Fig. 1: Anomalous tropical cyclone (TC) activity in 2023 relative to 1980–2022. | npj Climate and Atmospheric Science

Fig. 1: Anomalous tropical cyclone (TC) activity in 2023 relative to 1980–2022.

From: Unusual role of positive Indian Ocean Dipole in the record-low tropical cyclone genesis over the Western North Pacific in 2023

Fig. 1

TC track (lines) and genesis density anomalies (shading) during June–August (JJA; a) and September–November (SON; b). Blue dots denote the genesis location of TCs. Black and red lines indicate TC tracks in JJA and SON, respectively. Red box (5°–25°N, 120°–165°E) represents the central WNP (CWNP), where a significant TC decline occurred during SON 2023. c, d Time series of TC genesis frequency (TCGF) anomalies in the CWNP (green bar), sea surface temperature (SST) index over the tropical North Atlantic (TNA; black line), dipole mode index (DMI; red line), and Niño 3.4 index (blue line) during JJA and SON. Green bars show TCGF anomalies for 1980–2022; red bars indicate 2023 values. e, f Anomalous dynamic genesis potential index (DGPI; shading) and horizontal wind at 850 hPa (vectors; m/s) in 2023. The wind anomaly less than 0.5 m/s is omitted. g Quantitative contributions to DGPI changes (relative to 1980–2022 climatology): relative DGPI change (DGPI’), sum of the relative changes in four dynamic factors (Sum’), including vertical wind shear (VWS’), meridional gradient of zonal wind at 500 hPa (dUdY’), 500-hPa vertical velocity (W’), and 850-hPa absolute vorticity (Vort’). Blue and red bars represent JJA and SON values, respectively.

Back to article page