulk of observations from US possessions and affiliated nations north of the Equator, while NIWA is the primary source for data in the South Pacific.

The Global Historical Climatology Network – Daily (GHCN) data set is NCDC's data set of record for global daily climate observations. GHCN replaces a number of NCDC data sets, including the TD3200 Cooperative Summary of the Day data set. While both of these data sets use the same source data, they have different quality assurance schemes that lead to differences between the two data sets in some cases. Also, TD3200 was limited to the US first-order and cooperative observation networks so the geographic scope of GHCN is much greater.

The PACRAIN database includes a mix of GHCN and TD3200 data depending on when the data were ingested; prior to the 2011 data year most values are from TD3200. While GHCN data are available for the South Pacific, at this time PACRAIN exclusively uses NIWA data for this region. The existence of this overlapping data provides an opportunity to compare the PACRAIN database to GHCN with the goal of identifying differences between the two data sets.