1. Addressing Bias in Snow Water Equivalent Measurement Methods
Jordan French
Special Acknowledgments to:
Dr. Jeff Snider, UW Atmospheric Science, WyCEHG, NSF, and Snowmetrix

2. What is the significance of snow?
Largest precipitation type in northwestern US

3. Snowfall Measurement Methods
Snotel
Hotplate snow gauge
Manual “snowboard” method
Scales

4. Project in upstate NY
Lake snow effects
Discrepancy between methods

5. Hypotheses
The scale measurement of weight (precision ± 0.3 %) agrees with the value of a standard weight - within measurement error - and this agreement is apparent regardless of temperature.
The manual method measurement of SWE compares well with the hotplate measurement of SWE.
Objective: Improved confidence in snowfall measurements is expected to result from this research

7. Weighing Precision Mean: 𝑥 𝑝 = 1 𝑁 𝑁=1 10 𝑥 𝑖
𝑥 𝑝 = 1 𝑁 𝑁=1 10 𝑥 𝑖
where 𝑥 𝑖 =𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡 𝑜𝑓 𝑤𝑒𝑖𝑔ℎ𝑡
Standard Deviation:
𝑥 𝐴 = 1 𝑁 𝑁=1 10 (𝑥 𝑖 − 𝑥 0 )
Relative Precision:
𝜎 𝑃 𝑥

8. Scale Scale 2

9. Scale 3

10. Weighing Accuracy Average departure from reference:
𝑥 𝐴 = 1 𝑁 𝑁=1 10 (𝑥 𝑖 − 𝑥 0 )
Standard Deviation of departure:
𝜎 𝐴 = 1 𝑁−1 𝑁=1 10 ( 𝑥 𝑖 − 𝑥 0 ) 2
where 𝑥 0 =𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑚𝑎𝑠𝑠

11. Scale Scale 2

12. Scale 3

13. Snowfall Measurements in the Snowy Range

14. Snow Water Equivalent Measurement
Procedure
Single snow event
Extract snow core with tube
Determine weight of snow
𝑆𝑊𝐸= 𝑚 𝑠𝑛𝑜𝑤 𝜌 𝐻 2 𝑂 ∗( 1 𝐴 )
𝜌= 𝑆𝑊𝐸 𝑑 ∗( 𝜌 𝐻 2 𝑂 )

15. Snowboard Method Results
Tube 1
Tube 2
Tube 3
Snow Depth (mm) 20
SWE (mm)
0.448
0.442
1.329
ρ (kg/m^3)
22.384
22.090
66.452

16. Conclusion More fieldwork to be done