Row 4409

Row ID: 4409 | Dataset Entry | Axioma AXP Content Repository

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In most derivations of the Ekman spiral we begin by assuming a steady state in which only frictional (drag) and Coriolis forces are acting- and then we equate them to get the spiral. I have two issues with this:

a) how are Coriolis force and friction ever going to cancel out- are they not perpendicular to each other by definition?

b) how is this a steady state solution if there’s only friction but no energy input? Or rather, the friction term must both input and dissipate energy from the system, but how?

I’m afraid I’ve misunderstood something quite seriously because every textbook I check simply equates friction and Coriolis without addressing the perpendicular thing, so it’s probably not an issue to begin with but I haven’t been able to figure out why not.

Any help would be appreciated! At the top, the derivation of the Ekman spiral from Stewart’s introduction to physical oceanography is pictured, with C and F perpendicular in the force diagram and then equated immediately after.

https://preview.redd.it/8qea54bnbstc1.png?width=1518&format=png&auto=webp&s=09281394ea782e760659084d1fe0b499cdd0bf60

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FieldValue
text In most derivations of the Ekman spiral we begin by assuming a steady state in which only frictional (drag) and Coriolis forces are acting- and then we equate them to get the spiral. I have two issues with this: a) how are Coriolis force and friction ever going to cancel out- are they not perpendicular to each other by definition? b) how is this a steady state solution if there’s only friction but no energy input? Or rather, the friction term must both input and dissipate energy from the syste…
label r/oceanography
dataType post
communityName r/oceanography
datetime 2024-04-11
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Raw Record

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  "text": "In most derivations of the Ekman spiral we begin by assuming a steady state in which only frictional (drag) and Coriolis forces are acting- and then we equate them to get the spiral. I have two issues with this:\n\na) how are Coriolis force and friction ever going to cancel out- are they not perpendicular to each other by definition?\n\nb) how is this a steady state solution if there’s only friction but no energy input? Or rather, the friction term must both input and dissipate energy from the system, but how?\n\nI’m afraid I’ve misunderstood something quite seriously because every textbook I check simply equates friction and Coriolis without addressing the perpendicular thing, so it’s probably not an issue to begin with but I haven’t been able to figure out why not.\n\nAny help would be appreciated! At the top, the derivation of the Ekman spiral from Stewart’s introduction to physical oceanography is pictured, with C and F perpendicular in the force diagram and then equated immediately after.\n\nhttps://preview.redd.it/8qea54bnbstc1.png?width=1518&format=png&auto=webp&s=09281394ea782e760659084d1fe0b499cdd0bf60\n\n​",
  "label": "r/oceanography",
  "dataType": "post",
  "communityName": "r/oceanography",
  "datetime": "2024-04-11",
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