# Presentation: 515479

##  Operational Snow Modeling                        at the                               National Operational Hydrologic Remote       Sensing Center

** ****Operational Snow Modeling                        at the****                               National Operational Hydrologic Remote       Sensing Center**

**Tom Carroll**
**National Operational Hydrologic Remote Sensing Center**
***Hydrologic Services Division***
***Office of Climate, Water, and Weather Services***
**National Weather Service, NOAA**
**U.S. Department of Commerce**

## NOHRSC Operations

**Data and Product Archive**

**NOHRSC Snow Data Assimilation System**
**Energy-and-mass-balance snow modeling and observed snow data assimilation **

**Product Generation and Distribution**
***Elements:***
_***Daily National Snow Analyses:***_
** ****Water Equivalent**
** ****Snow Depth,**
** ****Snow Temperature**
** ****Sublimation **
** ****Condensation**
** ****Snow Melt**
***Formats:***
** ****Interactive Maps**
** ****Time-series Plots**
** ****Text Discussions**
** ****Alphanumeric and Gridded products**
***Distribution:***
_***NOHRSC Web Site***_**, AWIPS, direct FTP, NSIDC, NCDC**

**NOHRSC Operations**

## NOHRSC Snow Data    Assimilation System (SNODAS)

**Generation**
**Interactive Maps**
**Digital Data**
**Discussions**

**Snow Observations**
**Snow Water Equivalent**
**Snow Depth**
**Snow Cover**

**Temperature**
**Relative Humidity**
**Wind Speed**
**Solar Radiation**
**Atmos. Radiation**
**Precipitation**
**Precipitation Type**

**Hourly Input**
**Gridded Data (1 km)**

**Soils Properties**
**Land Use/Cover**
**Forest Properties**

**Static Gridded**
**Data (1 km)**

**Snow Energy and Mass Balance Model**

**Blowing Snow Model**

**Radiative Transfer Model**

**State Variables for**
**Multiple Vertical**
**Snow & Soil Layers**
**Snow Water Equivalent**
**Snow Depth**
**Snow Temperature**
**Liquid Water Content**
**Snow Sublimation**
**Snow Melt**

**Data Assimilation**

**NOHRSC Snow Data    Assimilation System ****(SNODAS)**

## NOHRSC IntegratedProducts and Services

**Users**
- NWS
- NOAA
- Federal Agencies
- Tribal Agencies
-    State Agencies
- Private Sector
- Public
- Academia

**High-resolution Gridded Snow Hydrology Products (to NSIDC, NCDC, NDFD)**

- Soil moisture and temperature states are also maintained in the NOHRSC model, but there is currently no focus on this capability (e.g. assimilation of soil moisture observations).

**Current Focus is CONUS**
**Larger Domains Possible**

**Applications**
- Drought
- Flood Management
- Water supply
- Transportation
- Emergency Management
- Agriculture
- Ecosystems Management
- Research

-  Snow Depth

-  Snow Water Equivalent

-  Snow Density

-  Snow Sfc. Temperature

-  Snow Avg. Temperature

-  Snow Melt

-  Sublimation

-  Snow Wetness

## NOHRSC IntegratedProducts and Services

**Gridded snowpack properties for the CONUS**
**1 km****2**** spatial resolution**
**1 hour temporal resolution**
**Near real-time modeling and assimilation**
**Incorporates **_***all***_** relevant information:**
**Ground-based snow data (depth and SWE)**
**Airborne gamma snow water equivalent**
**Satellite areal extent of snow cover**
**NWP model forcing fields**

## Snow Water Equivalent

**Snow Water Equivalent**

## NOHRSC California Airborne Flight Lines

## NOHRSC California Airborne Flight Lines

**Airborne snow water equivalent**
**Mean areal integration ( ****̴ ****10 km x 300 m)**
**Airborne soil moisture**
**Mean areal integration ( ****̴ ****10 km x 300 m)**
**Upper 20 cm of soil**
**Percent by weight**

## NOHRSC Contribution to HMT

**1 km****2**** spatial resolution                                1 hour temporal resolution**

-  Snow Depth

-  Snow Water Equivalent

-  Snow Density

-  Snow Sfc. Temperature

-  Snow Avg. Temperature

-  Snow Melt

-  Sublimation

-  Snow Wetness

**Input to **_***distributed***_** soil moisture accounting model**

**Hydrometeorological          test-bed domain        (American River basin)**

## Thank you www.nohrsc.noaa.gov

***Thank you***** ****www.nohrsc.noaa.gov**

**Tom Carroll**
**National Operational Hydrologic Remote Sensing Center**
***Hydrologic Services Division***
***Office of Climate, Water, and Weather Services***
**National Weather Service, NOAA**
**U.S. Department of Commerce**

## NOHRSC Snow Model Physics

**NOHRSC Snow Model Physics**

## Snow Modeling Framework

**Generation**
**Interactive Maps**
**Digital Data**
**Discussions**

**Snow Observations**
**Snow Water Equivalent**
**Snow Depth**
**Snow Cover**

**Temperature**
**Relative Humidity**
**Wind Speed**
**Solar Radiation**
**Atmos. Radiation**
**Precipitation**
**Precipitation Type**

**Hourly Input**
**Gridded Data (1 km)**

**Soils Properties**
**Land Use/Cover**
**Forest Properties**

**Static Gridded**
**Data (1 km)**

**Snow Energy and Mass Balance Model**

**Blowing Snow Model**

**Radiative Transfer Model**

**State Variables for**
**Multiple Vertical**
**Snow & Soil Layers**
**Snow Water Equivalent**
**Snow Depth**
**Snow Temperature**
**Liquid Water Content**
**Snow Sublimation**
**Snow Melt**

**Data Assimilation**

**Snow Modeling Framework**

## Preprocessing: Forcing Data

**FSL MAPS**

**NCEP RUC2**

**NESDIS SOLAR**

**Preprocessing: Forcing Data**

**(Full Resolution via Internet)**

## Downscaling: Thermodynamic

**(20-km Pressure, Temperature, and Relative Humidity)**

**Downscaling: Thermodynamic**

## Downscaling: Solar Radiation

**(0.5 degree Direct Beam and Diffuse Irradiance)**

**Downscaling: Solar Radiation**

## Preprocessing: Gap Filling

***Forcing data must be spatially and temporally continuous.***

**9Z RUC2**

**10Z RUC2**

**12Z RUC2**

**11Z RUC2**

**13Z RUC2**

**Method 1. Substitution**

**Preprocessing: Gap Filling**

## Preprocessing: Gap Filling

**9Z RUC2**

**10Z RUC2**

**12Z RUC2**

**11Z RUC2**

**13Z RUC2**

**Method 2. Interpolation**

**Gap-filling is automated**
**based on user-defined**
**prioritization of methods.**

**Preprocessing: Gap Filling**

***Forcing data must be spatially and temporally continuous.***

## Daily In-situ Snow Observations

**CDWR**** ****SNOTEL**

**NRCS**** ****SNOTEL& Snow Course**

**BC Hydro**** ****SNOTEL  **

**NWS**** ****COOP OBS**

**Federal, state, & private sources**

**Snow Water Equivalent and/or Snow Depth**

**Over 20,000 reporting stations are included in analyses**

## Snow Observation Assimilation

**Deltas (Observed – Modeled)**

**12/4/02 12Z to 12/5/02 6Z**

**Deltas between observed and modeled states are examined**
*Coherent spatial pattern is required to warrant update*
- Subgrid variability
**If pattern is explainable, update field is generated and used to nudge the model toward observed states **

***Daily SWE and Snow Depth Observations are used to update the model ***

## Data Processing Chronology

## Comprehensive snow hydrologic information products
Snow water equivalent, depth, wetness, temperature, melt, sublimation losses
GIS-based interactive                                                                 information distribution                                                                      on the Internet
Overlay administrative                                                                                             and basin boundaries,                                                                                          rivers, roads, cities
Zoom to full 1-km resolution
Query stations for time-                                                                                                series history
Export text data summaries                                                                                       for each basin

Up to 300,000 hits a day                                                               during peak season

**Comprehensive snow hydrologic information products**
*Snow water equivalent, depth, wetness, temperature, melt, sublimation losses*
**GIS-based interactive                                                                 information distribution                                                                      on the Internet**
*Overlay administrative                                                                                             and basin boundaries,                                                                                          rivers, roads, cities*
*Zoom to full 1-km resolution*
*Query stations for time-                                                                                                series history*
*Export text data summaries                                                                                       for each basin*
**Up to 300,000 hits a day                                                               during peak season**

**User Interactive Mapping on Internet**

## Full-Res Zoom
Snow Temperature
Feb 5, 2004 18Z
Red shows areas where snow is estimated to be at or near melting point
Blue shows areas where snow is estimated to be colder than –1C
NWS basin outlines shown in dashed lines
Stations that report snow observations are shown
Stations can be queried for time series history at location
Guidance and Diagnostics
Maps of snowpack variables besides water content are valuable to forecasters 
Aid in understanding snow conditions, where snowmelt is likely to occur

*Snow Temperature*
*Feb 5, 2004 18Z*
*Red shows areas where snow is estimated to be at or near melting point*
*Blue shows areas where snow is estimated to be colder than –1C*
*NWS basin outlines shown in dashed lines*
*Stations that report snow observations are shown*
*Stations can be queried for time series history at location*
**Guidance and Diagnostics**
*Maps of snowpack variables besides water content are valuable to forecasters *
*Aid in understanding snow conditions, where snowmelt is likely to occur*

**User Interactive Mapping on Internet**

## SWE, Depth, Density, and Melt
e.g. Washington DC (Reagan National Airport)
Jan 15 - Feb 15, 2004
Dark blue line show modeled SWE
Light blue line shows modeled snow depth
Light blue points show observed snow depth
Assimilation of observed snow depth on Jan 27 corrected for underestimated snow precipitation

**SWE, Depth, Density, and Melt**
*e.g. Washington DC (Reagan National Airport)*
*Jan 15 - Feb 15, 2004*
*Dark blue line show modeled SWE*
*Light blue line shows modeled snow depth*
*Light blue points show observed snow depth*
*Assimilation of observed snow depth on Jan 27 corrected for underestimated snow precipitation*

**Vertical Profile of Temperature, Density**
*Same location and time period*
*Snow remained relatively cold for 6-7 days following second storm*
*Rainfall on Feb 4 contributed to rapid warming of the snowpack, followed by melt*
*A smaller rain and snow event occurred on Feb 6*
*Gradual densification due to snow compaction*

**Time Series History Queries on Internet**

***User can query any of 40,000 stations shown on interactive map.***