Hello, I have an ncdf file with different variables for dimensions and dates where the dimensions are as follows, where X=i and Y=j creating a 88 by 188 set of cells. For each cell there are 12 readings for DO taken at 2 hour intervals and recoded by according to the Julian calendar under the ordinal dates variable. DO: [2280x188x85] DX: [188x85] DY: [188x85] X: [85x1] Y: [188x1] Ordinal_Dates: [2280x1] T: [2280x1] So far, I have set up each variable as follows, and I don?t know how to work with the 3D DO variable which contains 12 daily values per day setwd ("C:/Documents and Settings/Desktop/R") library(ncdf) profile1 <- open.ncdf("2005r1_v3_Ct=500_lerie_out_bot.nc", header=FALSE) name1<-get.var.ncdf( profile1, "DO") name2<-get.var.ncdf( profile1, "DX") name3<-get.var.ncdf( profile1, "DY") name4<-get.var.ncdf( profile1, "X") name5<-get.var.ncdf( profile1, "Y") name6<-get.var.ncdf( profile1, "Ordinal_Dates") name7<-get.var.ncdf( profile1, "T") I want to set a threshold, and calculate how many days have an average of DO greater then my threshold, and also what the daily averages of DO are Any help is appreciated! Emilija