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�SAILing with SPLASH:�Winter 2021-2022 Analysis to Inform the 2023 �Sublimation of Snow (SOS) Field Campaign �

Daniel Hogan, University of Washington

 J. D. Lundquist, E. D. Gutmann, G. de Boer, T. P. Meyers, C. J. Cox, M. Gallagher, D. Feldman, and J. Kochendorfer

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Mountain Meteorology Conference, Park City, Utah

30 June 2022

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Photo Credit: Michael Gallagher (2022)

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  • Accurate snow models are imperative to estimate seasonal water availability
  • Gaps persist between snowfall and river output

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Background & Motivation

Courtesy of USGS

Courtesy of NCRS

Colorado Basin

Snowpack

% of Normal

River Discharge

% of Normal

2020

111%

66%

2021

80%

47%

2020 Colorado River Basin Discharge

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Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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The Transition from Snow to Water Vapor

  • Sublimation is a large source of uncertainty in snow models (Slater et al. 2001, Xia et al. 2017)

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  • Driven by surface fluxes and blowing snow

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  • Estimates vary widely from 1-50% of seasonal snowfall (Mott 2018)

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  • Difficult to measure in complex terrain, need seasonal measurements

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Blowing snow

Sublimation

Water Vapor

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

Sublimation has Mass and Energy Components

Snow Mass Balance

 

Snow Surface Energy Balance

 

 

mass transfer

of water vapor

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Measurements For Quantifying Sublimation

Snow Mass Balance

 

Snow Surface Energy Balance

 

TLS Scans

Snow Scales

Snow surface temp.

Radiometers

Flux Towers

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Sublimation of Snow Campaign: Location is Vital

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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SOS Campaign Setup

10 m

20 m

10 m

Snow scale

10 m

Primary Wind Direction

  1. Tall tower to measure profile through inversion in strongly stable conditions.
  2. Multiple towers detect horizontal variability and direction of wave propagation.
  3. Terrestrial laser scanners (TLS) to measure blowing snow density and snow surface redistribution through time.
  4. Snow scales to weigh change in snow water equivalent through time.

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Snow & Mountains Challenge Sublimation Measurements

1. Difficult to Maintain Equipment in Challenging Conditions

Photo Credit: Benjamin Schmatz (2021)

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Photo Credit: billy barr (2021)

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Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Snow & Mountains Challenge Sublimation Measurements

1. Difficult to Maintain Equipment in Challenging Conditions

Credit: Ryan Currier (2021)

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Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Snow & Mountains Challenge Sublimation Measurements

2. Strong Stability Over Snow Dampens Turbulence

More Stable

Less stable

Courtesy of Winter ‘21-’22 SAIL MET measurements

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Sunny Conditions Persist (Unlike Seattle…)

90.0%

74.7%

89.1%

86.8%

84.0%

64.2%

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

Courtesy of SAIL Total Sky Imager

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Winter 21’ – ’22 Conditions

Sunny Conditions Persist (Unlike Seattle…)

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Energy is Available to Power Sublimation During Daytime

 

 

Away from surface

Towards surface

Solar Energy Available to Sublimate Snow

Energy Away from

Surface at Night

Energy Away from

Surface at Night

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

Courtesy of SPLASH RADSYS measurements

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Winter 21’ – ’22 Conditions

Blowing Snow Conditions

Adapted from Déry and Taylor (1996)

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61.4%

74.4%

57.9%

53.9%

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Strong Vapor Pressure Deficits Promote Sublimation/Condensation

 

Transfer coefficient

Vapor Pressure Deficit

Mean wind speed

Sublimation

Mass transfer of

water vapor

Condensation

(surface hoar)

Courtesy of SAIL met station and surface temperature measurements

Stable

Unstable

Transfer coefficient varies with wind speed

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Strong Vapor Pressure Deficits Promote Sublimation/Condensation

 

Transfer coefficient

Vapor Pressure Deficit

Mean wind speed

Sublimation

Mass transfer of

water vapor

Condensation

(surface hoar)

Courtesy of SAIL MET and surface temperature measurements

Stable

Unstable

Transfer coefficient varies with wind speed

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Occurrences of Near Surface Inversion

Median Inversion Depth: 40 meters

83.6%

16.4%

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Example Strong Near-Surface Inversion on 3 January 2022

Median Inversion Depth: 40 meters

Da

Courtesy of SAIL radiosonde measurements

700 hPa

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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SOS Campaign Hypotheses

Valley wind fields

(measured by SAIL)

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Turbulence Regimes

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

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Winter 21’ – ’22 Conditions

Turbulence Regimes

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

 

 

 

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Answering this SOS to help fill the gap between snowfall and water availability

Conditions Conducive to sublimation persist throughout the winter

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We seek to study sublimation in mountainous terrain to better understand:

    • Drivers of sublimation
    • Seasonal snow mass balance
    • Energy budget

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

Energy available to sublimate

Blowing snow conditions

Strong vapor pressure gradients

Turbulence generated multiple ways

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Thank you!

Sublimation & Turbulence

Background & Motivation

SOS Approach

Winter ’21-’22 Conditions

Summary

A special thank you to those at SPLASH and SAIL who were willing and able to share data and information used for this presentation.

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Liston, G. E., and M. Sturm, 1998: A snow-transport model for complex terrain. Journal of Glaciology, 44, 498–516, https://doi.org/10.3189/S0022143000002021.

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Mott, R., V. Vionnet, and T. Grünewald, 2018: The Seasonal Snow Cover Dynamics: Review on Wind-Driven Coupling Processes. Frontiers in Earth Science, 6.

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Pomeroy, J. W., and D. M. Gray, 1990: Saltation of snow. Water Resources Research, 26, 1583–1594,

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Slater, A. G., and Coauthors, 2001: The Representation of Snow in Land Surface Schemes: Results from PILPS 2(d). Journal of Hydrometeorology, 2, 7–25, https://doi.org/10.1175/1525-7541(2001)002<0007:TROSIL>2.0.CO;2.

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Sun, J., L. Mahrt, R. M. Banta, and Y. L. Pichugina, 2012: Turbulence Regimes and Turbulence Intermittency in the Stable Boundary Layer during CASES-99. Journal of the Atmospheric Sciences, 69, 338–351, https://doi.org/10.1175/JAS-D-11-082.1.

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Xia, Y., D. Mocko, M. Huang, B. Li, M. Rodell, K. E. Mitchell, X. Cai, and M. B. Ek, 2017: Comparison and Assessment of Three Advanced Land Surface Models in Simulating Terrestrial Water Storage Components over the United States. Journal of Hydrometeorology, 18, 625–649, https://doi.org/10.1175/JHM-D-16-0112.1.

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References

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1) Dry air is entrained into the surface layer, driving intermittent bursts of sublimation during stable conditions

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1) Sub-mesoscale motions above the stable boundary layer inject intermittent turbulence, increasing sublimation.

Valley wind fields

(measured by SAIL)

3) Blowing snow drives sublimation during strong wind events during near-neutral conditions

stable boundary layer

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3

x

z