NASAMergedTb.jl

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Downloading and Reading NASA Precipitation Datasets ​

In this page we show how you can download data for a given NASAMergedTb dataset.

Setup ​

@example
using NASAPrecipitation
using CairoMakie
using DelimitedFiles

download("https://raw.githubusercontent.com/natgeo-wong/GeoPlottingData/main/coastline_resl.txt","coast.cst")
coast = readdlm("coast.cst",comments=true)
clon  = coast[:,1]
clat  = coast[:,2]
nothing

Required dependencies ​

Since we are downloading from NASA's EOSDIS OPeNDAP servers, you are required to perform the following:

  1. You need to register an account with Earthdata and allow access to the NASA EOSDISC on it.

  2. Create a .netrc file with the following information: machine urs.earthdata.nasa.gov login <your login> password <your password>

  3. Create a .dodsrc file with the following lines: (1) HTTP.COOKIEJAR=/<home directory>/.urs_cookies and (2) HTTP.NETRC=/<home directory>/.netrc

If this sounds complicated however, fear not! You need only perform the first step yourself (i.e. create your own account), for NASAPrecipitation.jl will automatically set up the .dodsrc file (if you don't already have one), and once you have your <login> and <password>, you can use the function setup() to set up your .netrc file.

setup(
    login = <username>
    password = <password>
)

Downloading NASAPrecipitationDatasets ​

Downloading NASA Precipitation data is as simple as

julia
npd = NASAPrecipitationDataset(args...)
geo = GeoRegion(args...)
download(npd,geo)

Let us download the IMERGMonthly Dataset for 2020 over the Caribbean (as defined by the AR6 IPCC), for example

@example
npd = IMERGMonthly(start=Date(2020),stop=Date(2020))
geo = GeoRegion("AR6_CAR")
lsd = getLandSea(npd,geo)
download(npd,geo)

Reading data for a downloaded NASAPrecipitationDataset ​

And now that you have downloaded the data, you can use the function read() to call the NCDataset that points towards the downloaded data.

@example
ds = read(npd,geo,Date(2020))

As shown in the printout of the NCDataset, the precipitation data is saved under the field name precipitation, and is in units of kg m**-2 s**-1, or alternatively mm s**-1.

@example
prcp = ds["precipitation"][:,:,:] * 3600
close(ds)

fig = Figure()
_,_,slon,slat = coordGeoRegion(geo)
aspect = (maximum(slon)-minimum(slon))/(maximum(slat)-minimum(slat))

ax = Axis(
    fig[1,1],width=350,height=350/aspect,
    title="February 2020",xlabel="Longitude / º",ylabel="Latitude / º",
    limits=(minimum(slon)-2,maximum(slon)+2,minimum(slat)-2,maximum(slat)+2)
)
contourf!(
    ax,lsd.lon,lsd.lat,prcp[:,:,2],colormap=:Blues,
    levels=range(0,0.5,length=11),extendlow=:auto,extendhigh=:auto
)
lines!(ax,clon,clat,color=:black)
lines!(ax,slon,slat,color=:red,linewidth=5)

ax = Axis(
    fig[1,2],width=350,height=350/aspect,
    title="August 2020",xlabel="Longitude / º",
    limits=(minimum(slon)-2,maximum(slon)+2,minimum(slat)-2,maximum(slat)+2)
)
contourf!(
    ax,lsd.lon,lsd.lat,prcp[:,:,8],colormap=:Blues,
    levels=range(0,0.5,length=11),extendlow=:auto,extendhigh=:auto
)
lines!(ax,clon,clat,color=:black)
lines!(ax,slon,slat,color=:red,linewidth=5)

hideydecorations!(ax, ticks = false,grid=false)

resize_to_layout!(fig)
fig

Where is the data saved to? ​

You can check where the data is saved to for a given dataset, georegion and datetime by using the function npdfnc()

@example
fnc = npdfnc(npd,geo,Date(2020))

API ​

Missing docstring.

Missing docstring for NASAPrecipitation.setup. Check Documenter's build log for details.

Missing docstring.

Missing docstring for NASAPrecipitation.download. Check Documenter's build log for details.

Missing docstring.

Missing docstring for NASAPrecipitation.read. Check Documenter's build log for details.

Missing docstring.

Missing docstring for NASAPrecipitation.npdfnc. Check Documenter's build log for details.