AQI |
description |
allowed range |
main flags
|
-1 |
no AMF computation wanted
===> only step 'a' mentioned above is performed
|
-- |
0 |
computation of AMF successful |
-- |
initialisation errors
|
1 |
No cloud cover information available
===> no match with FRESCO data found,
or insufficient data available
(this combines with CCI = 4; see below)
|
-- |
2 |
Error in surface height array indexing |
-- |
3 |
Error in surface albedo array indexing |
-- |
error computing geometrical AMF
|
4 |
Solar zenith angle out of range
===> should never occur, as the analysis
limits the pixels to SZA <= 85 deg
|
0. <= solZen < 88. |
5 |
Viewing zenith angle out of range
===> it is unlikely that this will occur
|
abs(viewZen) < 40. |
error computing cloud radiance weight
|
6 |
Error in wavelength |
300. <= wavelNm <= 3000. |
7 |
Error in surface pressure |
200. <= pSfc <= 1500. |
8 |
Error in cloud-top pressure |
10. <= pCld <= 1500. |
9 |
Error in surface albedo |
0. <= aSfc <= 1. |
10 |
Error in cloud albedo |
0. <= aSfc <= 1. |
11 |
Error in mu0 = cos(solZen) |
0. <= mu0 <= 1. |
12 |
Error in mu = cos(abs(viewZen)) |
0. <= mu <= 1. |
13 |
Error in relative azimuth angle |
0. <= dphi <= 180. |
14 |
Error in cloud fraction |
0. <= c <= 1. |
15 |
Error in loop over pressure |
-- |
16 |
Error in radiance weight |
0. <= radWeight <= 1. |
error computing clear-sky and cloudy SO2 AMF
|
17 |
Error in interpolation for clear-sky AMF |
-- |
18 |
Error in interpolation for cloudy AMF |
-- |
Notes:
- Flags 2, 3 and 6 - 16 should in principle not occur; if any of
these does occur, something is wrong in the code.
- Flags 17 and 18 indicate that one of the input parameters
of the look-up tables is out of its allowed range.
- Flags 6 - 18 cannot occur if no AMF computation is
wanted (i.e. if only step 'a' is performed).
|
CCI |
description |
0 |
no cloud cover data
|
1 |
clear sky mode
===> the cloud-top pressure set to 1013.0 hPa, the value used
internally for the sea-level pressure, and the cloud
fraction is set to 0.0
|
2 |
normal FRESCO mode
|
3 |
snow/ice FRESCO mode
===> for the AMF calculation the cloud fraction is set to +1
and the cloud-top pressure is set to the surface pressure;
in the output the cloud fraction is set to -1.0
|
4 |
missing or invalid FRESCO data
===> if the AMF is calculated, this combines with AQI = 1
(see above)
|
With FRESCO v5.1 these flags are adapted to also include sunglint:
in case of sunglint "10" is added to the flag; for example flag
11 means "snow/ice + sunglint". Since we are not using sunglint,
the flag is simply corrected to be 0,..,4.
|
Two adjustments are made to the FRESCO data without any notification or flagging: