Notas sobre Frequência de Ciclones no Sudeste de África (Canal História e Royal Meteorological Society)

big waves under cloudy sky

History Chanel:

The deadliest natural disaster in American history remains the 1900 hurricane in the island city of Galveston, Texas. On September 8, a category four hurricane descended on the town, destroying more than 3,600 buildings with winds surpassing 135 miles per hour.

Estimates of the death toll range from 6,000 to 12,000, according to the National Oceanic and Atmospheric Association. Tragically, the magnitude of the disaster could’ve been lessened if the U.S. Weather Bureau hadn’t implemented such poor communication policies.

1780 was among the worst years in history for North Atlantic hurricanes. The season kicked off in mid-June, when a squall formed in the Caribbean and tore across St. Lucia and Puerto Rico. In August, two more storms struck the Caribbean islands and New Orleans, killing dozens of people and wrecking all the ships moored in the mouth of the Mississippi River. The month of September was relatively quiet, but October 3 brought the infamous Savanna-la-Mar hurricane, which drowned the coast of Jamaica in a deadly storm surge. “The sky on a sudden became very much overcast, and an uncommon elevation of the sea immediately followed,” British Colonel John Dalling later wrote. “Whilst the unhappy settlers…were observing this extraordinary phenomenon, the sea broke suddenly in upon the town, and on its retreat swept everything away with it, so as not to leave the smallest vestige of Man, Beast or House behind.”

A hurricane strikes the east coast of Florida, sinking 10 Spanish treasure ships and killing nearly 1,000 people, on this day in 1715. All of the gold and silver onboard at the time would not be recovered until 250 years later.

From 1701, Spain sent fleets of ships to the Western Hemisphere to bring back natural resources, including gold and silver. These groups of ships were heavily fortified against pirates, but there was little that could be done to protect them from bad weather.

On July 24, 10 Spanish ships and one French ship left Havana, Cuba, on their way to Europe, carrying tons of gold and silver coins, about 14 million pesos worth. The Spanish ships stayed very close to the Florida coast, as was the custom, while the French ship, the Grifon, ventured further out from the shore. A week later, as the ships were between Cape Canaveral and Fort Pierce, in modern-day Florida, the winds picked up dramatically.

The hurricane advanced quickly and, one by one, the ships were wrecked. The Nuestra Senora de la Regla sank, sending 200 people and 120 tons of coins to a watery grave. The Santa Cristo de San Ramon went down with 120 sailors aboard. In all, somewhere between 700 and 1,000 people lost their lives in the wrecks. Meanwhile, the Grifon was able to ride out the storm; most of its crew survived.







107 dead, Memba fishing port in ruins




204 dead, 1.5 million homeless, $240 million damage




11 dead




150 dead from storm, total 1000 casualties from flooding, 300 000 displaced, 4 ships sunk




100 deaths, 250 000 displaced, severe flooding




47 deaths, 19 deaths from flooding, 22 000 displaced, several days power outage in Nampula, $3.5 million in damage




17 dead, 23 000 homeless, 237 000 ha cropland destroyed, livestock losses




10 dead, 100 injured, 33 000 homeless, $71 million in damage




16 dead, 55 000 homeless, 75% of power lines in Nampula destroyed




15 dead from ship sinking, 56 000 homeless, 70 000 with no access to clean drinking water

3.2. The long‐term NOAA dataset

We compare three broadly defined periods (Figure 1) for recording cyclone landfalls over the south‐west Indian Ocean: 1850–1899 based primarily on ship logs; 1900–1943 based on ship logs, land‐based records and early air‐based observations; and 1944–2011 based primarily on aircraft reconnaissance and satellite imagery (Landsea, 2007). The mean number of recorded tropical cyclones which made landfall over Madagascar and Mozambique from 1850 to 1899 is 0.5 (σ = 0.7) and 0.1 (σ = 0.7) per annum respectively. Whilst the number of recordedcyclones increases substantially over this period for Madagascar (by 0.01/annum; r = 0.27, p = 0.06), the recorded frequency for Mozambique decreases (by 0.003/annum; p = 0.05, p = 0.73) (Figure 1(A and B)). Both the inter‐annual variability and increasing numbers of cyclones recorded for Madagascar between 1850 and 1899 are a likely product of changing shipping trends. A better indication of absolute numbers of tropical cyclone landfalls for this period would thus depend on more widespread historical documentary evidence.

Time‐trends through the mean five year cyclone count from the NOAA records for (A) Mozambique and (B) Madagascar for the periods 1850–1899, 1900–1943 and 1944–2011.

The number of recorded tropical cyclones making landfall from 1900 to 1943 averages 2.4 (σ = 1.41) and 0.32 (σ = 0) per annum for Madagascar and Mozambique respectively, with increases for both Madagascar (0.06/annum, r = 0.49, p = 0.0007) and Mozambique (0.004/annum, r = 0.13, p = 0.42) (Figure 1(A and B)). A pronounced increase in records is identified for Madagascar from 1925 onwards, with a mean of 3.5 (σ = 0.7) per annum for the period 1925–1943, and is likely due to the increased recording capacity of aerial reconnaissance.

The data from NOAA indicate negligible change in the average number of cyclones making landfall over Madagascar (3.1/annum, σ = 1) and Mozambique (1.1/annum σ = 0.5) during the last 68 years (Figure 1(A and B)). For both Madagascar and Mozambique, the NOAA record shows a decrease in the number of tropical cyclone landfalls during this period, by −0.01/annum (r = 0.11, p = 0.38) and −0.004/annum (r = 0.07, p = 0.60) respectively (Figure 1A, B); this is consistent with an earlier finding, suggesting reduced tropical cyclone formation over the region (Mavume et  al., 2009). However, as for the 1925–1943 period, a significantly larger number of cyclones have made landfall over Madagascar than Mozambique (∼300% difference).