How to access Copernicus ocean colour data

hello and welcome to you met search my name is Mark Higgins in this series of videos we're going to be walking through how you can discover download manipulate and visualize some of the amazing copernicus sentinel 3 data in the following videos we're going to introduce you to some of the you met SAP product experts they're going to walk you through how you use some of the free and open tools like Bratz snap and QGIS to really get under the skin of these data to manipulate it and visualize it we really hope that you will enjoy and use this data in your work or your curiosity about the earth and marine environment hello my name is Hayley was King and welcome to you met set I'm here today in front of the Copernicus Sentinel 3 Mission Control Center where data is coming down from this satellite and being received right in the room behind me today we're gonna have a look at some of that data we're going to look at the ocean color data that comes from the ocean land color instrument Ulchi aboard Sentinel 3 the first thing we're going to do is look at the Copernicus online data access portal or coder as it's known and we're going to download some ocean color data from the algae sensor so first thing I'm going to do is navigate to my area of interest using this so I'm interested in this area down here so I'm going to draw a box around the region that I'm interested in like that then I'm going to go up to the search criteria here and start looking for some data first thing I'm going to look at is the level 1 data and I'm going to select a time period y know something interesting was going on in the water I'm going to look at the end of September 2017 I'm going to select the product type from this box here the first thing I'm going to look at is the ulti level 1 full resolution data you can see that's full resolution by the fr here and the 1 indicates level 1 you select that then I'm going to select the non time critical data this is the data that has the most up-to-date meteorological parameters included in the processing so if you don't need it straight away this is the data you should probably go for we're looking at data from the ulti instrument and the product level is level one as I said before and here you can see that Cota has found us some swaths to have a look at some images that we can occur and you can see here in the Quick Looks that some of them have more or less cloud so let's have a look at one of those quick looks in detail this one you can see that the area around the coastline here of Southern Africa is quite clear so this might be quite a nice image for us to download and have a further look at so I'm interested in the level 1 data but I'm actually really interested in looking at the biomass that is in the water so this is the chlorophyll product you may have heard about chlorophyll as an ocean parameter so I'm going to go back and I'm going to look for the level 2 product which is where the chlorophyll is so I swap over here to the level 2 fr product I want to click search again I can see there that but data that I was previously interested has come up again here it's this file here it's worth taking a note sometimes of the actual exact date and the time of the acquisition that you'll see here if you want to make sure that you're definitely getting the same data at level 1 or level 2 or even if you're looking between different sensors such as the alt C sensor here or the SL STR sensor which you'll hear more about in further videos you can download the data by clicking here to look at the altie data we're going to open a piece of software called snap and we're going to then use that to display some of the data and look at some of the different quality flags and different indicators about the data so first thing to do is the open snap and this is what snap looks like and you can see here you've got some different options different menus different windows over here you've got the product Explorer window and this is a key one to know about because this is where most your data is going to come up and you'll be able to see what is within the data files you've then got other windows here such as pixel information which will tell you about individual pixels within that image that you're looking at and you've got other ones down here such as navigation you help you move around the image kind of manipulation to change the color schemes on different images that you open and create and there's other windows here that you might want to use to look at where your images in the world or some of the uncertainties associated with the data on the right-hand side of the window here you've also got some other interesting and windows that you might want to look at and we'll look at later including the mask manager here so let's open a date a data file to do this you go to file and open product this will navigate you to a directory and then you need to find where you've downloaded your data to so this is the file that I've just downloaded now it's on my desktop of my computer and within this file you'll see within the folder of this file you'll see all these different netcdf files that you know they're netcdf files because of the dot NC extension these include different variables that are within the file but you can actually open all of these together if you scroll down and look for this file here the xfd you manifest XML file if you click on that and click open snap will read the file and load in all different variables that are contained in the ulti file folders you can see in the product Explorer here that the data file is then loaded into snap and you can see here that it's displaying that it's a sentinel 3 alt key level 2 water product so this is the product that has been atmospherically corrected from the level 1 data the influence of the atmosphere on the ocean color signal has been removed so if you open this file by clicking here you can see all the different folders that are within that file a political interest to us which is where the data is actually stored is within the Bands folder and here you can see the different products that are available within the level to alter data you've got the reflectances this is the actual data that makes up the ocean color signal itself you've got errors associated with those and then you've got a whole array of different products here that are then derived from those reflectances including the one that I mentioned previously which is the chlorophyll here so let's have a look at some of the reflectances first you can see here these are the different wave bands associated with all TV's the wavelengths of light that it measures the ocean color at we can look at one of these here this is the for for 2.5 nanometer band if you right-click on this this data file here you can actually see more information about it particularly under the properties will tell you some different things about the data the data type the size of it whether you've got a valid or invalid pixel expression the wavelength as previously mentioned that it's measured at the bandwidth of that wavelength and other things this can be quite useful if you're then going to process this data with some programming languages to display this data you can simply double click on it and an image will pop up like so you can then use snap to zoom in some of these areas using this slider here and you can navigate around using the arrows you can also move the window on the left here in the navigation panel to center the area that you're interested in so here's an area that I'm interested in around the coast of Southern Africa the ology instrument measures the color of the ocean at lots of different wavelengths and you can see that here from the different reflectance bands that are present it's difficult however to look at all of these in this scale when you've got lots of different ones here that you could open you could open a stack of images and flick through them but snap also has other tools so that you can look at what we told the spectrum of the ocean color signal using this this program so if you go then into snap here and click on the optical options you can look at the spectrum view here this brings up this window you may want to minimize it so you can see your image around the side and this little box here is telling you that if you hold your shift key it will rescale the axis on this plot for you as you go across the image so let's have a look at what the ocean color signal looks like around this image here you look at this side for example if I hold down the shift key and I move my cursor across the image you can see from the offshore region here and here we're looking at the spectrum from the blue in the 400 up towards the red in the 800 region of the spectrum and you can see that offshore the water is as we might expect if we've looked at the ocean color with their own eyes it's more blue in the offshore area when you start moving in towards the coast you'll see that that amount of blue light diminishes and we start getting more signal in the green area of the spectrum and the further we get into the coast more interesting things get in here you'll see even things such as peaks in the red around 700 and 600 there you can also start seeing however some problems in the data here you might notice that the axis on this plot has now gone negative so this is where we can start looking at the quality indicator flags to understand where the data is performing well and where it's not and what we might do with it if it's not using the spectrum view we can start to understand how some of the products are derived from ocean color data we looked before at the change from the blue to the green as you move from the inshore offshore and this change in blue to green light ratio is related to the chlorophyll concentration that's in the water and this has been used to derive chlorophyll as a product using an algorithm and we can see the output of that product that algorithm in the products here in anoche if you look under the chlorophyll product on the left here in the pond Explorer you can see that we have several types of chlorophyll there's the chlorophyll and end product which is from a neural network and the chlorophyll OC for any product this comes from a ratio that uses the amount of blue to green light so we can open that product now and have a look at it so you can see that we've got variability in the chlorophyll as I said between the offshore and the onshore areas around the coast of southern Africa here to get a bit but a bit of a better look at this area what we can do is look at the color so if we take this map you can see here the distribution of the colors currently we can use this import color palettes option here to apply a color scheme to it so I'm going to choose this one the MERIS algal color palette and I'm going to automatically distribute the points based on what satyr we have and you can see there you can pick out the patterns now much more easily you can also log ten the distribution here which is commonly used for chlorophyll products looking at the chlorophyll image we have here we can see some patterns we would expect you can see the offshore waters are more blue have less chlorophyll on shore waters have more chlorophyll and a more red in this area here and down here you can see swirls and patterns which you might associate with ocean currents however you can also see some features that you might make you a bit suspect that you might think are not quite right in particular we've got lots of black speckling around this area of the coastline and we've got lots of little speckles around the edges of this area here we can look at some more information about these pixels that are showing these patterns from the pixel information if you look here you'll see that these pixels are NAND out so I'm going to call it you can then also start looking at the flags to understand a bit more about why these data might have this now and fill value in them to do that we're going to open the mask manager on the right-hand side here you can see from the mask manager here that we have lots of indicators of the quality of our data we can look at where we have invalid pixels where we have water where we have land interestingly and importantly where we have cloud so if I turn that one on there you'll see we have lots of cloud in the south of the image here we know it assists in the level one quick looks that we had a look at you can also look at other things such as glint which comes from the way the sensor is set up sometimes and at the edges of the swath in particular you can also look at where the processing between the level 1 and level 2 isn't performing so well you can have a look here at the atmospheric correction failure flag you turn that on you can see where it comes on and off and you can see in particular over here if you need to get more distinction in these flags you can also change the color which can be very helpful so I change that one to red it's a bit easier to see where it's coming on and off you can also look at where the algorithms themselves are not performing so well for the OSI for any algorithm let's make it blue there you can see them we've got lots of problems with that algorithm across these bits of water in the coastal area where we've got those non values the reason we are seeing some flags raised across this image it's because that not all types of atmospheric correction and algorithm for estimating chlorophyll for example are suitable to apply in all different types of waters that exist in our oceans in the coastal ocean for example they are what we call optically complex and this may mean that we have lots of different parameters that are varying in this area we could have lots of chlorophyll at higher levels than we've measured and calibrated our algorithms with we could have aerosols influences from the land we could have sediments that have come out of the onshore rivers and things like that so there are other products that exist and including them within the ultry data that can help address some of these issues you can go back to the chlorophyll folder here on the left in the product Explorer and you can open the chlorophyll in your own network product the neural network has a combined atmosphere and in water model and it's been more designed to work better in coastal ocean scenarios if we zoom in here to the same area we were looking at before we can also apply the same color scheme we looked at before you can see they were getting better coverage in this coastal area where previously the OSI for any algorithm was said to be failing we've still got some problems around the cloud edges here but you can actually mask them out using the cloud mask ambiguous flag that you've got in the mask manager you can use these products that are kept within the algae files to have a look at the water or in your areas of interest however you can also use snap it has a bunch of tools that will allow you to apply your own methods your own rhythms and your own analysis one of these for example is the BAM Maps tool which you can find here under the raster setting in here you could calculate a new chlorophyll algorithm for example if you know that in your water there's a particular relationship that holds between the ocean color signal and the concentration of chlorophyll during this video we've shown you how to search for and download ocean color data from the Ulchi sensor board Sentinel 3 we've also shown you how to open that data within snap to look at the products that are contained within the data files to assess the quality of different chlorophyll products and hopefully we've piqued your interest in using snap as a tool to develop your own methods for estimating parameters such as chlorophyll this has been the episode on ocean color data my name is haley OVAs king keep an eye on the channel for more data episode's coming up soon looking at sea surface temperature another data that's available from the sentinel 3 satellite

Channel: EUMETSAT

Views: 10,554

Keywords: EUMETSAT, Meteorology, Weather, Climate, Europe, Meteosat, Metop, Copernicus, Ocean

Id: V3NAuafvlFM

Length: 14min 18sec (858 seconds)

Published: Wed Nov 01 2017