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

knitr::opts_chunk$set(
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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-CMIP6 AMES servers for grids within a specified watershed.

NEX-GDDP-CMIP6 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 6 CMIP6 [@RN1450] and across two of the four "Tier 1" greenhouse gas emissions scenarios known as Shared Socioeconomic Pathways (SSPs) [@RN1451; @RN1452]. The CMIP6 GCM runs were developed in support of the Sixth Assessment Report of the Intergovernmental Panel on Climate Change IPCC AR6. This dataset includes downscaled projections from the 35 models and scenarios for which daily scenarios were produced and distributed under CMIP6.

The Bias-Correction Spatial Disaggregation BCSD method used in generating the NEX-GDDP-CMIP6 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-CMIP6 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_CMIP6 downscales the NEX-GDDP-CMIP6 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")

#CMIP6  example for air temperature

library(NASAaccess)

NEX_GDDP_CMIP6(
               Dir = "./NEX_GDDP_CMIP6/", 
               watershed = shape_path,
               DEM = dem_path,  
               start = "2060-12-1", 
               end = "2060-12-3",
               model = 'ACCESS-CM2', 
               type = 'tas', 
               slice = 'ssp245')

Let's examine the air temperature station file

NEX_GDDP_CMIP6.temperature.Master <- system.file('extdata/NEX_GDDP_CMIP6',
                                         'tasGrid_Master.txt', 
                                         package = 'NASAaccess')

NEX_GDDP_CMIP6.table<-read.csv(NEX_GDDP_CMIP6.temperature.Master)

head(NEX_GDDP_CMIP6.table)

dim(NEX_GDDP_CMIP6.table)

Built with

sessionInfo()

References

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