Table 1. Data availability (in percentage) at different stations at different pressure levels, 500 hPa, 150 hPa, pressures at CPT(obtained for each profile), 70 hPa and 50 hPa normalized to total number of observations for 10 year period (1999-2008). Star indicates the major data gaps which is discussed in the text. Reported data levels available (in percentage) in the range ≥5 – 10, ≥10 – 20, ≥20 – 30 and ≥30- 40 between 150-50 hPa at the five stations are also shown. % of data available up to different pressure levels 500 hPa 150 hPa Pressure at CPT 70 hPa 50 hPa Truk (7.44 N,151.83oE) 99 96 95 92 88 % of data level between150-50 hPa ≥5 ≥30≥10 ≥20 40 - 20 - 30 10 0 3 82 13 Rochambeau (4.83oN, 52.36oW) 99 98 98 91 88 4 75 19 100 99 99 94 91 1 9 64 99 96 96 88 78 5 24 40 100 98 97 88 83 5 27 55 Station o Singapore (1.03oN,103.87oE) Seychelles (4.66oS,55.53oE) Darwin (12.41oS, 130.88oE) 0 23 20 8.2 Number of observation. 6985 6837 6960 5838* 6964 Table 2. The overall percentage of occurrence of LT, ST, TT, fourth tropopauses, fifth tropopauses, and AT calculate for different threshold CPH 3 , CPH 4 , CPH 5 and CPH 6 for the five stations Truk, Rochambeau, Singapore, Seychelles and Darwin for the period 1999-2008. CPH 3 Darwin Seychelles Singapore Rochambeau Truk CPH 4 Over all % of occurrence for 1999-2008 LT ST TT Fourth Fifth AT Tropo. Tropo. 5.01 30.5 1.25 0 0 34.5 5.01 40.8 4.151 0.04 0 44.1 5.01 48 8.807 0.28 0.015 50.9 CPH 6 5.01 53.9 13.78 0.88 0.074 56.6 CPH 3 7.64 30.9 1.281 0 0 36.3 7.64 41 4.625 0.03 0 45.7 7.64 47 9.596 0.33 0 51.1 CPH 6 7.64 50.5 13.94 1.13 0.03 54.4 CPH 3 12.1 49 2.717 0 0 56.7 12.1 63.5 11.46 0.1 0 69.1 12.1 71.8 22.32 1.26 0 76.2 CPH 6 12.1 77.1 33.99 4.29 0.163 80.7 CPH 3 12.1 29.3 1.432 0 0 37.6 12.1 39.3 5.092 0.13 0 46.3 12.1 46.7 11.18 0.8 0 52.7 CPH 6 12.1 51.3 17.13 1.76 0.036 56.6 CPH 3 4.22 22.2 0.786 0 0 25.6 4.22 29.5 2.178 0.03 0 32.5 4.22 37.9 5.188 0.18 0 40.5 4.22 45.2 9.165 0.68 0 47.3 CPH 5 CPH 4 CPH 5 CPH 4 CPH 5 CPH 4 CPH 5 CPH 4 CPH 5 CPH 6