Very Naive Prediction Of Sea Levels Around Maldives

Growing up I had once heard, somewhere by someone, that one day the Maldives will be completely submerged by the sea. I decided today that I should try to see the likelihood of this happening using data available. However, this is only a naive prediction taking very few factors into consideration and should not be interpreted seriously. I hope that you have as much fun reading it as I had writing it!

Getting Sea Level Data

Note: If you feel lost it is recommended that you read the previous post about data before continuing.

We start by looking for a source of data. For this post we are using that of the Physical Oceanography Distributed Archive Center. More specifically the data and the user handbook can be found in the links below.

Data: ftp://podaac-ftp.jpl.nasa.gov/allData/ostm/preview/L2/GPS-OGDR/
User Handbook: ftp://podaac-ftp.jpl.nasa.gov/allData/ostm/preview/L2/GPS-OGDR/docs/userhandbook.pdf

Understanding Sea Level Data

Using Panoply to visualize the data we see the following.

Notice that we have latitude, longitude and sea surface height. Latitude and Longitude can be used to monitor the sea levels around Maldives specifically. But the description of sea surface height had left me perplexed about what the reference ellipsoid was. Thankfully, reading through the documentation we can then find out the following:

Now that everything is clear and simple, we can start by processing some sample data(not all, blaming my internet connection) from 2009 to 2015.

Using Sea Level Data

First thing we do is to identify a useful filter variable for our data, the surface type which we would conveniently set to Ocean.
Then, we find the latitude and longitude bounds of Maldives, approximately 74.4E 7.5S to 72.0E 1.3S.

Going through the documentation and after analysing the sea surface height of this area we come to realise that the values are negative. This is likely due to the fact the reference ellipsoid is an approximation and that it is above ocean surface(in this area), making the range bigger than the altitude, hence giving the sea surface height a negative value. However, we should still be able to use the negative values to get an idea of the change in sea surface height. Taking only September values of years 2015 to 2009 we get the following data(again limited by my internet connection):
 

year	ssh(m)	change(m)
2015	-22.21	0.029
2014	-22.239	-0.021
2013	-22.218	-0.003
2012	-22.215	0.006
2011	-22.221	0.023
2010	-22.244	-0.004
2009	-22.24

and

SSH(y-axis)

Change in SSH(y-axis)

these weird line graphs, but it is somewhat consistent with the overall rate of change of sea level which is 3.22mm per year. 2009 to 2015 with a rate change of 3.22mm would give a rise of 19.32mm, here we have an average change of 5mm. I must definitely be doing something wrong but also may be that is only true for the area around Maldives.

Moving forward anyway, Maldives hasan average ground level elevation of 1.5 metres (4 ft 11 in) above sea level, taken from Wikipedia this time. But more interestingly as depicted by the following article is that Maldives will lose 77% of it's land with 50 cm of sea level rise.

Here 50cm sea rise will be 500/5 will be 100 years, which is not that much, and a number scarily matching that of the article's!

Final words

After trying to predict sea level and failing at it, I ended with a new found respect for people who study oceanography. It is definitely more complex than what it looks like.