## Search found 10 matches

Wed Nov 02, 2022 10:24 am America/New_York
Forum: Home
Replies: 6

### Re: SeaDAS atmospheric correction algorithms

Hi Matt,

You are right, aer_opt=1 chooses r30f95v01, aer_opt=2 chooses r30f80v01......

alpha listed in the products tab means polarization rotation angle. angstrom in the tab means angstrom exponent.
I don't know if there is a good reference for those aerosols models.

Good luck,
Minwei
Thu Mar 31, 2022 5:37 pm America/New_York
Forum: Home
Question: how to generate the look-up-table of rayleigh and aerosol？
Replies: 1

### Re: how to generate the look-up-table of rayleigh and aerosol？

Hi,

These LUTs are generated through running radiative transfer model under different atmosphere conditions and different sun and observation geometries. You can refer to this paper for detailed procedure to generate LUTs: https://ieeexplore.ieee.org/document/7120080.

Best,
Minwei
Tue May 25, 2021 11:20 am America/New_York
Forum: Home
Question: confusion to the transmittances in calculating rhos using SeaDAS
Replies: 2

### Re: confusion to the transmittances in calculating rhos using SeaDAS

Hi Zhigang,

Aerosol transmittance is not included in t_sen and t_sol when calculating rhos.

Minwei
Fri May 14, 2021 10:47 am America/New_York
Forum: Home
Question: the confuse about phase function of aerosol model
Replies: 4

### Re: the confuse about phase function of aerosol model

You need to transform these big values in the LUTs to log(). These log transformed values are then used for the interpolation. The interpolated value is then transformed back using exp().
Minwei
Thu May 13, 2021 11:14 am America/New_York
Forum: Home
Question: the confuse about phase function of aerosol model
Replies: 4

### Re: the confuse about phase function of aerosol model

(1) Splint () returns the phase function interpolated from LUTs using the scattering angle (scatt1[ig]). (2) The reason for the exponential function is that before the interpolation, the phase function in the LUTs is transformed to log(phase). So after interpolation, the phase function need to be tr...
Tue Jan 19, 2021 10:26 am America/New_York
Forum: Home
Question: Difference between Rhos and Rrc ?
Replies: 5

### Difference between Rhos and Rrc ?

sorry for the confusion. It is ( pi * ((Lt / (tg_sen * tg_sen)) - Lr)) / ( F0 * mu0 * tsol * tsen ).  The / t_o2 / t_h2o is not removed. I don't know the reason for the division of t_o2 and t_h2o but it seems t_o2 only affects band at 765 nm and t_h2o affects sensor SeaWIFS. For the majorit...
Wed Jan 13, 2021 9:52 am America/New_York
Forum: Home
Question: Difference between Rhos and Rrc ?
Replies: 5

### Difference between Rhos and Rrc ?

Hello,
rhos in SeaDAS is calculated from:  pi / F0 / mu0* (Lt/tg_sen/tg_sol - Lr)/tsol/tsen.
I don't think there is a Rrc product from SeaDAS. For FAI, Rrc= pi / F0 / mu0* (Lt/tg_sen/tg_sol - Lr).

Minwei
Thu Oct 01, 2020 10:37 am America/New_York
Forum: Home
Question: Processing speed for L2 rhos product
Replies: 2

### Processing speed for L2 rhos product

you can set atmocor=0 to disable aerosol calculation.

This post may help.
https://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=57133

Minwei
Thu Aug 20, 2020 1:12 pm America/New_York
Forum: Home
Question: L2gen processing speed
Replies: 8

### L2gen processing speed

Hi Amita,

MODIS 250m data alone doesn't work to derive L2. You may need 1000m and 250 m data to generate L2 with a spatial resolution of 250m.

Best,
Minwei
Tue Aug 18, 2020 10:14 am America/New_York
Forum: Home
Question: L2gen processing speed
Replies: 8

### L2gen processing speed

Hi Jonathan,

You may try setting aer_opt to -99 (AERNULL) in the input .par file. The setting will skip the aerosol calculation, which takes most of the atmospheric correction time.  Please let me know if it works.

Best,
Minwei