Search found 1465 matches

by OB.DAAC - SeanBailey
Tue Jul 02, 2024 6:24 pm America/New_York
Forum: Home
Question: Low/Negative SST values in tropical region
Replies: 1

Re: Low/Negative SST values in tropical region

Check the flags. If the SST seems unreasonably low, it is likely a cloud. The data are not masked at L2, only flagged. When binnng SST, the code selects qual_sst of 2 or greater (keeping the highest quality data for the bin). If the qual_sst is a 3 for the pixels you find low SST, that means it's a ...
by OB.DAAC - SeanBailey
Wed Jun 05, 2024 7:15 am America/New_York
Forum: Home
Question: Questions about the level3 remote sensing reflectance data of MODIS images
Replies: 2

Re: Questions about the level3 remote sensing reflectance data of MODIS images

The Rrs data are stored in the L3 mapped netCDF files as scaled short integers. If your software does not apply the scale_factor and add_offset information (contained in the variable attribtues) to convert the scaled integers into floating point values, you will need to do so after reading the data ...
by OB.DAAC - SeanBailey
Tue Jun 04, 2024 4:20 pm America/New_York
Forum: Home
Question: How can i obtain the MODIS Rayleigh correction reflectance from SeaDAS L2gen?
Replies: 1

Re: How can i obtain the MODIS Rayleigh correction reflectance from SeaDAS L2gen?

The rhos product is Rayleigh and gaseous absorption corrected reflectance. If you want a product that only removes the Rayleigh radiance component, you'll have to output Lt and Lr (and likely the Rayleigh transmittances, t_sen and t_sol) and do the math. The rhos that l2gen ouputs is: rhos = pi / Fo...
by OB.DAAC - SeanBailey
Tue Jun 04, 2024 3:22 pm America/New_York
Forum: Home
Question: MODIS/Aqua-derived PAR data have many plaids
Replies: 3

Re: MODIS/Aqua-derived PAR data have many plaids

It is everywhere, but the color palette "hides" it. Look a the lower portion of your image and you will see the blocky pattern in the western side as well.

Sean
by OB.DAAC - SeanBailey
Mon Jun 03, 2024 10:40 am America/New_York
Forum: Home
Question: MODIS/Aqua-derived PAR data have many plaids
Replies: 3

Re: MODIS/Aqua-derived PAR data have many plaids

The PAR algorithm uses a coarse ancillary data field (9km resolution), and given the different grids of L2 and the L3 ancillary, the result can show as as bit patchwork. As for the magnitude differences, you should verify the inputs match exactly what our production system used.

Regards,
Sean
by OB.DAAC - SeanBailey
Fri May 31, 2024 4:00 pm America/New_York
Forum: Home
Question: CHLOROPHYLL A UNIT
Replies: 3

Re: CHLOROPHYLL A UNIT

Yes, 50-100 is on the high end. What is your region of interest?

Sean
by OB.DAAC - SeanBailey
Fri May 31, 2024 3:56 pm America/New_York
Forum: Home
Question: AQUA-MODIS, SNPP-VIIRS and NOAA20-VIIRS
Replies: 1

Re: AQUA-MODIS, SNPP-VIIRS and NOAA20-VIIRS

Emanuele, We're still evaluating calibration updates for MODIS-Aqua and are hopeful that we can initiate a mini-reprocessing (yes, the issue extends back a couple years) sometime in the next month. I have to check with the team about the VIIRS sensors. I believe it is just waiting on the nod from th...
by OB.DAAC - SeanBailey
Fri May 31, 2024 3:47 pm America/New_York
Forum: Home
Question: Help plotting future PACE orbits
Replies: 2

Re: Help plotting future PACE orbits

There is an overflight prediction tool that can provide the times PACE instruments will view a location on the Earth, but we do not have the reverse (showing where PACE will view the Earth in the future). I will inquire with the Worldview team about adding the ability to plot the PACE orbits into th...
by OB.DAAC - SeanBailey
Fri May 31, 2024 3:29 pm America/New_York
Forum: Home
Question: PACE L2 OCI wavelength bands
Replies: 2

Re: PACE L2 OCI wavelength bands

Correct, the wavelength_3d is in the sensor_band_parameters group. Some background... The sensor_band_parameters group contains informational parameters and has been part of the L2 ocean color metadata since the days of SeaWiFS and includes a wavelength parameter that is the list of wavelengths for ...
by OB.DAAC - SeanBailey
Fri May 31, 2024 2:34 pm America/New_York
Forum: Home
Question: Sunglint calculation
Replies: 6

Re: Sunglint calculation

Looks like the calculation of alpha in getglint.f is unnecessary with the assumptions made. Yes. The code is capable of supporting wind direction, but it is not used to do so. The windspeed is also assumed to be isotropic (because of the lack of wind direction information), so there are indeed some...