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Merge ERA5-Land and AmeriFlux Data

Source: R/03A_merge_ERA5_Flux.R
merge_ERA5_Flux.Rd

This function is used to merge data from AmeriFlux and data from ERA5-Land, ensuring they both have the same start and end timestamps.

Usage

merge_ERA5_Flux(
  filename_FLUX = NULL,
  filename_ERA5 = NULL,
  varname_FLUX = NULL,
  varname_ERA5 = NULL
)

Arguments

filename_FLUX

(character) The file path to a CSV file of AmeriFlux BASE data downloaded from https://ameriflux.lbl.gov/.

filename_ERA5

(character) The file path to a CSV file of ERA5-Land meterological data downloaded from https://cds.climate.copernicus.eu/datasets/reanalysis-era5-land. Please note that the original ERA5-Land files are in .nc format. You may want to convert these files into CSV format using the function netcdf_to_csv().

varname_FLUX

(character) A vector of variable names in AmeriFlux BASE data to be merged with ERA5-Land data.

varname_ERA5

(character) A vector of variable names in ERA5-Land data to be merged with AmeriFlux BASE data.

Value

(data.frame) A data frame with the following characteristics:

  • Datetime stamp column named "time" with the format: "%Y-%m-%d %H:%M:%S".

  • Time step of the "time" column is the same with that of AmeriFlux file.

  • It also includes the columns of varname_FLUX, the columns of varname_ERA5.

Note

Please note that the length of varname_FLUX must be the same as the length of varname_ERA5; at the same location, varname_FLUX and varname_ERA5 should refer to the same variable despite the fact that AmeriFlux and ERA5-Land may use different names for the same variable. For example, for incoming shortwave radiation, ERA5-Land uses "ssrd", but AmeriFlux uses "SW_IN".

Author

Ammara Talib and Junna Wang

Examples

# Point to AmeriFlux CSV data
filename_FLUX <- system.file("extdata",
                             "example_AmeriFlux",
                             "AMF_US-GL2_BASE-BADM_2-5",
                             "AMF_US-GL2_BASE_HH_2-5.csv",
                             package = "ERA5Flux")

# Point to ERA5-Land CSV data
filename_ERA5 <- system.file("extdata",
                             "example_processed_ERA5",
                             "US_GL2_2024_2025_ssrd.csv",
                             package = "ERA5Flux")

# List AmeriFlux variable(s) to be merged with ERA5-Land
varname_FLUX <- c("SW_IN")
# List ERA5-Land variable(s) to be merged with AmeriFlux
varname_ERA5 <- c("ssrd")

# Merge AmeriFlux and ERA5-Land data together
merged_data <- merge_ERA5_Flux(filename_FLUX, filename_ERA5, varname_FLUX, varname_ERA5)
head(merged_data)
#>                  time   ssrd SW_IN
#> 1 2024-12-31 19:00:00 670.36    NA
#> 2 2024-12-31 19:30:00 335.18    NA
#> 3 2024-12-31 20:00:00   0.00    NA
#> 4 2024-12-31 20:30:00   0.00    NA
#> 5 2024-12-31 21:00:00   0.00    NA
#> 6 2024-12-31 21:30:00   0.00    NA