STATE OF THE CLIMATE IN 2009

Geophysical and Astronomical Services Administration(PAGASA), which also named two other TDs(Bising and Crising) in the 2009 typhoon (TY) season.Twenty-five reached TS intensity (three of which werenot named), 14 became TYs, and 5 reached supertyphoon(STY) intensity. In Fig. 4.20a the number ofTSs, TYs, and STYs per year is shown for the period1945–2009. The TC data used here is from the JointTyphoon Warning Center (JTWC) best-track datasetfor 1945–2008, and preliminary operational data for2009, for the TCs forming in the WNP. Preliminarydata for the storms forming in the Central Pacificregion is from CPHC. Climatology is defined usingthe period 1971–2000.The 2009 WNP TC season (see Fig. 4.20) startedin May, with TYs Kujira and Chan-Hom. These wereFig. 4.20. (a) Number of TCs for the period 1945–2009. (b) Cumulative number of NSs per month: 2009(black line), and climatology (1971–2000) shown as box plots [interquartile range: box, median: red line,mean: blue asterisk, values in the top or bottom quartile: blue crosses, high (low) records in the 1945–2008period: red diamonds (circles)]. (c) Number of NSs per month in 2009 (black curve), mean climatologicalnumber of NS per month (blue curve), the blue plus signs denote the maximum and minimum monthlyhistorical values (1945–2009) and green error bars show the interquartile range for each month. In thecase of no error bars, the upper and/or lower percentiles coincide with the median. (d) Cumulativenumber of TYs: 2009 (black line), and climatology (1971–2000) shown as box plots. (e) Number of TY permonth in 2009 (black curve), mean climatological number of TY per month (blue curve), the blue plussigns denote the maximum and minimum monthly historical values (1945–2009) and green error barsshow the interquartile range for each month. (Source: 1945–2008 JTWC best-track dataset, 2009 JTWCpreliminary operational track data.)S92 | juNE 2010