Real Time Nowcasting In The Western Us OR Why you cant 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 westwide forecast system challenges index station method for real-time forcing generation implementation details progress / results to date future plans 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 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 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 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 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: Drought Severity and Spatial Extent Monitor Webpage daily updates 1-2 day lag soil moisture & SWE percentiles degree resolution archive from 1915-current uses ~2130 index stns Background: UW SW Monitor trends: 1 week 2 week 1 month Archive! 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 Background: UW SW Monitor Background: West-wide Forecasting System Soil Moisture Initial Condition Snowpack Initial Condition Background: West-wide Forecasting System NEW: West-wide overview of flow forecasts (mouse-over/clickable for more details) As previously, flow location maps give access to monthly hydrograph plots, and also to data. Background: West-wide Forecasting System Now clicking the stream flow forecast map also accesses current basin- averaged conditions An earlier G. Thomas contribution: Automating plots of west-wide SWE data Background West-wide Forecasting System Daily Updating West-at-a-glance SWE from NRCS, EC, CADWR Analyses: Current Anomalies Percentiles: Current 1-week change 2-week change 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 # stations time 3 months before present present VIC model spinup methods: index stations estimating spin-up period inputs dense station network for model calibration sparse station network in real-time 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 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 Index station method: example for precipitation Index stn pcp (mm) pcp percentile gridded to 1/8 degree 1/8 degree dense station monthly pcp DISTRIBUTION (N years for each 1/8 degree grid cell) (MM) 1/8 degree pcp (mm) disagg. to daily using interpolated daily fractions from index stations monthlydaily 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. case 1: current day is less than day 21 of month treated as 1 period for percentile calculation months case 2: current day is greater than day 20 of month treated as 2 periods for percentile calculation the first month becomes fixed in forcing data months Index station method test of method for streamflow 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 Nowcast Information Flow VIC Retrospective Simulation Daily, 1915 to Near Current VIC Real-time Simulation (~1 month long) Hydrologic State NOAA ACIS / Other Prcp Tmax Tmin Coop Stations Index Station Method Gridded Forcing Creation Hydrologic values, anoms, %-iles w.r.t. retrospective PDF climatology (PDF) of hydrologic values w.r.t. defined period vals, anoms %-iles w.r.t. PDF Hydrologic State (-1 Day) 1930s 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 / 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) Implementation Details SW Monitor coding scheme download obs P, tx, tn update force VIC Station Index files climatology Forcings 2 mon Params Soil, etc. output Implementation Details SW Monitor coding scheme NCAST implementation download obs P, tx, tn update force VIC Station Index files climatology Forcings 2 mon Params Soil, etc. output obs P, tx, tn update force VIC output Forcings 2 mon Params Soil, etc. climatology Station Index files Node 0-2Node 0-6 Loop over basins ca, colo, gbas, riog Loop over basins pnw, mexn, mexs Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources Implementation Details Observation data: Real-time and retrospective stations. 3 Primary sources 1. ACIS for CONUS 2123 stations 1915-present 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 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 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 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 Real-Time: EDAS (Eta DAS) daily re-analysis 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 Results daily forecast of SM percentiles Results daily forecast of SM percentiles animations of recent forecasts Results daily forecast of SM percentiles - comparison with SW Monitor Results daily forecast of SM percentiles - comparison with CPC Drought Monitor Results daily forecast of SM percentiles - 2 week change - comparison with SW Monitor Results April 1 SWE Archive (1997 2006) 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 Future Work Ongoing and Future Work data products expansion (Arkansas, etc.) routing constraints using SWE END Thank you!