improving intensity estimates using operational information john knaff noaa/nesdis regional and...
TRANSCRIPT
![Page 1: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/1.jpg)
Improving Intensity Estimates Using Operational Information
John Knaff
NOAA/NESDIS
Regional and Mesoscale Meteorology Branch
Fort Collins, CO
![Page 2: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/2.jpg)
Acknowledgements
Significant Work:• Joe Courtney (BOM)• Dan Brown (NHC)• Jack Bevin (NHC)• Gregg Gallina (SAB)
Manuscript Comments:• Chris Landsea (NHC)• Hugh Cobb (NHC)• Ray Zehr (Retired)• Mark DeMaria (RAMMB)
![Page 3: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/3.jpg)
Outline
• Updates on the Knaff and Zehr wind-pressure relationship (WPR)– Lessons learned since publication– Increasing operational applicability (i.e., Courtney
and Knaff 2009)– Preliminary evaluations from RSMC La Reunion
• Improving the calibration of Dvorak Intensity Estimates
• Combining results to provide objective guidance
![Page 4: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/4.jpg)
Knaff and Zehr (2007)
• Statistical method to estimate MSLP from maximum winds / max winds from MSLP– Accounts for translation– … latitude (φ)– … size (S) – calculated from numerical analyses– … environmental pressure (Penv) – calculated from
numerical analyses
*Issues
![Page 5: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/5.jpg)
Wind from MSLP
63.0max 5.1738.9518.0755.0960.14633.18 cPPSV
![Page 6: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/6.jpg)
MSLP from Wind
envsrm
srm PSV
VMSLP
*483.0*587.12
254.24483.0286.23
2
![Page 7: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/7.jpg)
Lessons Learned (i.e., Knaff and Zehr 2008)
• The method did not mesh with operations; required extra effort to calculate parameters S (TC size) and Penv (environmental pressure)– There was a desire by some forecast centers to use quantities
already routinely available/estimated in operations
• There was an issue with very low latitude storms (that were not in the developmental dataset)
• Using the low-level winds to estimate V500 ( for S) did not account for land exposures, resulting in an erroneously estimate of S when land was within 500 km.
• Eye size / radius of maximum wind still matters - remains a problem.
![Page 8: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/8.jpg)
![Page 9: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/9.jpg)
The Courtney & Knaff (2009) Modification
• Low latitude issue addressed• TC size (S) is estimated from R34• Environmental Pressure (Penv) estimated from
the Pressure of the Outer Closed Isobar (POCI).
![Page 10: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/10.jpg)
Low Latitudes (<18 degrees)
envsrm
srm PSV
V
2
11 26.18
MSLP
63.0max 5.1984.8515.0238.5446.6 cPPSV
The equation for Vmax has to be iterated because S is a function of Vmax
No dependence of latitude…
![Page 11: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/11.jpg)
TC Size
The tangential wind at 500 km is estimated using a simple relationship involving the average radius of gales, R34
Where r34 is the average of the non-zero quadrants
The rest of the calculation of size remains the same
Where V500c is an Atlantic climatological V500 based on max wind, latitude.
39/34500 rV
cVVS 500/500
![Page 12: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/12.jpg)
Environmental Pressure
• Environmental pressure (Penv) is estimated from the Pressure of Outer Closed Isobar (POCI)
hPaPOCIPenv 2
![Page 13: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/13.jpg)
Operational Constraints at BoM
• S has a minimum value of 0.4• Dvorak intensities are used• 10-minute wind is converted to 1-minute
equivalent using 0.88• MSLP is estimated to the nearest hPa above
980 hPa• MSLP is estimated to the nearest 5 hPa below
980 hPa
![Page 14: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/14.jpg)
Australian Region VerificationName Date Observed Calculated Comments
LatitudeGale
radius MotionMax Wind Pe Press. Press.
Max wind
S nm knots knots hPa hPa hPa knots
Agnes 1 6 Mar 1956 19.2 300 10 60 (52) 1002 961 963 (968) 62 Max wind estimate.2 25 Dec 1974 12.5 30 3 95 (81) 1004 950 949 (962) 94 Max wind estimate.
Kathy 23 Mar 1984 15.6 40 5 100 1010 940 946 106Max wind before instrument failure.
Orson 22 Apr 1989 19.2 200 12 105 1008 905 935 131
Max wind derived from measurement at 36m.
Ian 2 Mar 1992 20.8 45 6 80 1010 960 964 84Max wind sampled at 5 minutes
Oliver 7 Feb 1993 17.1 100 3 90 1010 950 957 97Limited sampling of max wind.
Olivia 10 April 1996 20.3 200 12 105 1008 927 926 105Varanus Is pressure; Barrow Is Max wind
Rachel 7 Jan 1997 20.3 100 6 70 1010 971 973 72
Port Hedland pressure; Bedout Is Max wind
1 Maximum wind value is an open water estimate, lower value in parenthesis is based on the conversion of observed gusts to mean winds.2 Maximum wind is an estimate based upon reanalysis (Courtney&Shepherd 2008), the lower value in parenthesis is from BoM (1977).
Another small eye case?
![Page 15: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/15.jpg)
HurSAT MovieOf Tropical CycloneOrson 1989
Courtesy of NCDC
![Page 16: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/16.jpg)
Preliminary Results from La Reunion
Courtesy of Sebastien Langlade Tropical cyclone forecaster - RSMC La Reunion
![Page 17: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/17.jpg)
Validation (BoM & La Reuion)
![Page 18: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/18.jpg)
Observations from C&K Concerning the Dvorak Technique
• K&Z and C&K produced high MSLP biases for Dvorak-based intensities less than or equal to 55 kt (CI=3.5), suggesting that the accounting for translation speed was causing an error.
• However, when we reexamined the aircraft based intensities in this range, this was not the case.
• Was there a bias in Dvorak-based intensities causing this issue?
![Page 19: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/19.jpg)
Re-examining Dvorak Intensity estimates
• The last systematic examinations completed 2003 and 1988
• 1989-2007• All Dvorak fixes within 2-h of an aircraft fix• Two agencies (TAFB, SAB)• Stratify by
– Intensity• + latitude• + intensity trend• + TC size (ROCI)• + translation
![Page 20: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/20.jpg)
Locations
HurricanesNon-Hurricanes
![Page 21: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/21.jpg)
Time Series
• general bias between TAFB and SAB that has diminished since 2002• upward trend in TAFB errors•No visually detectable change points related to technological changes
**An average of the fixes from SAB and those from TAFB reduced the errors and biases.
![Page 22: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/22.jpg)
Statistics WRT Intensity
• low bias between 35 and 65 kt, and above 120 kt•High bias between 75 and 100 kt• There is a “sweet spot” between 100 and 120 kt.
Sweet spot
Sweet spot
![Page 23: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/23.jpg)
Errors in terms of T-number
Sweet spot
TAFB Biases
![Page 24: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/24.jpg)
Differences Between Agencies
• Timing differences– Coordination
• Calibration issues• Center location
– CDO and Embedded eye
![Page 25: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/25.jpg)
Timing Differences
Time lagIntensity differences (First Homogenous fix)
TAFB Leads
![Page 26: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/26.jpg)
Calibration
• 10-bit, 8-bit, 7-bit image resolution– NMAP– MCIDAS
• BD curve differences
![Page 27: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/27.jpg)
Center Location
• CDO• Shear (lower)• Embedded Eye (higher)
• Classification is subjective to some degree• Dependent on center position
![Page 28: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/28.jpg)
Further Stratifications12-h Intensity Trend [kt]
Weakening Steady/Intensifying Rapid
< -2.5 ≥ -2.5 and < 7.5 ≥7.5
Latitude[o]
< 20 20 to 30 > 30
<20 ≥ 20 and < 30 ≥30
Translation Speed [kt]
Slow Average Fast
<6.0 ≥6.0 and < 14.0 ≥ 14.0
Radius of Outer Closed Isobar [nmi]
Small Average Large
< 165 ≥ 165 and < 270 ≥ 270
![Page 29: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/29.jpg)
100 nmi
200 nmi
300 nmi
ROCI
![Page 30: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/30.jpg)
Results
Summary• Intensity trends are most important and effect all intensity ranges•Latitude is important for more intense storms at high latitude.•Translation effects intensities estimates of Hurricanes 65-120 kts•Size introduces biases at the higher intensities (>100kt)
![Page 31: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/31.jpg)
Summary of Findings
• Errors are a function of Intensity
• Biases are a function of intensity, intensity trends, latitude, TC size and translation speed.
3
max
2
maxmaxmax 364.32930.10
776.0484.11)(
VVVVRMSE
max63.0
4
max
3
max
2
maxmax
305.0018.05.1884.0sin144.25
577.32247.14723.4255.2545.49
VROCIc
VVVVBias
![Page 32: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/32.jpg)
Sensitivities
Factors Predicted Bias Sensitivity
Latitude (mean=23 degrees) ≈-0.32kt per degree
Sin Latitude (mean=0.39) -28.9 kt per sin unit
Translation Speed ( mean=9.9 kt) ≈-0.33 kt per kt
Speed Factor (mean=6.3 kt) -0.88 kt per kt
ROCI (mean=195 n mi) 0.018 kt per n mi
Intensity trend ( mean= 3.4) -0.35 kt per kt
![Page 33: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/33.jpg)
Bias Correction/Error Estimation
Bias = 1.4ktRMSE = 8.9 kt
Bias = -0.5ktRMSE = 9.5kt
Bias = 2.1ktRMSE=10.2 kt
Bias=0.0 ktRMSE=10.7 kt
![Page 34: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/34.jpg)
MSLP from bias corrected Dvorak
![Page 35: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/35.jpg)
Summary
• The Knaff & Zehr WPR has been modified for easy use in most operational settings.– Used at BoM in operations; standardizing estimates between Perth,
Darwin, PNG, Brisbane.– Has been favorably evaluated by RSMC La Reunion
• This work lead to a re-examination of the Dvorak technique.– Biases and errors have been documented– a method for bias correction and error estimation has been
developed
• Combining the WPR and the Dvorak bias correction objective analysis can create unbiased wind estimates and corresponding MSLP estimates.
![Page 36: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/36.jpg)
Remaining Issues / Future Topics
• Continue to validate the WPRs vs. NHC best track and aircraft-based MSLP.
• RMW/eye size correction for WPRs• TC size (S) for this application estimated
directly from IR imagery • Same sort of bias, RMSE analysis for the
AMSU intensity and size estimates• Do better bogus estimates make better
forecasts… HFIP?
![Page 37: Improving Intensity Estimates Using Operational Information John Knaff NOAA/NESDIS Regional and Mesoscale Meteorology Branch Fort Collins, CO](https://reader035.vdocument.in/reader035/viewer/2022062423/5697c00c1a28abf838cc8f45/html5/thumbnails/37.jpg)
Questions?