7 8

Wyoming SnowFWater Equivalent Variability Based on Historical SNOTEL9 Data;enitza ;q Voutchkova F Scott jq >iller

Wyoming ,enter for {nvironmental ~ydrology and 'eophysics F

;epartment of {cosystem Science and >anagement

University of Wyoming

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,luster dendrogram

j#T{S

data5 SW{max J44Yb9YJ7 Bn:97 x p:6YT

BJ464bJ404O J44%O 9YJ%O 9YJ8 excludedT

transformation5 centered and scaled1 |5scale {base}

distance5 euclideanO |5dist {stats}

clustering5 hierarchical

aglomeartion5 wardq;9 methodO |5hclust {stats}

uncertainty5 approximately unbiased pbvalues BwTO

computed by multiscale bootstrap resampling1

|5pvclust {pvclust} with replication ):JYLYYYO

sample sizes nL:cBJJO J7O J2O J0O 9YO 97O 98

96O 94O 79TO reproducibility iseed:JY

W y o m i n gW y o m i n g

%L9Y6mqaqsql

j

4%%mqaqsql Y %Y 0Y km

BJ7L0Y% ftTB7LY44 ftT

WyomingSj#T{+ stations

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,heyenne

South @latte

jorth @latte

WhitebYampa

'reat ;ividebUpper 'reen

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9YYJ 9YY9 9YY7 9YY% 9YY8

9YY2 9YY6 9YY0 9YY4 9YJY 9YJJ 9YJ9 9YJ7

SW{max dataset used for cluster analysis

6Y stations

year

SW{max

d : maxBSW{maxT : J

d

97 years

colors5clusters Jb8

SW{max

tmax

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Sj#T{+ is automated snowpack monitoring network5

b operated by the jatural |esources ,onservation Service Bj|,STO

b 67Y remote high elevation stations in JJ Western statesO

b openbaccessO nearbreal time F ~7Y years of historical dataq

@U|@#S{5 forecasting of water supplies in the West

xf xxx = h / k 6 7 8 9WORK FLOW

download daily data

n:6Y WY stations

period5J464b9YJ8

exclude incomplete water

years F convert units

Bfeet in mmT

extract SW{ signatures

all stations F years

check SW{ signatures

for errors Btoo lowAhighO

earlyAlateO negative periodsT

check raw data F

maintenance comments

select common period

for all 6Y stations

hierarchical clustering

SW{max variability

pbvalues via multiscale

bootstrap resampling

linear trends for 8

regions in WY

multiannual variability

8year moving window

implications F future work

numberofSj#T{+sites 6Y

2Y

8Y

%Y

7Y

9Y

JY

YPressure transducer types

6Y

2Y

8Y

%Y

7Y

9Y

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YPillow type

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8 new pressure transducersBno change in typeT

new site Bn:%T or replacedpillow Bno change in typeT

Jq8 @si Usbr

2YLL @illow Usbr b Validyne

JYYLL Transducer b ;ruck

8YLL Transducer b Sensotec

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unconfirmed from archives

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= {quipment F maintenance h 6 @retreatment F selection

{levation BmqaqsqlT

/ SW{ signatures

taprqJ tY

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nmms

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BSW{T accumulation

SW{max annual peak accumulation

SW{aprqJ snow water equivalent accumulation on =pril Jst

@melt duration of snowbablation period

S rate of ablation in mmAday

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J44Y

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incomplete water years

per cluster

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9Y

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water years per station

wy J464b9YJ8

Y J 9 7 % 8 2 6 0 JY

incomplete water years BnT

frequency

Y

8

JY

J8

9Y

w

;id Wyoming snowbwater equivalent BSW{T change

in the period J464b9YJ8-

/s there a subbregional difference in SW{ variability in WY-

What are the implications for water resources-

9

x979F=fxksignificant changeBlinear regressionsT

s

SW{max

tmax tY

82 mmAJYy Bp3YqY8T

8Y mmAJYy Bp3YqY8T

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x99fF=fxk no significant trendsO except5 @melt IJq0 dAJYy Bp3YqJT

+inear trends summary

mean

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b J S;

b 9 S;

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Duration of snowFablation

daysdqwqyq

xf Variability summary

high

9YJ8

centralwateryear

low

J44Y

x Yq8S;x JS;

Periods with highplow SWEmax

pattern brakes

Jst period

9nd period

Similaritiesbetweenclusters

SW{max

SW{max timing

SW{:Y timing

rate of snowbablation

snowbablation duration

highestlatestlongestfastest

lowestearliestshortestslowliest

Top k

@roject funding5

BJT jational Science }oundation B{@S J9Y04Y4T though the Wyoming ,enter for {nvironmental ~ydrology and

'eophysics BWy,{~'T

B9T University of Wyoming #ffice of |esearch and {conomic ;evelopment

Travel grants5

BJT Wyoming Women in Science and {ngineering BWW/S{T program funded by jS} 'rant K {@S J9Y04Y4

B9T ,onsortium of Universities for the =dvancement of ~ydrologic Science B,U=~S/T

xx /mplications F future work

>ultiannual variability of SW{ signatures

j#T{S

data5 subbregional means Bmean from

the stations in each clusterT

analysis5 centered 8byear moving average

?UST/}/,=T/#j5

We use subbregional means in order to reduce

the effect of potential data quality problems

for individual stationq

ThenO we smooth the interannual variability

of the subbregional means with 8byear moving

averageO in order to study the multiannual patterns

xf

Data limitationsBJT Short time record5limits the ability to study longterm trendsO multiannual or decadal

variabilityO and the changes in itq |egional linear trends Bsee 4T may be biased by

the fewer stations up to J44Yq

B9T ;ata quality5data quality evaluation is limited by the lack of or the inconsistency of

existing metabdataq The equipment maintenance comments are not standartizedq

The metabdata and the daily observations are not linked in a databaseq

twitter5(;enitzaV waterbresearchqinfo

Future workBJT {levation control on SW{ trends and variabilityq =ll 6Y stations are at high

elevations Bx9YYYmTO nevertheless there may be differences in the longterm trends

and variability depending on elevationq

B9T ,oupling SW{ with streamflowO precipitation and data on vegetation disturbances

for high elevation headwater watersheds to evaluate potential

changes in streamflowq

Understanding snowpack dynamics is important step in studying hydrological responce

and water resources availability in the Westq

}ocusing on subbregional differences in snowpack dynamics helps local water

managementO eqgq irrigation and water supply planningq

j#T{S5

BJT 96w of the stations Bn:J4T have an active backup pillow and transducer up to end of water year 9YJ81

B9T different types of instrumentation within the spatial and temporal extent of the study1

B7T errors in labelingO maintenance comments in free textO no unification of codesO not a database1

B%T annual summer maintenance includes5zero sensors and pillowsO fixing equipment due to single damage

events BbearsO falling branchesTO moving equipmentAlocation due to wild firesO or not known reasonsO

cutting vegetation around the site

n:J%

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jorthbWest W

Y5YellowsoneplateauOWind

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{ast slopes of =bsaroka and Wind |iver |anges

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)ighorn>ountains

SW{max : JqJ9 P SW{aprqJ I J8q26 | |9 : Yq47 | pbvalue : 39q9ebJ2

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