SWE Data Apps

SNODAS Cell-Based Implementation (to include elevation zone data in queries)

1. Each SNODAS cell within the study area is assigned a unique Cell_ID value.

2. Each SNODAS cell is attributed with an elevation zone value (elev_zone) and a list of AOI's IDs (stationTriplet) it falls within.

3. All SNODAS SWE cell data are imported and stored as a record in a daily table. 

The database schema is shown below.

SQL Query Example

PSQL Data Output Example

Benchmark and Database Optimization

Baselines performance:

1.  It took about 10 seconds to query the stats for '06330000:MT:USGS', the largest AOI in the lower 48 states.

2. Most AOIs need only less than 2 seconds to get the stats.

DB Optimization

eSNODAS APP & UI Design

1. Output format spec

2. Implementation: PostgreSQL Python connector (see https://www.postgresqltutorial.com/postgresql-python/)

AOI-Based Implementation (No Elevation Zone Data)

• 1. Use a server-side AOI boundary to report the summary statistics (mean, max, mix, etc) of SWE of the managed rasters. The server-side AOI boundary will come from the eBAGIS AOI database. The return values are cached on a server database table for subsequent retrieval. If the exact same query is requested at a later date, the output will be pulled from the database so we don't have to recalculate.

  2. Use a client-side shapefile (or featureclass) to perform tasks specified in #1 above. The return values are displayed on the screen but not cached

  3. Use a client-side point location (x, y) (or server-side, e.g., the pourpoint of an AOI) to report the pixel values. The return values are displayed on the screen but not cached

  4. Example interface (NWCC Interactive Map); interface (Colorado SNODAS SWE App)

Key functions:

• AOI query

• Arbitrary shape query

• Point query

• Time series report of the 3 query modes (output .csv files)

Summary variables:

Mosaic dataset details (obsolete information)

• • Contains temperature and precipitation data

  • 30 year average for 1970-2000 and 1980-2010

  • Time intervals: daily, monthly, annual, 30-year average

  • User to supply date range

  • Sample queries:

    • • Average min temp for the 1st quarter (Jan 1 through Mar 31) using monthly (or daily) data from 1990 through 2010

      • Range (i.e., max - min) and standard deviation of the min temp for January 1 using daily data from 1978 through 2008

      • Rank of this precipitation amount (e.g., 10 inches) based on the annual (or summer) precipitation data from 1970 through 2000 (the result will be a number, e.g., 15, that is, 10 inches is the 15th highest precipitation record based on 1970 - 2000 records.)