How to classify aerosol in CALIPSO profiles products

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jane997
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How to classify aerosol in CALIPSO profiles products

by jane997 » Sat Nov 12, 2022 1:40 pm America/New_York

I want to calculate mean extinction profile of aerosol subtype by CALIPSO l2 Aprof products ,and this article are referenced ,https://www.google.com.hk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi04az7oan7AhWU7WEKHTo1C94QFnoECBAQAQ&url=https%3A%2F%2Fwww-calipso.larc.nasa.gov%2Fresources%2Fcalipso_users_guide%2Ftools%2Ffiles%2FGenerate_Mean_Extinction_Profile_v3.pdf&usg=AOvVaw1q_5ynojms6XEFJ2n9yrVR
"isAerosol = squeeze(ftype(:,:,1) == 3 | ftype(:,:,2) == 3);" is to get the feature type.

subtype is AVD data(bits 10 - 12), and it can be used to classify aerosol.
However, CALIPSO extinction is two dimensional, but AVD is three dimensional to account for the two 30 m features per 60 m extinction range bin below 20.2 km. When the aerosol types corresponding to two 30 m features are different, which kind of CALIPSO aerosol subtypes does the 60 m extinction layer belong to?
Forexample , to calcaulate dust information:
1. "isDust = squeeze(subtype(:,:,1) == 2 | subtype(:,:,2) == 2);" ?
2. "isDust = squeeze(subtype(:,:,1) == 2 & subtype(:,:,2) == 2);" ?
3. just delet the data of this 60m extinction layer ?

Thanks!
Last edited by jane997 on Mon Nov 14, 2022 11:24 am America/New_York, edited 1 time in total.

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ASDC - cheyenne.e.land
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Re: How to classify aerosol in CALIPSO profiles products

by ASDC - cheyenne.e.land » Mon Nov 14, 2022 10:02 am America/New_York

Hello,

A Subject Matter expert has been notified and will answer your question as soon as possible.

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Re: How to classify aerosol in CALIPSO profiles products

by ASDC - cheyenne.e.land » Fri Dec 09, 2022 10:44 am America/New_York

Hello,

We apologize for the delay, but to answer your question: When the aerosol types corresponding to two 30 m features are different, which kind of CALIPSO aerosol subtypes does the 60 m extinction layer belong to?

The answer is both – given the AVD is at 30 m resolution and the extinction is at 60m resolution.

So for a 60m bin in which the AVD is defined as smoke in the upper 30m and dust in the lower 30m the 60m extinction would contribute equally to each.

For instance, in our level 3 products we have the ability to generate monthly profiles of extinction on a lat/lon grid for each aerosol speciation. As part of the algorithm we take the 60m bin extinction profile and recast to a 30m bin so it can be mapped to the same resn as the AVD, with the upper 30m and lower 30m containing a replication of the entire 60m bin.


How profile descriptive flags are stored:

Ideally, each profile descriptive flag would be an array of the size [# altitude bins, # profiles] with each array element providing a complete description of the range-resolved atmospheric state. However, because the range resolution of the Level 1 profile data below ~8.3-km is 30 m, and because the feature-finder, scene classification, and extinction algorithms all operate at this finer spatial resolution, providing a genuinely complete description of the atmospheric state for each 60 m Level 2 range bin requires that the profile descriptive flags be stored as 3-D arrays of the size [#profiles, # altitude bins, 2]. The first dimension, [ : , : , 1], corresponds to the standard altitude array of the Profile Products. Thus, below 8.3 km, the first dimension contains the descriptive flags of the higher of the two full resolution (30 m) bins that comprise the single 60 m bin reported in the Profile Products. Meanwhile, below 8.3 km, the second dimension [: , : , 2] contains the descriptive flags for the lower of the two 30 m range bins.

Again, apologies for the delay.

Regards,
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