Variable preparation

Introduction

This vignette will walk through the steps needed to create mean ‘whatever’ states during all of the MHWs detected in the previous SST preparation vignette. These ‘whatever’ states are any of the abiotic variables present in the NAPA model that have been deemed relevant w.r.t. forcing of extreme ocean surface temperatures.

# Packages used in this vignette
library(jsonlite, lib.loc = "../R-packages/")
library(tidyverse) # Base suite of functions
library(ncdf4) # For opening and working with NetCDF files
library(lubridate) # For convenient date manipulation

# Load functions required below
source("code/functions.R")

# Set number of cores
doMC::registerDoMC(cores = 50)

# Disable scientific notation for numeric values
  # I just find it annoying
options(scipen = 999)

# Corners of the study area
NWA_corners <- readRDS("data/NWA_corners.Rda")

# The NAPA data location
NAPA_files <- dir("../../data/NAPA025/1d_grid_T_2D", full.names = T)

# The NAPA model lon/lat values
NAPA_coords <- readRDS("data/NAPA_coords.Rda")

# Load NAPA bathymetry/lon/lat
NAPA_bathy <- readRDS("data/NAPA_bathy.Rda")

# Load MHW results
NAPA_MHW_sub <- readRDS("data/NAPA_MHW_sub.Rda")

# MHW Events
NAPA_MHW_event <- NAPA_MHW_sub %>%
  select(-clims, -cats) %>%
  unnest(events) %>%
  filter(row_number() %% 2 == 0) %>%
  unnest(events)

For the upcoming variable prep we are also going to want the NAPA coordinates that are within our chosen study area as seen with NWA_corners. We will also create a subsetted bathy coord file, too, so as to have an effective land mask. This will help us to reduce a lot of computational cost as we go along because many of the pixels over land are given 0 values, rather than missing values, which is a strange choice…

# The NAPPA coordinates for the study area only
NAPA_coords_sub <- NAPA_coords %>% 
  filter(lon >= NWA_corners[1], lon <= NWA_corners[2],
           lat >= NWA_corners[3], lat <= NWA_corners[4])
# saveRDS(NAPA_coords_sub, "data/NAPA_coords_sub.Rda")

# Tha NAPA bathymetry for the study area only
NAPA_bathy_sub <- NAPA_bathy %>% 
  right_join(NAPA_coords_sub, by = c("lon_index", "lat_index", "lon", "lat")) %>% 
  na.omit()
# saveRDS(NAPA_bathy_sub, "data/NAPA_bathy_sub.Rda")

Chosen variables

There are many variables present in the NAPA model, more than we would really need to use for this project. We have therefore chosen to narrow our investigation. Listed below are all of the variables found within a given NAPA surface layer NetCDF file.

# Spreadsheet of variables present in the NetCDF files
NAPA_vars <- ncdump::NetCDF(NAPA_files[1])$variable[1:6]
NAPA_vars

# A tibble: 20 x 6
   name         ndims natts prec   units            longname              
   <chr>        <int> <int> <chr>  <chr>            <chr>                 
 1 emp_ice          3    10 float  kg/m2/s          Evap minus Precip ove…
 2 emp_oce          3    10 float  kg/m2/s          Evap minus Precip ove…
 3 fmmflx           3     9 float  kg/m2/s          Water flux due to fre…
 4 mldkz5           3    10 float  m                Turbocline depth (Kz …
 5 mldr10_1         3    10 float  m                Mixed Layer Depth (ds…
 6 nav_lat          2     3 float  degrees_north    Latitude              
 7 nav_lon          2     3 float  degrees_east     Longitude             
 8 qemp_oce         3     9 float  W/m2             Downward Heat Flux fr…
 9 qla_oce          3    10 float  W/m2             Latent Downward Heat …
10 qns              3     9 float  W/m2             non solar Downward He…
11 qsb_oce          3    10 float  W/m2             Sensible Downward Hea…
12 qt               3    10 float  W/m2             Net Downward Heat Flux
13 runoffs          3    10 float  kg/m2/s          Water Flux into Sea W…
14 ssh              3    10 float  m                sea surface height    
15 sss              3    10 float  0.001            Sea Surface Salinity  
16 sst              3    10 float  degree_C         Sea Surface Temperatu…
17 taum             3    10 float  N/m2             wind stress module    
18 time_center…     1     6 double seconds since 1… Time axis             
19 time_center…     2     0 double ""               time_centered_bounds  
20 time_counte…     2     0 double ""               time_counter_bounds   

These variable are not an unruly amount of information and so we will extract and compile most of them when creating the data packets that will be fed into our SOMs later. Many of these variables are likely to have very high auto-correlative relationships in which case we will need to select only the most representative of them. I foresee the multiple heat terms coming to a head with one another, though I can’t yet say from this early vantage point which will be best.

It should go without saying, but we will not be accounting for lon/lat or the three time variables at the end of the above spreadsheet as these are not proper abiotic variables. Also, upon closer examination it was discovered that the heat terms for sensible (qsb_oce) and latent (qla_oce) heat flux into the ocean do not contain any data, so they cannot be used here. Lastly, we only want to use variables that are present in all of the regions. This means that river runoff (runoffs) is not relevant to this work as it’s localised effects will be reflected in changes to sss, which is a variable present in all regions, whereas river runoff is not. We will also exclude evaporation/preciptation over ice (emp_ice) as this variable is only present in the northern regions. That being said, we will keep water flux due t0 freezing/melting ice (fmmflx), even though this variable does not have data in all regions, because we suspect it may play a role in the formation of MHWs. Specifically as they pertain to phenological shifts in ice formation.

Therefore our initial variable list is as follows:

# Remove unwanted variables
NAPA_vars <- ncdump::NetCDF(NAPA_files[1])$variable[c(2:5, 8, 10, 12, 14:17), 1:6]

# Save
# saveRDS(NAPA_vars, "data/NAPA_vars.Rda")

NAPA_vars

# A tibble: 11 x 6
   name     ndims natts prec  units   longname                            
   <chr>    <int> <int> <chr> <chr>   <chr>                               
 1 emp_oce      3    10 float kg/m2/s Evap minus Precip over ocean        
 2 fmmflx       3     9 float kg/m2/s Water flux due to freezing/melting  
 3 mldkz5       3    10 float m       Turbocline depth (Kz = 5e-4)        
 4 mldr10_1     3    10 float m       Mixed Layer Depth (dsigma = 0.01 wr…
 5 qemp_oce     3     9 float W/m2    Downward Heat Flux from E-P over op…
 6 qns          3     9 float W/m2    non solar Downward Heat Flux        
 7 qt           3    10 float W/m2    Net Downward Heat Flux              
 8 ssh          3    10 float m       sea surface height                  
 9 sss          3    10 float 0.001   Sea Surface Salinity                
10 sst          3    10 float degree… Sea Surface Temperature             
11 taum         3    10 float N/m2    wind stress module                  

Synoptic states

With the variables chosen, the next step is to create mean synoptic states for each variable during each of the MHWs detected in all sub-regions. In order to make that process go more smoothly we will first create a date index of all of the NAPA files present on Eric Oliver’s local server. Unfortunately that means that from here out the code in this vignette will only run on said server. The output of this vignette will however be publicly available here.

# Pull out the dates
NAPA_files_dates <- data.frame()
for(i in 1:length(NAPA_files)){
  file_name <- NAPA_files[i]
  date_start <- ymd(str_sub(basename(as.character(file_name)), start = 29, end = 36))
  date_end <- ymd(str_sub(basename(as.character(file_name)), start = 38, end = 45))
  date_seq <- seq(date_start, date_end, by = "day")
  date_info <- data.frame(file = file_name, date = date_seq)
  NAPA_files_dates <- rbind(date_info, NAPA_files_dates)
}

# Order by date, just for tidiness
NAPA_files_dates <- dplyr::arrange(NAPA_files_dates, date)

# Save
# saveRDS(NAPA_files_dates, "data/NAPA_files_dates.Rda")

# Load functions required below
source("code/functions.R")

# NB: The creation of a clim for one variable is too large to run via ldply
# Rather they must be run one at a time via a for loop and the memmory dumped after each
for(i in 1:nrow(NAPA_vars)){
  clim_one_var(NAPA_vars$name[i])
  gc()
}

# Load all variable climatologies and join variables with a for loop
  # NB: This should be optimised...
NAPA_clim_vars <- data.frame()
# system.time(
for(i in 1:length(NAPA_vars$name)){
  var_one <- readRDS(file = paste0("data/NAPA_clim_",NAPA_vars$name[i],".Rda"))
  if(nrow(NAPA_clim_vars) == 0){
    NAPA_clim_vars <- rbind(var_one, NAPA_clim_vars)
  } else {
    NAPA_clim_vars <- left_join(NAPA_clim_vars, var_one, 
                                by = c("lon", "lat", "doy"))
  }
}
# ) # 115 seconds for all
rm(var_one, i); gc()

# Convert DOY to MM-DD for joining to daily data below
NAPA_clim_vars$doy <- format(as.Date(NAPA_clim_vars$doy, origin = "2015-12-31"), "%m-%d")

# Change column names to highlight that these are climatology values
colnames(NAPA_clim_vars)[-c(1:3)] <- paste0(colnames(NAPA_clim_vars)[-c(1:3)],"_clim")

# Reorder columns
# NAPA_clim_vars <- dplyr::select(NAPA_clim_vars, lon, lat, doy, everything())

# saveRDS(NAPA_clim_vars, "data/NAPA_clim_vars.Rda")

# Load NAPA file date index
NAPA_files_dates <- readRDS("data/NAPA_files_dates.Rda")

# Load full variable climatology file
NAPA_clim_vars <- readRDS("data/NAPA_clim_vars.Rda")

# Function for extracting the desired variables from a given NetCDF file
# testers...
# file_name <- NAPA_files[1]
extract_all_var <- function(file_name){
  
  # Extract and join variables with a for loop
    # NB: This should be optimised...
  NAPA_vars_extracted <- data.frame()
  system.time(
  for(i in 1:length(NAPA_vars$name)){
    extract_one <- extract_one_var(NAPA_vars$name[i], file_name = file_name)
    if(nrow(NAPA_vars_extracted) == 0){
      NAPA_vars_extracted <- rbind(extract_one, NAPA_vars_extracted)
    } else {
      NAPA_vars_extracted <- left_join(NAPA_vars_extracted, extract_one, 
                                       by = c("lon_index", "lat_index", "lon", "lat", "bathy", "t"))
    }
  }
  ) # 18 seconds for one
  NAPA_vars_extracted <- dplyr::select(NAPA_vars_extracted,
                                       lon_index, lat_index, lon, lat, t, bathy, everything())
  
  # Exit
  return(NAPA_vars_extracted)
}

# Function for extracting variables from as many files as a MHW event requires
# testers...
# event_sub <- NAPA_MHW_event[23,]
data_packet <- function(event_sub){
  
  # Create date and file index for loading
  date_idx <- seq(event_sub$date_start, event_sub$date_end, by = "day")
  file_idx <- filter(NAPA_files_dates, date %in% date_idx) %>% 
    mutate(file = as.character(file)) %>% 
    select(file) %>% 
    unique()
  
  # Load required base data
  # system.time(
  packet_base <- plyr::ldply(file_idx$file, extract_all_var) %>% 
    filter(t %in% date_idx) %>% 
    mutate(doy = format(t, "%m-%d"))
  # ) # 125 seconds for seven files
  
  # Join to climatologies
  packet_join <- left_join(packet_base, NAPA_clim_vars, by = c("lon", "lat", "doy"))
  
  # Create anomaly values and remove clim columns
  packet_anom <- packet_join %>% 
    mutate(emp_oce_anom = emp_oce - emp_oce_clim,
           fmmflx_anom = fmmflx - fmmflx_clim,
           mldkz5_anom = mldkz5 - mldkz5_clim,
           mldr10_1_anom = mldr10_1 - mldr10_1_clim,
           qemp_oce_anom = qemp_oce - qemp_oce_clim,
           qns_anom = qns - qns_clim,
           qt_anom = qt - qt_clim,
           ssh_anom = ssh - ssh_clim,
           sss_anom = sss - sss_clim,
           sst_anom = sst - sst_clim,
           taum_anom = taum - taum_clim) %>% 
    dplyr::select(lon, lat, doy, emp_oce:taum_anom, 
                  -c(colnames(NAPA_clim_vars)[-c(1:3)]))
    # dplyr::select(-c(colnames(packet_base)[-c(3,4,ncol(packet_base))]), 
    #               -c(colnames(NAPA_clim_vars)[-c(1:3)]))
  
  # Create mean synoptic values
  packet_mean <- packet_anom %>% 
    select(-doy) %>% 
    # NB: The lowest pixels are a forcing edge and shouldn't be included
      # We can catch these out by filtering pixels whose SST is exactly 0
    filter(sst != 0) %>% 
    group_by(lon, lat) %>% 
    summarise_all(mean, na.rm = T) %>% 
    arrange(lon, lat) %>% 
    ungroup() %>% 
    nest(.key = "synoptic")
  
  # Combine results with MHW dataframe
  packet_res <- cbind(event_sub, packet_mean)
  
  # Test visuals
  # ggplot(packet_mean, aes(x = lon, y = lat)) +
  #   geom_point(aes(colour = sst_anom)) +
  #   scale_colour_gradient2(low = "blue", high = "red") +
  #   coord_cartesian(xlim = NWA_corners[1:2],
  #                   ylim = NWA_corners[3:4])
  
  # Exit
  return(packet_res)
}

# Set number of cores
  # NB: Was set to 25 as someone else was using the server at the time
doMC::registerDoMC(cores = 25)

# Create one big packet
# system.time(
synoptic_states <- plyr::ddply(NAPA_MHW_event, c("region", "sub_region", "event_no"), data_packet, .parallel = T)
# ) # 82 seconds for first 2, 6125 seconds (102 minutes) for all

# Save
# saveRDS(synoptic_states, "data/synoptic_states.Rda")

Session information

sessionInfo()

R version 3.6.0 (2019-04-26)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.5 LTS

Matrix products: default
BLAS:   /usr/lib/openblas-base/libblas.so.3
LAPACK: /usr/lib/libopenblasp-r0.2.18.so

locale:
 [1] LC_CTYPE=en_CA.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_CA.UTF-8        LC_COLLATE=en_CA.UTF-8    
 [5] LC_MONETARY=en_CA.UTF-8    LC_MESSAGES=en_CA.UTF-8   
 [7] LC_PAPER=en_CA.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_CA.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] bindrcpp_0.2.2       tidync_0.2.1         heatwaveR_0.3.6.9004
 [4] data.table_1.11.6    lubridate_1.7.4      ncdf4_1.16          
 [7] forcats_0.3.0        stringr_1.3.1        dplyr_0.7.6         
[10] purrr_0.2.5          readr_1.1.1          tidyr_0.8.1         
[13] tibble_1.4.2         ggplot2_3.0.0        tidyverse_1.2.1     
[16] jsonlite_1.6        

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.18      lattice_0.20-35   utf8_1.1.4       
 [4] assertthat_0.2.0  rprojroot_1.3-2   digest_0.6.16    
 [7] foreach_1.4.4     R6_2.2.2          cellranger_1.1.0 
[10] plyr_1.8.4        backports_1.1.2   evaluate_0.11    
[13] httr_1.3.1        pillar_1.3.0      rlang_0.2.2      
[16] lazyeval_0.2.1    readxl_1.1.0      ncmeta_0.0.4     
[19] rstudioapi_0.7    whisker_0.3-2     R.utils_2.7.0    
[22] R.oo_1.22.0       rmarkdown_1.10    htmlwidgets_1.3  
[25] munsell_0.5.0     broom_0.5.0       compiler_3.6.0   
[28] modelr_0.1.2      pkgconfig_2.0.2   htmltools_0.3.6  
[31] tidyselect_0.2.4  workflowr_1.1.1   codetools_0.2-15 
[34] doMC_1.3.5        fansi_0.3.0       viridisLite_0.3.0
[37] crayon_1.3.4      withr_2.1.2       R.methodsS3_1.7.1
[40] grid_3.6.0        nlme_3.1-137      gtable_0.2.0     
[43] git2r_0.23.0      magrittr_1.5      scales_1.0.0     
[46] cli_1.0.0         stringi_1.2.4     xml2_1.2.0       
[49] iterators_1.0.10  tools_3.6.0       glue_1.3.0       
[52] RNetCDF_1.9-1     maps_3.3.0        hms_0.4.2        
[55] ncdump_0.0.3      parallel_3.6.0    yaml_2.2.0       
[58] colorspace_1.3-2  rvest_0.3.2       plotly_4.9.0     
[61] knitr_1.20        bindr_0.1.1       haven_1.1.2