HICO radiometric calibration

huhuhu · by **huhuhu** » Tue Dec 15, 2020 10:50 pm America/New_York

Dear colleague:
I was trying to find how HICO Lt is vicariously calibrated during L1B =>L2. There are two files under the SeaDAS folder ocssw/share/hico/cal:
Gao_scaling_factor_Final_1_2012.txt
HICO_10727_scaling_factors.txt

Which one is actually used? Is there a paper to document the calibration?
Thanks, Chuanmin Hu/USF

OB.DAACx - SeanBailey · by **OB.DAACx - SeanBailey** » Wed Dec 16, 2020 8:44 am America/New_York

Chuanmin,

The Gao_scaling_factor_Final_1_2012.txt file is used in processing the HICO L0 data to L1B. The vicarious calibration used by l2gen is in the msl12_defaults.par file and were computed by Amir Ibrahim for his 2018 paper (https://doi.org/10.1016/j.rse.2017.10.041)

Sean

huhuhu · by **huhuhu** » Thu Dec 17, 2020 7:22 am America/New_York

Thanks Sean. Neither calibration appears correct. Furthermore, the Lt output appears smeared over small bright targets but rhos has the original resolution. Who is in charge of coding l2gen for HICO? Amir? I need to talk to him through email then. Cheers, Chuanmin

OB.DAACx - SeanBailey · by **OB.DAACx - SeanBailey** » Thu Dec 17, 2020 8:12 am America/New_York

Oh, HICO is quite a challenging little instrument. You may want to talk with Bo-Cai Gao, Marcos Montes and Jeff Bowles at NRL, as they would be much more familiar with the on-board calibration and the process of getting to L1B.

Sean

huhuhu · by **huhuhu** » Thu Dec 17, 2020 9:25 am America/New_York

Thanks again. In addition to calibration, I am puzzled by the SeaDAS Lt output for HICO - they are smeared for most (but not all) pixels. In contrast, rhos output is not smeared. Then I must assume that SeaDAS output Lt is different from the Lt used to calculate rhos. This doesn't make any logical sense but appears to be the only explanation. Chuanmin