GCIP LSA-NW EAOP00 SNOTEL Hourly Surface Data
1.0 General Description
The Natural Resources Conservation Service (NRCS) Snowpack
Telemetry (SNOTEL) dataset is one of several surface datasets
provided in the GEWEX Continental-Scale International Project (GCIP)
Large Scale Area-North West (LSA-NW) Enhanced Annual Observing Period
(EAOP) 2000. This dataset contains data for the GCIP LSA-NW EAOP-00
domain and time period (01 April 2000 through 31 March 2001). The
GCIP LSA-NW EAOP-99 domain is approximately 90W to 115W longitude and
36N to 51N latitude. These data were not quality controlled by the
University Corporation for Atmospheric Research/Joint Office of
Science Support (UCAR/JOSS) and are provided as is.
2.0 Detailed Data Description
The NRCS installs, operates, and maintains an extensive,
automated system to collect snowpack and related climatic data in the
Western United States. Since 1980, SNOTEL has produced
water supply forecasts and supported the resource management
activities of the NRCS and others. This dataset contains 228 SNOTEL
stations equipped with a pressure sensing snow pillow, storage
precipitation gage, and air temperature sensor. These instruments
take hourly readings of accumulated precipitation, snow depth, snow
water equivalent, temperature maximum for day, temperature minimum for
day, average temperature for day, and temperature at observation time.
More information for these SNOTEL sites can be found at:
http://www.wcc.nrcs.usda.gov/snotel/SNOTEL_Info/snotel_info.html.
2.1 Detailed Format Description
This data is provided "as is" and has not been modified or
quality controlled by UCAR/JOSS. Each file contains a header section
followed by columnar ascii data. Data parameters are followed by two
flags describing the data. Below is a listing of parameters and their
possible flags.
Data Parameters:
:wrccNo - WRCC internal station ID
:YrMoDyHr - Year Month Day Hour in Local Standard Time
:Prec - Accumulated Precip Since Oct 1 in inches x 100
:SDep - Snow Depth (not used now)
: SWE - Snow Water Equivalent in inches x 10
:Tmax - Temperature Maximum for Day (F)
:Tmin - Temperature Minimum for Day (F)
:Tave - Temperature Average for Day (F)
:Tobs - Temperature at Observation Time (F)
: FF - Flag1 and Flag 2
: Flag 1 - M - Missing
: Flag 2 is often blank
List of flags for Snotel:
Treat all flags as case-sensitive.
Many of these are the same as NCDC flags.
Last updated 19991128
Flag 1 - Measurement flag
A - Accumulated value since last measurement (set aside but not used)
M - Missing
E - Estimated (flag 2 gives more details)
S - Included in a subsequent value (set aside but not used)
T - Trace (probably never used)
- [blank] no other flag needed
Flag 2 - Quality flag
0 - Original data element (from NRCS holdings)
1 - Validated original data element, inspected by QC process
2 - Invalid data element (original value, to be replaced by subsequent value)
3 - Invalid data element with no replacement
4 - Validity not known
5 - Edited to missing value, replacement for invalid non-missing value.
f - Field edits from Data Collection Officers
r - Provisional realtime data through NWS Gateway (LDM ingestion)
p - Provisional realtime data direct from NRCS (via ftp, for example)
v - Provisional data, NRCS evaluation - data bad (UU NRCS flag).
A - Made extreme max/min compatible with previous day
B - Absolute bounds exceeded
F - Flatliner, constant for 6 days or longer
L - Switched Tmax and Tmin
N - Revised based on Nearest Neighbors, areal comparisons
Q - Provisional data, quality is suspect according to NRCS real-time QC
S - General manual edit for whatever reason
T - Other automated edit
U - Unknown NRCS flag
W - WRCC edit not covered by other flags
X - Original missing replaced by areal estimate
[ ] - other letters to be assigned during WRCC QC
3.0 Quality Control Processing
These data were not quality controlled by UCAR/JOSS, and are
available "as is".
4.0 References
The National Water & Climate Center: SNOTEL Information and Technology
http://www.wcc.nrcs.usda.gov/snotel/SNOTEL_Info/snotel_info.html;
June 12, 2002