R/calcEmisNitrogenPasturePast.R

In pik-piam/moinput: Model Operations Input Data Library

#' @title calcEmisNitrogenPasturePast
#' @description 
#' Calculates nitrogenous emissions from pastures for the historical period
#'
#' @param method IPCC: emissions are calculated according the the IPCC 2006 National Guidelines for Greenhouse Gas Inventories. Nsurplus: Emissions in 2005 are calculated according to IPCC, and the scaled with nitrogen losses from croplands.
#' @return List of magpie object with results on country level, weight on country level, unit and description.
#' @author Benjamin Leon Bodirsky
#' @seealso
#' \code{\link{calcEmisNitrogenPast}},
#' \code{\link{calcExcretion}}
#' @examples
#' 
#' \dontrun{ 
#' calcOutput("EmisNitrogenPasturePast")
#' }
#' 


calcEmisNitrogenPasturePast<-function(method="IPCC"){
  
  if (method=="IPCC"){
    budget<-calcOutput("NitrogenBudgetPasture",aggregate = FALSE,deposition="CEDS")
    excretion<-dimSums(calcOutput("Excretion",aggregate=FALSE)[,,c("grazing","stubble_grazing")][,,"nr"],dim=c(3.1,3.3))
    # add emissions from fertilizer on pasture
    ef<-setYears(readSource("IPCC","emissionfactors",convert=FALSE),NULL)
    ef3_prp<-setYears(calcOutput("EF3prp",aggregate=FALSE),NULL)
    
    out <- dimSums(excretion*ef3_prp,dim=3.1)
    out<-add_dimension(out,nm = "pasture_soils",dim = 3.1)
    

  } else if (method %in% c("Nsurplus","Nsurplus2")){
    
    baseyear="y2005"
    
    # first iteration: calculate atmospheric deposition based on CEDS and estimate leaching
    # second iteration: calculate deposition based on Nsurplus and Oceans based on leaching    
    if(method=="Nsurplus2"){
      dep <- calcOutput("AtmosphericDeposition",aggregate=FALSE,cellular=FALSE,datasource="Nsurplus")
      budget<-calcOutput("NitrogenBudgetPasture",aggregate=FALSE,deposition="Nsurplus")
      method="Nsurplus"
    } else {
      dep <- calcOutput("AtmosphericDeposition",aggregate=FALSE,cellular=FALSE,datasource="CEDS")
      budget<-calcOutput("NitrogenBudgetPasture",aggregate=FALSE,deposition="CEDS")
    }
    
    # anthropogenic emissions ####
    emis <- calcOutput("EmisNitrogenPasturePast",method="IPCC",aggregate = FALSE)
    
    # Add indirect deposition emissions for N2O ####
    ef<-setYears(readSource("IPCC","emissionfactors",convert=FALSE),NULL)
    emis_dep <- dimSums(
      dep[,,"past"]
      ,dim=3) * ef[,,"ef_5"]
    emis[,,"n2o_n_direct"]<-emis[,,"n2o_n_direct"]+emis_dep
    
    # Add natural emissions ####
    emis_natural<-collapseNames(calcOutput("EmisNitrogenPreagriculture",aggregate=FALSE,deposition=FALSE)[,,"past"][,,c("n2_n","accumulation"),invert=TRUE])
    emis<-emis+emis_natural
    
    # add dinitrification ####
    emis_sum <- dimSums(emis,dim=c(3.1))
    
    n2<-setNames(budget[,,"surplus"]-dimSums(emis_sum,dim=3),"n2_n")
    n2[n2<0]<-0
    
    emis_sum<-add_columns(emis_sum,addnm = c("n2_n"),dim=3.1)
    
    emis_sum[,,"n2_n"]<-n2
    
    
    # Scaling emissions with surplus ####
    
    denitrification_shr = setNames(dimSums(emis_sum[,,c("n2o_n_direct","n2_n")],dim=c(1,3))/dimSums(budget[,,"surplus"],dim=c(1,3)),NULL)
    unscaled<-mbind(emis_sum[,,c("nh3_n","no2_n","no3_n")],
                    setNames(denitrification_shr*budget[,,"surplus"],"denitrification"))
    
    emission_shares<-setYears(unscaled[,baseyear,]/dimSums(unscaled[,baseyear,],dim=3),NULL)
    emission_shares_glo<-setYears(dimSums(unscaled[,baseyear,],dim=1,na.rm=TRUE)/dimSums(unscaled[,baseyear,],dim=c(1,3),na.rm=TRUE),NULL)
    emission_shares[which(dimSums(emis_sum[,,],dim=c(2,3))<0.001),,]=emission_shares_glo
    
    #distributing cropland surplus according to these shares.
    emissions<-collapseNames(budget[,,"surplus"])*emission_shares
    
    # assume globally same fraction of N2O in dentrification process. For comparison: Bessou et al comes to approximately 11%.
    # Bessou, C., B. Mary, J. Léonard, M. Roussel, E. Gréhan, and B. Gabrielle. 2010. “Modelling Soil Compaction Impacts on Nitrous Oxide Emissions in Arable Fields.” European Journal of Soil Science 61 (3): 348–63. doi:10.1111/j.1365-2389.2010.01243.x.
    emissions<-add_columns(x=emissions,addnm=c("n2o_n_direct","n2_n"),dim = 3.1)
    emis_n2on_share=sum(emis_sum[,baseyear,c("n2o_n_direct")])/sum(emissions[,baseyear,c("denitrification")])
    emissions[,,"n2o_n_direct"]=dimSums(emissions[,,c("denitrification")],dim=3.1)*emis_n2on_share
    emissions[,,"n2_n"]=dimSums(emissions[,,c("denitrification")],dim=3.1)*(1-emis_n2on_share)
    
    out<-emissions[,,"denitrification",invert=TRUE]
    out<-add_dimension(out,nm = "pasture_soils",dim = 3.1)
  }

  
  return(list(
    x=out,
    weight=NULL,
    unit="Mt Nr in various forms",
    min=0,
    description="Nitrogen emissions from pasture soils"))
}