README.TXT Weather data from Purple Valley (near the head of Milne Fiord), northern Ellesmere Island, Nunavut (May 2009 to October 2019) Recommended Citation: Copland, L. , Mueller, D. 2021. Weather data from Purple Valley (near the head of Milne Fiord), northern Ellesmere Island, Nunavut (May 2009 to October 2019). Nordicana D93, doi: 10.5885/45735XD-011EA11523034D87 Abstract: This dataset provides a long-term weather record from Purple Valley, Ellesmere Island. This location is near the head of Milne Fiord and can serve as an index location for the region adjacent to the ice shelves of northern Ellesmere Island. Weather data were observed every 4 minutes by an automated weather station, averaged and recorded hourly and transmitted daily using a satellite data connection. The station was a 3 m tripod with a Hobo Energy Pro logger, an Iridium satellite transceiver, a solar panel/battery bank, and the following data are available: air temperature at 1 m above surface, air temperature at 2 m above surface, relative humidity at 2 m above surface, wind direction and wind speed at 4 m above surface, incoming radiation at 3 m above surface, atmospheric pressure, and snow depth. The station is located at the east end of Purple Valley (82.483986°N, 80.7881122°W at 20 m asl) above the valley floor and a few hundred metres south of a little bay in Milne Fiord. It is on a small area of level ground at the top of a bench along the slope of an arrete that borders Milne Fiord. The immediate surroundings are bare, flat ground with sparse polar desert vegetation. Note that the snow conditions at this site are not representative of the general area as the bench where the station was located is exposed and often blows clear. Keywords: Weather, Climate, Air temperature, Relative humidity, Wind direction, Wind speed, Snow depth, Barometric pressure, Cryosphere, Ice shelf Variables and units: DateTime [UTC time zone] in ISO format– local time is UTC-5 hours air_temperature_2m_C [degrees C] air_temperature_1m_C [degrees C] relative_humidity_percent [%] surface_downwelling_shortwave_flux_in_air_Wm2 [W m-2] wind_speed_ms [m s-1] wind_speed_of_gust_ms [m s-1] wind_from_direction_deg [degree (azimuth from True North)] air_pressure_Pa [Pa] surface_snow_thickness_m [m] Notes on accuracy, precision and instrument heights: None of the instruments were calibrated after they were first installed. Surface_snow_thickness is not very reliable since the snow conditions at this site are not representative of the general area since the station is exposed to wind and often blows clear. There is also a lot of noise in the data in spite of data filtering (see below). Details on each instrument are in the following comma-delimited table. Variable,Model,Serial Number,Manufacturer,Installation height (m),Accuracy,Precision/Resolution,Calibration Range,Response time (s),Notes air_temperature_2m_C,S-THB-M00X,1274746,Onset Computer Corporation,2,±0.21°C from 0° to 50°C,0.02°C at 25°C,-40°C to 75°C,300,Thermistor in a radiation shield air_temperature_1m_C,S-THB-M0xx,1264342,Onset Computer Corporation,1,< ±0.2°C from 0° to 50°C,<0.03°C from 0° to 50°C,-40°C to 100°C,120,Thermistor in a radiation shield relative_humidity_percent,S-THB-M00X,1274746,Onset Computer Corporation,2,±2.5% from 10% to 90% RH typical to a maximum of ±3.5% including hysteresis at 25°C; below 10% and above 90% ±5% typical ,0.1% RH,0 to 100% RH,300,Hygrometer in a radiation shield surface_downwelling_shortwave_flux_in_air_Wm2,S-LIB-M003,2317248,Onset Computer Corporation,3,"Typically within ±10 W/m2 or ±5%, whichever is greater in sunlight; Additional temperature induced error ±0.38 W/m2/°C from 25°C",1.25 W/m2,0 to 1280 W/m2,Unknown,Silicon pyranometer wind_speed_ms,S-WCA-M003,2319717,Onset Computer Corporation,3.92,± 0.5 m/s ± 3% 17 to 30 m/s ±4% 30 to 44 m/s ,0.19 m/s,0 to 44 m/s,NA,Anemometer (wind speed and direction) [also recorded wind_speed_of_gust] wind_from_direction_deg,S-WCA-M003,2319717,Onset Computer Corporation,3.92,± 5 degrees,1.4 degrees,0-358 degrees,NA,Anemometer (wind speed and direction) air_pressure_Pa,S-BPA-CM10,1272859,Onset Computer Corporation,2,±3.0 mbar,0.1 mbar,660 mb to 1070 mb,NA,Barometer placed inside the logger enclosure surface_snow_thickness_m,ToughSonic TS-15S,Unknown,Senix,1.75,±0.172 mm,"Nominal 0.2% of range @ constant temp. Affected by target, distance, environment",-40 to 70 C,NA,Sonic ranger pointed at ground Photos: Station photos, photographer, caption and dates (UTC yyyymmddThhmm) are given in the comma-delimited table below FileName,DateTime,Photographer,Weather,Caption LookingEastInMay.JPG,20120517T1434,Luke Copland,Clear Skies,Looking to the East at the station in May (when there is snow) LookingEast.JPG,20180722T0123,Derek Mueller,Clear Skies,East view from the station LookingNorth.JPG,20180722T0123,Derek Mueller,Clear Skies,North view from the station LookingSouth.JPG,20180722T0123,Derek Mueller,Clear Skies,South view from the station LookingSouthEast.JPG,201907182T1511,Derek Mueller,Clear Skies,Southeast view from the station AreaOverviewLookingNorth.JPG,20180724T1900,Jérémie Bonneau,Clear Skies,"Looking North from the top of a nearby mountain to the Arctic Ocean (far background), Milne Fiord (right ice-covered), Purple Valley (approx. east-west on left side). The station is circled in red. " AreaOverviewLookingNNE.JPG,20180718T1513,Jérémie Bonneau,Clear Skies,Looking NNE from a helicopter to Milne Fiord (ice-covered) and to the arête that divides it from this unnamed valley. The end of Purple Valley can be seen in the background on the left. The station is circled in red. LookingDownOnStation.JPG,201900706T12022,Jérémie Bonneau,Clear Skies,Looking straight down on the station from a helicopter Collaborators: Adrienne White, Laboratory for Cryospheric Research, Department of Geography, Environment and Geomatics, University of Ottawa (now at the Canadian Ice Service, Environment and Climate Change Canada) – contributed to the maintenance of the station, lead author of a paper that analyzed the data. Andrew Hamilton, Department of Civil and Environmental Engineering, University of British Columbia (now at the Department of Earth and Atmospheric Sciences, University of Alberta) – contributed to the maintenance of the station, lead author of a paper that analyzed the data. Acknowledgments: We thank the following funding and logistics agencies for support: Polar Continental Shelf Program, Natural Sciences and Engineering Research Council of Canada, ArcticNet Network of Centres of Excellence, Canada Foundation for Innovation, Ontario Research Fund, University of Ottawa. The following individuals helped to maintain the station: Sierra Pope, Colleen Mortimer, Adrienne White, Andrew Hamilton, Miriam Richer-McCallum, Tyler de Jong, Nat Wilson, Kelly Graves, Sam Brenner, Kevin Xu, Jill Rajewicz, Adam Garbo, Gregory Crocker, Dorota Medrzycka, Peter Wray, Jinsuk Kim, Drew Friedrichs, Yulia Antropova, Jérémie Bonneau. We thank the pilots and staff of the Polar Continental Shelf Program for their assistance getting our teams in and out of the field. We acknowledge the communities of Resolute (Qausuittuq) and Grise Fiord (Aujuittuq) for providing their permission for us to conduct our research and are grateful for the support of the Nunavut Research Institute for their assistance with research licences. Links to previously published work using this dataset: Bonneau, J. (2020). Winter Dynamics in an Epishelf Lake (MASc thesis). University of British Columbia, Department of Civil Engineering, Vancouver, BC. https://doi.org/10.14288/1.0392852 Bonneau, J., Laval, B. E., Mueller, D., Hamilton, A. K., Friedrichs, A. M., & Forrest, A. L. (2021). Winter dynamics in an epishelf lake: Quantitative mixing estimates and ice shelf basal channel considerations. Journal of Geophysical Research - Oceans, In revision. Hamilton, A. K. (2016). Ice-ocean interactions in Milne Fiord (PhD Dissertation). University of British Columbia, Department of Civil Engineering, Vancouver, BC. https://doi.org/10.14288/1.0314106 Hamilton, Andrew K., Laval, B. E., Mueller, D. R., Vincent, W. F., & Copland, L. (2017). Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness. The Cryosphere, 11(5), 2189–2211. https://doi.org/10.5194/tc-11-2189-2017 Mortimer, C. (2011). Quantification of volume changes for the Milne Ice Shelf, Nunavut, 1950-2009 (MSc thesis). University of Ottawa, Department of Geography. http://dx.doi.org/10.20381/ruor-4428 Mortimer, C. A., Copland, L., & Mueller, D. R. (2012). Volume and area changes of the Milne Ice Shelf, Ellesmere Island, Nunavut, Canada, since 1950. Journal of Geophysical Research, 117(F4), F04011. https://doi.org/10.1029/2011JF002074 Pope, S. (2010). Changes in Multiyear Landfast Sea Ice in the Northern Canadian Arctic Archipelago (MSc thesis). University of Ottawa, Department of Geography. Pope, S., Copland, L., & Mueller, D. (2012). Loss of multiyear landfast sea ice from Yelverton Bay, Ellesmere Island, Nunavut, Canada. Arctic, Antarctic, and Alpine Research, 44(2), 210–221. https://doi.org/10.1657/1938-4246-44.2.210 Richer-McCallum, M. (2015). Analysis of ice types along the northern coast of Ellesmere Island, Nunavut, Canada, and their relationship to Synthetic Aperture Radar (SAR) backscatter (MSc thesis). Carleton University, Ottawa, Canada. https://doi.org/10.22215/etd/2015-10920 White, A. (2012). Dynamics and historical changes of the Petersen Ice Shelf and epishelf lake, Nunavut, Canada, since 1959. University of Ottawa. http://dx.doi.org/10.20381/ruor-6251 White, A., & Copland, L. (2018). Area change of glaciers across Northern Ellesmere Island, Nunavut, between ~1999 and ~2015. Journal of Glaciology, 64(246), 609–623. https://doi.org/10.1017/jog.2018.49 White, A., & Copland, L. (2019). Loss of floating glacier tongues from the Yelverton Bay region, Ellesmere Island, Canada. Journal of Glaciology, 65(251), 376–394. https://doi.org/10.1017/jog.2019.15 White, A., Copland, L., Mueller, D., & Van Wychen, W. (2015). Assessment of historical changes (1959–2012) and the causes of recent break-ups of the Petersen Ice Shelf, Nunavut, Canada. Annals of Glaciology, 56(69), 65–76. https://doi.org/10.3189/2015AoG69A687 White, A. C. (2019). Glacier changes across northern Ellesmere Island (PhD Dissertation). Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, Canada. http://dx.doi.org/10.20381/ruor-23350 Notes on data cleaning: In summary, the data were cleaned as follows: Date and time: From 20121130 to 20130515 time stamp is at 25 minutes past the hour From 20170907 to 20180722 time stamp is at 37 minutes past the hour All timestamps were converted to 'on the hour' by rounding the timestamp to hourly; Date/Time variable was expanded to fill the entire record at an hourly time step air_temperature2m_C and air_temperature1m_C : Spurious data < -60C and > 30C were removed relative_humidity_percent: Spurious data << 0 removed surface_downwelling_shortwave_flux_in_air_Wm2: Adjusted the record to match 0 during winter (subtracted 0.6 W m-2) wind_speed_of_gust_ms: Spurious data < -800 were removed wind_speed_of_gust_ms and wind_speed_ms: Data from May 2012 to July 2013 were only available in kph. Converted to m/s Set wind speed and wind gust speed to NA due to suspected rime when there was >72 hrs of continuous wind gust = 0 - this occurred only in winter (below freezing temperatures) Note that it is possible that the anemometer was rimed for periods less then 72 hours, but it becomes increasingly difficult to distinguish between rime and no wind. Note that wind distribution seems to change after January 2014 where lower wind speeds are more prevalent. This may be due to instrument issues. wind_from_direction_deg: Note that a 72 hour rolling (linear not circular) standard deviation of wind direction was examined. No periods of this length had a standard deviation of 0 for wind direction, therefore long term riming of weather vane was not suspected air_pressure_Pa: Removed a few bad sections with unreasonable values surface_snow_thickness: Removed spurious data well above and below reasonable values; Removed bad sections of data; Determined a reasonable correction to ground level based on July 18-23 histogram every year; Removed high frequency noise using a 23 hour rolling median filter; values below 0 were set to 0. All variables were rounded to reasonable number of digits based on instrument specifications. The data are now cleaned and ready to use. However, caution should be exercised regarding the surface_snow_thickness_m (noisy values due to small changes in vegetation/surface conditions, plus station was sited in a location with frequent winds stripping away snow) and wind data (due to the possibility of riming). For more information about this dataset, please contact: Luke Copland, Laboratory for Cryospheric Research, Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, Canada, luke.copland@uottawa.ca Derek Mueller, Water and Ice Research Laboratory, Department of Geography and Environmental Studies, Carleton University, Ottawa, Canada, derek.mueller@carleton.ca