NARCCAP Data Organization & Download

This document describes how NARCCAP data is organized and provides a walkthrough for downloading it from the Earth System Grid. To download NARCCAP data:

1. Go to the Earth System Grid homepage, http://www.earthsystemgrid.org/.
2. Click the "Login" tab and log in to the system. You can't download NARCCAP data unless you are logged-in and your account has been approved for NARCCAP access. (See http://www.narccap.ucar.edu/users.html for more information about NARCCAP access requirements.)
3. From either the "Home" tab or the "Data" tab, clik on NARCCAP under "Browse Dataset Catalogs".
4. NARCCAP data is organized by model and driver. The top-level catalog page for NARCCAP shows a grid with RCM along the vertical axis and GCM (or NCEP observed data) along the horizontal axis. Click the folder icon of the RCM/driver combination you're interested in.
5. At the next level, data files are organized by variable into tables (groups). See the data tables page to find which table contains the variable you are interested in. For example, if you want surface temperature data, you want variable tas from Table 2. Note that primary impacts-assessment variables are all in Table 2. Click the appopriate link.
6. The page will list individual datafiles. To download a file, just click on its name.

NARCCAP data filenames are of the form VariableName_ModelName_Time.nc.

• VariableName is the IPCC/CF-convention Variable Name as listed in the data tables
• ModelName is the 4-character RCM identifier
• Time is the starting time of the file, in the form YearMonthDayUTC.

So, for example, tas_RCM3_1981010103.nc contains data for variable tas from the RegCM3 regional model starting at 03 UTC on January 1st, 1981 and ending at 00 UTC on January 1st, 1985.