library(tidync)
## I found an old stale oscar.nc in my legacy public_html/R/ directory
## so I found this OpenDAP source to revisit
## we have Copernicus these days but Oscar was an early
u <- "https://podaac-opendap.jpl.nasa.gov:443/opendap/allData/oscar/preview/L4/oscar_third_deg/oscar_vel1992.nc.gz"
(tnc <- tidync(u))
## not a file:
## ' https://podaac-opendap.jpl.nasa.gov:443/opendap/allData/oscar/preview/L4/oscar_third_deg/oscar_vel1992.nc.gz '
##
## ... attempting remote connection
## Connection succeeded.
##
## Data Source (1): oscar_vel1992.nc.gz ...
##
## Grids (6) <dimension family> : <associated variables>
##
## [1] D2,D1,D0,D3 : u, um, v, vm **ACTIVE GRID** ( 8087534 values per variable)
## [2] D0 : depth
## [3] D1 : latitude
## [4] D2 : longitude
## [5] D3 : time
## [6] D4 : year
##
## Dimensions (5):
##
## dimension id name length unlim coord_dim
## <chr> <dbl> <chr> <dbl> <lgl> <lgl>
## 1 D0 0 depth 1 FALSE TRUE
## 2 D1 1 latitude 481 FALSE TRUE
## 3 D2 2 longitude 1201 FALSE TRUE
## 4 D3 3 time 14 FALSE TRUE
## 5 D4 4 year 14 FALSE TRUE
tnc %>% hyper_filter()
## # A tibble: 1 x 2
## access
## <dttm>
## 1 2017-08-03 00:51:00
## # ... with 1 more variables: source <chr>
## filtered dimension summary:
## # A tibble: 4 x 5
## name coord_dim min max length
## <chr> <lgl> <dbl> <dbl> <int>
## 1 longitude TRUE 20 420 1201
## 2 latitude TRUE -80 80 481
## 3 depth TRUE 15 15 1
## 4 time TRUE 16 82 14
library(dplyr)
##
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
##
## filter, lag
## The following objects are masked from 'package:base':
##
## intersect, setdiff, setequal, union
d <- tnc %>% hyper_filter(longitude = between(longitude, 120, 220),
latitude = between(latitude, -60, -30),
time = index < 7) %>%
hyper_tibble()
library(ggplot2)
ggplot(d, aes(x = longitude, y = latitude, fill = sqrt(u*u + v * v))) +
geom_raster() + scale_fill_gradient2() + facet_wrap(~time)
ggplot(d %>% dplyr::filter(longitude %in% seq(120, 220, by = 10)),
aes(y = time, x = latitude, fill = sqrt(u* u + v * v))) +
geom_raster() + scale_fill_gradient2() + facet_wrap(~longitude)
## old style
library(RNetCDF)
print.nc(open.nc(u))
## dimensions:
## depth = 1 ;
## latitude = 481 ;
## longitude = 1201 ;
## time = 14 ;
## year = 14 ;
## variables:
## int time(time) ;
## time:units = "day since 1992-10-05 00:00:00" ;
## time:long_name = "Day since 1992-10-05 00:00:00" ;
## float year(year) ;
## year:units = "time in years" ;
## year:long_name = "Time in fractional year" ;
## float depth(depth) ;
## depth:units = "meter" ;
## depth:long_name = "Depth" ;
## double latitude(latitude) ;
## latitude:units = "degrees-north" ;
## latitude:long_name = "Latitude" ;
## double longitude(longitude) ;
## longitude:units = "degrees-east" ;
## longitude:long_name = "Longitude" ;
## double u(longitude, latitude, depth, time) ;
## u:units = "meter/sec" ;
## u:long_name = "Ocean Surface Zonal Currents" ;
## u:missing_value = NaN ;
## double v(longitude, latitude, depth, time) ;
## v:units = "meter/sec" ;
## v:long_name = "Ocean Surface Meridional Currents" ;
## v:missing_value = NaN ;
## double um(longitude, latitude, depth, time) ;
## um:units = "meter/sec" ;
## um:long_name = "Ocean Surface Zonal Currents Maximum Mask" ;
## um:missing_value = NaN ;
## double vm(longitude, latitude, depth, time) ;
## vm:units = "meter/sec" ;
## vm:long_name = "Ocean Surface Meridional Currents Maximum Mask" ;
## vm:missing_value = NaN ;
##
## // global attributes:
## :VARIABLE = "Ocean Surface Currents" ;
## :DATATYPE = "1/72 YEAR Interval" ;
## :DATASUBTYPE = "unfiltered" ;
## :GEORANGE = "20 to 420 -80 to 80" ;
## :PERIOD = "Oct.21,1992 to Dec.26,1992" ;
## :year = "1992" ;
## :description = "OSCAR Third Degree Sea Surface Velocity" ;
## :CREATION_DATE = "12:38 18-Sep-2012" ;
## :version = 2009 ;
## :source = "Gary Lagerloef, ESR (lager@esr.org) and Kathleen Dohan, ESR (kdohan@esr.org)" ;
## :contact = "Kathleen Dohan (kdohan@esr.org) or John T. Gunn (gunn@esr.org)" ;
## :company = "Earth & Space Research, Seattle, WA" ;
## :reference = "Bonjean F. and G.S.E. Lagerloef, 2002 ,Diagnostic model and analysis of the surface currents in the tropical Pacific ocean, J. Phys. Oceanogr., 32, 2,938-2,954" ;
## :note1 = "Maximum Mask velocity is the geostrophic component at all points + any concurrent Ekman and buoyancy components" ;
## :note2 = "Longitude extends from 20 E to 420 E to avoid a break in major ocean basins. Data repeats in overlap region." ;