The NASA SnowEx Mission (2017-2023)

Photo credit: Kate Hale

Presented by: HP Marshall, SnowEx 2018-2021 Project Scientist, NASA GSFC

SnowEx Leadership Team: Carrie Vuyovich, Sveta Stuefer, H.P. Marshall, Kelly Elder, Mike Durand, Megan Mason, Dragos Vas, Chris Hiemstra

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

Why is seasonal snow important?�

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• Approximately 2 billion people depend on seasonal snow for water supply. Seasonal snowmelt - over 70% of water resources in Western U.S.
• Massive impact on surface albedo and global energy balance – over 1/3 of the Earth’s land surface covered by snow annually
• Contributes to disasters (floods, droughts, avalanches, wildfires)
• Patterns are changing - earlier melt, more frequent rain-on-snow, changing snowlines
• But challenging to measure and model:
• Length scale of variability in depth 20-200m
• Dynamic changes on time scales of hours-days
• No current satellite remote sensing product for SWE in mountainous regions
• Models show widespread both temporally and spatially, largely due to uncertainties in forcing data

​

Solution to global snow monitoring: fusion of remote sensing, models, ground obs.

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

What is SnowEx?

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SnowEx is a multi-year coordinated airborne and ground experiment to evaluate different snow remote sensing technologies throughout the season in various landscapes. Results will help inform future snow satellite missions.

snow.nasa.gov

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

NASA SnowEx Mission and community events 2013-2024

Boulder 2013

Baltimore 2019

SnowEx Hackweeks 2020-2024

NASA/CUAHSI SnowSchools 2016-2024

SnowEx Alaska

2022-23

Community meeting

THP Snow Roadmap, future mission proposal opportunities, snow OSSE, SnowEx priorities

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

SnowEx Science Plan

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The Science Plan lays out a recommended SnowEx plan to test sensor capabilities and sensitivities and address the most critical gaps in snow remote sensing. Identified gaps in current capabilities:

• Prairie snow
• Tundra snow
• Mountain Snow
• Maritime snow

Durand, M., C. Gatebe, E. Kim, N. Molotch, T. Painter, M. Raleigh, M. Sandells, and C. Vuyovich, NASA SnowEx Science Plan: Assessing approaches for measuring water in Earth's seasonal snow, Version 1.6, 

• Forests
• Wet snow
• Snow surface energetics

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

NASA SnowEx Science Plan Capabilities Chart

Current capabilities

from SnowEx

Science Plan

​

Rows =

• sensing techniques
• models

​

Columns =

• gaps,
• snow parameters,
• space potential

no capability

Demonstrated, TRL>5

Potential, TRL 3-5?

Potential, TRL 1-2?

Capability Color Key

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

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Primary Science Questions:

1. What is the distribution of SWE and the snow energy balance in different canopy types, canopy densities, and terrain?
2. What is the sensitivity and accuracy of different SWE sensing techniques in different canopy types, canopy densities, and terrain?
3. What is the optimum combination of sensing techniques to measure SWE globally?

NASA SnowEx 2017

L-band InSAR results showing agreement with lidar and depth obs

Highlights:

• 100 participants (scientists, students, international)
• 24 institutions
• 5 of 5 aircraft & 9 of 10 sensors flown
• 154 snow pits; 165 transects
• 30 ground remote sensors
• Extensive community-building activities
• Snow.nasa.gov website stood up
• 1^st SnowEx workshop Aug 2017; 92 attendees

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

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Primary Objectives:

1. Test L-band InSAR phase change for Δ SWE/snow depth among different snow climates & landscapes
2. Test SWE retrieval from active & passive microwave
3. Value of satellite thermal IR observations for energy balance & modeling

​

NASA SnowEx 2020

SWESARR Radar data collected over Grand Mesa, CO during the Feb 2020 IOP. The data were processed with a Time Domain Back Projection algorithm and used for snow water equivalent (SWE) retrieval.

Data Collected

Campaign design:

• Over 100 students, researchers from 20+ organizations
• Time Series of weekly to biweekly UAVSAR flights, Dec-March
• Intensive observing period (IOP) in Grand Mesa, CO, Nov/Jan/Feb

09VH

13VH

17VH

09VV

13VV

17VV

L-band InSAR

Depth change (cm)

Lidar

Depth change (cm)

Preliminary results from SnowEx 2020 show good snow depth change agreement between L-band InSAR and lidar data: R-value = 0.76, RMSD=4.7cm depth, 0.9cm SWE.

2020 Experiment Plan

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

NASA SnowEx 2021

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Primary Objectives:

1. Quantify the accuracy of L-band InSAR SWE retrievals in preparation for NISAR
2. Define the snow conditions where L-band InSAR is likely to maintain coherence
3. Evaluate the spatiotemporal variability in snow albedo, the controls on this variability, and the uncertainty of remote sensing measurements relative to mountains, forests, and as snow albedo declines over time.
4. Characterize the spatial heterogeneity of snow characteristics at an agricultural site

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SnowEx 2020 & 2021 Campaign sites

Dec, 2019 – Mar 2020; Dec 2020 – May 2021

Prairie site at Central Agricultural Research Center, MT (left) showing shallow snow redistributed by wind into ditches and fields. UAVSAR image of CARC (right).

2021 Experiment Plan

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

NASA SnowEx 2023

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Understanding unique snow remote sensing challenges in the tundra and boreal forest

Primary Objectives:

1. SWE:  How do microstructure accuracy and scaling issues impact the use of models to inform Ku-band volume scattering retrievals in tundra snow? How much does Ku-band penetrate forest canopies in boreal forests?
2. Snow depth:  How well do snow depth retrieval methods (e.g., lidar and SfM) work where “bare earth” surfaces fluctuate, due to the variable permafrost, water, and vegetation characteristics ubiquitous at high latitudes?
3. Snow albedo: What is the nature of spatial variability of snow reflectance/albedo and physical properties in the boreal forest, and how does it change with scale?

Data Collected

2023 Experiment Plan

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

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NASA Terrestrial Hydrology Program SnowEx Summary:

NRL P-3

Twin Otter

Cessna 206

Four SnowEx campaigns were conducted at 20 different locations in the Western US and Alaska (red dots). Base map shows snow classes defined in Sturm & Liston (2021). Map credit: Svetlana Stuefer, UAF

NASA SnowEx, Accomplishments to Date

• Over 250 Participants
• From 49 Institutions
• 8 Aircraft
• 14 Airborne Instruments
• 184 Individual Datasets
• >40 Publications using SnowEx data
• 26 PhD Dissertations and 6 Masters Theses complete or in progress
• 2 satellite mission proposals to the Earth System Explorer solicitation

SnowEx References

What’s missing?

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

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SnowEx Data

Data collected through instrumentation and processing funded by the Terrestrial Hydrology Program (THP).

​

Partnered Data

Data collected through partnerships outside of the THP resources, with the agreement of being shareable and publicly accessible.

​

Data Inventory Update

Provided by Megan Mason, NASA GSFC

SnowEx Data Inventory

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

SnowEx Publications – Gaps Addressed

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Science Plan Gaps

Forest

(13)

Mountain

(8)

(5)

Wet Snow (4)

(1)

Prairie (2)

Surface Energetics (3)

Global focus

(8)

Other (1)

*Not specifically addressed (yet):

• Maritime
• Tundra

• Uncertainty estimates focused on specific gaps
• Strong focus on forest questions (18) address main objectives of SnowEx
• Several algorithm development and basic measurement studies can be broadly applied

​

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

Outreach

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SnowEx-MAIANSE Internships, 2000-present

• 7 Interns to date from American Indian and Alaska Native serving institutions
• Projects developed based on SnowEx data needs & student interest and ongoing local activities
• Student paired with mentor to work on the project

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University of Alaska student measuring SWE at Fairbanks campus during SnowEx 2023

Fond Du Lac Tribal and Community College students measuring SWE at Minnesota campus location

SnowEX-ED: NASA STEAM Education With Snow

To bring the excitement and science of SnowEx to the public:

1. Designed and built snow science kits (~800)
2. Distributed these across the US through outdoor schools & nature centers
3. Facilitated press releases highlighting snow science and society’s reliance on snow for water
4. Delivered fun in-person outdoor snow experiences to thousands of adults and youths across Alaska.

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

Community Training

Hackweeks

Hackweeks are participant-driven workshops designed to foster collaboration, provide education in the tools and methods of open science, and align community members around shared software and NASA datasets. https://snowex.hackweek.io/

CUAHSI Field Measurement Schools

4-day hands-on field school; prepare researchers at all career levels to make quality field observations using standard techniques (depth, density, temperature, grain size/type, SWE, etc), in addition to some exposure to new technologies

• K-12 program that takes over 35,000 students into the snow environment to teach science. 80+ local programs across the U.S.
• Students learn the importance of snow, how to measure SWE, depth, stratigraphy, in addition to winter ecology, shelter building, etc
• Pre/Post classroom visits, demonstrated increases in learning
• Students made measurements for SnowEx, improved SnowSchool curriculum

Winter Wildlands Alliance Snow School

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

What next for the snow community?

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• Goal of SnowEx – improve understanding for satellite-based snow retrievals
• Better prepared for SBG, NISAR
• Two SWE satellite proposals submitted in 2023. Both rejected 2024.
• EVS mission proposal (SnowEx follow-on) airborne campaign rejected.
• Grass-roots effort needed to keep momentum. We are the underdogs. Hackweeks are critical for this effort.

• Projects during Hackweek can lead to long term collaborations, working groups, open science
• UAVSAR_pytools, ML with time lapse cameras, thermal IR work
• Projects can build on each other!
• Snowmelt detection, fSCA -> required for all radar retrieval efforts
• Microstructure -> required for Ku-band SAR retrieval
• SnowEx SQL database / NSDIC access -> required for sensor fusion, technique comparison
• Fusion products (e.g. radar + lidar) -> more robust cal/val information

NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

SnowEx Collaborations & Partnerships�

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NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah

Snow science is a team sport!�

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NASA Earth Sciences and UW Hackweek

19-23 August 2024, eScience Institute, Seattle, WA

https://tinyurl.com/4shkf2ah