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Thanks a lot Norman!!

I am going to follow that post!

Dear all,

I am wondering if you could give me some insights in how you produced image gallery figures, in which the ocean dynamics are highlighted (e.g. Submesoscale variability in and around the Bay of Biscay). 

Your images are really cool and it will be great to able of producing similar ones for presentations, but focused in some specific areas (Pacific off Mexico and Central American coast).

Thank you for all! :wink:
Topic Questions about Zeu Lee By amaru Date 2018-07-04 23:53
Dear all,

I have some questions about Zeu from Lee et al. algorithm.
    ** Could you suggest me resources to read about evaluation products? For example, When a product is considered standard or in evaluation? What this implies?
    ** Are there a description of the sources of uncertainties and bias of this algorithm output? Could be related to IOP determination?  

Kind regards,

Topic Reprojection L2 and plot with GMT By tmarquez Date 2015-11-30 18:42
Dear George,

Thank you so much for sharing your knowledge!
I am learning a lot with this forum!!!

Best regards,

Topic Reprojection L2 and plot with GMT By tmarquez Date 2015-11-30 10:43
Dear George,

Thanks a lot!
I made trials with the most recent version of snap (V2.0 Beta 5) and that's solved my problem.


Topic Reprojection L2 and plot with GMT By tmarquez Date 2015-11-27 15:12
Dear George, thank you very much for answer to my question.

In the gmt lists I found some similar problems and because of that I tried with the command grd2xyz.
Also, in some messages pointed out that similar grids are projected and they could be read in GMT with some work.
I tried with the gdal import tools of gmt, but I can not read the file.

The grdinfo output is:
grdinfo: Error: grid x increment <= 0.0
grdinfo: Error: grid y increment <= 0.0
grdinfo (GMT_read_grd_info): Pixel format grids do not have repeating rows or columns [] Title: Command: Remark: Gridline node registration used [Geographic grid] Grid file format: nf = GMT netCDF format (32-bit float), COARDS, CF-1.5 x_min: 0 x_max: 0 x_inc: 0 name: longitude [degrees_east] nx: 0 y_min: 0 y_max: 0 y_inc: 0 name: latitude [degrees_north] ny: 0 z_min: NaN z_max: NaN name: Aerosol optical thickness at 869 nm scale_factor: 1 add_offset: 0 format: classic

And for gdalinfo:
Driver: netCDF/Network Common Data Format
Size is 512, 512
Coordinate System is `'
  NC_GLOBAL#start_date=28-OCT-2015 20:57:10.500000
  NC_GLOBAL#stop_date=28-OCT-2015 20:57:10.500000
  SUBDATASET_1_DESC=[1471x1610] aot_869 (32-bit floating-point)
  SUBDATASET_2_DESC=[1471x1610] angstrom (32-bit floating-point)
  SUBDATASET_3_DESC=[1471x1610] Rrs_412 (32-bit floating-point)
  SUBDATASET_4_DESC=[1471x1610] Rrs_443 (32-bit floating-point)
  SUBDATASET_5_DESC=[1471x1610] Rrs_469 (32-bit floating-point)
  SUBDATASET_6_DESC=[1471x1610] Rrs_488 (32-bit floating-point)
  SUBDATASET_7_DESC=[1471x1610] Rrs_531 (32-bit floating-point)
  SUBDATASET_8_DESC=[1471x1610] Rrs_547 (32-bit floating-point)
  SUBDATASET_9_DESC=[1471x1610] Rrs_555 (32-bit floating-point)
  SUBDATASET_10_DESC=[1471x1610] Rrs_645 (32-bit floating-point)
  SUBDATASET_11_DESC=[1471x1610] Rrs_667 (32-bit floating-point)
  SUBDATASET_12_DESC=[1471x1610] Rrs_678 (32-bit floating-point)
  SUBDATASET_13_DESC=[1471x1610] chlor_a (32-bit floating-point)
  SUBDATASET_14_DESC=[1471x1610] chl_ocx (32-bit floating-point)
  SUBDATASET_15_DESC=[1471x1610] Kd_490 (32-bit floating-point)
  SUBDATASET_16_DESC=[1471x1610] pic (32-bit floating-point)
  SUBDATASET_17_DESC=[1471x1610] poc (32-bit floating-point)
  SUBDATASET_18_DESC=[1471x1610] ipar (32-bit floating-point)
  SUBDATASET_19_DESC=[1471x1610] nflh (32-bit floating-point)
  SUBDATASET_20_DESC=[1471x1610] par (32-bit floating-point)
  SUBDATASET_21_DESC=[1471x1610] l2_flags (32-bit integer)
  SUBDATASET_22_DESC=[1471x1610] longitude (32-bit floating-point)
  SUBDATASET_23_DESC=[1471x1610] latitude (32-bit floating-point)
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0,  512.0)
Upper Right (  512.0,    0.0)
Lower Right (  512.0,  512.0)
Center      (  256.0,  256.0)

With panoply I got the error message:

                        Data error
There was an error preparing the data:
lon axis include NaN values(s).

It wasn't possible to my produce a plot. Therefore, I tried to export the lon-lat (1D) and longitude and latitude (2D) arrays, and I noted that there are only NaN values.
Because of that, I think this issue could be related to the output of the reprojection tool, but also I could be missing something important.

To reproject the data I used as geodetic datum, the World Geodetic System 1984, the geographic projection Lat/Lon(WGS 84) and the nearest neighbour resampling method.
The original file used as input was obtained from the NRT subscription.

I downloaded the file, from [url=][/url]

My aim is to plot reprojected l2 files and add the positions of sampling stations.

If you could give me some advice, I will be really grateful

Kind regards,

Topic Reprojection L2 and plot with GMT By tmarquez Date 2015-11-27 01:20
Hello all,

I am trying to plot reprojected L2 files in Generic Mapping Tools (5.1.0) running on Fedora 22

I followed these steps:

I first used the reprojection tool of seadas 7.2.
After that, I exported the file in netcdf-CF using raster export.
Finally, I was trying to plot the .nc files in GMT using the above commands into a shell script:


gmt grdimage $IN_FILE -Ccolor.cpt $PROJ $REG -Q -K > $PS_FILE

but I got this errors:

Grid x increment <= 0.0 []

I think could be a problem with the format.

I tried with some other ways like:
grd2xyz > x.dat

and these were the printed messages in my console:

grd2xyz: Error: grid x increment <= 0.0
grd2xyz: Error: grid y increment <= 0.0

grd2xyz (GMT_read_grd_info): Please select compatible -R and -I values []
grd2xyz: Warning: No valid values in grid []

Do you know something about this kinds of issues?
Topic Help with L2-L3 By tmarquez Date 2015-11-13 18:14
Dear Sean,

Thank you so much!
I changed the parameters and now all looks fine.
I am really grateful for your answers!!

Kind regards,

Topic Help with L2-L3 By tmarquez Date 2015-11-13 14:54
Dear all,

I am trying to produce daily data of chlorophyll form MODIS-Aqua form individual swaths but, I got unexpected results.
My final results has many no data, like sparse white dots (Sorry, I do not know the terminology)

I ordered and downloaded all L2 files from

At this moment, I am trying to get daily data from these L2 files and I followed this procedures:

1. I used l2bin over individual swaths using the parameters indicated below:

2. After that, I run l3bin in a list files of a particular day. For example all scenes for the calendar day 319 of 2002 (2002319). I used this parameters:

3. Finally, I used l3mapgen to produce my mapped data. The parameters were:
              product= chlor_a 

I do not known what is wrong with this process and I really need help. :confused:
I attach a figure to shown an example of my results and  three L2 files that I used to got it. 
Your help will be really useful for me.
Thanks a lot!
Attachment: A2002319_L3m_DAY_CHL_chlor_a.png - Example of my results. I used this swaths A2002319201000, A2002319201500, A2002319215000 (188k)
Topic Binning L2 files By tmarquez Date 2015-10-01 19:19
Dear Sean,

Thank you very much for your soon reply.

I would like to ask if you or your colleagues can suggest me some mechanism to plot the subsetted files in IDL or Python.

In IDL I tried this:

IMAGE(REVERSE(ALOG10(CHL),2), IMAGE_DIMENSIONS=[18.988789,18.988789], IMAGE_LOCATION=[-119.99479, 14.005208], LIMIT=[14.0, -120.0, 33.0, -101.0], GRID_UNITS=2, MAP_PROJECTION = 'Cylindrical Equal Area')

However, I noted an offset  between the chl coordinates and the coast that I plot using MAPCONTINETS(). I do not know how to correct that. Probably my mechanism is wrong.
I used the following metadata of the smi file:

Northernmost_latitude: 33.0
southernmost_latitude: 14.0
westernmost_longitude: -120.0
easternmost_longitude: -101.0
Number of lines: 1824
Number of columns: 1824
sw_point_latitude: 14.005208
sw_point_longitude: -119.99479

Thanks a lot.

Best regards,

Attachment: test.jpg - offset in the coordinates of SMI files using IDL code (869k)
Topic Binning L2 files By tmarquez Date 2015-09-30 15:37
Hello all,

I am beginning to learn Seadas and I am trying to produce 1Km data of chlorophyll concentration of the Gulf of California (GC) using individual L2 scenes, but I have some questions.

Is it possible to bin all the individual scenes in the same grid? I would like to get daily data of all the GC to make my own analysis.
I tried to use l2bin and after l3mapgen, but the coordinates of the files produced do not coincided at any point.

Also I would like to ask if it is possible to combine different scenes of the same day to get only one.

I really appreciate your help. 


Topic MODIS 250m Data By tmarquez Date 2014-07-04 11:53
I would like to know if the 250m data to determine chlorophyll concentrations are reliable in ocean colour applications. What are the limitations? May you recommend me some literature to learn about it? I am  a begginer and I would appreciate some advices.

Thank you in advance

Topic Difference between MODIS-T and MODIS-A By tmarquez Date 2013-10-18 19:15
Is it possible use the MODIS-T to analyse the chlorophyll concentration with accuracy? or is it a better a idea use the MODIS-A datasets? What is the differences between them?

Thank you in advance!


Topic non-interactive dowload By tmarquez Date 2013-09-14 16:16
Hello, I would like to ask about if it is possible download L2 data products non-interactively and extracting a subset of the data. Can I use wget  to do the same task of the L2 browser but not interactively? I want to extract an specific area.

Thank you in advance. Best regards,

Topic Missing data in SeaWiFS 1998 By tmarquez Date 2013-02-05 21:48

Searching in the SeaWiFS data archive I noted a gap between days 320 and 325 of daily mapped products in 1998. I would like to know why this happens

Topic Problem downloading data By tmarquez Date 2013-01-31 18:42
I am trying to download data of MODISA 2002 using the following command:  wget -q -O - | grep CHL | wget -N -wait=0.5 -random-wait -force-html -i -

But the terminal shows this message: unable to resolve host address `xn--force-html-nu6e'
No URLs found in -
I am using ubuntu quantal 12.10. I appreciate your help

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