README.md

In sieste/realstorms: Storm track analysis

Storm tracking for Real Projections

An R package to analyse and plot storm tracks and storm track density from reanalyses and climate model data.

The package uses data.table and ggplot2 for fast computation and high quality graphics.

Installation

devtools::install_github('sieste/realstorms')
library(realstorms)

Usage example

We are working with files of standard ascii output format produced by the TRACK storm tracking software. (Currently, no data is included with the package, but will soon be.)

stormsfile = 'storms.txt'
writeLines(readLines(stormsfile, n=8))

## 0
## PER_INFO 1    186.00000
## 0 0
## TRACK_NUM      1184 ADD_FLD    6  16 &111110
## TRACK_ID  127 START_TIME 1979100312
## POINT_NUM  30
## 1979100312 353.681549 47.666767 2.346363e+00 & 3.533451e+02 & 4.970964e+01 & 1.007385e+03 & 7.031000e-01 & 4.526300e+01 & 1.215763e+01 & 3.550781e+02 & 4.666655e+01 & 1.042684e+00 & 3.529688e+02 & 5.087706e+01 & -7.438669e-01 & 7.031000e-01 & 4.526300e+01 & 1.215763e+01 & 1.157416e-01 & 
## 1979100315 354.703278 48.574390 2.604560e+00 & 3.537430e+02 & 5.029348e+01 & 1.006312e+03 & 1.406200e+00 & 4.526300e+01 & 1.209936e+01 & 3.557812e+02 & 4.807005e+01 & 1.145681e+00 & 3.529688e+02 & 5.087706e+01 & -9.429607e-01 & 1.406200e+00 & 4.526300e+01 & 1.209936e+01 & 1.584442e-01 &

The function read_tracks parses TRACK output into a data.table. Variable names can be passed as a function argument:

trx = read_tracks(stormsfile, var=c('vor850', 'mslp', 'speed', 'precip', 'omega'))
head(trx)

##                ID       date lon_vor850 lat_vor850 var_vor850 lon_mslp
## 1: 1979100312_127 1979100312  -6.318451   47.66677   2.346363  -6.6549
## 2: 1979100312_127 1979100315  -5.296722   48.57439   2.604560  -6.2570
## 3: 1979100312_127 1979100318  -4.857239   49.65100   2.899219  -5.9150
## 4: 1979100312_127 1979100321  -4.318573   50.21724   3.184141  -5.9635
## 5: 1979100312_127 1979100400  -4.361511   51.63484   3.541903  -5.4617
## 6: 1979100312_127 1979100403  -3.812408   52.54179   3.929281  -4.9509
##    lat_mslp var_mslp lon_speed lat_speed var_speed lon_precip lat_precip
## 1: 49.70964 1007.385    0.7031   45.2630  12.15763    -4.9219   46.66655
## 2: 50.29348 1006.312    1.4062   45.2630  12.09936    -4.2188   48.07005
## 3: 50.62696 1004.724    1.4062   45.9648  13.09993    -6.3281   51.57881
## 4: 51.28530 1003.757    2.8125   46.6665  15.49924    -6.3281   52.98231
## 5: 51.55520 1001.974   -7.7344   51.5788  14.98526    -5.6250   52.98231
## 6: 52.19911 1000.530    0.7031   57.1928  15.12454    -7.0312   52.28056
##    var_precip lon_omega lat_omega  var_omega  lon_V6  lat_V6   var_V6
## 1:   1.042684   -7.0312  50.87706 -0.7438669  0.7031 45.2630 12.15763
## 2:   1.145681   -7.0312  50.87706 -0.9429607  1.4062 45.2630 12.09936
## 3:   1.333872   -7.0312  51.57881 -1.0721690  1.4062 45.9648 13.09993
## 4:   1.780192   -7.0312  52.28056 -1.3256610  2.8125 46.6665 15.49924
## 5:   2.081553   -7.0312  51.57881 -1.0744200 -7.7344 52.2806 14.71069
## 6:   2.893448   -6.3281  55.08756 -1.0830790 -7.0312 52.2806 15.01214
##       var_V7
## 1: 0.1157416
## 2: 0.1584442
## 3: 0.1752217
## 4: 0.2139297
## 5: 0.2372818
## 6: 0.4409288

The function track_density splits the world up into grid boxes of width and height bw (in degrees) and calculates track count, track density, feature count and feature density:

# calculate track density on a 5x5 degree grid
td = track_density(trx, bw=1)
head(td)

##                      bin feature_count track_count feature_density
## 1: (-180,-179],(-90,-89]             0           0               0
## 2: (-179,-178],(-90,-89]             0           0               0
## 3: (-178,-177],(-90,-89]             0           0               0
## 4: (-177,-176],(-90,-89]             0           0               0
## 5: (-176,-175],(-90,-89]             0           0               0
## 6: (-175,-174],(-90,-89]             0           0               0
##    track_density lon_min lon_max lat_min lat_max    lon   lat
## 1:             0    -180    -179     -90     -89 -179.5 -89.5
## 2:             0    -179    -178     -90     -89 -178.5 -89.5
## 3:             0    -178    -177     -90     -89 -177.5 -89.5
## 4:             0    -177    -176     -90     -89 -176.5 -89.5
## 5:             0    -176    -175     -90     -89 -175.5 -89.5
## 6:             0    -175    -174     -90     -89 -174.5 -89.5

The object trx is of class stormtracks, and the object td is of class track_density. Both classes have S3 plotting methods:

plot(trx, var='vor850')

plot(td, what='track_density', contour_smooth=2) + 
coord_cartesian(xlim=c(-100,100), ylim=c(25,75))

sieste/realstorms documentation built on May 13, 2019, 1:09 p.m.