Patrick,
I followed you suggestion, very useful. I am able to get geo_pos (i.e.
y_pos) but it has only NaNs. "geo_posEndOfPpath" needs as input
"ppath", which I generate from "PpathCalc", which in turn requies
(among the others) "rte_pos", "rte_los" and "rte_pos2".
Here my first doubt. "rte_pos2" should be the result of the
combination of "rte_pos" and "rte_los". Anyway, I set
rte_pos=sensor_pos (satellite position) and rte_los=[180,0] (that
should be nadir looking). I set rte_pos2=[0,0,0] but I am totaly not
sure about "rte_pos2". If you could shed light on this, it would be
very useful for me.
Thanks,
Leo Pio
Leo,
If you want to know the complete path through the atmosphere, you
can do as you outline. If you only are interested in where you end
up at the surface, you can use the geo_pos mechanism. You need to
set geo_pos by adding the WSM: geo_posEndOfPpath
Exactly how geo_pos is handled has been changed, and I don't
remember exactly the status in v2.5.0. But I hope you can figure it
out.
With this done, the "geo pos" comes out from yCalc as y_geo.
Please note that you get out proper lat and lon only if running 3D
calculations. For 1D you bascially get some relative lat and lon.
Bye,
Patrick
On 2023-11-29 10:57, [email protected] wrote:
Hi Richard,
many thanks for your answer. I try to answer to your questions.
I am using ARTS 2.5.0
My entry point is 'yCalc', you are correct. I have some Python
script which call ARTS commands, so I would say that I run ARTS via
custom language interface.
Currently, I am getting and saving 'sensor_pos' and 'sensor_los'
(that match 'y_pos' and 'y_los' but are not the same, right?). But,
if I understand well, you are saying that I can set 'rte_pos2' and
'rte_los' equal to 'y_pos' and 'y_los' and then run 'ppathCalc'.
Best,
Leo Pio
Hi Leo,
What you have encountered can be shortly summarized as rte_pos only
existing inside the Agenda you call. You don't have it at hand anywhere
else. rte_pos also does not represent what you think it does, it is simply
a radiative transfer equation position and it can be anywhere inside or
outside of the atmosphere.
Before any other specific help can be given, you need to specify what
version of ARTS you are using? Are you running ARTS via python or via the
custom language interface? Is your entry point to the calculations via
`yCalc`?
Because those details matter for the answer you might need. Generally, if
you want to investigate the atmospheric path you are using, you will want
to generate a `ppath` and extract the relevant information. The way to do
that depends on the answers above and any attempt to answer this without
first filling in these details will give details that are perhaps not
needed.
If you are running it via `yCalc`, you get `y_pos` and `y_los` as outputs.
Those can be used to generate `rte_pos{,2}` and `rte_los` required for
`ppathCalc` to run. You can then extract the relevant information from the
generated `ppath` either via custom language commands or just by accessing
the data it holds in python. The documentation for accessing data in
ppath for the latest version of ARTS available via conda-forge can be found
here:
https://atmtools.github.io/arts-docs-master/stubs/pyarts.arts.Ppath.html#pyarts.arts.Ppath
//Richard
Den tis 28 nov. 2023 kl 15:51 skrev <[email protected]>:
Dear ARTS community,
I am a new user of ARTS. One of my tasks is to simulate passive
microwave radiometers onboard low Earth orbit satellite. To this end,
I would know which region of Earth surface the satellite is looking
at. I set the satellite position through "sensor_pos" and the line of
sight of the satellite through "sensor_los". When I try to get and
save on a XML file the geographical position for starting radiative
transfer calculation (i.e. rte_pos), I get the following error:
Method WriteXML needs input rte_pos but it is uninitialized.
Can anyone help me on this? Many thanks.
Best regards,
Leo Pio
