Fig. 1

Diagram of tropical cyclone turning angle θ in 12 hours "

Fig. 2

Tracks of Typhoon Nock-ten (a) and its variation of min pressure and max wind (b) Severe tropical storm. The blue dotted line indicates 48-hour warning line, and the blue solid line indicates 24-hour waring line. "

Fig. 3

Same as Fig. 2, except for Typhoon Orma"

Fig. 4

Total flows at 500 hPa of typhoons Nock-ten and Orma (units: m·s-1). (a, d) are 24 hours before unusual turning time; (b, e) are 12 hours before unusual turning time; (c, f) are unusual turning times. Pink symbol represents the TC’s location, and red line represents the track of typhoon, shading is for speed"

Fig. 5

Same as Fig. 4, except for anomalous flows of typhoons Nock-ten and Orma (units: m·s-1) . The blue arrow is the schematic of the“belt” "

Fig. 6

Rotational flow field of typhoons Nock-ten (a, b) and Orma (c, d) at 200 hP. (a, c) are at 24 hours before unusual turning time, and (b, d) are at unusual turning times. Shading is for the speed of rotational wind"

Fig. 7

Vertical cross sections of divergence anomaly (a, c; units:10-5s-1) and vorticity anomaly(b, d; units: 10-5s-1) of Nock-ten at 1800 UTC 24 October 2004 (12 hours before unusual turning) along longitude (a, b) and latitude (c, d) where the TC was located. Green symbol represents the location of the typhoon, solid contour represents positive values, and dashed contour represents negative values"

Fig. 8

Vorticity anomaly of Nock-ten (10-5s-1) at 700 hPa during the unusual turning. a) 48 hours before unusual turning time; b) 24 hours before unusual turning time; c) 12 hours before unusual turning time; d) at the unusual turning time; e) 12 hours after unusual turning time; f) 24 hours after unusual turning time. The red lines is the track of Typhoon Nock-ten, and the pink marker represents the location of Nock-ten. The solid lines are positive, and the dashed lines are negative"

Fig. 9

Prediction of vorticity anomaly of Orma (10-5s-1) starting from 1800 UTC 24 October 2004 using CBAM. a) 0000 UTC 25, b) 0600 UTC25, c) 1800 UTC 25, and d) 0600 UTC 26. The brown box indicates the predicting location of the typhoon vortex. The typhoon track and its current location are indicated by the red solid curve and the pink symbol, respectively.The solid line indicates that vorticity anomaly is positive, while the broken line indicates negative."

Fig. 10

Same as Fig. 9, except for using ABAM"

Fig. 11

Same as Fig. 9, except for using GBAM"

Fig. 12

Same as Fig. 7, except for Orma at 1200 UTC 4 September 1992 (12 hours before the unusual-western turning)"

Fig. 13

Same as Fig. 8, except for Orma"

Fig. 14

Predictions of vorticity anomaly of Orma starting from 1200 UTC 4 October 2004 using the CBAM model. a) 1800 UTC 4 September, b) 0000 UTC 5 September, c)1200 UTC 5 September, and d) 0000 UTC 6 September. The others are the same as those in Fig. 9"

Fig. 15

Same as Fig. 14, except for using ABAM "

Fig. 16

Same as Fig. 14, except for using the GBAM model"