Weather myths about convective storms: an objective assessment of their validity and their psychological basis

Transcription

1 Weather myths about convective storms: an objective assessment of their validity and their psychological basis Martin Göber (1,4), Anastasia Karb(2), Kathrin Wapler (1), Nadine Fleischut (3,4) 1) Deutscher Wetterdienst, DWD 2) Institut for Meteorology, Freie Universität Berlin 3) Max-Planck Institute for Human Development 4) Hans-Ertel-Centre for Weather Research (HErZ) Alexandra Mikhaylushkina ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 1

2 Motivation KONRAD ( KONvection development in RADar produtcs ) Part of FeWIS ( Fire brigade Weather Information System ) ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 2 fileadmin/_migrated/pics /Landesbranddirektor_Dipl.- Ing._Wilfried_Graefling_600.jpg

3 - KONRAD ( KONvection development in RADar products ) - Localises and tracks convective cells - convective cell: compact group of at least 15 pixels with a reflectivity of > = 46dBZ - based on 2D precipitation scan, with resolution of 1 km*1 km, every 5 minutes - KONRAD analysis from cell snap shots cell tracks KONRAD data - Parameter: time, location, velocity vector, number of recognitions, hail flag ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 3

4 Absolute frequency of cells within 20*20 km box, orography Number of days with lightning within 15 km over 6 years ( ) Wapler, 2013: High-resolution climatology of lightning characteristics within Central Europe. Met. Atmos. Physics,122, ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 4

5 Thunderstorms are deflected/dissolved by Berlin. ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 5

6 latitude (km) Cell frequency Berlin + surroundings smoothed, 1*1 km 2 resolution Orography in m longitude (km) ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 6

7 The inner box approach Hamburg control region Berlin Orography in m ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 7

8 The inner box approach - Definition einer Innenbox, km großen Abgrenzung, die an die Fläche Berlins angepasst ist Eingenschaften Berlin Median der 17,0 Lebensdauer (Min.) Anzahl der Tracks 319 ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 8

9 Inner box and outer frame approach Options for a track coming from the outer frame Not move into the inner frame Move from outer frame into inner box Right or left moving ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 9

10 Inner box and outer frame approach Percentage of cells, which did NOT reach the inner box Did not reach the inner box Berlin (%) Hamburg (%) Control region (%) Median whole Germany 61,7 43,2 51,7 55,2 ± 11,1 ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 10

11 a) Partitioning and smoothing of tracks ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 11

12 Relative frequency in % Statistics of directional changes of cell tracks Berlin Control region Hamburg straight within ± 5 left mover right mover ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 12

13 Thunderstorms do not cross the river. ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 13

14 Number of cells along major german rivers (20 km resolution) ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 14

15 Absolute cell frequency Thunderstorms don t cross the river Elbe Before Before Before Behind Behind Behind Position from origin along the river in km ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 15

16 Absolute frequency Frequency of cells before and behind the river Elbe Distance from river in km ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 16

17 What claims may people believe in? 1. People report an observed pattern: Thunderstorms often do not reach Berlin, but are deflected or dissolve. 2. People imply a comparison: The pattern is different from (a) the countryside or (b) other cities in Germany. 3. People give a causal explanation: The size or climate of cities or Berlin in particular have a special effect on thunderstorms. ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 17

18 Relevant psychological phenomena Confirmation bias Coincidence as evidence Illusory correlations Search Interpretation Intuitive causal theories availability Over- or underestimation ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 18

19 and potential explanations Non-random sampling Distribution of information Processing goals Influence of causal theory causal beliefs interact topdown with new information prior plausibility of a belief Search Interpretation Heuristic recall Assess frequency or probability by: number of items that come to mind fluency Over- and underestimation Estimation requires knowing: what are ordinal relations what values are plausible ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 19

20 Summary Convective cells over the city of Berlin do not exhibit a significantly different occurence and movement to other areas Cells do cross the river Elbe Social and behavioural research and education is needed to explain meteorological variability and thus to prevent the development and survival of false heuristics ( myths ) ECSS 2015 Convective weather myths: Göber, Karb, Wapler, Fleischhut 20