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The Need for an Advanced Sounder on GOES The Numerical Weather Prediction Perspective

The Need for an Advanced Sounder on GOES The Numerical Weather Prediction Perspective. Robert M. Aune Center for Satellite Applications and Research, NESDIS For GUC6 Panel Discussion 3 – 5 November 2009 Madison, Wisconsin. ► How can a GEO sounder be used to improve

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The Need for an Advanced Sounder on GOES The Numerical Weather Prediction Perspective

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  1. The Need for an Advanced Sounder on GOES The Numerical Weather Prediction Perspective Robert M. Aune Center for Satellite Applications and Research, NESDIS For GUC6 Panel Discussion 3 – 5 November 2009 Madison, Wisconsin ► How can a GEO sounder be used to improve numerical weather prediction (NWP)? ► Operational use of GOES sounders at EMC ► New application – Near-Casting ► What does HES bring to NWP? ► Future UW-Madison

  2. GOES Sounder Images Hyper-spectral Sounder GOES-I P (Q?)Sounders A high spectral resolution advanced sounder would have more and sharper weighting functions compared to current GOES sounder. Current GOES (18) Pressure (hPa) Pressure (hPa) Weighting Functions UW/CIMSS

  3. Computing brightness temperatures from model output provides a link between the forecast model and reality as seen by satellites 11μ (window) images are generated by applying a vertically integrated, cloud-mass weighted transmissivity to the model predicted skin temperature. If the cloud mass exceeds a threshold, the radiating temperature is set to the model layer temperature. GOESTRAN, a 101-level radiative transfer model, is used to compute 6.7μ brightness temperatures. Model temperatures and mixing ratios are used as input. Transmittance coefficients for GOES-11 and GOES-12 are used. Clear sky only. Forecast 11μ (window) images (top) from the CIMSS Regional Assimilation System. Validating images (bottom) are shown with the same enhancement. Forecast 6.7μ cloud-clear water vapor images (top) from the CIMSS Regional Assimilation System. Validating images (bottom) are shown with the same enhancement.

  4. To improve forecast accuracy the North America CRAS is now assimilating each GOES sounder scan at each specific central scan time. CRAS forecast IR image from 12-hour spin-up forecast commencing 00UTC 13Jun08, 10-min frames.

  5. Initializing Water Vapor and Clouds in the South America CRAS using Precipitable Water and Cloud-top Pressure from the GOES-10 Sounder GOES-10 CRAS analysis cycle CRAS analysis cycle 12-hour loop of simulated 11 micron images showing the hourly cloud adjustments due to the assimilation of GOES-10 sounder products. 12-hour loop of total precipitable water images showing the hourly adjustments to water vapor due to the assimilation of GOES-10 sounder products.

  6. Assimilating Precipitable Water from the GOES sounder TORNADO WARNINGNATIONAL WEATHER SERVICE QUAD CITIES IA IL823 PM CDT THU APR 13 2006 THE NATIONAL WEATHER SERVICE IN THE QUAD CITIES HAS ISSUED A TORNADO WARNING FOR WESTERN MUSCATINE COUNTY IN EAST CENTRAL IOWA UNTIL 930 PM CDT.  AT 820 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A TORNADO 15 MILES WEST OF NICHOLS...OR ABOUT 8 MILES SOUTH OF IOWA CITY...MOVING EAST AT 35 MPH.   36-hour forecast rain-rate loop (mm/hr) from the CIMSS Regional Assimilation System (CRAS) commencing 12:00 UTC, April 13, 2006. Intense convection was predicted 13 hours into the forecast for Eastern Iowa. In this case the moisture gradients in the CRAS initial conditions were accurately specified by assimilating 3-layer precipitable water from the GOES sounder. Composite Radar Summary (dBz) valid 00:45 UTC, April 14, 2006. (Courtesy of Unisys Weather).

  7. 3-Layer Precipitable Water from GOES Sounders Improves NCEP Eta Forecasts Robert Aune (NESDIS) and Eric Rodgers (NWS) A negative rms error difference indicates an improved forecast

  8. Cloud Initialization in the Rapid Update Cycle (RUC) RUC 1-hour cloud-top pressure (hPa) forecasts with and without GOES sounder cloud-top pressure assimilation valid 1200 UTC 14 May 1999. Clearing and building are performed. 1-h fcst w/o GOES cloud assim 1-h fcst w/ hourly GOES cloud assim NESDIS cloud-top (verification)

  9. A comparison of GOES sounder precipitable water to NCEP NAM initial conditions Initial precipitable water, NAM GOES sounder TPW vs NAM Initial precipitable water differences GOES sounder TPW minus NAM

  10. Using the GOES Sounder to Nearcast Severe Weather Fill the Gap Between Nowcasting & NWP • Issues: • - Poor forecast accuracy in short-range NWP • - Lack of moisture observations over land (US) • Excessive smoothing of moisture in NWP • Time delay in delivering guidance products GOAL: Generate useful short-range forecasts of the timing and locations of severe thunderstorms Solution: Develop an objective “nearcasting” tool that leverages information from the GOES Sounder to assist forecasters with identifying pre-convective environments 1-6 hours in advance CIMSS collaborator: Ralph Petersen

  11. Using the GOES Sounder to Nearcast Severe Weather Poster by Ralph Petersen and Robert Aune New example of advantage of Equivalent Potential temperature ( Theta-E or Θe) Theta-E measures TOTAL moist energy in atmosphere, not only latent heat  Low-level Theta-E NearCasts shows warm / moist air band moving into far NW Iowa, where deep convection formed rapidly by 2100 UTC.  Vertical Theta-E Difference shows complete convective instability - GOES temperature data adding information to vertical moisture gradient data used earlier. 6 hr NearCast for 2100 UTC Low level Theta-E Negative ∂Θe/∂Z (blue to red areas) indicates Convective Instability Rapid Development of Convection over NE IA between 2000 and 2100 UTC 9 July 2009 6 hr NearCast for 2100 UTC Low to Mid level PW Difference 6 hr NearCast for 2100 UTC Low to Mid level Theta-E Differences

  12. Real-time 6-hour nearcast of atmospheric de-stabilization, 2-layer thetaE from the GOES-12 sounder commencing 19UTC Novenber 3, 2009. Hourly loop is from T- 6 hours to T+ 6 hours.

  13. GOES Sounder Nearcasts of Convective Destabilization In AWIPS GOES sounder nearcast products are now available in AWIPS in real-time. An AWIPS display of precipitable water lapse rate is shown. Significance: Nearcasting severe weather up to 6 hours in advance fills the gap between nowcasting observations and numerical weather prediction. It supports NOAA’s Weather and Water mission goal.

  14. Using GOES imager and sounder cloud products in a nearcasting model CRAS forecast cloud cover (%) The CIMSS Regional Assimilation System (CRAS) uses cloud and water vapor observations from GOES to define initial cloud fields. CRAS forecast tendencies are used to drive a Lagrangian cloud trajectory model to nearcast cloud optical depth and surface solar fluxes. Nearcasting Shadows for the Solar Power Industry % Knowing each plant’s rated output, nearcasts of cloud cover can be used to compute the actual output of each plant in real time. Photo voltaic arrays need nearcasts of cloud shadows to maintain load levels

  15. What does a geostationary hyper-spectral sounder bring to numerical weather prediction? 1. VERTICAL RESOLUTION! UW-Madison

  16. What does a geostationary hyper-spectral sounder bring to numerical weather prediction? 1. VERTICAL RESOLUTION! 2. VERTICAL RESOLUTION!! UW-Madison

  17. What does a geostationary hyper-spectral sounder bring to numerical weather prediction? 1. VERTICAL RESOLUTION! 2. VERTICAL RESOLUTION!! 3. VERTICAL RESOLUTION!!! UW-Madison

  18. Improvements in Retrievals with Interferometers Model background not required! RH errors less than 10% are only available from high spectral resolution measurements Temperature errors less than 1 degree are only available from high spectral resolution measurements Compatible with modern assimilation techniques!

  19. An Observing System Simulation Experiment (OSSE) to Test the Impact of a GeostationaryHyper-Spectral Sounder Goal: Assess the potential impact of Geo Interferometer “Nature” Forecast: UW NMM Model Simulated Observations: Soundings (T, Td) from GOES (18 channels) Soundings (T, Td) from GIFT (2000 channels) Insitu Observations: Winds (cloud drift / water vapor) Aircraft Reports (T, winds) Profiler Network (T, Td) Sfc obs, RAOBs Assimilating Model: Rapid Update Cycle (RUC) 12-hour forecasts with different combinations of observations were compared to assess impact

  20. Significant Finding from Geo-Interferometer OSSE Geo Interferometer penetrates Boundary Layer (BL) to provide low level (850 RH) moisture information: Geo Radiometer only offers information above BL (700 RH)

  21. 3 May 1999 -- Oklahoma/Kansas tornado outbreak ARM / CART Site All three solutions show rapid atmospheric destabilization (decreasing LI) between 14 and 20 UTC. GIFTS better depicts the absolute values and tendencies compared to GOES. The total precipitable water (TPW) increases through the period. Both current and future sounding measurements capture the correct trends. UW-Madison/CIMSS

  22. IMG demonstrates interferometer capability to detect low level inversions: example over Ontario with inversion (absorption line BTs warmer) and Texas without (abs line BTs colder)

  23. Hot off the press! The top seven observing systems that contribute to ECMWF forecast error reduction (QJRMS, Oct, 2009): 1. AMSU-A (4 satellites)  17.2% 2. IASI (one satellite) 12.0% 3. AIRS (one satellite) 11.8% 4. AIRREP (aircraft temperature and winds) 9.3% 5. GPSRO (bending angles)-8.5% 6. TEMP (radiosonde winds, humidity, and temps)-7.9% 7. QuikSCAT (scatterometer surface winds)-5.2% UW-Madison

  24. Summary A geostationary hyper-spectral sounder (upstream of North America) will provide the greatest improvement in 24-48 hour forecast accuracy in the history of operational mesoscale NWP at NCEP! • Enable assimilation of T, Td retrievals • Retrievals over water AND land • 15 minutes between scans • See deeper into the atmosphere • Allow above cloud retrievals • Improved height assignment of satwinds • Provide additional tracers for satwinds UW-Madison

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