OMI L2 NO2 validity flag

HARP
,
1

Greetings Sander,

I have a question regarding the ingestion definition of the OMI L2 OMNO2 product.

According to the manufacturer, README.OMNO2.pdf (nasa.gov), page 21:

We provide a summary quality flag–a single bit that may be interrogated
to select data. This is the least-significant bit of the field VcdQualityFlags
(See Section 4.3). We strongly recommend that users select only data
for which the least-significant bit of VcdQualityFlags is zero, indicating
good data. This may be done using a bitwise logical and operation on
VcdQualityFlags and the integer ‘1’. For example, in fortran,
goodData = ( IAND( VcdQualityFlags , 1 ) .EQ. 0 )

This VcdQualityFlags is ingested as validity by harp.

Is the operation validity==0 the appropriate one? or am I kicking out valid measurements by over-filtering?

Many thanks,
MariLiza

2

HARP supports bitfield operations for this exact use case. See the documentation. In this case you would use validity !& 1

3

Many thanks, I am by no means expert in bitfield operations!