**THORPEX-HYDRO Project**

March 25, 2008

**Project Team**

1)  NCEP/EMC and its THORPEX and other collaborators - Zoltan Toth, NCEP
    Project Leader

2)  OHD and its collaborators - DJ Seo, OHD Project Leader

**Partners**

HMT -- Tim Schneider, Program Manager (ESRL)

Test experimental hydrometeorological products in HMT testbeds; Provide
feedback for product/service development efforts

ESRL/GSD -- Paul Schultz, Group Leader

Develop methods for downscaling coarser resolution ensemble forecasts to
NDFD resolution (precipitation, temperature, etc.)

University of Virginia -- Roman Krzysztofowicz, Professor

Develop statistical bias correction algorithms and codes

HPC -- QPF/HMT Desks, Ed Danaher (NCEP/HPC)

Provide guidance and advice on interpretation and use of
hydrometeorological ensembles in high impact forecast situations on
operational basis

National Precipitation Verification Unit (NPVU)

Coordinate PQPF verification activities

CPPA Core Project -- Pedro Restrepo, John Schaake (OHD) and Ken Mitchell
(NCEP)

Interface with land surface and hydrologic modeling capabilities
designed for seasonal applications

**Introduction**

This document summarizes a 2-year work plan with an outlook beyond FY09
for the joint effort between the THORPEX program and the Hydrology
Program, in collaboration with the Hydrometeorology Testbed (HMT)
Program and the Climate Prediction Program for the Americas (CPPA), to
produce reliable and skillful ensemble forecasts of hydrometeorological
variables at the weather scale, in particular for high-impact events.
The targeted users are the NWS River Forecast Centers (RFC) for
operational hydrologic ensemble forecasting via the eXperimental
Ensemble Forecast System (XEFS) and the water resources managers and end
users for various hydrology and water resources applications.

**Overarching Goals\
**

1)  Accelerate development of reliable and skillful hydrometeorological
    (precipitation, temperature and potential evaporation) ensemble
    forecast products for hydrology and water resources applications

2)  Fast-track infusion of new and improved hydrometeorological ensemble
    and probabilistic guidance products into the RFC operations through
    the eXperimental Ensemble Forecast System (XEFS)

**Objectives**

1)  Develop and operationally implement real-time bias correction,
    downscaling and hindcasting techniques that are applicable to
    global, regional, and climate ensembles

2)  Develop capabilities for routine ingestion, testing, and use in XEFS
    of NCEP ensembles by OHD and RFCs

3)  Improve land surface modeling capabilities for large-scale
    hydrologic evaluation of hydrometeorological ensembles at the
    weather scale and for collaborative research and development of
    hydrologic ensemble techniques and products that may best utilize
    them

4)  Enhance capabilities for seamless verification of
    hydrometeorological and hydrologic ensembles across NCEP, OHD and
    RFCs

![](media/image1.wmf){width="6.002083333333333in"
height="4.500694444444444in"}

Fig 1 THORPEX-HYDRO Project -- Overarching Goals

**Tasks and Milestones**

**Objective 1**: Develop and operationally implement real-time bias
correction, downscaling and hindcasting techniques that are applicable
to global and regional ensembles.

Tasks

1)  Accelerate development, testing, evaluation and operational
    implementation of the Bayesian ensemble processor (BEP), developed
    jointly with Roman Krzysztofowicz. In tests, a single-value (not
    ensemble) forecast version of his algorithm outperformed NWS MOS for
    precipitation forecasting.

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a)  Collaborate with NCEP/CPC and OHD on best observational 6-hourly
    precipitation analysis (CPC global precipitation analyses for
    global, NWS-operational gage-radar estimates for CONUS).

b)  Collaborate with GSD/ESRL on conversion of zero forecast
    precipitation into "pseudo-precipitation" values. This conversion
    will make precipitation a continuous variable, facilitating the use
    of a uniform BEP for all variables.

c)  Collaborate with Krzysztofowicz on developing and porting Bayesian
    algorithms and codes for use at NCEP.

d)  Operationally implement BEP for 6-hourly precipitation for the NAEFS
    ensemble system.

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2)  Develop, evaluate and, if determined operation-ready, implement the
    real-time hindcast generation algorithm.

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a)  Facilitate use of hindcast data in BEP.

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3)  Collaborate with GSD/ESRL in their development and testing of
    precipitation downscaling algorithms.

4)  Test and evaluate bias-corrected and downscaled precipitation
    forecasts in hydrologic applications at OHD and EMC through:

    a.  Global river flow ensemble experiments at EMC, and

    b.  XEFS at OHD.

FY08-09 Milestones

1)  December 2007 -- Implement NAEFS forecasts downscaled to 5x5 km NDFD
    grid over CONUS (6-hrly output to 16 days based on global NCEP
    high-resolution control and ensemble plus Canadian ensemble for 2m
    temp, 10m u/v wind, mean sea level pressure).

2)  Summer 2008 -- Implement downscaled NAEFS forecasts for Alaska
    domain, including additional new near-surface variables also for
    CONUS (2m min/max & dewpoint temp, 10m wind speed and direction).

3)  Fall 2008 -- Implement stochastic perturbations into ensemble
    integrations as well as increase resolution for global and regional
    ensembles and/or introduce hindcasts for ensemble control.

4)  Spring 2009 -- Implement climatological downscaling for NAEFS
    precipitation forecasts over CONUS. Complete downscaling of
    precipitation from model grid to NDFD grid using global CPC global
    precipitation analysis datasets with operational NWS gage and
    radar-based 6-hr analysis fields inserted over CONUS.

5)  Fall 2009 -- Implement BEP for 6-hr precipitation forecasts for
    NAEFS and SREF on model grids to reduce systematic errors in
    ensemble distribution.

Prospective Milestones Beyond FY09

1)  Spring 2010 -- Include FNMOC and ECMWF ensembles into NAEFS.

2)  Fall 2010 -- Increase resolution for global and regional ensembles.
    Implement hindcast system that uses the latest version of the data
    assimilation and numerical modeling system, allowing high-quality
    bias correction of precipitation and river flow.

3)  Spring 2011 -- Upgrade 6-hrly precipitation forecast downscaling
    with addition of stochastic processes.

4)  Fall 2011 -- Apply BEP on all model variables on model grids for
    NAEFS & SREF ensembles, including potential evapotranspiration.

5)  Spring 2012 -- Produce probabilistic/ensemble guidance based on a
    suite of available numerical guidance. Merge and bias-correct
    information from global and regional high-resolution control and
    ensemble forecast systems (NAEFS, GFS, NAM, SREF). Establish
    bias-corrected ensemble forecast database consistent with best
    available probabilistic guidance. Back-propagate value-added changes
    made by forecasters into numerical ensemble guidance database.

6)  Fall 2012 -- Add new downscaled variables with use of SMARTINIT,
    including potential evapotranspiration, for 5x5 km or higher
    resolution output.

7)  Spring 2013 -- Introduce feature-based bias corrections.

**Objective 2**: Develop capabilities for routine ingestion, testing,
and use of NCEP ensembles by OHD and RFCs.

Tasks

1)  Develop capabilities at OHD and RFCs to process and evaluate NCEP
    prototype ensemble products.

2)  Provide access to and tools for using operational and experimental
    NCEP ensemble products in XEFS.

3)  Provide feedback to NCEP to influence future development, testing
    and implementation of ensemble forecast systems, products and
    services.

FY08-09 Milestones

1)  Dec 2007 -- Make available individual ensemble members by adding
    downscaling vector and coarse resolution member data (20 members per
    cycle, 80 per day from NCEP, 40 members from Canada):

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a)  Engage and collaborate with OHD and RFCs in ongoing evaluation.

b)  Explore testing in winter season at some RFCs in collaboration with
    HMT.

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2)  May 2008 -- Produce downscaled temperature information on 5x5 km
    NDGD grid, 4 times/day 6-hourly output, from NAEFS ensemble, out to
    16 days:

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a)  Products include mean, mode of ensemble, values for 10, 50, 90
    percentile ensemble distribution.

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3)  Sep 2008 -- Demonstrate capabilities to ingest and process NCEP
    ensembles for XEFS prototype development at OHD and experimental use
    with ESP at an RFC.

4)  Sep 2009 -- Carry out comparative evaluation of NCEP ensembles for
    prognostic verification.

Prospective Milestones beyond FY09

1)  Implement in the Ensemble Pre-Processor III (EPP3) of XEFS
    capabilities for ingest and processing of NCEP ensembles.

2)  Carry out joint analysis of multiscale and multimodel ensembles for
    development of blending and merging procedures in EPP3.

**Objective 3:** Improve land surface modeling capabilities for
large-scale hydrologic evaluation of hydrometeorological ensembles at
the weather scale and for collaborative research and development of
hydrologic ensemble techniques and products that may best utilize them.

The tasks under this objective heavily leverage the CPPA Core Project.

Tasks

1)  Improve capabilities for CONUS-wide hydrologic evaluation of
    hydrometeorological ensembles:

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a)  Start testing hindcasts when available.

b)  Use ensembles from the gridded Ensemble Pre-Processor (EPP) as
    comparative reference.

c)  Improve land surface and river routing model components.

d)  Verify streamflow ensemble results against observed flow.

e)  Include and improve post processing for accounting of hydrologic
    uncertainty.

f)  Include DA component.

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2)  Transfer/adapt OHD/RFC and community hydrologic modeling
    capabilities to facilitate testing over CONUS and global domains:

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a)  OHD high resolution river routing model over CONUS.

b)  Alternative land surface models (funded via CPPA).

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3)  Develop/test methods to represent uncertainty related to land
    surface and hydrologic modeling

4)  Develop/test methods for assimilation of land surface and hydrologic
    observations

5)  Develop/test statistical methods to represent hydrologic uncertainty
    due to water management decisions

6)  Develop global ensemble hydrologic prediction capability at NCEP:

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a)  Run as part of NCEP suite

-   Initially for international use

-   In the future for possible operational use

b)  Initially focus on large rivers.

# FY08-09 Milestones

1)  Sep 2008 -- Demonstrate capability for large-scale evaluation of
    precipitation and streamflow ensembles using improved land-surface
    and routing model components.

2)  Sep 2009 -- Carry out large-scale comparative evaluation of
    streamflow ensembles forced by the GFS and gridded EPP-generated
    precipitation and temperature ensembles.

**Objective 4:** Enhance capabilities for integrated verification of
hydrometeorological and hydrologic ensembles across NCEP/EMC, NCEP/HPC,
OHD, RFCs, and NPVU.

Tasks

1)  Coordinate and leverage ensemble verification efforts at OHD and
    NCEP for integrated systematic diagnostic verification of
    hydrometeorological and hydrologic ensembles.

2)  Develop ensemble/probabilistic verification products and context
    information for NCEP hydrometeorological ensembles for use in XEFS.

3)  Demonstrate and quantify marginal value of improvement in
    hydrometeorological ensembles to hydrology and water resources
    applications.

.

FY08-09 Milestones

Sep 2008 -- Develop a science strategy for integrated ensemble
verification across weather and water predictions. Identify candidate
verification measures and supplemental information, including multiscale
verification information that may be passed across NCEP, OHD and RFCs
for diagnostics and for operational hydrologic forecasting via XEFS.

Sep 2009 -- Jointly carry out basic integrated verification of
operational and experimental hydrometeorological and hydrologic ensemble
forecasts and quantify the margin of improvement.

Prospective Milestones Beyond FY09

Sep 2010 - Evaluate ensemble precipitation forecasts for various
accumulation periods and various size areas to facilitate hydrologic
interpretation of the results.

Sep 2011 -- Evaluate ensemble hydrologic forecasts against river gage
observations.