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Total Solar Eclipse of 2001 June 21

Weather Prospects for Madagascar

Fred Espenak and Jay Anderson

Adapted from NASA TP 1999-209484 "Total Solar Eclipse of 2001 June 21"

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Madagascar

Exotic Madagascar, lying in the path of the Indian Ocean trade winds, would seem to be poorly served for the eclipse observer, but its mountainous terrain blocks the moisture-laden easterly flow and forms a delightful pocket of clear skies on the southwest coast. Moisture-bearing winds, when forced to rise by topography, cool and become saturated. Clouds form (heavy cloudiness if there is enough moisture) and precipitation becomes steady and widespread. The windward side of an ocean-facing mountain chain usually develops immense rain forests from the steady supply of liquid, though the occurrence of cloud and rain may be moderated by dry and wet seasons.

The counterpart of the moist upslope flow is the descending airflow that comes on the lee side of the peaks. Just as the upward flow becomes cloudy, so the downward becomes dry and sunny. The drying can be very dramatic, as it is in Madagascar, with tropical rain forests being replaced by semi-arid vegetation on the western side of the island. Climatological records and satellite images mark this western coast as the second best eclipse site along the track, bested only by western Zambia and Angola.

Southwest Madagascar near Toliara is known for its spiny forests, cactus-like trees inhabited by exotic birds, and for the Mahafaly, Masikoro and Bara tribes, famous for the design of their tombs. The Sun is only 12 degrees above the horizon at totality and actually sets moments before the eclipse ends at fourth contact. Observers here will be treated to an image of a fiery red orb with a tiny bite taken out, setting over the ocean horizon to the west. Perhaps a green flash will complement the view!

The center of the eclipse comes ashore north of Morombe, into a landscape of dry scrub forest and occasional rivers. The town, small and dusty with a bustling beach waterfront, lies 306 km north of Toliara, one of Madagascar's major cities. The road from Toliara to Morombe is slow and grating, being composed of the broken remains of a formerly paved highway that has aged into a mixture of sandy potholes and abrupt edges. Speeds will be slow—perhaps only 30 km/h or so—and so the trip between the two communities takes the better part of one or two days depending on the mode of transportation. An alternative route runs northward from Toliara along the coast, but this is a convoluted single-lane sand trail which is only passable by four-wheel drive vehicles. A guide is essential. Fortunately Morombe has an airport, and so the most convenient access to the centerline is by air.

The eclipse-seeker's eventual destination is the village of Ambahikily on the south side of the Mangoky River, where the road from Toliara to Morombe reaches its most northerly point, a few kilometers from the centerline. Though maps show a road leading northwest from Ambahikily across the middle of the track, no such route actually exists. Once off the highway there is only a direction to travel, not a route, for the trails are made mostly by bullock carts which travel freely in any direction without the confines of curb or ditch. Travel is easy, though slow, by four-wheel drive vehicles, but frequent stops are needed for directions from one community to another, and the vegetation is seldom open enough to allow a view of such a low altitude eclipse.

The Mangoky River is wide and steep-banked, (and inhabited by crocodiles), and most of the coastal beaches are blocked by inland swamps which harbor a magnificent collection of birds, but which make access nearly impossible. Morombe is likely the only reasonable location from which the eclipse could be viewed as it settles onto the Mozambique Channel, but this site will come with a severe time penalty, being about half-way toward the south limit.

Ambahikily is a bustling village about an hour-and-a-half from Morombe (37 km) with gregarious children who delight in having their pictures taken. Its market straddles the highway, presenting an opportunity to collect essential last-minute supplies for the eclipse. Open spaces are at a premium, but there are a number of sites in and around the village that will lend themselves to a good view of totality. We were unable to find any location that would allow the eclipse to be followed right to the horizon, and so those dedicated to seeing fourth contact will have to remain at the beach in Morombe.

Sunshine records for Toliara promise an average of 9.2 hours per day in June, 86% of the maximum possible, bettered only by the exceptionally dry conditions in Zambia and Angola. Some stations in western Madagascar north of the eclipse track (Maintirano, for instance) promise even more sunshine. This suggests that conditions along the centerline will be even more favorable than the statistics for Toliara would indicate. The fact that the eclipse comes late in June is also an advantage, for July is an even drier month on the island, and the statistics for June probably slightly overestimate the cloudiness that is characteristic of eclipse day.

At Morombe, average precipitation declines from 123 mm in January to 59 mm in March and to 6.8 mm in June. In recent years it has been only slightly variable, with no rain reported for June in 1997 and 9 mm reported in 1996. In 1972 a monthly rainfall of nearly 60 mm was recorded at Toliara, considerably larger than the normal 11 mm. These statistics indicate that the climatological record is a fairly reliable planning tool, though perhaps not so secure as over Zambia and Angola.

The prospects are not as good for the windward side of the island's mountain backbone. Taolagnaro, south of the eclipse track on the Indian coast, receives an average of 122 mm of precipitation in June, and the very muted dry season doesn't arrive until September. Cloudiness is common, with over 15% of observations at eclipse time reporting precipitation. High altitude locations southwest of Ihosy along the main highway will provide a very good view of the eclipse if the day is sunny, but the cloudiness is more of a threat here than along the west coast. The centerline crosses the route about half way between Ranohira and Ihosy, slightly on the leeward side of the mountain peaks, and so there is some help from the terrain in clearing the cloudiness which often lies along the east side. This is not a reliable location, but if forecasts prove promising or luck holds out, the view could be among the best along the entire track.

Satellite imagery for 1998 showed heavy cloud in the region north of Toliara on only 4 days of 37, comparable with the prospects near Lusaka. Southeastern Madagascar near Fort Dauphin, where the track is exposed to the uninterrupted flow of Indian Ocean winds, showed only seven days of heavy cloudiness, though there was often a band of sea breeze cloud inland from the coast. Watchers in this area will find that oceanfront locations are best, away from the sea breeze cloudiness a few kilometers inland.

It is difficult not to be pessimistic when examining the record for the windward side of Madagascar. The percent of possible sunshine has declined to 66% at Fort Dauphin and the frequency of broken or greater cloudiness is nearly 50%. This high frequency of broken cloudiness is further aggravated by the low sun angle, less than 10°, which further increases the chances of the eclipse view being blocked. With only a day needed to reach the much more suitable conditions in western Madagascar, it is likely that the southeast will not appeal to many travelers.

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Adapted from NASA TP 1999-209484 "Total Solar Eclipse of 2001 June 21". Permission is freely granted to reproduce this information and data when accompanied by an acknowledgment of the source:

"From Total Solar Eclipse of 2001 June 21 by Fred Espenak and Jay Anderson, NASA"

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Last revised: 1999 Dec 09 - F. Espenak