noaa_stage1: NOAA GEFS tables

In eco4cast/neon4cast: Helper Utilities for the EFI NEON Forecast Challenge

NOAA GEFS tables

Description

Access NOAA Global Ensemble Forecast System (GEFS) forecast predictions at NEON sites. The GEFS is NOAA's longest horizon forecast, extending up to 30 days at present, issued at 0.5 degree spatial resolution. EFI downsamples these forecasts at the coordinates of all NEON sites and provides efficient access to archives of these forecasts in a simple tabular format for a subset of variables of interest.

Usage

noaa_stage1(
  cycle = 0,
  version = "v12",
  endpoint = "data.ecoforecast.org",
  verbose = TRUE,
  start_date = ""
)

Arguments

cycle	Hour at which forecast was made, as character string ("00", "06", "12" or "18"). Only "00" (default) has 30 days horizon.
version	GEFS forecast version. Prior versions correspond to forecasts issued before 2020-09-25 which have different ensemble number and horizon, among other changes, and are not made available here. Leave as default.
endpoint	the EFI host address (leave as default)
verbose	logical, displays or hides messages
start_date	forecast start date yyyy-mm-dd format

Details

WARNING: This combined dataset contains billions of rows. Filtering to a forecast issued on specific start_dates or other subsets before collect()ing data into R is essential. Be patient, especially on slow network connections, and handle this data with care. See examples.

At each site, 31 ensemble member forecasts are provided at 3 hr intervals for the first 10 days, and 6 hr intervals for up to 30 days (840 hr) horizon. Forecasts include the following variables:

• TMP - temperature (K)

• RH - Relative humidity (%)

• PRES - Atmospheric pressure (Pa)

• UGRD - U-component of wind speed (m/s)

• VGRD - V-component of wind speed (m/s)

• APCP - Total precipitation in interval (kg/m^2)

• DSWRF - Downward shortwave radiation flux in interval

• DLWRF - Downward longwave radiation flux in interval

GEFS forecasts are issued four times a day, as indicated by the start_date and cycle. Only forecasts at midnight, cycle = "00" extend for the full 840 hour horizon. Other cycles 06, 12, 18 are provided only 6hrs ahead, as mostly being of interest for short-term forecasts. (Though users should note that other NOAA products provide more much accurate and higher resolution short term forecasts than GEFS.)

All variables are given at height 2m above ground, as indicated in height. See https://www.nco.ncep.noaa.gov/pmb/products/gens/ for more details on GEFS variables and intervals.

References

https://www.nco.ncep.noaa.gov/pmb/products/gens/

Examples

weather <- noaa_stage1()
# 5.7M rows of data:
weather |> 
  dplyr::filter(start_date == "2022-04-01") |>
  dplyr::collect()

eco4cast/neon4cast documentation built on Sept. 14, 2024, 6:50 a.m.