Wednesday, September 12, 2007

Storm surge is not tidal wave!

My friend Rob Stormer has a much wider information source for his blog than ordinary people. I am obliged to him for alerting me this news item (see here) about a giant wave impact on the state Orissa, India -- a littoral state with a long coast line situated on the east coast of India. The news starts with:
At least 13 houses were washed away and three more houses damaged under the impact of high tidal waves in Podampeta, a sea-side village under Palibandha gram panchayat in Ganjam district, official sources said here on Monday. The powerful waves lashed the village inhabited mostly by fishermen during the last three days. Alarmed over another depression formed over the Bay of Bengal, the district administration apprehended more tidal waves and asked the fishermen families residing very close to the sea to shift to the nearby cyclone shelter.
Later on it reports:
The sea, which was about one km from the village, is now flooding it. Meanwhile, the huge waves which have been bothering the administration caused more damage to the coastline at Puri and Gopalpur, two of Orissa's finest beach resorts. The waves also washed away a portion of the newly-built marine drive at Puri on Sunday paralysing traffic.
As it is basically confined to the local concerns, understandably it did not receive wider media attention. For the local fishermen who only wish to cast their net in the Bay of Bengal peacefully, this unwelcome, unfriendly, natural phenomenon can be very devastating.What it struck me, however, was their use of the term "tidal wave" which is somewhat uncustomary to me, because it is clearly unrelated to tide. According to Wikipedia, the term "tidal wave" can customarily refer to a tidal bore, a tsunami, or the crest of a tide as it moves around the earth. In this case the phenomenon they called "tidal wave" does not fit into any of the three indications the Wikipedia classified. I think based on the description given in the article and the fact that they are worrying about the depression formed in the Bay of Bengal, the more customary term to use could be the "storm surge" which is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone according to Wikipedia. Clearly they have been vexed by storm surges in the region as they have already built "cyclone shelter" to cope with it. So "storm surge is not tidal wave" may be just minor semantics squabbles, but customary use of proper terminology can certainly minimize unnecessary confusions in the long run. That's why we prefer to use the term "freaque wave" for the sudden onset of an unexplainable, unusually large wave come out of nowhere in the open ocean instead of a host of the currently available terms: rogue wave, freak wave, giant wave, monster wave, sleeper wave, sneaker wave, killer wave, or even mad-dog wave, and others.

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