custom sensor altitude

[Slava Kerner]

Hello Robin,

trying to set custom sensor altitude, as in:

s.altitudes.set_sensor_custom_altitude(alt, aot=aot, water=water, ozone=ozone)

this works for alt=99.9999, failing at alt=100km, with the error: 
"At line 1270 of file main.f (unit = 5, file = 'stdin')\nFortran runtime error: Bad integer for item 1 in list input\n"

i imagine it's a hardcoded limitation in 6s fortran code, so not much Py6S can do..

so the questions:

1) any way to bypass it?

2) providing alt=99km, rather than 700-800km typical for landsat/sentinel/.. - would you estimate the error be significant?

is alt. only used to estimate pressure, or it enters additional computations?

Thanks,

Slava

[Sam Murphy]

Hi Slava,

There shouldn't be a difference between a sensor at 100 or 700 km. The 6S code models the entire atmosphere as being 8 km in height (which is reasonable as this is where almost everything happens). Anything above this altitude is counted as being in space (i.e. the sensor would be a 'satellite'). As such, the following answers might be reasonable.

1) s.altitudes.set_sensor_satellite_level()

2) there will be no difference because it is beyond the model altitude of the atmosphere used by 6S

Hope that (is correct) and helps,

Sam

[Robin Wilson]

Hi,

Thanks for responding Sam.

6S does actually model the atmosphere as being more than 8km in height (for example, the temperature and ozone profiles used go up to 100km, as shown in the graph on p98 of the 6S manual). However, Sam's suggestions as to what to do are quite correct: anything above 100km should be set to satellite level, and there is no difference between the different satellite levels (700km, 800km etc).

Cheers,

Robin

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[Slava Kerner]

Thank you Sam, Robin!

[rone...@gmail.com]

Hi

I'm a newbie with all this, and this conversation already answered my question - so - thanks!!

- 6S is modelling atmospheric effects at Altitudes <100km; understood.

- Nevertheless "radiance at satellite level" must start vanishing at some altitude.

- I'm even quite sure that the default sat level of 1000km is already significant enough, relative to Earth radius.

What do you think? am I missing a point here?

...and, Robin, let me congratulate you for this great piece of software!

Many thanks in advance

Ronen.