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Real Time Nowcasting In The Western Us OR Why you can’t use nodes C0-2

Real Time Nowcasting In The Western Us OR Why you can’t use nodes C0-2. George Thomas Andy Wood Dennis Lettenmaier Department of Civil and Environmental Engineering LAND SURFACE HYDROLOGY RESEARCH GROUP Group Seminar July 5, 2006. Outline. Objective background surface water monitor

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Real Time Nowcasting In The Western Us OR Why you can’t use nodes C0-2

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  1. Real Time Nowcasting In The Western UsORWhy you can’t use nodes C0-2 George Thomas Andy Wood Dennis Lettenmaier Department of Civil and Environmental Engineering LAND SURFACE HYDROLOGY RESEARCH GROUP Group Seminar July 5, 2006

  2. Outline • Objective • background • surface water monitor • westwide forecast system • challenges • index station method for real-time forcing generation • implementation details • progress / results to date • future plans

  3. Objective • Monitor the hydrologic state of the US land surface • Initially, western US; soon, mexico + remainder of US • 1/8 degree • Daily updates in real-time (lag of 12-36 hrs) • Soil moisture, snow, runoff • Fully automated • Consistent with retrospective: back to at least 1950 • Can be used for hazard assessment • Drought • Flood risk • Can be used to initialize hydrologic forecasts • Short lead, 1-15 day • Long lead, 1-12 month

  4. Background • This nowcast draws upon procedures and data from two existing systems assembled by Dr. Wood • UW Experimental Surface Water Monitor (1/2 degree) • Methods for real-time forcing generation & model updating • UW West-wide Seasonal Hydrologic Forecasting System • VIC model data at 1/8 degree • Eventually, forecast methods The nowcast will eventually be an integral part of the West-wide forecasting system

  5. SW Monitor Background • An outgrowth of the west-wide forecasting system that adds a national scale perspective on land surface moisture • directly relevant to retrospective drought reconstruction work going on in our group • Andreadis et al. (2005) paper on drought • ½ degree VIC input parameters • enabled by recent NCDC extension of digital data archives back to 1915 • will be used as platform for drought and hydrologic analyses in real-time • nowcasts are used now by US Drought Monitor & US Drought Outlook authors (at CPC and elsewhere) • many products possible, such as following one:

  6. Drought Severity and Spatial Extent

  7. Monitor Webpage daily updates 1-2 day lag soil moisture & SWE percentiles ½ degree resolution archive from 1915-current uses ~2130 index stns

  8. Background: UW SW Monitor trends: 1 week 2 week 1 month Archive!

  9. Background: UW SW Monitor Archive from 1915-current current conditions are a product of the same simulation (same methods, ~same stations) as historical conditions allows comparison of current conditions with historical ones can navigate by month or year People: Andy, Ali, Kaiyuan, Dennis

  10. Background: UW SW Monitor

  11. Background: West-wide Forecasting System Snowpack Initial Condition Soil Moisture Initial Condition

  12. Background: West-wide Forecasting System NEW: West-wide overview of flow forecasts (mouse-over/clickable for more details)

  13. Background: West-wide Forecasting System As previously, flow location maps give access to monthly hydrograph plots, and also to data. Now clicking the stream flow forecast map also accesses current basin-averaged conditions

  14. Daily Updating • West-at-a-glance • SWE from • NRCS, EC, CADWR Analyses: • Current Anomalies • Percentiles: • Current • 1-week change • 2-week change BackgroundWest-wide Forecasting System An earlier G. Thomas contribution: Automating plots of west-wide SWE data

  15. # stations time 3 months before present present Background: Central Challenge • Model simulations are calibrated and validated using a uniform or consistent set of forcing data • Nowcasts and forecasts use models calibrated and validated retrospectively • Problem: the station data used to create forcings are not as widely available in real-time as they are for the retrospective calibration/validation period • Solution: the “index-station method”

  16. dense station network for model calibration VIC model spinup methods: index stationsestimating spin-up period inputs sparse station network in real-time

  17. Outline • Objective • background • surface water monitor • westwide forecast system • challenges • index station method for real-time forcing generation • implementation details • progress / results to date • future plans

  18. Index station method: example for precipitation • uses time-varying precipitation signal ONLY FROM stations that report reliably in real-time and for over 45 years (many go back longer) • precipitation percentiles calculated from raw precip for time period no shorter than 21 days. • percentiles interpolated to 1/8 degree grid • at 1/8 degree, percentiles used to extract corresponding observed value from 1/8 degree restrospective distribution (based on dense observing network, standard VIC forcing methods) • period 1/8 degree precip amount disaggregated using the fractional daily precipitation for that period (interpolated to 1/8 degree grid). • temperature is treated differently – daily interpolated anomalies for Tmin & Tmax are used

  19. Index station method: example for precipitation monthly daily Index stn pcp (mm) gridded to 1/8 degree pcp percentile 1/8 degree pcp (mm) disagg. to daily using interpolated daily fractions from index stations 1/8 degree dense station monthly pcp DISTRIBUTION (N years for each 1/8 degree grid cell) (MM)

  20. case 1: current day is less than day 21 of month months treated as 1 period for percentile calculation case 2: current day is greater than day 20 of month months treated as 2 periods for percentile calculation the first month becomes fixed in forcing data Index station method: example for precipitation • In real-time, with daily updates, this method actively updates the forcings for a period from 3 weeks to 7 weeks.

  21. Index stationmethod • test of method for streamflow

  22. Outline • Objective • background • surface water monitor • westwide forecast system • challenges • index station method for real-time forcing generation • implementation details • progress / results to date • future plans

  23. Index Station Method Gridded Forcing Creation Nowcast Information Flow NOAA ACIS / Other Prcp Tmax Tmin Coop Stations 1930s 1955+ VIC Retrospective Simulation Daily, 1915 to Near Current Hydrologic State VIC Real-time Simulation (~1 month long) Hydrologic State (-1 Day) Hydrologic values, anom’s, %-iles w.r.t. retrospective PDF climatology (PDF) of hydrologic values w.r.t. defined period vals, anoms %-iles w.r.t. PDF

  24. Implementation Details Computing Environment: Flood Cluster 46 cores 9 AMD Opteron 2x dual core 2 Intel Xeon 2X single core 1 AMD Opteron 2x single core Rocks 4.0.0 / CentOS 4.0 Linux Nowcasting is implemented on nodes c0-2 and c0-6 Useful phrases: WTF?! (what the flood?!) RTFM!! (read the flood manual)

  25. Implementation Details SW Monitor coding scheme download obs P, tx, tn update Station Index files climatology force Forcings 2 mon Params Soil, etc. VIC output

  26. Implementation Details SW Monitor coding scheme – NCAST implementation Node 0-2 Node 0-6 download obs P, tx, tn obs P, tx, tn update update Station Index files Station Index files climatology climatology Loop over basins ca, colo, gbas, riog Loop over basins pnw, mexn, mexs force force Forcings 2 mon Params Soil, etc. Params Soil, etc. Forcings 2 mon VIC VIC output output

  27. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources

  28. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present

  29. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present 2. Environment Canada 10 stations 1915-present

  30. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present 2. Environment Canada 10 stations 1915-present

  31. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present 2. Environment Canada 10 stations 1915-present 3. Mexico (retrospective) 739 stations 1925-2003

  32. Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present 2. Environment Canada 10 stations 1915-present 3. Mexico (retrospective) 739 stations 1925-2003 Real-Time: EDAS (Eta DAS) daily re-analysis

  33. Outline • Objective • background • surface water monitor • westwide forecast system • challenges • index station method for real-time forcing generation • implementation details • progress / results to date • future plans

  34. Results daily forecast of SM percentiles

  35. Results daily forecast of SM percentiles – animations of recent forecasts

  36. Results daily forecast of SM percentiles - comparison with SW Monitor

  37. Results daily forecast of SM percentiles - comparison with CPC Drought Monitor

  38. Results daily forecast of SM percentiles - 2 week change - comparison with SW Monitor

  39. Results April 1 SWE Archive (1997 – 2006)

  40. Outline • Objective • background • surface water monitor • westwide forecast system • challenges • index station method for real-time forcing generation • implementation details • progress / results to date • future plans

  41. Future Work Ongoing and Future Work • data products • expansion (Arkansas, etc.) • routing • constraints using SWE

  42. END Thank you!

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