"Upon closer"?? What's the meaning?

[keannu]

Can anyone tell me what's the meaning of "upon" in the following sentence?

Even categorizing countries as "developed" or "emerging" is dangerous.
Upon closer analysis, "emerging" countries are not only vastly different from one another, they are also composed of numerous unique individuals and communities.

 

[5jj]

Can anyone tell me what's the meaning of "upon" in the following sentence?

Even categorizing countries as "developed" or "emerging" is dangerous.
Upon closer analysis, "emerging" countries are not only vastly different from one another, they are also composed of numerous unique individuals and communities.

Upon (and on) can convey the meaning of 'when...':

(Up)on arrival at the office, he went straight to reception.'

So, 'upon closer analysis' = 'when you analyse (the situation) more closely'.