2006(-07)TAMDAR aircraft impact experiments for RUC humidity, temperature and wind forecasts

2006(-07)TAMDAR aircraft impact experiments for RUC humidity, temperature and wind forecasts

Stan Benjamin, Bill Moninger,

Tracy Lorraine Smith, Brian Jamison, Ed Szoke, Tom Schlatter

NOAA Earth System Research Laboratory (ESRL),

Global Systems Division (GSD)

Boulder, CO

• Provide high-frequency (hourly) mesoscale analyses, short-range model forecasts

• Assimilate all available observations• Users:

– aviation/transportation– severe weather forecasting– general public forecasting

• Focus on 1-12 hour forecast rangeKEY QUESTION: Can TAMDAR add to RH/T/V forecast

skill in RUC model competing with other obs?

Purpose for Rapid Update Cycle (RUC) model run

operationally at NCEP

Observation needs for aviation NWP addressed by deployment of automated weather data from regional carriers

Goal: Improved forecasts for aviation hazards –• Icing, low ceiling conditions, precipitation forecasts • Convective environment, especially for convective initiation (T, RH, V - all important)• Lower tropospheric wind profiles (e.g.,CTAS)

via High density (regional airports) high-frequency (>6-8 soundings/day)

• temperature and moisture profiles • winds from ascent/descent, enroute

=> Examine tropospheric profile of T/RH/V forecast skill

Real-time TAMDAR impact experiment design

• Parallel 20km RUC 1-h cycles• Uses latest code in RUC13 (but at 20km)• Dev cycle – all obs data but no TAMDAR

• Dev2 cycle – dev + TAMDAR data

• Lateral boundary conditions – same for Dev and Dev2

• Control design• Initialize Dev and Dev2 runs at exact same time – same observations used (except TAMDAR)

• Reset dev and dev-2 background field at 1000z every 48 h

• Ensure against any computer processing differences between dev and dev2 cycles

1000-1800z

Dev-Dev2 difference – 0h analysisInit 1800z 24 Aug 2005 – 500 mb

Verification regions for GSD-RUC TAMDAR impact

Large region (eastern half of US) -- 38 RAOB sites

Small region (Great Lakes) includes 14 RAOBs

Key dates for RUC analysis/QC changes

• 8 June 2005 - Introduction of improved aircraft reject list• 1 Sept 2005 – Updated reject list• 15 Sept 2005 – Incorporate RUC13 moisture analysis• 15 Nov 2005 – Add new QC step in RUC analysis using ob-background (O-B) difference – (important for isolated observations)• 1 Dec 2005 – Revised aircraft RH observation error to higher value (4% to 12%, now same as raob, was previously “overfitting” TAMDAR RH data)• 15 Dec 2005 – Flag TAMDAR winds on descent• 15-30 March 2006 – Incorrect use of TAMDAR-RH in dev2. Corrected on 31 March• June 2006 – Further improvement in O-B QC

Figure 3a. RMS RH at 500 hPa for 3h forecasts for the old verification system (centered at 15% RH).

Figure 3b. RMS RH at 500 hPa for 3h forecasts for the new verification system (centered at 19% RH).

New verification software – Bill Moninger - verify every 10mb, not just at mandatory levels - use all raob data, no QC screeningExample - More improvement in 500mb RH forecasts from TAMDAR from including all obs.

Temp errors vs. raobs– 850 mb

• 3h fcsts• Valid 00z• Gt.Lakes region• Running 30-day avg

Dev –no TAMDARDev2- w/TAMDAR

• Strongest effect at this level – 0.25 C improvement• Slightly improved in 2006

Temp errors vs. raobs– 1000-800 mb avg


• Most accurate results in 2006 since mid-Nov

Dev –no TAMDARDev2- w/TAMDARDiff – dev-dev2

Wind errors vs. raobs– 850-700-500 mb avg


• Consistent improvement from TAMDAR

Dev –no TAMDARDev2- w/TAMDAR3h persistence –dev2

RH errors vs. raobs– 850-700-500 mb avg

• Consistently positive since Jan 2006



RH errors vs. raobs– 850 mb


• Consistent positive impact from TAMDAR in 2006, unlike in 2005

Dev –no TAMDARDev2- w/TAMDAR

RH errors vs. raobs– sfc-800 mb avg

• Positive impact throughout 2006• Average 1% in 1000-800mb layer



RH errors vs. raobs– 900-500 mb avg

• Increased impact in last 3 months



Temperature

wTAM

noTAM

April-October 2006Warm season + transition

Dec06-Jan07Cold seasonwTAM noTAM

Relative humidity

wTAMnoTAM


Dec06-Jan07Cold season

wTAM

noTAM

Wind

wTAM noTAM


wTAM

noTAM

Dec06-Jan07Cold season

TAMDAR impact study with RUC parallel cycles

• 2005-2007 (ongoing)•Further improvement in RH, temperature, wind

Forecast errors – RUCdev (no TAMDAR), RUCdev2 (w/ TAMDAR)

noTAMwTAM

Temp RH

Wind

wTAM

wTAM

noTAM

noTAM

GSD-RUC TAMDAR impact experiment results – updated 17Jan 2007• Recent results – 2006

• RH impact improved in 2006 – Consistent 1-2%RH reduction of RMS error (20-30% reduction – peaks at 900-800mb, 600-400mb• Temperature impact

• strongest from 950-800mb layer – inversion top!• 25% reduction of 3h forecast error (0.25K)

• Better temp impact apparent w/ higher vert resolution (Nov06-current)• Wind impact – ~10% reduction of 3h fcst errors in 850-700-500mb layer. About same as in 2005.

• Heading accuracy w/ Saab/Mesaba winds• Increase turboprop wind obs errors? (now used in devRUC13).

• Results (TAMDAR impact) have improved during continued TAMDAR evaluation

2006(-07)TAMDAR aircraft impact experiments for RUC humidity, temperature and wind forecasts

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