Fig. 1.
Location of 61 weather observation stations used to obtain precipitation data for this study.
Fig. 2.
Points of tropical cyclones (TCs) weakened around Korea (32–36°N, 122–132°E) during the period 1979–2008, and their tracks for (a) WEC (weakened to extratropical cyclone), (b) WTD (weakened to tropical depression).
Table 1.
Definition of affecting time point and approaching time point of TC.
Table 2.
Weakened time point of all TCs for WEC and WTD.
[i] The time indicates the time difference between weakened time of TC and affecting time point (in Table 1).
Fig. 3.
Mean TC track (interval 6 h) from approaching time point (–12 h) of TC and 500 hPa mean geopotential height (gpm) at approaching time point for (a) WEC and (b) WTD.
Fig. 4.
Monthly frequency of TC weakened to extratropical cyclone (WEC) and tropical depression (WTD).
Fig. 5.
Spatial distribution of rainfall accumulated over 48 h from approaching time point (–12 h) of TC for (a) WEC, (b) WTD and (c) their difference (WEC minus WTD). Dashed lines indicate negative value.
Table 3.
Mean rainfall accumulated over 48 h at 61 weather observation stations from the approaching time point (–12 h) of TC and maximum rainfall of all the weather observation stations.
Sancheong (47,289)115.0 mm
Geoje (47,294)
Fig. 6.
Verification using Student’s t-test (0.1 significance level) for the rainfall difference shown in Fig. 5c. Closed circles denote areas (Region 1) that there is a difference in rainfall while open circles denote areas (Region 2) that a difference in rainfall is similar.
Fig. 7.
Rainfall in (a) Region 1 and (b) Region 2 at each latitude as TCs approach Korea. Numbers over bars denote the accumulated rainfall time (h).
Fig. 8.
Time evolution of 3-h interval accumulated rainfall (bars) from the approaching time point (–12 h) of TC to 48 h later for (a) Region 1 and (b) Region 2. Lines with an open circle indicate distances between the TC center and Seoul or Gwangju (star-marked point in embedded map). Solid vertical line indicates the mean time (+7.7 h) that TCs were weakened to EC and dashed vertical line indicates mean time (+24 h) that TCs were weakened to TD.
Fig. 9.
Potential vorticity of 300–200 hPa (shaded every 0.2 PVU starting at 0.4 PVU, where 1 PVU = 10−6 K kg−1 m2 s−1), 850 hPa air temperature (dashed lines, °C) and mean location of TCs at the approaching time point (–12 h) for (a) WEC and (b) WTD. Jet stream of 200 hPa (shaded every 5 m s−1 starting at 30 m s−1), 200 hPa divergence (thick contours, every 3 × 10−6 s−1 starting at 3 × 10−6 s−1) and 850 hPa convergence (thin contours, every –2 × 10−6 s−1 starting at –2 × 10−6 s−1) at the approaching time point (–12 h) for (c) WEC and (d) WTD. Dashed vertical line is used for the analysis of the vertical cross section in Fig. 10.
Fig. 10.
Vertical cross section over the dashed vertical line in Fig. 9 for (a) WEC and (b) WTD. Shaded area indicates ascending flow (hPa h−1). Thick lines and thin lines indicate divergence (10−6 s−1) and convergence (10−6 s−1), respectively. Square box indicates a latitude region where Korea is located.
Fig. 11.
Rainfall intensity (mm h−1) over 48 h from the approaching time point (–12 h) of the representative Typhoon NEIL (9905) of WTD (from 0600UTC 26 July to 0300UTC 28 July in 1999, interval 3 h) using TRMM dataset. This typhoon was weakened to TD at ‘+24 h’, 1800UTC 27 July.
Fig. 12.
Same as Fig. 11, but for representative Typhoon MINDULLE (0407) of WEC (from 0600UTC 3 July to 0300UTC 5 July in 2004). This typhoon was weakened to EC at ‘+06 h’, 0000UTC 4 July.
Fig. 13.
Time evolution of area proportion of detected rainfall intensity above (a) 5 mm h−1 or (b) 1 mm h−1 within the northern 800 km radius of the center of Typhoon MINDULLE and Typhoon NEIL. Solid and dashed vertical lines indicate the extratropical transition time point and weakening time point of each TC, respectively.
Fig. 14.
Time evolution of 3-h interval rainfall (bars) from the approaching time point (–12 h) of each typhoon (MINDULLE and NEIL) to 48 h later for (a) Region 1 and (b) Region 2. Lines with an open circle indicate distances between the TC center and Seoul or Gwangju (star-marked point in embedded map). Solid vertical line indicates the time (+6 h) that Typhoon MINDULLE was weakened to EC and dashed vertical line indicates the time (+24 h) that Typhoon NEIL was weakened to TD.