FIP/FIS (aka IPA) Overview

1. FIP/FIS (aka IPA)Overview Cory A. Wolff 5 – 7 November 2013

2. Anchorage NCAR Icing Research • FAA AWRP • Late 1980’s • History of accidents and icing incidents • Observational and Modeling Studies • Field Programs • CO, OH, AK, Canada, others • Product Development • T & RH Algorithms • Added observations, model improvements

3. Resulting in…

4. IPA Forecast • Icing Probability (FIP) • Calibrated likelihood of icing conditions • Icing Severity (FIS) • Relative amount of liquid water present • Supercooled Large Drop (SLD) Potential • Forecast large drops in and out of precipitation

5. Membership Functions • Used to create interest maps • A method to get an algorithm to “think” like a forecaster so large volumes can be covered • The interest in icing varies based on the values of given variables

6. Cloud Identification • Cloud Tops • Requires at least 2 levels w/ RH > 70% • Then looks at vertical gradients where RH > 70% • RH • VV • TotC • θe • Combine using interest maps

7. Cloud Identification • Cloud Bases and Layers Cloud Layer: At least 3 levels < 50% Cloud Base: RH > 80%

8. Precipitation Identification • Where is precipitation falling? • Precipitable condensate • Sum of the three condensates in the model that can reach the surface (rain, snow, graupel) at the lowest 3 levels • Maximum value is the precipitable condensate • If this value is greater than 0.01 g kg-1 then precipitation is forecast

9. Precipitation Identification • What type of precipitation? • Decision tree scheme from Baldwin et al. (1994) • Gives forecasts of RA, SN, FZRA, and PE • Modified to add DZ and FZDZ • CTT > -12 °C combined with surface temperature

10. Icing Probability • Initial Calculation • Based on T, RH, and CTT • Interest maps provide a likelihood of icing for a given value • Based on cloud physics principles, but adjusted by PIREPs compared with model data • Multiply the 3 maps together

11. Icing Probability • Final Calculation • Adjustments • Precipitation type • SN and RA decrease the likelihood while others can increase it • VV • Upward motion = boost, downward = decrease • SLW • If the model has any SLW then boost the likelihood • Why not just use SLW? Sinking Air Rising Air

12. Icing Probability • The previous slides resulted in an icing potential • Uncalibrated likelihood of icing conditions • Probability requires calibration • Study done in 2006 • Based on comparisons with PIREPs in the Great Lakes • Lots of reports • For a diagnosis an icing potential of 1 gave an 85% chance of icing • 3 hr forecast  74% • 12 hr forecast  43%

13. SLD Potential • Supercooled large drops: SLW with a diameter ≥ 50 μm • Precipitating clouds • Requires a forecast of DZ, FZDZ, FZRA, or PE • These precipitation types are direct indicators of SLD aloft • Non-precipitating clouds • Requires a CTT > -14 °C • Total condensate of at least 0.45 g m-3 (boundary layer) or 0.15 g m-3 (non-boundary layer) • Supercooled rain water also contributes

14. Icing Severity • No Precipitation • Cloudy, but no precipitation forecast • All Snow • Snow is forecast • Cold Rain • Rain is forecast • Warm Precipitation • Collision-Coalescence forms the precipitation • CTT ≥ -12 °C and precipitation is DZ or FZDZ Scenarios • Cold Non-Snow/Rain • Precipitation is something other than snow or rain and the CTT < -12 °C • Classical Precipitation Above a Melting Layer • Classical Precipitation Below a Melting Layer • Convection • Certain CAPE, LI, KI, and TT thresholds must be met Each one has different icing properties. None have the same fields applied in the same way.

15. Icing Severity

16. Icing Severity SEV = w1*i1 + …. + wn*in w1 + …. + wn + (dw1*t_df + dw2*ctt_df + dw3*pcond_df) where w = weight, i = interest, and dw = damping weight • Weight • What is the influence of this field for determining SLW production or depletion in this scenario? • 1 = very little; 5 = maximum • SLW production terms • Moisture, VV, potential condensate, distance from cloud base, total water path, others • Scenario specific • SLW depletion terms • T, CTT, precipitation

17. Combo Map Moisture 50% RH 30% Liquid Cond. 20% Ice Cond. Simple Map Vertical Velocity Scenario Specific Map No Precipitation All Snow Cold Rain Interest • Provides the meaning of a field’s range of values in terms of icing severity 0 = no interest 1 = maximum interest

18. Depletion • Extra denominator fields give information about the depletion of SLW • Temperature • If too cold SLW more likely to become frozen • If too warm plane’s airspeed will discourage icing • Used in all scenarios except below the warm nose and convection • Cloud Top Temperature • Cold temperatures  more ice crystals • Only applied in top 10,000 ft. of cloud • Used in all scenarios except below the warm nose and convection • Amount of Precipitation • Indicator of ice production with increasing values • Only applied in bottom 5000 ft. of cloud • Used in all scenarios except below the warm nose, convection, and no precipitation

19. Damping Membership Functions Temperature Cloud Top Temperature Precipitable Condensate

20. Final Icing Severity Final Severity (0-1) Categorical Severity (None, Trace, Light, Moderate, Heavy) Thresholds Applied

21. Performance • Based on PIREPs from February and March 2013 • CONUS version is generally similar in performance but with less volume

22. Plans • IPA Forecast • Experimental version finalized: May 2014 • Verification: Summer 2014 • Experimental ADDS: December 2014 • Operational version development: 2015+ • Experimental version of IPA Diagnosis • Experimental version: 2015 • Combined product

23. Cases

24. 18 Sep 2013 • UA /OV FAI320009 /TM 2125 /FL070 /TP C208 /TA M01 /IC MOD CLR • 1379539500 20130918 2125 C208 64.93 -148.09 7000 7000 7000 5 2

25. 18 Sep 2013 • UA /OV FAI320009 /TM 2125 /FL070 /TP C208 /TA M01 /IC MOD CLR • 1379539500 20130918 2125 C208 64.93 -148.09 7000 7000 7000 5 2

26. 19 Sep 2013 • UA /OV BRW /TM 1814 /FLUNKN /TP B737 /IC MOD RIME 017-008 /RM ICGIC, RY7 BRAG • 1379614440 20130919 1814 B737 71.29 -156.77 1300 800 1700 5 1

27. 10 Oct 2013 • UUA /OV BKA343019/TM 2320/FL050/TP AT72/TA M14/IC SEVER CLEAR 050-110/RM DURC ZAN CORRECTION • 1381360800 20131009 2320 AT72 57.16 -135.72 5000 5000 11000 8 2

28. 19 Oct 2013 • UA /OV TED360016/TM 1647/FL090/TP B737/TA M08/IC LGT RIME • UA /OV TED 340030/TM 1656/FL140/TP DH8A/TA M19/IC MOD RIME 140-120 LGT RIME 120-100/RM DURGD

29. 12 August 2013 • I looked at IC4D and concentrated on the areas where it was expecting icing. There were two areas: Northwest coastal area to the western Brooks Range. The second area was over the se panhandle. • synoptic - A HI PRES ridge over northwest Alaska. The second area had a hi pres extends from cook inlet to southeast ak. • FIP - In these two situations FIP was showing significant values (80+). I would not have expected that. • Soundings didn't show a moist layer above the freezing layer. Soundings were available on awips but not on the internet. • PIREPs • JNU UA /OV SSR090040/TM 2012/FL100/TP B737/TA M05 /IC LGT RIME 150-105/RM DURD /CWSU ZAN= • JNU UA /OV JNU /TM 2221 /FL120 /TP SR22 /SK OVC-TOP012/OVC035-TOP048/OVC078-TOP120 /TA M05 /IC LGT RIME 100-120 /RM TOP110-120/TA 00-M05= • ORT UUA /OV ORT114045/TM 0213/FL120/TP C120/TA M07/RM IC MOD-HEAVY RIME= • Convection was occurring in the vicinity of the pirep for ORT/Northway

30. 12 August 2013

31. 31 October 2012 • A frontal system is over the gulf of Alaska, lynn Canal, central southeast north of Kake, and coastal waters of AK. • FIP Over southeast Alaska (Eastern Gulf Coast, Coastal Southeast Alaska, Central Southeast Alaska, and Lynn Canal zones values of 50 - 90 were mainly at FL060. The values improve by 090 over Lynn Canal. • FIS values of 50 were over these same areas at the 060 and 090 levels. • Attached are the pireps...indicating ICING over SE Alaska. • This was so right on the money. I don't know what to say. NICE!

32. 31 October 2012 UA /OV JNU /TM 1443 /FL085 /TP B737 /TA M12 /IC MOD MX 085-060 /RM DURD RWY 8. MOD MX/RIME ICE 085-060. TEMP AT 060 M08. AT 085 M12 UA /OV SIT290002 /TM 1536 /FL010 /TP AT72 /SK BKN-OVC010 /TB LGT-MOD /IC NEG /RM LGT-MOD TB DURING DESCENT JNU-SIT/NEG ICE DURING ENTIRE APCH UA /OV SIT160004 /TM 1633 /FL047 /TP AT72 /SK BKN-OVC012 /TA M04 /IC NEG /RM DURC/IMC UA /OV CDV /TM 1640 /FL070 /TP B190 /TA M05 /IC LGT RIME 070-035 /RM DURD UA /OV BKA/TM 1750/FL050/TP PA31/TA M04/IC LGT-MOD RIME/RM DURC 075 RATE OF ACCUMULATION IS DIMINISHING ZAN UA /OV JNU100010/TM 1824/FL050/TP B737/SK TOP100/IC MOD RIME/RM DURC ICING 050-100 ZAN UA /OV SIT300021 /TM 1835 /FL070 /TP B734 /TA M10 /IC LGT RIME 095-070 /RM DURD RWY 11/OVR BASSU UA /OV SSR /TM 1921 /FL080 /TP AT72 /SK OVC020-TOP110 /TA M07 /TB LGT-MOD /IC MOD RIME 080-040 /RM LGT-MOD TB DURD RY8 JNU. AIS 3MILE FINAL. TOWER DID NOT INDICATE TYPE CLD LAYER UA /OV SIT /TM 1956 /FL040 /TP C130 /IC LGT RIME 080-040 /RM DURD RWY 11/NO TEMPS UA /OV CDV /TM 1956 /FL200 /TP B190 /SK OVC040-TOP200 /IC LGT RIME /RM DURD RY9 TA UNKN UA /OV JNU /TM 1959 /FL105 /TP AT72 /SK OVC033-TOP105 /TA M15 /IC MOD RIME /RM DURD RY8. TA M01 FL033 UA /OV BKA350040/TM 2000/FL085/TP C130/TA M05/IC LGT RIME 040-085/RM DURC ZAN UA /OV CGL210010/TM 2004/FL100/TP AT72/SK OVC030/IC LGT RIME SFC-100/RM DURC ZAN UA /OV SIT350050/TM 2027/FL100/TP PA31/SK TOP090/TA M10/IC CONT LGT RIME 050-090/RM DURC ZAN UA /OV SSR035015/TM 2106/FL190/TP B734/TB NEG/IC NEG/RM DURC ZAN UA /OV SSR045025/TM 2141/FL110/TP B737/TB OCNL LGT100/IC NEG/RM DURC ZAN UA /OV BKA/TM 2357/FL090/TP BE20/SK OVC020 TOPS 070/TA M8 AT 6500/IC LGT RIME 065-070

33. Thank you for your time • cwolff@ucar.edu • http://www.rap.ucar.edu/icing/products/fipak • http://www.rap.ucar.edu/icing/products/ic4d_form