PRECIPITATION-RUNOFF MODELING SYSTEM (PRMS) SNOW MODELING OVERVIEW.
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Transcript of PRECIPITATION-RUNOFF MODELING SYSTEM (PRMS) SNOW MODELING OVERVIEW.
PRECIPITATION-RUNOFF MODELING SYSTEM
(PRMS)
SNOW MODELING OVERVIEW
PRMS
PRMS Parameters
original version
PRMSParameters
MMS Version
SNOW PROPERTIES
• Porous media
• Undergoes metamorphosis
• Surface albedo changes with time
• Density increases with time
• Has a free-water holding capacity
Energy Balance Formulation
Hm = Hsn + Hln + Hc + He + Hg + Hp + Hq
Temperature-Index FormulationM = Cm * ( Ta - Tb)
Modifications
Seasonal adjustment to Cm
Vary Cm for forest and open
Use equation only for non rain days
Account for Hg and Hq
Snowpack Energy Balance Components
Energy Balance FormulationHm = Hsn + Hln + Hc + He + Hg + Hp + Hq
Model Formulation (on each HRU)
PRMS SNOW MODEL
Hsn = swrad * (1. - albedo) * rad_trncf
Hln = emis * sb_const * tavg4 ( T4)
Hc + He = cecn_coef(mo) * tavg (ppt days)
= 0 (dry days)
Hp = tavg * net_precip
Hg assumed 0 Hq is computed
Snow Surface Albedo vs Time
Solar Radiation Transmission Coefficient vs Cover Density
Net Longwave Radiation
Hlw = (1. - covden_win) * [(emis * air) -snow)]
emis = emis_noppt no precip
= 1.0 precip
air and snow = sb_const * tavg4 [ ( T4)
where tavg is temp of air and temp of snow surface
+ covden_win * (air -snow)
Energy Balance FormulationHm = Hsn + Hln + Hc + He + Hg + Hp + Hq
Model Formulation
PRMS SNOW MODEL
Hsn = SWRin * (1. - ALBEDO) * TRNCF
Hln = T4
Hc + He = Cce * Tavg (ppt days)
= 0 (dry days)
Hp = Tavg * PTN
Hg assumed 0 Hq is computed
SNOWPACK DYNAMICS• 2-layered system
• energy balance: 2 12-hour periods
• energy exchange between layers -- conduction and mass transfer
• Tsurface = min(tavg or 0o C)
• Tpack is computed
• density = f(time, settlement constant)
• albedo decay = f(time, melt)
• melt volume: use depth-area depletion curve
Areal Snow Depletion Curve
MELT SEQUENCEcal_net > 0
snowmelt = cal_net / 203.2
pk_temp < 0o C
refreeze to satisfy pk_def
pk_temp = 0o C
satisfy free water holding capacity(freeh2o_cap)
remaining snowmelt reaches the soil surface
Max Temperature-Elevation Relations
TEMPERATURE
tmax(hru) = obs_tmax(hru_tsta) - tcrx(mo)
tmin(hru) = obs_tmin(hru_tsta) - tcrx(mo)
tcrx(mo) = [ tmax_lapse(mo) * elfac(hru)] -
For each HRU
where
elfac(hru) = [hru_elev - tsta_elev(hru_tsta)] / 1000.
-------------tmax_adj(hru)
Precipitation-Elevation Relations
Schofield Pass and Crested Butte (1975-97)
0
0.05
0.1
0.15
0.2
0.25
0.3
1 2 3 4 5 6 7 8 9 10 11 12
M onth
Av
era
ge
da
ily
pre
cip
ita
tio
n,
in i
nc
he
s
Schofield Pass
Crested Butte
Mean Daily PrecipitationSchofield Pass (10,700 ft) vs Crested Butte (9031 ft)
MONTH
Mea
n da
ily
prec
ip, i
n.
Precipitation Gage Catch Error vs Wind Speed (Larsen and Peck, 1972)
Rain (shield makes little difference)
Snow (shielded)
Snow (unshielded)
Precipitation Gauge Intercomparison Rabbit Ears Pass, Colorado
PRECIPITATION
- DEPTH
hru_precip(hru) = precip(hru_psta) * pcor(mo)
pcor(mo) = Rain_correction or Snow_correction
For each HRU
Precipitation Distribution Methods(module)
• Manual (precip_prms.f)
• Auto Elevation Lapse Rate (precip_laps_prms.f)
• XYZ (xyz_dist.f)
PCOR Computation
• Auto Elevation Lapse Rate
PCOR Computation
For each HRU
hru_psta = precip station used to compute hru_precip
[ hru_precip = precip(hru_psta) * pcor ]
hru_plaps = precip station used with hru_psta to compute ------ -------precip lapse rate by month [pmo_rate(mo)]
hru_psta
hru_plaps
PCOR Computation
pmn_mo
padj_sn or padj_rn
elv_plaps
Auto Elevation Lapse Rate Parameters
adj_p = pmo_rate *
• Auto Elevation Lapse Rate
PCOR Computation
For each HRU
snow_adj(mo) = 1. + (padj_sn(mo) * adj_p)
if padj_sn(mo) < 0. then snow_adj(mo) = - padj_sn(mo)
pmo_rate(mo) =pmn_mo(hru_plaps) - pmn_mo(hru_psta)
elv_plaps(hru_plaps) - elv_plaps(hru_psta)
hru_elev - elv_plaps(hru_psta)
pmn_mo(hru_psta)
PRECIPITATION
- FORM (rain, snow, mixture of both)
For each HRU
RAIN
tmin(hru) > tmax_allsnow
tmax(hru) > tmax_allrain(mo)
SNOW
tmax(hru) <= tmax_allsnow
PRECIPITATION
- FORM (rain, snow, mixture of both)
prmx = [(tmax(hru) - tmax_allsnow) / -------------------------(tmax(hru) - tmin(hru)] * adjmix_rain(mo)
For each HRU
Precipitation Form Variable
Snowpack Adjustment
MIXTURE
OTHER
PARAMETER ESTIMATION
PRMS Parameters Estimated
• 9 topographic (slope, aspect, area, x,y,z, …)
• 3 soils (texture, water holding capacity)
• 8 vegetation (type, density, seasonal interception, radiation transmission)
• 2 evapotranspiration
• 5 indices to spatial relations among HRUs, gw and subsurface reservoirs, channel reaches, and point measurement stations
BASIN DELINEATION AND CHARACTERIZATION
Polygon Hydrologic Response Units (HRUs) (based on slope, aspect, elevation, vegetation)
Grid Cell Hydrologic Response Units (HRUs) (Equal to Image Grid Mesh)
Focus of operational modeling Focus of research modeling
Upper San Joaquin River, CAEl Nino Year
ANIMAS RIVER, CO
SURFACE GW
SUBSURFACE
PREDICTED
MEASURED
EAST FORK CARSON RIVER, CA
SURFACE
GW
SUBSURFACE
CLE ELUM RIVER, WA
SURFACE
GW
SUBSURFACE
REMOTELY SENSED SNOW-COVERED AREA AND SNOWPACK WATER
EQUIVALENT
Satellite Image for Snow-Covered Area Computation
NASA Regional Earth Science Applications Center
Objective - Integrate remotely sensed data into operational resource management applications
~ 1 km pixel resolution of NOAA snow-covered area product on 750 km2 basin
SW Center - U of AZ, U of CO, USGS, --------------Lawrence Berkeley Labs
East Fork Carson River, CA
1986
1986
1988
Observed and Simulated Basin Snow-Covered Area
SIMULATED vs SATELLITE-OBSERVED SNOW-COVERED AREA
SIMULATED vs SATELLITE-OBSERVED SNOW-COVERED AREA
GUNNISON RIVER BASIN LOCATION
Upper Colorado River Basin
Gunnison River Basin
SUBBASINS WITH CONCURRENT STREAMFLOW AND SATELLITE DATA
East River
Taylor River
Lake Fork
Cochetopa Creek
Tomichi Creek
Cochetopa Creek
East River
Lake Fork
Taylor River
Tomichi Creek
eastEast River
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1996
Per
cen
t B
asin
Sn
ow
cove
r
MODELSATELLITE
East River
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1992
Per
cen
t B
asin
Sn
ow
cove
r
MODEL
SATELLITE
Percent Basin in Snow Cover
eastEast River
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1996
Per
cen
t B
asin
Sn
ow
cove
r
MODELSATELLITE
East River
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1992
Per
cen
t B
asin
Sn
ow
cove
r
MODEL
SATELLITE
East River
0
0.2
0.4
0.6
0.8
1
1/0 2/19 4/9 5/29 7/18 9/6
1995
Per
cen
t B
asin
Sn
ow
cove
r
MODEL
SATELLITE
Percent Basin in Snow Cover
coch
Cochetopa Creek
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1994
Per
cen
t B
asin
Sn
ow
cove
r
MODELSATELLITE
Cochetopa Creek
0
0.2
0.4
0.6
0.8
1
1/0 2/19 4/9 5/29 7/18 9/6
1995
Pe
rce
nt
Ba
sin
Sn
ow
co
ve
r
MODELSATELLITE
Percent Basin in Snow Cover
lake
Lake Fork
0
0.2
0.4
0.6
0.8
1
1/0 1/20 2/9 2/29 3/20 4/9 4/29 5/19 6/8 6/28 7/18
1991
Per
cen
t B
asin
Sn
ow
cove
r
MODEL
SATELLITE
Lake Fork
0
0.2
0.4
0.6
0.8
1
1/0 2/19 4/9 5/29 7/18 9/6
1995
Per
cen
t B
asin
Sn
ow
cove
r
MODELSATELLITE
Percent Basin in Snow Cover
STARKWEATHER COULEE, ND
DEPRESSION STORAGE
ESTIMATION (BY HRU)
USING THE GIS WEASEL
(AREA & VOLUME)
WETLANDS HYDROLOGYDEPRESSION STORES (flowing and closed)
HRU 1
HRU 2
STORAGE HRU
FL
OW
GW
P ET
FLOW
Snow-covered Area1997
April 17
March 20
April 22May 6
SNOW
NO SNOW
1997
April 12 April 22
Snowpack Water Equivalent
Snow-covered Area
Snow-covered Area 1999
March 25
April 1
April 8
April 13
SNOW
NO SNOW
1999
April 7 April 8
Snowpack Water Equivalent
Snow-covered Area