For data content questions, contact Niwot LTER data manager
For methodology questions, contact Hope Humphries
INSTAAR, University of Colorado
1560 30th St., UCB 450
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1. Use our data freely. All Niwot LTER data products (except some recent data sets for which metadata but not data are available) are released to the public and may be freely copied, distributed, edited, remixed, and built upon under the condition that you provide acknowledgement as described below.
2. Give proper acknowledgement. Publications, models and data products that make use of these data sets must include proper acknowledgement, including citing data sets in a similar way to citing a journal article. See http://www.datacite.org/whycitedata). The following acknowledgment should accompany any publication or citation of these data: Logistical support and/or data were provided by the NSF supported Niwot Ridge Long-Term Ecological Research project and the University of Colorado Mountain Research Station
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This serially complete dataset includes hourly, quality-controlled, infilled meteorological data for three sites at the Niwot Ridge LTER: C1, Saddle, and D1, representing subalpine, alpine, and high-alpine environments, respectively. Raw observations of air temperature, relative humidity, wind speed, and incoming shortwave radiation were subjected to a rigorous hierarchical quality control and infilling protocol to make a robust, continuous dataset. Incoming longwave radiation was estimated using air temperature, relative humidity, and incoming shortwave radiation. Precipitation data were accessed from the Niwot Ridge LTER quality controlled datasets and Kittel et al. (2015). Precipitation values from C1 and Saddle were then corrected for gage undercatch (C1) and overcatch (Saddle) based on observations of snow accumulation at the Niwot SNOTEL station and snow pits located near the met stations (D1 precipitation data were not corrected as there were no available observation of snow accumulation). Daily precipitation values were temporally disaggregated to the hourly time step of the dataset.
This dataset was originally created to force a physics-base snow model and is suitable for use in other research models that require hourly forcing data. Please contact the dataset's creators or the LTER data manager if you have any questions regarding the data or its applicability/suitability to your project.
Disclaimer: These data come as-is with no warranty. The user must decide whether or not to use different variables and time periods within the dataset and whether further processing is warranted. In general, the data quality is higher and there are fewer infilled values from 2000 to 2013. The higher number of infilled entries before 2000 may preclude the 1990–1999 period from being used in a given analysis. This is particularly true for relative humidity and incoming solar radiation. The Niwot Ridge LTER is not responsible for the methodological choices made by those using the data.
For cross-validation statistics on the infilling procedure and further information on the protocol, please see Jennings et al. (2017) in The Cryosphere: Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget. (DOI for paper will be added when available)
C1: latitude 40.036336, longitude -105.543542, elevation 3022 m
Saddle: latitude 40.05421, longitude -105.589042, elevation 3528 m
D1: latitude 40.059798, longitude -105.616393, elevation 3739 m
1990-1-1 to 2013-12-31
air temperature, relative humidity, wind speed, incoming shortwave radiation, incoming longwave radiation, precipitation
Elevation: 3048 m
Elevation: 3500 m
Elevation: 3750 m
Niwot Ridge (USFS - UNESCO Biosphere Reserve)
Located in: USFS - UNESCO Biosphere Reserve
(Click to learn more about these locations)
More data from: C1, Saddle, D1
Core Data Set: No
Discipline: Climatology/meteorology, Hydrology, Atmospheric science
Award Or Grant: DEB1027341, DEB1637686
Quality control: The quality control procedure for air temperature, incoming shortwave radiation, relative humidity, and wind speed is based on Meek and Hatfield (1994). Data are subject to three checks, in the following order: (1) Maximum/minimum threshold; (2) Rate of change threshold; and (3) Stuck sensor (if the same value is recorded for 4 or more time steps in a row). Longwave radiation was estimated from quality controlled, infilled values of air temperature, relative humidity, and incoming shortwave radiation. Daily precipitation observations were disaggregated to an hourly time step and these data came from Kittel et al. (2015) (C1 and D1 1990–2010) and the Niwot Ridge LTER quality controlled dataset (Saddle 1990–2013; C1 and D1 2011–2013). Gage corrections were applied to C1 and Saddle precipitation observations relative to snowfall accumulation measurements. No further quality control or infilling procedures were applied to the precipitation data.
Infilling: If data fail the quality control checks, then they are infilled using the following scheme based on Liston and Elder (2006), Henn et al. (2012), and Kittel (2010): (1) Gaps of 1 h are filled using a linear interpolation between the time step before and after the gap; (2) Gaps > 1 h and <= 24 h are filled with an average of the value 24 hours before the observation and 24 hours after; (3) Gaps > 24 h and <= 72 h are filled with a forecasted and backcasted ARIMA model weighted by the temporal distance from the beginning/end of gap; (4) Gaps >= 72 h are filled with a linear regression from 1 or 2 of the other meteorological stations, or the climatic mean if no stations are reporting.
In (4) above, regressions are fit using observations that passed the quality control checks for each variable, for each combination of stations, for each month, in 3 hour time blocks. This produces a total of 288 regression equations per station per variable (station X ~ station Y + station Z, X ~ Y, X ~ Z; Jan–Dec; 0100–0300 h, 0400–0600 h, 0700–0900 h, 1000–1200 h, 1300–1500 h, 1600–1800 h, 1900–2100 h, 2200–2400 h, all time ranges inclusive). In addition, the climatic mean for each month and 3 h time block was computed and was used as an infilling value when no stations were reporting.
Incoming shortwave radiation was only quality controlled and infilled using the procedure above for daylight hours. Otherwise, all non-zero entries were set to zero.
Before 2000, relative humidity observations exhibited periods of instrument drift. Drift was corrected by rescaling the observations to match the range of measured relative humidity values within the 2000–2013 record.Instrument drift was less post-2013, but values were rescaled to ensure RH did not exceed 100%. To note, instrument drift corrections exceeded 60% pre-2000, but were generally less than 5% post-2000. RH data before 2000 should be therefore used carefully. Additionally, infilling regressions were performed on dewpoint temperature.
Incoming longwave radiation was estimated based on quality controlled, infilled air temperature, relative humidity, and incoming shortwave radiation as outlined in Flerchinger et al. (2009). Estimates exhbited low biases relative to shorter term observations of incoming longwave radiation at the Subnivean Laboratory for the Saddle and the Niwot AmeriFlux Tower for C1. No comparisons were available for D1.
Precipitation data for C1 and D1 from 1990–2010 came from the Kittel et al. (2015) quality controlled, infilled dataset. Precipitation data for Saddle (1990–2013) and C1 and D1 (2011–2013) came from the quality controlled Niwot Ridge LTER core datasets (http://niwot.colorado.edu/index.php/data/data/precipitation-data-for-c1-chart-recorder-1952-ongoing, http://niwot.colorado.edu/index.php/data/data/precipitation-data-for-saddle-chart-recorder-1981-ongoing, http://niwot.colorado.edu/index.php/data/data/precipitation-data-for-d1-chart-recorder-1964-ongoing). The daily time step of the observations was disaggregated to hourly by dividing each daily value by 24 and distributing it equally across each hour of the day (i.e., if 24 mm of precipitation were recorded in a day, each hour would be assigned an hourly rate of 1 mm h-1). C1 solid precipitation observations were corrected for gage undercatch relative to snowfall accumulation on the Niwot SNOTEL snow pillow. Monthly scaling factors were created for Saddle precipitation gage overcatch relative to snow pit snow accumulation measurements. The Saddle precipitation gage catches blowing snow and often overreports the total precipitation received at the site (Williams et al., 1998). No snow accumulation observations were available at D1, so no corrections were applied to the precipitation data.
The flagging structure has the format qcXinY, where X indicates the quality control protocol applied, if any, and Y indicates the infilling protocol applied, if any.
X can have the following values: 0 (observation passed all quality control checks); 1 (observation removed because it falls outside of the maximum/minimum threshold for that variable); 2 (observation removed because it exceeded the rate of change threshold); 3 (observation removed because the sensor was stuck); 4 (variable missing from raw data due to power outage, missing files, datalogger issue, etc.).
Y can have the following values: 0 (no infilling applied); 1 (gap = 1 h, infilled by using linear interpolation between previous and following observations); 2 (gap > 1 h and <= 24, infilled by taking average value of observation 24 hours before and after missing value); 3 (gap > 24 and <= 72 h, infilled with forecasted and backcasted ARIMA model); 4 (infilled using multiple linear regression of observations from both other met stations); 5 (infilled using linear regression from closest met station); 6 (infilled using linear regression from farthest met station); 7 (infilled using climatic mean for that month and 3 h time block).
Exceptions: For relative humidity, a 'd' next to the quality control number indicates the observation was drift-corrected. For incoming solar radiation, an 'n' in the infill slot indicates nighttime (i.e., shortrad_in = 0 W m-2) There are no flags associated with incoming longwave radiation values as they are estimates based on air temperature, relative humidty, and shortwave radiation. Please see those variable flags to see the status of the input data. There are no flags associated with the precipitation data. Please see the relevant Niwot Ridge LTER daily precipitation datasets for quality control and infilling information.
Flerchinger, G.N., Xaio, W., Marks, D., Sauer, T.J., Yu, Q., 2009. Comparison of algorithms for incoming atmospheric long-wave radiation: ATMOSPHERIC LONG-WAVE RADIATION ALGORITHMS. Water Resour. Res. 45, n/a-n/a. doi:10.1029/2008WR007394
Henn, B., Raleigh, M.S., Fisher, A., Lundquist, J.D., 2012. A Comparison of Methods for Filling Gaps in Hourly Near-Surface Air Temperature Data. J. Hydrometeorol. 14, 929–945. doi:10.1175/JHM-D-12-027.1
Kittel, T.G.F., Williams, M.W., Chowanski, K., Hartman, M., Ackerman, T., Losleben, M., Blanken, P.D., 2015. Contrasting long-term alpine and subalpine precipitation trends in a mid-latitude North American mountain system, Colorado Front Range, USA. Plant Ecol. Divers. 8, 607–624. doi:10.1080/17550874.2016.1143536
Kittel, Timothy, 2010. The Development and Analysis of Climate Datasets for National Park Science and Management.
Liston, G.E., Elder, K., 2006. A meteorological distribution system for high-resolution terrestrial modeling (MicroMet). J. Hydrometeorol. 7, 217–234.
Meek, D.W., Hatfield, J.L., 1994. Data quality checking for single station meteorological databases. Agric. For. Meteorol. 69, 85–109.
Williams, M.W., Bardsley, T., Rikkers, M., 1998. Overestimation of snow depth and inorganic nitrogen wetfall using NADP data, Niwot Ridge, Colorado. Atmos. Environ. 32, 3827–3833.
For more details:
For cross-validation statistics on the infilling procedure and further information on the protocol, please see Jennings et al. (2017) in The Cryosphere: Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget. (DOI for paper to be added when available)
meteorological, climate, climatology, forcing data, hourly, infilling, chart data, logger data, air temperature, relative humidity, wind speed, incoming shortwave radiation, incoming longwave radiation, precipitation, C1, D1, saddle, alpine, subalpine, NWT, Niwot Ridge LTER, long term
COL1. label=LTER_site, type=string, units=none, missing value indicator=NaN, minimum=NWT, maximum=NWT, precision=, definition=Niwot Ridge LTER site
COL2. label=local_site, type=string, units=none, missing value indicator=NaN, minimum=c1, maximum=sdl, precision=, definition=local site: c1; sdl=saddle; d1
COL3. label=date-time, type=string, units=none, missing value indicator=NaN, minimum=1990-01-01 00:00, maximum=2013-12-31 22:00, precision=, definition=date-time (yyyy-mm-dd hh:mm)
COL4. label=year, type=integer, units=none, missing value indicator=NaN, minimum=1990, maximum=2013, precision=l, definition=year
COL5. label=jday, type=integer, units=none, missing value indicator=NaN, minimum=0, maximum=366, precision=l, definition=Julian day
COL3. label=date, type=string, units=none, missing value indicator=NaN, minimum=1990-01-01, maximum=2013-12-31, precision=, definition=date-time (yyyy-mm-dd hh:mm)
COL6. label=hour-min, type=string, units=none, missing value indicator=NaN, minimum=0000, maximum=2300, precision=, definition=hour-min (hhmm)
COL7. label=airtemp_avg, type=real, units=celsius, missing value indicator=NaN, minimum=, maximum=, precision=, definition=average air temperature in degrees celsius
COL8. label=airtemp_flag, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=, definition=flag denoting QC and infill protocol applied to raw data - see methods for explanation
COL9. label=rh_avg, type=real, units=percent, missing value indicator=NaN, minimum=, maximum=, precision=, definition=average relative humidity in percent
COL10. label=rh_flag, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=, definition=flag denoting QC and infill protocol applied to raw data - see methods for explanation
COL11. label=ws_avg, type=real, units=meterPerSecond, missing value indicator=NaN, minimum=, maximum=, precision=, definition=average wind speed in meters per second
COL12. label=ws_flag, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=, definition=flag denoting QC and infill protocol applied to raw data - see methods for explanation
COL13. label=shortrad_in, type=real, units=wattPerMeterSquared, missing value indicator=NaN, minimum=, maximum=, precision=, definition=incoming shortwave radiation in watts per meter squared
COL14. label=shortrad_flag, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=, definition=flag denoting QC and infill protocol applied to raw data - see methods for explanation
COL15. label=longrad_in, type=real, units=wattPerMeterSquared, missing value indicator=NaN, minimum=, maximum=, precision=, definition=incoming longwave radiation in watts per meter squared
COL16. label=ppt_tot, type=real, units=millimeterPerHour, missing value indicator=NaN, minimum=, maximum=, precision=, definition=precipitation in millimeters per hour
*Note: To ask a question about data content, please contact the data manager HERE
To ask a question about methodology, please contact Hope Humphries,
Jennings, K.S., T.G.F. Kittel, and N.P. Molotch. 2017. Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget. The Cryosphere (submitted).
Documentation for this data set was developed from metadata provided by Keith Jennings.[HCH 16 November 2017]
Jennings, Keith. Kittel, Timothy. Molotch, Noah. 2017. Infilled climate data for C1 Saddle D1 from 1990-1-1 to 2013-12-31, hourly. http://niwot.colorado.edu
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-1637686. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necesarily reflect the views of the National Science Foundation.
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