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Displaying the Verification Results of Terminal Aerodrome Forecasts for Thunderstorms and Visibility Jadran Jurkovi 1 Zoran Pasari 2 and Igor Kos 1 1 Croatia Control ltd 2 University of Zagreb, Dept. Of Geophys. 7th International Verification

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Displaying the Verification Results

  • f Terminal Aerodrome Forecasts

for Thunderstorms and Visibility

Jadran Jurković 1 Zoran Pasarić2 and Igor Kos 1

1 Croatia Control ltd 2 University of Zagreb, Dept. Of Geophys.

7th International Verification Methods Workshop | Berlin 2017 1

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Outline

  • Introduction
  • Diagnostic purpose
  • Displaying Results

– Thunderstorms – Visibility

  • Conclusion

7th International Verification Methods Workshop | Berlin 2017 2

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Introduction: TAF

  • Terminal aerodrome forecast
  • Standard ICAO product
  • but each country has its own style (Sharpe

2016)

– „…as agreed by the meteorological authority with the ATS authority and operators concerned” – duration 24h (9-32h) – Other: standards and recommendations , criteria for groups of changes (and/or AMD)

7th International Verification Methods Workshop | Berlin 2017 3

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Introduction: TAF verification

  • ICAO Annex 3 attachment B

– Operationally desirable accuracy of forecasts – The same in EASA documents (without changes)

  • Several basic approaches

– Harris (2000), Mahringer (2008), Sharpe (2016)

  • Other features for TAF verifications:

– TAF statements are deterministic, probabilistic and temporal – Results: scores, contingency tables – Rare events

  • forecast for a given point
  • the verification time period is just one hour
  • aviation requirements usually refer to high impact weather

– Climatological difference

7th International Verification Methods Workshop | Berlin 2017 4

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7th International Verification Methods Workshop | Berlin 2017

Diagnostic verification

  • Basic principles

– G. Mahringer (2008) – Best (FC and OBS) and worse (FC and OBS) conditions are verified

  • Diagnostic verification

– Weakness and strength of forecast – Verification of special problems for aviation in Croatia

  • Convection (TS)
  • Fog (reduced visibility)
  • Wind (especially bora events)

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7th International Verification Methods Workshop | Berlin 2017

Verification

  • Verification scores

– p0, Bias, TCC/PCC (tetrachoric/polychoric correlation coefficient) – Juras and Pasarić (2006): Application of tetrachoric and polychoric correlation coefficients to forecast verification (link)

  • Pearson (1900)
  • measure of association in contingency tables
  • TCC=-1, 1, TCC=0 for random
  • TCC/PCC do not depend on bias nor on marginal frequencies

=> independent information between them

  • TCC/PCC are particularly good for rare events (fig.2)

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7th International Verification Methods Workshop | Berlin 2017

Verification

  • Verification of hours with TS
  • FC: „worst conditions”=> all group of changes
  • OBS: METAR 0:00 or 0:30

– Contingency table 2x2

  • Frequency of observed hours with TS at airports in Croatia => 0.8-1.5% =>

rare event

  • Relatively large false alarms

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7th International Verification Methods Workshop | Berlin 2017

TS verification: hit a)

  • Analysis of hit event

– Months – Hours – Issue time – Lead time – Chronological – Contingency table – Forecast expression of TS in TAFs

Challenges in meteorology 3 21-22 November 2013.,Zagreb

ANALIZA PROGNOZE GRMLJAVINE (TS)

Termini prognozirani: a = Točno (pogodak) (Prognozirano: DA Motreno: DA) (interno) Zračna Luka: LDZA Razdoblje: 2009-2013 Da Ne Ukupno a= 1062 b= 8059 9121 c= 820 d= 164308 165128 1882 172367

174249

Načini i i izvještavanje za događaje "a" LDZA Ne ... ... Ukupno METAR TAF

70 TS 41 TSRETS 41 TS TS 25 TS 22 -TSRARETS -RA 20 -TSRA -TSRA 19 -TSRA TS 15 TSRA TSRA 15 TSRETS 15 VCTS 14 -TSRA TSRA 12 -TSRA -RA 12 TS TSRETS 11 -TSRA 9 -TSRARETS 8 RARETS RA 8 RETS 8 -TSRARETSRA 8 TS -TSRA 6 TSRARERA 6 TSRARETS RA 6 -TSRA -TSRARETS 6 TSRA -TSRARETS 5 -TSRARERA - TSRARERA 5 TSRARETS 5 -TSRA TSRARERA 5 TSRETS RETS 4 +TSRARESHRA -TSRA 4 -RA -RARETS 183 NSW TE SHRA P40 TSRA 99 NSW TE TSRA 86 NSW P40 TSRA 78 NSW TE SHRA P30 TSRA 57 NSW P30 TSRA 27 NSW TE TSRA P30 TSGR 12 RA TE TSRA 10 NSW TE SHRA TE TSRA 9 NSW P40 SHRA P30 TSRA 6 NSW TE RA P30 TSRA 6 NSW TE TSRA BE RA 5 NSW TE TSRA P40 TSGR 4 NSW TE SHRA P40 TSRA BE RA BR 4 NSW TE RA P40 TSRA 4 RA P30 TSRA 4 BR P40 BCFG P30 TSRA 3 NSW BE TSRA 3 NSW P40 TS 3 NSW TE SHRA P40 TSRA BE RA 3 NSW TE TSRA P30 TSRAGR 3 NSW TE SHRA TE TSRA P30 TSGR 2 NSW FM RA TE SHRA P30 TSRA 2 TSRA 2 NSW TE TSRA P30 TSRA 2 NSW BE RA P30 TSRA 2 NSW P40 SHRA TE TSRA

Motreno Prognozirano Da

1 21 56 279 311 265 173 94 37 13 20 40 500 1 2 3 4 5 6 7 8 9 10 11 12 Pr.br. Kl. TS termina METAR (polusatni) Br."Propust" ili motrenih TS sati

Raspodjela prognoziranih sati "Točno (pogodak)" po mjesecima

KLIMA pros. br. TS termina

  • Uk. verif. "Točno (pogodak)" sati 2009-2013
  • Uk. Motreni TS termini 2009-2013

29 25 22 8 13 12 23 13 9 10 32 35 78 101 95 86 117148 102 98 51 36 50 57 50 100 150 200 100 200 300 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Pr.br. Kl. TS termina METAR (polusatni) Br."Propust" ili motrenih TS sati Sat u danu (UTC)

Raspodjela prognoziranih sati "Točno (pogodak)" po satu (UTC) u danu

KLIMA pros. Br. TS termina

  • Uk. verif. "Točno (pogodak)" sati 2009-2013
  • Uk. Motreni TS termini 2009-2013

74 77 56 44 67 65 55 52 37 32 54 65 52 54 39 31 47 68 51 54 45 33 44 54 50 100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Sat nastupa TAF-a Raspodjela prognoziranih sati "Točno (pogodak)" po vremenu nastupa(1-24) TAF-a

5 11 17 23 Ukupno Točno (pogodak)" sati

294 332 336 288 200 300 400 5 11 17 23 Raspodjela prognoziranih sati "Točno (pogodak)" po vremenu izdanja TAF-a 0 0 0 2210 6993 35 3 5 0 4 0 0 9 0 19243257 1 0 0 0 0 0 0 8 75 104 36 0 12 9 0 9 0 0 2 11 643930 9 2310 0 0 0 1 8 4 47364463 32 3 0 0 100 200 2009-1 2009-4 2009-7 2009-10 2010-1 2010-4 2010-7 2010-10 2011-1 2011-4 2011-7 2011-10 2012-1 2012-4 2012-7 2012-10 2013-1 2013-4 2013-7 2013-10 Br."Propust" ili motrenih TS sati

Raspodjela prognoziranih sati "Točno (pogodak)" po mjesecima kronološki 2009-2011

  • Uk. verif. "Točno (pogodak)" sati 2009-2013
  • Uk. Motreni TS termini 2009-2013

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7th International Verification Methods Workshop | Berlin 2017

Bias / TCC display

Example of contingeny tables for different bias and TCC

Example: frequency (a+c) of hours with TS je 1.3%

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0,65% 9,10% 0,90% 9,10% 1,15% 9,10% 0,65% 89,60% 0,40% 89,60% 0,15% 89,60% 1,30% 98,70% 1,30% 98,70% 1,30% 98,70%

5

0,55% 6,50% 0,79% 6,50% 1,09% 6,50% 0,75% 92,20% 0,51% 92,20% 0,21% 92,20% 1,30% 98,70% 1,30% 98,70% 1,30% 98,70%

3

0,41% 3,90% 0,64% 3,90% 0,90% 3,90% 0,89% 94,80% 0,66% 94,80% 0,40% 94,80% 1,3% 98,7% 1,3% 98,7% 1,3% 98,7%

0,5 0,65 0,8 TCC

bias

a b c d

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7th International Verification Methods Workshop | Berlin 2017

Bias / TCC display example 2

Dispersive results are expected

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Tablica kontningencije Tablica kontningencije Verifikacijski indeksi Ostali pomoćni pokazatelji

Razdoblje: 9.2.2012-31.12.2014.

Aspolutne čestine [sat] Relativne čestine [%] Točnost Pristranost

Pa+Pb Pa+Pc a/(a+c) a/(a+b) a/(a+b+c) (PSS+HSS)/2

Ime_EERS a b c d Pa Pb Pc Pd

TCC

Bias a-c/(a+c)

Pfc

Pobs

POD pTSfc CSI KPI

Puhalo Dragović, Nataša(729) 480 93 521 66 10756 0,8% 4,6% 0,6% 94,1%

0,70 3,9 159 0,17 5,4% 1,4% 0,58 0,15 0,14 0,26

SMB 4111 703 4684 549 92366 0,7% 4,8% 0,6% 94,0% 0,67 4,3 0,12 5,6% 1,3% 0,56 0,13 0,12 0,25

Raspodjela događaja a (pogodak), b (krivi alarm), c(propust)

Broj TAFova

Motreni TS sati

1,0 2,0 3,0 4,0 5,0 6,0 7,0 0,4 0,5 0,6 0,7 0,8 0,9 1,0

Pristranost (Bias)

Točnost (TCC)

Indeksi verifikacije TS prognoze u TAF-u po prognostičaru za razdoblje 9.2.2012-31.12.2014.

FC Ostali SMB PO godinama

20 40 60 2 4 6 8 10 12 14 16 18 20 22

SAT U DANU

b c a 20 40 60 1 3 5 7 9 11 13 15 17 19 21 23

NASTUPNI SAT

b c a 50 100 150 200 5 11 17 23

IZDANJE

50 100 150 200 1 2 3 4 5 6 7 8 9 10 11 12

MJESEC

XY

7th International Verification Methods Workshop | Berlin 2017

TS verification: forecaster LDZA

Challenges in meteorology 3 21-22 November 2013.,Zagreb

TCC BIAS

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7th International Verification Methods Workshop | Berlin 2017

Bias / TCC display example 3

  • Verification of visibility

– According to categories with limits 150, 350, 600, 800, 1500, 3000 and 5000m – Best (FC and OBS) and worse (FC and OBS) conditions are verified – 2 contingency tables NxN: polyhoric correlation coefficient is used

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7th International Verification Methods Workshop | Berlin 2017

Bias / TCC display example 4

Better results when p0 is higher Bias is larger

  • p0 smaller

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7th International Verification Methods Workshop | Berlin 2017

Conclusions

  • Diagnostic verification

– Based on approach by Mahringer (2008)

  • Verified elements in TAFs are rather rare
  • Displayed results are used with triplet

– marginal frequency, bias and tetrachoric coefficient (Juras and Pasarić 2006) – Bias and TCC represents forecast – 4 examples for thunderstorms and visibility

  • Additional conclusion : verification results depend on

– climatology (frequency of an event) – forecaster

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7th International Verification Methods Workshop | Berlin 2017

Literature

  • Harris GR. 2000. Comparison of different scoring methods for TAFs and other

probabilistic forecasts. 15th AMS Conference on Probability and Statistics in the Atmospheric Sciences, 8–12 May 2000, Asheville, NC.

  • International Civil Aviation Organization (ICAO). 2010. Meteorological Services for

International Air Navigation. Annex 3 to the Convention on International Civil Aviation, 15th edn. ICAO: Montreal.

  • Mahringer G. 2008. Terminal aerodrome forecast verification in Austro control

using time windows and ranges of forecast conditions. Meterol. Appl. 15: 113–123.

  • Pearson, K. 1900: Mathematical contributions to the theory of evolution. VII. On

the correlation of characters not quantitatively measurable, Philos. Tr. R. Soc. S.–A, 195, 1–47.

  • Juras J., Pasarić Z. 2006, Application of tetrachoric and polychoric correlation

coefficients to forecast verification, Geofizika 23, 59-82

  • A. Sharpe M., E. Bysouth C. , Trueman M. 2016, Towards an improved analysis of

Terminal Aerodrome Forecasts, Meterol. Appl. 23, 698–704.

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