the need for an advanced sounder on goes the numerical weather prediction perspective robert m. aune...
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The Need for an Advanced Sounder on GOES
The Numerical Weather Prediction PerspectiveRobert M. AuneCenter for Satellite Applications and Research, NESDIS
For GUC6 Panel Discussion3 – 5 November 2009Madison, Wisconsin
UW-Madison
► 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
Hyper-spectral Sounder
GOES Sounder ImagesP
ress
ure
(h
Pa)
Pre
ssu
re (
hP
a)
UW/CIMSS
A high spectral resolution advanced sounder would have more and sharper weighting functions compared to current GOES sounder.
Current GOES (18)
Weighting Functions
GOES-I P (Q?) Sounders
Computing brightness temperatures from model output provides a link between the forecast
model and reality as seen by satellites
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.
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.
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.
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.
Initializing Water Vapor and Clouds in the South America CRAS using Precipitable Water and
Cloud-top Pressure from the GOES-10 SounderGOES-10
12-hour loop of total precipitable water images showing the hourly adjustments to water vapor due to the assimilation of GOES-10 sounder products.
12-hour loop of simulated 11 micron images showing the hourly cloud adjustments due to the assimilation of GOES-10 sounder products.
CRAS analysis cycle CRAS analysis cycle
Assimilating Precipitable Water fromthe GOES sounder
36-hour forecast rain-rate loop (mm/hr) fromthe 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).
TORNADO WARNING NATIONAL WEATHER SERVICE QUAD CITIES IA IL 823 PM CDT THU APR 13 2006THE 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.
3-Layer Precipitable Water from GOES Sounders Improves NCEP Eta Forecasts
Impact of GOES-8/9 PW on 12hr Eta Forecast RHVs. RAOBs (West)
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RM
S E
rro
r D
iffe
ren
ce
(GO
ES
-NO
GO
ES
)
850 hPa
700 hPa
500 hPa
400 hPa
300 hPa
A negative rms error difference indicates an improved forecast
Robert Aune (NESDIS) and Eric Rodgers (NWS)
1-h fcst w/o GOES cloud assim
1-h fcst w/ hourly GOES cloud assim NESDIS cloud-top (verification)
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.
Cloud Initialization in the Rapid Update Cycle (RUC)
A comparison of GOES sounder precipitable water
to NCEP NAM initial conditions
Initial precipitable water, NAM
Initial precipitable water differencesGOES sounder TPW minus NAM
GOES sounder TPW vs NAM
GOAL:Generate useful short-range forecasts of the timing and locations
of severe thunderstorms
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
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
Using the GOES Sounder to Nearcast Severe Using the GOES Sounder to Nearcast Severe WeatherWeather
Fill the GapBetween Nowcasting & NWP
CIMSS collaborator: Ralph Petersen
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.
Neg
ativ
e ∂Θ
e/∂
Z (b
lue
to re
d ar
eas)
in
dica
tes
Con
vect
ive
Inst
abili
ty
6 hr NearCast for 2100 UTCLow to Mid level Theta-E Differences
6 hr NearCast for 2100 UTCLow level Theta-E
6 hr NearCast for 2100 UTCLow to Mid level PW Difference
Rapid Development of Convection over NE IA between 2000 and 2100 UTC 9 July 2009
Using the GOES Sounder to Nearcast Severe Using the GOES Sounder to Nearcast Severe WeatherWeather
Poster byRalph Petersen and Robert Aune
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.
GOES Sounder Nearcasts of Convective GOES Sounder Nearcasts of Convective Destabilization In AWIPSDestabilization In AWIPS
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.
GOES sounder nearcast products are now available in AWIPS in real-time. An AWIPS display of precipitable water lapse rate is shown.
Photo voltaic arrays need nearcasts of cloud shadows to maintain load levels
Nearcasting Shadows for the Solar Power Industry
Using GOES imager and sounder cloud products in a nearcasting model
Knowing each plant’s rated output, nearcasts of cloud cover can be used to compute the actual output of each plant in real time.
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.
%
CRAS forecast cloud cover (%)
UW-Madison
What does a geostationary hyper-spectral sounder bring to numerical weather prediction?
1. VERTICAL RESOLUTION!
UW-Madison
What does a geostationary hyper-spectral sounder bring to numerical weather prediction?
1. VERTICAL RESOLUTION!
2. VERTICAL RESOLUTION!!
UW-Madison
What does a geostationary hyper-spectral sounder bring to numerical weather prediction?
1. VERTICAL RESOLUTION!
2. VERTICAL RESOLUTION!!
3. VERTICAL RESOLUTION!!!
Improvements in Retrievals with Interferometers
Temperature errors less than 1 degree are only available from
high spectral resolution measurements
RH errors less than 10% are only available from high spectral resolution measurements
Model background not required!
Compatible with modern assimilation
techniques!
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
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)
UW-Madison/CIMSS
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.
3 May 1999 -- Oklahoma/Kansas tornado outbreakARM / CART Site
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)
UW-Madison
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%
Hot off the press!
UW-Madison
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!
1. Enable assimilation of T, Td retrievals2. Retrievals over water AND land3. 15 minutes between scans4. See deeper into the atmosphere5. Allow above cloud retrievals6. Improved height assignment of satwinds7. Provide additional tracers for satwinds