This is a data set in R binary format that has daily summaries of
surface ozone measurements for the Eastern US in the period 1995-1999.
Summary is the maximum 8 hour average in a 24 hour period based on hourly 
data. 

ozmax is a list with components:

days - Julian dates of measurements ( days since 1JAN1970)
lon.lat -  matrix of station locations longitude/latitude
years - time of measurements in year and fraction of year.
dates - chron package  date object for measurement date ( see help(chron))

PPB - a 920X513 matrix of daily ozone values in parts per billion (PPB)
      rows index day and columns index stations. The dimension names give the
      dates and the station ids. 


To load into an R session

load( "ozmax8.rda")


# example of plotting data in time for two close stations

 ind<- c(125,  149)
 ind2<- years(ozmax8$dates) ==1997
 matplot( ozmax8$years[ind2], ozmax8$PPB[ind2,ind],
   type="l", col=c(1:3), lty=1,
   ylab="PPB max 8 hour average", xlab="days")
title("Two individual stations")