Here below you can find a a selection of the most frequently asked question to GHRSST.

The newest questions are at the very bottom of the page.

Question 1) This is just a brief remark about the quality of the lake data included in the GHRSST datasets. I have identified a large number of issues with the lake data which suggests to me that they are not of science-quality. There are a large number of data artifacts including repeated values, sudden drastic changes, and large outliers. Most of the 300 large lakes that I have investigated have substantial artifacts such as these. I would be happy to provide evidence of these artifacts if you would like. I would suggest masking the lake data from the datasets or do a more robust cross validation against in situ lake observations.

Dear user,

Thank you for the feedback. GHRSST is aware of the issue you are raising, all products include a mask with a specific value for lakes, so users can filter these values out themselves if needed.
There is strong ongoing effort to improve lake surface temperatures, which face several challenges related to spatial resolution, lake size, complex atmospheric correction algorithms over small lakes, etc.
Product user manuals describe such issues and there is always relevant literature, eg https://www.tandfonline.com/doi/full/10.3402/tellusa.v66.21247 and references therein.

Please note you may find relevant posters and presentations on the GHRSST Science Team Meeting Proceedings of past years, e.g. 2016 (https://www.zenodo.org/record/5412437), 2017 (https://www.zenodo.org/record/5163869), 2019 (https://www.zenodo.org/record/5113359) and in the search of the GHRSST webpage (https://www.ghrsst.org/?s=lake+surface+temperature).

Hope this helps.

The GHRSST Project Office

Question 2) I am trying to find and download data that corresponds to sea surface temperature for coordinates (19.9934S,57.5913E) for the period Jan 2017-Jan 2019 on the GHRSST website. Could you please provide some support?

Thank you for your email and for contacting GHRSST. Please have a look at https://www.ghrsst.org/ghrsst-data-services/products/ so you can have a more complete idea of what kind of SST product you want, depending on your application.

You can access and download SST data from Copernicus Marine Service, https://resources.marine.copernicus.eu/products

For example:

https://resources.marine.copernicus.eu/product-detail/SST_GLO_SST_L4_NRT_OBSERVATIONS_010_005/INFORMATION
https://resources.marine.copernicus.eu/product-detail/SST_GLO_SST_L3S_NRT_OBSERVATIONS_010_010/INFORMATION
https://resources.marine.copernicus.eu/product-detail/SST_GLO_SST_L4_REP_OBSERVATIONS_010_011/INFORMATION
https://resources.marine.copernicus.eu/product-detail/SST_GLO_SST_L4_REP_OBSERVATIONS_010_024/INFORMATION

Hope this helps.

The GHRSST Project Office

Question 3) If I wanted to use your data to find sst breaks for fishing, could you tell me which product I should use and how?

You can use SQUAM https://www.star.nesdis.noaa.gov/socd/sst/squam/index.php
and select L4 SST datasets like MUR, OSTIA, etc https://www.star.nesdis.noaa.gov/socd/sst/squam/analysis/l4/?l4sst=MUR&ref=GPB05&aggtime1=daily&var-stats2=MEAN&sstonly=on&c_year=2022&c_month=01&c_day=30#maps

Another source is the following on Ocean Virtual Laboratory (ESA) where you can also select different products under the Temperature Tab, including MUR (as the link above) which is a L4, i.e. gap-free product, which is produced from satellite SST and some post-processing.

If you are interested in the original SST, that will have gaps because of clouds, you can also look at:

And finally, below the temperature tab there is also a salinity tab which may be useful to you as well.
The links form the Ocean Virtual Laboratory (linked above) land to pages which show maps – on the right hand side of these maps there is a +/- icon which typically is used for zoom in/zoom out.
Below this, you will be able to see the date of acquisition for the data. The bottom part of the map is a Year/Month/Day bar where you can select which date you want visualised.

Regarding latency, it depends on the product you want to visualise. The L3 products, i.e. the last 4 links in my previous email, that show gaps, will be available on the same day – so Near Real Time.
The L4 product, i.e. without gaps, is available on the same day as well but it appears with a few days latency in the OVL link at least.
Another, maybe easier option to visualise the L4 MUR product is the PO.DAAC tools.

If you really want to see an SST field and be able to click on the map and read values on your browser, i.e. not downloading the data files and processing them through some software, maybe a better option is the OSTIA

As you may have inferred from the information, there is a vast amount of data – directly from the satellites – and also post-processed through many sources available daily, which is great if you are able/willing to download and process them further your self yet when it comes to visualising datasets on browsers, not all products are available.

This of course is changing and more web-browsing capabilities but we are not there yet.

Hope this helps.

The GHRSST Project Office

Question 4) I met some problem when I use your ghrsst-L4 data, so I write this email for some help. Because the time resolution of  L4 data I download is one day, but actually the satellites attain the data at an instantaneous moment. Now I need know the accurate time of every  pixel in your SST product. In the early time, I search many information but didn’t find a method to satisfy my need. I would appreciate it you can give me a way to acquire shooting time of SST product.

As there is a wide range of L4 SST data available and from different download sources it is very hard for us to provide and further guidance since none of this information is mentioned in your email. In any case, the GHRSST Project Office does not produce or distribute data directly, so you best write to the producers of the dataset you are using.  This can be easily found if you look at the global attributes of one nc file, typically called “creator name” or “creator email”.

Furthermore, GHRSST L4 data typically have a variable called time, i.e. the reference time of sst field. L4 data are Optimally Interpolated using only night-time observations for a certain temporal window, e.g. 22:00-04:00 (or however the producer describes the product) so there is no specific time stamp at each grid point. For that you should investigate using L3 data.

Hope this helps.

The GHRSST Project Office