In imohamme/nasaaccess: Downloading and Reformatting Tool for NASA Earth Observation Data Products

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NASAaccess has a handy tool to access, extract, and reformat climate change data of rainfall and air temperature from NASA Earth Exchange Global Daily Downscaled Projections NEX-GDDP GSFC servers for grids within a specified watershed.

NEX-GDDP dataset is comprised of downscaled climate scenarios for the globe that are derived from the General Circulation Model GCM runs conducted under the Coupled Model Intercomparison Project Phase 5 CMIP5 [@RN824] and across two (RCP45 & RCP85) of the four greenhouse gas emissions scenarios known as Representative Concentration Pathways RCPs [@RN1281]. The CMIP5 GCM runs were developed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change IPCC AR5. This dataset includes downscaled projections from the 21 models and scenarios for which daily scenarios were produced and distributed under CMIP5.

The Bias-Correction Spatial Disaggregation BCSD method used in generating the NEX-GDDP dataset is a statistical downscaling algorithm specifically developed to address the current limitations of the global GCM outputs [@RN1282;@RN736;@RN1393;@RN1283]. The NEX-GDDP climate projections is downscaled at a spatial resolution of 0.25 degrees x 0.25 degrees (approximately 25 km x 25 km). The NEX_GDDP_CMIP5 downscales the NEX-GDDP data to grid points of 0.1 degrees x 0.1 degrees following nearest point methods described by @RN1207.

Basic use

Let's use the example watersheds that we introduced with GPMswat and GPMpolyCentroid. Please visit NASAaccess GPM functions for more information.

#Reading input data
dem_path <- system.file("extdata",
                        "DEM_TX.tif", 
                         package = "NASAaccess")

shape_path <- system.file("extdata", 
                          "basin.shp", 
                           package = "NASAaccess")


library(NASAaccess)

NEX_GDDP_CMIP5(Dir = "./NEX_GDDP_CMIP5/", 
              watershed = shape_path,
              DEM = dem_path, 
              start = "2060-12-1", 
              end = "2060-12-3",
              model = 'IPSL-CM5A-MR', 
              type = 'pr', 
              slice = 'rcp85')

Let's examine the precipitation station file

NEX_GDDP.precipitationMaster <- system.file('extdata/NEX_GDDP_CMIP5',
                                         'prGrid_Master.txt', 
                                         package = 'NASAaccess')

NEX_GDDP_CMIP5.table<-read.csv(NEX_GDDP.precipitationMaster)

head(NEX_GDDP_CMIP5.table)

dim(NEX_GDDP_CMIP5.table)

Here we processed precipitation data from Institut Pierre Simon Laplace Model CM5A-MR under the Representative Concentration Pathways (RCP85) for our example watershed during the December 2060 (1st to 3rd).

Changing type parameter in the NEX_GDDP_CMIP5 function from pr to tas gives us minimum and maximum air temperatures.

Built with

sessionInfo()

References

imohamme/nasaaccess documentation built on Nov. 14, 2024, 11:24 a.m.