This README_SWE_sample_logsheet.txt file was generated on 2022-03-31 by Ian Howat

GENERAL INFORMATION

1. Title of Dataset:  Weekly Snow Board Accumulation Measurements, 2017-2020, Summit Camp, Greenland

2. Author Information
	Corresponding Investigator 
		Name: Ian Howat
		Institution: Byrd Polar & Climate Research Center, Ohio State University
		Email: howat.4@osu.edu

3. Date of data collection: 2017-03-16 to 2020-03-05

4. Geographic location of data collection: Summit Camp, Greenland (72°34′46.5″N, 38°27′33.07″ W)

5. Funding sources that supported the collection of the data: US National Aeronautics and Space Administration (NASA)

6. Reuse: Must use following citation when data used or presented: Howat I., 2022, Data from: Temporal variability in snow accumulation and density at Summit Camp, Greenland ice sheet, Dryad, Dataset, doi:10.5061/dryad.f7m0cfxz9

7. Publication Describing these Data:  Howat, IM, 2022, Temporal Variability in Snow Accumulation and Density at Summit Camp, Greenland Ice Sheet, Journal of Glaciology. doi.org/10.1017/jog.2022.21 

DATA & FILE OVERVIEW

1. Description of dataset

Observations were obtained using the snow board method, where accumulation atop a board, which serves as a depth reference, is repeatedly sampled and measured. A shallow, rectangular pit is excavated, and a piece of plywood is placed over the floor of the pit. The pit is then allowed to fill with snow and settle over a period of at least two weeks. A plastic tube is used to remove a core sample of the snow from the surface to the plywood, which serves as a depth reference for each subsequent sample. The sample is taken from a different location on the board each time, as measured from flagged poles at the corner of the plywood, to provide an undisturbed sample. The snow water equivalent (SWE) of the sample is obtained from both its mass and water volume, providing redundancy for quality control. To obtain the SWE thickness of the sample from its mass, the sample is brought indoors in its sampling tube and weighed. The weight of the empty sampling tube is subtracted, and this weight is divided by the cross-sectional area of the tube. To obtain the SWE thickness from the sample volume, the sample is allowed to melt and the liquid volume is divided by the cross-sectional area of the core. The snow depth at each sampling site is also recorded. The SWE estimate divided by this depth gives an estimate of sample density. Measurement precisions and resulting uncertainties are provided in Howat (2022).

When no undisturbed locations remain on the board, or the snow becomes too deep to sample, sampling moves to a new, adjacent snow board site. During the change to a new site, samples are taken at the same time at both the old and new site. The snow board sampling sites were in a designated area of undisturbed snow, upwind of other field instrumentation and buildings to minimize their influence on accumulation.

2. Data File Desription:

File Name: SWE_sample_logsheet.txt
File Description: Weekly Snowboard Measurements 
File Format: tab-delimited text
Missing values = -999

3: Date Field Descriptions

Field 1: "Measurement Date (YYYYMMDD)"
Field 2: "Sample Site ID", Letters identifying each snow board used for sampling.
Field 3: "Sample Distance (cm)", Distance of the sample from the corner of the board.
Field 4: "Beginning Weight (g)", Weight of empty sampling tube.
Field 5: "Total Weight (g)", Weight of sample and sampling tube.
Field 6: "Snow Weight (g)", Total Weight minus Beginning Weight.
Field 7: "Water Volume (mL)", Sample water volume after melting.
Field 8: "Snow Depth (cm)", Thickness of snow above board at sampling site. 
Field 9: "Core Diameter (cm)", Diameter of sampling tube.
Field 10: "Comments", Notes by sampling personnel.