Spatialtemporal Smoothing of Data

There are options in NASAPrecipitation.jl to spatialtemporally smooth data.

smoothing(
    <NASAPrecipitation Dataset>,
    <GeoRegion>,
    <smoothing options> ...,
)

It is important to see the documentation and see which options are available for each type of dataset, but we summarize it in the table below:

Setup

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

Spatial Smoothing Example

Let's define a rectangular domain in Southeast Asia and download some NASAPrecipitation data for this region:

npd = IMERGMonthly(start=Date(2015),stop=Date(2015,3))
geo = RectRegion("TMP","GLB","Southeast Asia",[15,-15,125,95],savegeo=false)
download(npd,geo)
lsd = getLandSea(npd,geo)

The Land-Sea Dataset (no Topography) has the following properties:
    Longitude Points    (lon) : Float32[95.05, 95.15, 95.25, 95.35, 95.45, 95.55, 95.65, 95.75, 95.85, 95.95  …  124.05, 124.15, 124.25, 124.35, 124.45, 124.55, 124.65, 124.75, 124.85, 124.95]
    Latitude Points     (lat) : Float32[-14.95, -14.85, -14.75, -14.65, -14.55, -14.45, -14.35, -14.25, -14.15, -14.05  …  14.05, 14.15, 14.25, 14.35, 14.45, 14.55, 14.65, 14.75, 14.85, 14.95]
    Region Size (nlon * nlat) : 300 lon points x 300 lat points

We then proceed to perform a spatial smoothing (1.0º longitude, 0.2º latitude) of the data.

npd_smth = IMERGMonthly(start=Date(2015,2),stop=Date(2015,2))
smoothing(npd_smth,geo,smoothlon=1,smoothlat=0.2)

[ Info: 2024-02-17T00:57:27.353 - NASAPrecipitation.jl - Setting up data structure containing information on IMERG Monthly data to be downloaded
[ Info: 2024-02-17T00:57:28.532 - NASAPrecipitation.jl - Checking to see if the specified GeoRegion "TMP" is within the "IMERG" GeoRegion
[ Info: 2024-02-17T00:57:28.533 - GeoRegions.jl - Retrieving information for the GeoRegion defined by the ID IMERG
[ Info: 2024-02-17T00:57:28.534 - GeoRegions.jl - Performing a check to determine if the Southeast Asia GeoRegion (TMP) is inside the Global IMERG Dataset GeoRegion (IMERG)
[ Info: 2024-02-17T00:57:28.534 - GeoRegions.jl - The GeoRegion TMP (Southeast Asia) is indeed a subset of the GeoRegion IMERG (Global IMERG Dataset)
[ Info: 2024-02-17T00:57:28.536 - NASAPrecipitation.jl - Retrieving the regional IMERG Land-Sea mask for the "TMP" GeoRegion ...
[ Info: 2024-02-17T00:57:28.536 - NASAPrecipitation.jl - Preallocating data arrays for the analysis of data in the Southeast Asia Region ...
[ Info: 2024-02-17T00:57:28.583 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 January ...
[ Info: 2024-02-17T00:57:29.430 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-01-01
[ Info: 2024-02-17T00:57:29.431 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:29.437 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-01-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:29.440 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 February ...
[ Info: 2024-02-17T00:57:30.318 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-02-01
[ Info: 2024-02-17T00:57:30.318 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:30.319 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:30.325 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-02-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:30.328 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 March ...
[ Info: 2024-02-17T00:57:31.179 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-03-01
[ Info: 2024-02-17T00:57:31.179 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:31.180 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:31.186 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-03-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:31.189 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 April ...
[ Info: 2024-02-17T00:57:32.056 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-04-01
[ Info: 2024-02-17T00:57:32.056 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:32.057 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:32.063 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-04-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:32.066 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 May ...
[ Info: 2024-02-17T00:57:32.951 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-05-01
[ Info: 2024-02-17T00:57:32.951 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:32.952 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:32.958 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-05-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:32.961 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 June ...
[ Info: 2024-02-17T00:57:33.812 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-06-01
[ Info: 2024-02-17T00:57:33.812 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:33.813 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:33.819 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-06-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:33.822 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 July ...
[ Info: 2024-02-17T00:57:34.688 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-07-01
[ Info: 2024-02-17T00:57:34.689 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:34.690 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:34.695 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-07-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:34.698 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 August ...
[ Info: 2024-02-17T00:57:35.566 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-08-01
[ Info: 2024-02-17T00:57:35.566 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:35.567 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:35.574 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-08-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:35.577 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 September ...
[ Info: 2024-02-17T00:57:36.437 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-09-01
[ Info: 2024-02-17T00:57:36.437 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:36.438 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:36.444 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-09-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:36.446 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 October ...
[ Info: 2024-02-17T00:57:37.304 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-10-01
[ Info: 2024-02-17T00:57:37.304 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:37.305 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:37.311 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-10-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:37.314 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 November ...
[ Info: 2024-02-17T00:57:38.183 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-11-01
[ Info: 2024-02-17T00:57:38.183 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:38.184 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:38.190 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-11-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc
[ Info: 2024-02-17T00:57:38.192 - NASAPrecipitation.jl - Performing spatial smoothing (1.00x0.20) on IMERGv7 Monthly Precipitation Rate data in Southeast Asia during 2015 December ...
[ Info: 2024-02-17T00:57:39.051 - NASAPrecipitation.jl - Saving IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-12-01
[ Info: 2024-02-17T00:57:39.051 - NASAPrecipitation.jl - Overwrite stale NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:39.052 - NASAPrecipitation.jl - Creating NetCDF file /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc ...
[ Info: 2024-02-17T00:57:39.058 - NASAPrecipitation.jl - IMERGv7 Monthly data in the Southeast Asia GeoRegion for 2015-12-01 has been saved into /home/runner/imergv7monthly/TMP/imergv7monthly-TMP-smooth_1.00x0.20_00steps-2015.nc

Now let us compare the difference between the raw and smoothed data.

ds_raw  = read(npd_smth,geo,Date(2015))
ds_smth = read(npd_smth,geo,Date(2015),smooth=true,smoothlon=1,smoothlat=0.2)

prcp_raw  = ds_raw["precipitation"][:,:,11]  * 86400
prcp_smth = ds_smth["precipitation"][:,:,11] * 86400

close(ds_raw)
close(ds_smth)

fig = Figure()
aspect = (maximum(lsd.lon)-minimum(lsd.lon)+2)/(maximum(lsd.lat)-minimum(lsd.lat)+2)

ax1 = Axis(
    fig[1,1],width=350,height=350/aspect,
    title="November 2015 (Raw)",xlabel="Longitude / º",ylabel="Latitude / º",
    limits=(minimum(lsd.lon)-1,maximum(lsd.lon)+1,minimum(lsd.lat)-1,maximum(lsd.lat)+1)
)
ax2 = Axis(
    fig[1,2],width=350,height=350/aspect,
    title="November 2015 (Smoothed 1.0ºx0.2º)",xlabel="Longitude / º",
    limits=(minimum(lsd.lon)-1,maximum(lsd.lon)+1,minimum(lsd.lat)-1,maximum(lsd.lat)+1)
)
contourf!(
    ax1,lsd.lon,lsd.lat,prcp_raw,colormap=:Blues,
    levels=range(0,20,length=11),extendlow=:auto,extendhigh=:auto
)
contourf!(
    ax2,lsd.lon,lsd.lat,prcp_smth,colormap=:Blues,
    levels=range(0,20,length=11),extendlow=:auto,extendhigh=:auto
)
lines!(ax1,clon,clat,color=:black)
lines!(ax2,clon,clat,color=:black)

resize_to_layout!(fig)
fig

And we see that the data is smoothed in the longitude-direction. Because they are not smoothed equally in both longitude and latitude, the fields look stretched in the longitude direction.

API

smoothing(;
    npd :: Union{IMERGHalfHourly},
    geo :: GeoRegion = GeoRegion("GLB");
    spatial  :: Bool = false,
    temporal :: Bool = false,
    hours     :: Real = 0,
    smoothlon :: Real = 0,
    smoothlat :: Real = 0,
    verbose :: Bool = false
)

smoothing(;
    npd :: Union{IMERGDaily,TRMMDaily},
    geo :: GeoRegion;
    spatial  :: Bool = false,
    temporal :: Bool = false,
    days :: Int = 0,
    smoothlon :: Real = 0,
    smoothlat :: Real = 0,
    verbose :: Bool = false
)

smoothing(;
    npd :: Union{IMERGMonthly,TRMMMonthly},
    geo :: GeoRegion;
    smoothlon :: Real = 0,
    smoothlat :: Real = 0,
    verbose :: Bool = false
)