Calipso Level 2 Aerosol profile night flags

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Calipso Level 2 Aerosol profile night flags

by EarthdataForumContributor » Mon Jan 06, 2020 10:48 am America/New_York

I am working on Calipso Level 2 Aerosol profile datasets. I have downloaded
only night time datasets.
So, will you please tell me from what UTC time night datasets are taken and
up to what UTC time?

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Re: Calipso Level 2 Aerosol profile night flags

by asdc_user_services » Mon Jan 06, 2020 10:56 am America/New_York

On Jan 6, 2020 Brian Getzewich (Calipso Team) responded

CALIPSO is roughly a 90-minute orbit, 45 minutes in day and 45 minutes in night.

For instance, if you look at the browse images below and look at the left most column the map is white for day and brown for night. The orbit tracks in the upper maps also show which orbital segments are day (red) and night (blue).

https://www-calipso.larc.nasa.gov/produ ... 2020-01-01

Determination of the day/night flag is not coupled to time, rather to the solar zenith angle, and drifts as a function of time of year.

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Re: Calipso Level 2 Aerosol profile night flags

by asdc_user_services » Mon Jan 06, 2020 11:15 am America/New_York

On Jan 2, 2020 Brian Getzewich (Calipso Team) responded
Profile time in the Lidar Level 2 Aerosol Profile product is reported in both TAI and UTC format….the definitions are below.

Profile_Time
Time, expressed in International Atomic Time (TAI). Units are in seconds, starting from January 1, 1993. For the 5 km profile products, three values are reported: the time for the first pulse included in the 15 shot average; the time at the temporal midpoint (i.e., at the 8th of 15 consecutive laser shots); and the time for the final pulse.

Profile_UTC
Similar to Profile Time, but for time expressed in Coordinated Universal Time (UTC), and formatted as 'yymmdd.ffffffff', where 'yy' represents the last two digits of year, 'mm' and 'dd' represent month and day, respectively, and 'ffffffff' is the fractional part of the day.

The definitions were taken from the link below.
https://www-calipso.larc.nasa.gov/resou ... ofile_time

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