Inquiry on CALIPSO L3 V4.2 Upper-Tropospheric AOD Noise Floor and Trend Uncertainty (8–12 km)

[ASDC - micook]

Submitted on behalf of the user.

Dear CALIPSO Science Team,

I hope this message finds you well.
I am a graduate student in Atmospheric Science at Lanzhou University, currently investigating the long-term vertical evolution of global aerosol distributions. My study utilizes the CALIPSO Level 3 (V4.2) monthly tropospheric aerosol products to analyze interannual AOD trends within the upper troposphere (8–12 km).
During the peer review process of my manuscript, a referee raised critical concerns regarding the quality of CALIPSO upper-tropospheric retrievals. Specifically, the reviewer highlighted that:
Accurate discrimination between elevated smoke, dust, and thin cirrus remains challenging in the upper troposphere, leading to potential cloud-aerosol misclassification.
The dataset contains a substantial noise floor that is not fully accounted for in the standard L3 product.
These inherent limitations are suspected to introduce systematic biases—particularly systematic negative biases—that could distort long-term aerosol trend estimations in the 8–12 km layer.
I have thoroughly reviewed the official CALIPSO user guides, product specifications, and relevant published literature. However, I have not found clear documentation addressing the following points:
The formal systematic error ranges and quantitative uncertainty magnitudes for 8–12 km aerosol signals in the L3 V4.2 product.
Official trend evaluation reports that explicitly assess trend biases caused by both the noise floor and cloud–aerosol misclassification.
Publicly available correction strategies or empirical coefficients to mitigate such systematic negative biases in upper-tropospheric trend analysis.
Given the CALIPSO team’s authoritative expertise in instrument calibration, noise floor characterization, and upper-tropospheric aerosol uncertainty evaluation, I sincerely write to seek your professional guidance. Any relevant technical reports, uncertainty assessment results, or practical correction suggestions would greatly help me quantify and refine the reliability of trend estimates in my research.
I apologize for taking up your valuable time, and I would deeply appreciate any feedback or support you could kindly provide.
Thank you very much for your generosity and guidance.

Best regards,

[ASDC - micook]

Hello @yq20221014,

May I suggest using version 5.00 of the Level 3 Tropospheric Aerosol Data. Below is the data description and quality summary for this data where it highlights the most significant changes that were made from version 4.2:
https://asdc.larc.nasa.gov/documents/calipso/quality_summaries/cal_lid_l3_tropoaero_V5-00_desc_qs.pdf

Please let us know if you have any further questions.

Thanks,