ACIS Dataset Comparison Tool

Select the variable of interest from the menu and click off the datasets you would like to compare. You can select as many sources as you like. Hit "Go" and a "button bar" will be displayed where you can select the decade of interest from those available for that station. After clicking on one of the decades in the button bar, the appropriate data will be displayed in a table.

There are four possible outcomes for each day:

• Data values are the same for all datesets being analyzed (no shading);
• A value in a dataset differs from the value contained in the dateset displayed in the first column (indicated by yellow shading);
• Value in first column is missing, but there are non-missing values in another dateset (red shading);
• Non-missing data are present in the first dataset, but missing in another (cyan shading).

After the table is displayed, it can be manipulated using the "Display days" button bar that appears under the decade bar. Initially, all types of days are displayed (all buttons lit up with colors described above). Clicking on the buttons in this bar will turn the various classes of results off (button becomes gray) and on (button restored to original color).

Dataset Notes

• TD-3200/TD-3210 - ACIS displays subsequent values when provided from these data sources; GHCN-Daily always displays original values.

GHCN Data Sources (current as of GHCN Version 3.03)

GHCN source flags are as follows. Sources with strike-through are not ingested into ACIS.

• Blank = No source (i.e., data value missing)
• 0 = U.S. Cooperative Summary of the Day (NCDC DSI-3200)
• 6 = CDMP Cooperative Summary of the Day (NCDC DSI-3206)
• 7 = U.S. Cooperative Summary of the Day - Transmitted via WxCoder3 (NCDC DSI-3207)
• A = U.S. Automated Surface Observing System (ASOS) real-time data
• a = Australian data from the Australian Bureau of Meteorology
• B = U.S. ASOS data for October 2000-December 2005 (NCDC DSI-3211)
• C = Canadian data
• b = Belarus update
• E = European Climate Assessment and Dataset (Klein Tank et al., 2002)
• F = U.S. Fort data
• G = Official Global Climate Observing System (GCOS) or other government-supplied data
• H = High Plains Regional Climate Center real-time data
• I = International collection (non U.S. data received through personal contacts)
• K = U.S. Cooperative Summary of the Day - Digitized from paper forms (2011 to present)
• M = Monthly METAR Extract (additional ASOS data)
• N = Community Collaborative Rain, Hail,and Snow (CoCoRaHS)
• Q = Data from several African countries
• R = NCDC Reference Network Database (CRN and HCN-Modernized)
• r = All-Russian Research Institute of Hydrometeorological Information-World Data Center
• S = Global Summary of the Day (NCDC DSI-9618) derived from hourly synoptic reports
• s = China Meteorological Administration
• T = SNOwpack TELemtry (SNOTEL) data obtained from the WRCC
• U = Remote Automatic Weather Station (RAWS) data obtained from the WRCC
• u = Ukraine update
• W = WBAN/ASOS Summary of the Day from NCDC's Integrated Surface Data (ISD).
• X = U.S. First-Order Summary of the Day (NCDC DSI-3210)
• Z = Datzilla official additions or replacements
• z = Uzbekistan update

GHCN source priority order (from highest to lowest): Z,R,0,6,X,W,K,7,F,B,M,r,E,z,u,b,a,G,Q,I,A,N,H,S

Up-to-date source list available at - https://www1.ncdc.noaa.gov/pub/data/ghcn/daily/readme.txt

ACIS Dataset Precedence

Effective 3-September-2013, when values from more than one data set are present in ACIS, the order of precedence is as follows:

1. GHCN-Daily
2. TD-3210
3. TD-3200
4. TD-3206
5. TD-3299
6. TD-3298
7. TD-3205
8. CLI/CF6
9. DSM
10. Shef