Earthdata Forum

Hi,

I am new to python and I am struggling to read HICO L1 .nc files properly. Im using python3 on Linux.

For some reason I cannot read solar_azimuth and sensor_azimuth data in python, but if I try with seadas it is ok. So the data is there.

Here are the comand lines I use:

#----------------------------------
from netCDF4 import Dataset
nc = Dataset('H2014045025457.L1B_ISS.nc','r')
sza = nc.groups['navigation']['solar_zenith'][1,1]
vza = nc.groups['navigation']['sensor_zenith'][1,1]
saa = nc.groups['navigation']['solar_azimuth'][1,1]
vaa = nc.groups['navigation']['sensor_azimuth'][1,1]
print(sza)
print(vza)
print(saa)
print(vaa)
#----------------------------------

And the output I get is:
58.751854
18.975159
--
--

Can anyone help? Thanks,
Mariana

Mariana,

My suspicion is that the L1 file is lying to you.  Well,not you specifically :wink:
The valid_min/max attributes for the azimuth angles listed in the file are -180 to 180 degrees, but the values in the array seem to be 0 to 360.
If the python reader is honoring the valid_min/max attributes, then it will treat the values above 180 as not valid. 

...we may need to regenerate the files to correct this...:cry:

Sean

Sean,

it seams to be related to python/modules/linux version I am using. Today I am working with another computer and works.

But another question now. I looked at the X and Y values for a specific coordinate in both L1 and L2 .nc files and they report different values. Same lat/lon, different X/Y.

Were the L2.nc files not generated from the L1 files that are available to download?

Best,
Mariana

In SeaDAS or python? 
SeaDAS may flip the L2 array so north is at the top - but might not get it right for the L1.

Sean

SeaDAS,

I wanted to extract Ltoa and Rrs spectra for a specific sites (AERONET).

So if I use the lat/lon info I will be fine right?

Cheers,
Mariana

Yes.  The geolocation is correct (well, consistent anyway) in both.
Sean