Roger A. Pielke, Jr. and Christopher W. Landsea
6 April 1999
Submitted to Bulletin of the American Meteorological Society
Table 1. Categorization of the Atlantic hurricane season into El Niño (based upon the August-September-October Niño 3.4 SST anomalies warmer than or equal to +0.4C) and La Niña (August-September-October Niña 3.4 SST anomalies cooler than or equal to -0.4C) events from 1925-97. The 10 most intense events of each type are highlighted in bold.
| El Niño | La Niña |
| 1925 | 1933 |
| 1929 | 1938 |
| 1930 | 1942 |
| 1940 | 1944 |
| 1941 | 1945 |
| 1951 | 1948 |
| 1953 | 1949 |
| 1957 | 1950 |
| 1963 | 1954 |
| 1965 | 1955 |
| 1969 | 1956 |
| 1972 | 1961 |
| 1976 | 1964 |
| 1977 | 1967 |
| 1982 | 1970 |
| 1986 | 1971 |
| 1987 | 1973 |
| 1990 | 1974 |
| 1991 | 1975 |
| 1993 | 1978 |
| 1994 | 1988 |
| 1997 | 1995 |
Table 2. Median and mean losses (with standard deviation) by phase of ENSO cycle presented in normalized 1997 US dollars.
| Median ($)million |
Mean ($)million |
Standard Deviation ($)million | |
| La Niña | 3,292 | 5,887 | 6,991 |
| Neutral | 927 | 6,979 | 15,856 |
| El Niño | 152 | 2,056 | 4,228 |
Table 3. Levels of significance in differences in losses between phases of the ENSO cycle calculated using a two-tailed t test. Mean values calculated using a logarithmic transformation; median values are not transformed.
| La Niña | Neutral | |
| Neutral | log-mean = 94%
median = 61% |
|
| El Niño | log-mean = >99%
median = 98% |
log-mean = 81%
median = 83% |
Table 4. Number of damaging events that exceed certain thresholds by phase of the ENSO cycle, shown as years and percentages.
| La Niña | Neutral | El Niño | |
| > $1 Billion | 17 (of 22)
77% |
14 (of 29)
48% |
7 (of 22)
32% |
| >$5 Billion | 8 (of 22)
36% |
8 (of 29)
28% |
3 (of 22)
14% |
| >$10 Billion | 4 (of 22)
18% |
6 (of 29)
21% |
3 (of 22)
14% |
Table 5. Levels of significance calculated using a two-tailed t test, comparing phase of ENSO cycle for three loss-exceedance thresholds.
| La Niña | Neutral | |
| Neutral | >$1 Billion = 96%
>$5 Billion = 48% >$10 Billion = 22% |
|
| El Niño | >$1 Billion = >99%
>$5 Billion = 90% >$10 Billion = 27% |
>$1 Billion = 74%
>$5 Billion = 74% >$10 Billion = 48% |
|
Roger Pielke Environmental and Societal Impacts Group National Center for Atmospheric Research (NCAR) PO Box 3000 Boulder, Colorado 80307 USA 303-497-8111 (voice) 303-497-8125 (fax) rogerp@ucar.edu
|
Christopher W. Landsea AOML/Hurricane Research Division National Oceanic & Atmospheric Administration 4301 Rickenbacker Causeway Miami, Florida 33149 USA (305) 361-4357 (voice) (305) 361-4402 (fax) landsea@aoml.noaa.gov |
NCAR is sponsored by the National Science Foundation