How to access Copernicus Altimetry 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 [Music] in the following videos we're going to introduce you to some of the you met Sam 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 welcome to you mats at my name is Bruna Lucas and I'm standing here in front of the Sentinel 3 Mission Control Center where we receive the Copernicus data of Sentinel tree and we command the spacecraft on this video I'm going to show you how to download Sentinel tree altimeter data and how to visualize it with Brad we will start by downloading the data from from coda I will start by selecting the the region of interest for this video we want to to look in this video to some of the hurricanes that we had in the oricon season of 2017 that passed here close to the Caribbean and we would like to see our altimeter was measuring the Hurricanes that passed so we'll be looking into level 2 of shroud and the product type is SR 2 what what as in water so remember this is this is marine data here we have three different timeliness so we are going to choose non time critical so non time critical is the the timeliness where we have the best quality data so all the the the best orbit and the corrections already taken into account into this product and this is made available up to 30 days after the sensing of the data so I will select non time critical one because we want to look at the best possible data I have selected one track that I think it will be interesting for us to look at hurricane Irma and Hosea were just passing by on this track I will now explain you a little bit on on the products that we have for Sentinel 3 altimeter once we don't have a quick look because a strong and the altimeter is not an optical instrument but on the the product details besides the ground track we have here the content of the product per se so we have this manifest this is just an XML file it's text is another it tells you all the file was processed it tells you the processor version and it also lists all the resources that are inside the the the Sentinel 3 product The Sentinel 3 product is this directory and it has no data inside all the data is inside the net CD f's and you have three net CBF's you have the standard the reduced and the enhanced and basically the content is the following we are recording data in our resolution and in lower resolution so the eye resolution you get the measurement every twentieth of a second so 20 Hertz data and the low resolution you will get it into one Earth's so one every second and on the reduce you really just have the low resolution data on the announced you'll have all the I resolution data the low resolution data some very specific flags that are useful for advanced users and you also have the level 1b waveforms we are going to use today the standard that is a middle ground between the two of them where you have the low resolution data and the more useful high resolution data you can download it directly from here just the standard or you can download everything on a zip and that's what we're going to do today so now we are going to visualize the data and we're going to use braat braat is an open source tool box developed by easy and Mike Ness and you can get it for free at altimetry dot info I have just started Brad on my computer and the first thing that you need to do with breadth is to is to create a workspace a work sprays you can consider it like a project it will have all your settings and all the operations that are going to do so and I'll just create one and I'm going to call it code Sentinel 3 workspace and I'll just use the default location for it now that I have created my workspace I will create a data set and the data set is a logical group of products that have a meaning to you on this case I'm going to look at hurricane IRRI and hosea so that's going to be the name of my data set if I wanted to look into Hurricane Ophelia I would create another data set for this for instance and all the operations that we had done on one data set it's easy just to move it to a new data set that's that's all the concept here now that the data set is created we'll just add the the standard measurement file that we have downloaded and I'll add the standard don't add the other ones just the standard Brett is now reading the file you will display here on this main window just the ground track of the data that you have downloaded if you want to see more details about the file you just click on it and here on this pane you'll have a description of the file what is what is on the global attributes of the netcdf and now here you have all the fields that are within the product ok and this is just a standard so don't get lost don't get scared because if you just click on one of them you get in the description you have a comment explaining what it is it will tell you about the units the information is there if you just want to quickly visualize a file all that you need to do is just to move into the operations tab and on the quick pane you already have predefined the the main fields of the product first let's take a look at sea surface height this is measured by the altimeter when is flying is the altimeter is emitting echoes down to the surface and these echoes bounce back by measuring the amount of time it takes for these echoes to return you know the distance so you know the surface height now the problem is that you have the atmosphere in in in between so you have to take into account all the water vapor the ionosphere all of this you have to correct the height for this and all these Corrections are available within the product so if you need to remove some of them it's easy and you have all the information on the product what provides you more information than the surface ID per se is the the variation to the mean so we've been flying altimeter for over 25 years and we have measured these points over and over in time so if you just do a long-term average of 20 years of data of the of the height and when you're flying now in this instant you measure it again and you see that there is a difference of now to what we are done on the average and the amount of difference will tell if something is happening right now where you're measuring or not it can be just a strong current or not so strong current can be an eddy that is a turbulence on the water it can be another Cane that is passing by so on the product we have this and this is called SLA or ssh a so surf sea surface height anomaly and we can take a look at it later on now what the altimeter can also do is to measure wind speed and significant wave height and we measure this because we are not just sending one pulse down or sending many many pulses down and then when they come back up into the satellite we aggregate them into what we call waveform and then depending on the amount of forces that come back and then on the shape of this waveform we can derive other geophysical parameters such as the significant wave height and the wind speed okay so so far you have not seen any any data you just in the ground track here and but no data will now start by visualizing the sea level anomaly and you just select it here and you say that you want to do a map breath will ask you every time if you want to proceed you just say yes here you just see the ground track as it is with the sea level anomaly this color scale is too wide because you are crossing twice and you're crossing to land and this will distort the sea level anomaly values we'll just limited them to something meaningful and in this case we're going to limit them to plus or minus one meter you can do it here we're on the color range don't forget to give an enter otherwise the breath will not take it okay and then we're going to zoom in into the our area of interest that was here and we see these two black dots and okay Brad displays this by default in in a course granny way you can change that later on if you go into the Advanced Settings you can see that things are around zero and then here you have these two very dark dots and that they are where the hurricane was passing by now if we want to look into the significant wave height you can also do it it's the same procedure as before again just say yes this is the area that we're looking at before and you can see that here we are measuring wave heights above 8 meters right on this red spot 8 meters might not seem a lot to you but on the open ocean and we are on the open ocean the average value is between 2 & 3 meters so we are measuring very high wave heights at this point and if we look into the wind speed again the procedure is the same yes and now you have your visualization if you want to play with the color scale as we have done you just click on on data options then you go to the color range if we zoom in into the area of interest we can limit this to 15 for now and we can see that all these red region is we have a wind speed of 15 meters per second and that corresponds to about 50 kilometers per hour and if you just want to step it up now we're looking at 20 meters per second and we can go all the way to to the maximum that is the 28 meters per second here a measure this corresponds to about 100 kilometers per hour of wind speeds just on this average point here so this is quite an eye speed that the altimeter could measure while passing by the path of the hurricane I will stop my demonstration with breath right now but you can do a lot more with breath you can visualize this data into 2d plots 3d plots you can export the data into images KML for Google Earth and into text files one thing that I did not cover was the filtering you can filter the data you can feel it stir it by location or you can also filter it by by dates and of course on your data set you don't you don't need just wave one file you can have a very large amount of files and Brad can cope with it Brad allows you also to communicate with it via an API so you can use Python or MATLAB or C or whatever pleases you to you the tools that Brett as because Brett has a lot of functionalities that we just didn't demonstrate here so this was our altimetry video I hope that you'd find it useful and keep an eye on our YouTube channel where you can find further videos on how to visualize Copernicus data my name is Brenna Lucas and thank you for watching

Channel: EUMETSAT

Views: 5,753

Keywords: EUMETSAT, Meteorology, Weather, Climate, Europe, Copernicus, Sentinel-3, Altimetry

Id: vucr65nIUfI

Length: 12min 56sec (776 seconds)

Published: Tue May 15 2018