Anyone skilled in OGF geography ?

Posted by Portier on 27 February 2019 in French (Fran├žais)

Hello, there, I map the Free Kingdom of Sudharka (TA097b, in northern Tarephia). Because I took my inspiration mostly from the kingdom of Sarawak, in Borneo, I decided to make it an asian-like country, using what I think to be asian-like names. But I consider changing this location, and turn it either to a northern-Africa-like country, or to a south-american-like one. I would nonetheless ask there if anybody could tell me what this part of the continent is really supposed to look like. I didn't find a lot of geographical information on the wiki, and, tough the latitude and longitude corresponds, if I remember well, to somewhere in southern Asia, OGF geography may differ from Earth's.

I hope someone have information on this subject.

Location: -2,594, 36,488

Comment from Ramasham on 27 February 2019 at 23:42

Howdy from a fellow Tarephian. I own Castine on the west coast ( I'm really interested in climates and what shapes them, and just like you I did a good deal of thinking about my country's climate before I did any serious mapping.

Tarephia has a lot in common with Africa in terms of latitude and location relative to other continents, so that's where I looked for analogs in our world. For Castine, I settled on Senegal as the closest, which is fantastic because it has a huge range of climates for such a small country.

But let's turn to Sudharka. In the tropics, the major driver of climate is rainfall and the major driver of rainfall is latitude. That's because most of the rainfall is derived from the intertropical convergence zone (ITCZ), a globe-circling strip of rain and thunderstorms that forms where the subtropical trade winds from the northern and southern hemispheres come together. The ITCZ oscillates around the equator annually, always moving toward whichever hemisphere is experiencing summer.

Generally, locations within +/- 5-10 degrees of the equator will always be inside the ITCZ, so they'll experience a tropical rainforest climate. That's what's assumed for much of Commonia in the OGF world, I believe. Farther from the equator, rainfall will be seasonal with a summer wet season and very dry conditions for the rest of the year. Those are the tropical savanna or wet-and-dry climates.

But since you're so close to the equator, it would seem like a uniformly wet rainforest climate is what you'd have. That's what almost all east coast locations at that latitude experience. But if we look at cities of similar latitude on the east coast of Africa we have a surprise.

Mombasa (4.0 deg S): unusual savanna climate low-moderate rainfall (107 cm/yr) but no pronounced wet/dry seasons (,

Mogadishu (2.0 deg N): semi-arid climate, 43 cm/yr (

By contrast, in South America Macapa, Brazil (2.2 deg N) receives 254 cm/yr and is within the Amazon rainforest biome.

So why is equatorial East Africa is unusually dry? Two things seem to be at play. First, ocean current and monsoon dynamics make the ocean temperature along the coast cooler than it 'should' be given the latitude, which suppresses evaporation. Since the OGF continents are laid out like those of our world, particularly with an India-like landmass to your northeast, it's a fair bet this would happen along eastern Tarephia as well. On the other hand, the waters in that bay your country faces would be sheltered from this effect, and that bay is probably big enough to generate a decent amount of rainfall on its own.

Second, humid air moving east from the Congo basin in Central Africa runs into the Ethiopian and Kenyan highlands. This sets up a rain shadow effect where the highlands squeeze the moisture from the air. Some highlands in Ethiopia receive a tremendous amount of rain, but since you're on a coastal location this would only matter if you create some sharp topography. Then I think you'd want to consider that highlands would probably catch a lot more rainfall than your lowlands. So is there a big mountain range running down the eastern spine of Tarephia (as in, through TA13, Vodeo, Hleziria)? I have no clue!

TL;DR: For Sudharka, I think you could come up with a reasonable justification for any type of climate in the lowlands from semi-arid through rainforest. Any highlands you create would be wetter, though I think you'd need to have above 2,000 m of elevation gain if you wanted semi-arid lowlands to coexist with lush forested uplands.

Hope that's helpful!

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Comment from Luciano on 28 February 2019 at 00:34

Possibly useful, 'de facto canon'

An OGF eastern hemisphere climate map with real-world parallels

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