Abstract:
A forecast tool has been developed called the Orbital Cyclone Strike
Index [OCSI] to make the risk assessment of a tropical cyclone strike
along the North American coast each year. The OCSI is based on the
premise that the sun’s orbit causes changes in the torque on the earth's
atmosphere that are similar to the changes in the torque of the sun’s
atmosphere which can be traced through the solar cycle. The authors use
this premise to create the index based on the solar cycles. The OCSI has
been used for forecasting tropical storms and hurricane landfalls since
1985. This paper compares these forecasts to the actual events.
Two types of forecasts were verified, the first one was the prediction of
the likelihood of a hurricane or tropical storm making landfall on a certain
section of the Atlantic coast of North America. This forecasts included
predictions of when tropical cyclone strikes were likely as well as a
forecasts when tropical cyclones were unlikely. This was a forecast that
was designed to test the theory. The phases of the OSCI and the coast that
were chosen to forecast a strike were selected were selected as outlined
below.
The phases and coasts chosen for a strike had an expectation that was equal
to or more than the mean expectation for the coast plus one standard
deviation of the expectation for a phase. The phases and coasts chosen for
no strike had an expectation that was equal or less than the mean expectation
minus one standard deviation. This rule allowed us to make 12 forecasts of
strikes and 7 forecasts of no strikes per cycle. The OCSI was tested as a
forecast tool over 10 cycles and found accuracy from 57% to 100% with most
of them near 70%. The second forecast was to predict which section of the
coast line each year had the highest and second highest probability of
experiencing a tropical cyclone. The first type of forecasts was verified
from 1987 to 1996. The second type of forecasts was verified for the coasts
and the phases of the solar cycle that had the highest probability each year
and those that had the second highest probability each year and was verified
for the years 1985 to 1987.
The first type of forecast for strikes verified 67% and the expectation in
this case was 71%. The authors considered this a good forecast. The
verification for no strikes verified 75% and the expectation for no strike
was 78%.