This function shows the reference ground track time and locations for specific date ranges. "Updated KML files have been posted to the 'tech-specs' website (see the 'references' section for more details) containing individual files for each Reference Ground Track (RGT) with a date and time stamp posted every 420 kilometers along-track (roughly 1 minute of flight time in between each point). The first RGT is 234; this is where the time series begins. The date of each RGT is in the file name, so the user can easily ascertain where and when ICESat-2 will be on a particular day."
time_specific_orbits(
date_from = NULL,
date_to = NULL,
RGT_cycle = NULL,
download_method = "curl",
threads = 1,
verbose = FALSE
)either NULL or a character string specifying the start date in the format 'yyyy-MM-dd' (such as '2020-01-01'). If this parameter is NULL then the 'RGT_cycle' parameter must be specified
either NULL or a character string specifying the end date in the format 'yyyy-MM-dd' (such as '2020-01-01'). If this parameter is NULL then the 'RGT_cycle' parameter must be specified
a character vector specifying the RGT (Reference Ground Track) cycle(s) (the specific revisit times of ICESAT-2). This parameter can be greater or equal to 1 with a maximum 'RGT-cycle' names as determined by the output of the 'available_RGTs(only_cycle_names = TRUE)' function. The computation time of a single 'RGT-cycle' might take approximately 15 minutes utilizing 8 threads (in parallel) and require approximately 2 GB of memory.
a character string specifying the download method. Corresponds to the 'method' parameter of the 'utils::download.file()' function. Can be one of 'internal', 'wininet' (Windows only), 'libcurl', 'wget', 'curl' or 'auto'
an integer that specifies the number of threads to use in parallel when processing the data
a boolean. If TRUE then information will be printed out in the console
an 'sf' object that will include one or more Reference Ground Tracks (see the 'RGT' column of the output object)
https://icesat-2.gsfc.nasa.gov/science/specs
if (FALSE) {
require(IceSat2R)
#................................................
# RGTs (Reference Ground Tracks) for a single day
#................................................
res_rgt_one = time_specific_orbits(date_from = '2019-06-01',
date_to = '2019-06-01',
download_method = 'curl',
threads = 1,
verbose = TRUE)
str(res_rgt_one)
#..........................................................
# RGTs (Reference Ground Tracks) for a specific time period
#..........................................................
res_rgt_many = time_specific_orbits(date_from = '2019-06-01',
date_to = '2019-06-03',
download_method = 'curl',
threads = 1,
verbose = TRUE)
str(res_rgt_many)
#.........................................................
# processing more than one RGTs for a specified date range
#.........................................................
res_rgt_inters = time_specific_orbits(date_from = '2021-03-23',
date_to = '2021-03-26',
download_method = 'curl',
threads = 1,
verbose = TRUE)
str(res_rgt_inters)
table(res_rgt_inters$cycle)
table(res_rgt_inters$day_of_year)
table(res_rgt_inters$RGT)
#...............................................................
# RGTs (Reference Ground Tracks) for a selected 'cycle'
# Observe the available RGT-cycles and use all available threads
#...............................................................
avail_cycles = available_RGTs(only_cycle_names = TRUE,
verbose = TRUE)
avail_cycles
choose_cycle = avail_cycles[3]
res_rgt_many = time_specific_orbits(RGT_cycle = choose_cycle,
download_method = 'curl',
threads = parallel::detectCores(),
verbose = TRUE)
}