Description & code

 

Forcing and initialisation of the model

 

Deposition of Fe and Si from dust
The DGOM PlankTOM5 uses monthly iron deposition values ( Jickells et al. 2005) as input in kg dust /m2/s ( NetCDF 1°×1°). We assume there are 0.035 g of iron per g of dust (NetCDF ORCA2). The solubility of Fe in water is set in the namelist of the model (0.01). We assume there are 0.308 g Si per g dust. The solubility of Si is set to 0.075. Variables irondep and sidep are in mol/L/time_step for Fe and Si, respectively. The molecular weights of Fe and Si are 55.85 and 28.01, respectively.

Atmospheric deposition of N
Transient simulations with increasing atmospheric N deposition were performed (Jickells et al. 2017). Inorganic N (NOy and NHx) were provided by Lamarque and Lindsay. DON was provided by Kanakidou. N that was recycled from the ocean (emitted to the atmosphere and subsequently redeposited to the ocean) was removed. DON is available for individual years only. 1850 deposition was used until 1950. Deposition after 1950 was interpolated linearly between the earlier and later years. Both inorganic and organic N were interpolated linearly dayly between the values for the middle of each month. (NetCDF on original grids). In the PlankTOM model NOy was added to ocean NO3, and NHx and DON were added to ocean NH4. DON was not added to ocean DOM, because that would entail addition of DOC and DOP that was not wanted. (NetCDF ORCA2).

Input of nutrients and carbon from rivers
River input of NO3, PO4, SiO3, DIC, Fe (including Fe in DOM), DOC, POC, and POFe (download on the ORCA2 grid, or on the DDM30 grid (0.5 °)). This file is described in da Cunha et al. (2007).

Gas exchange with the atmosphere
Gas exchange of CO2 and O2 is calculated according to Wanninkhof et al (1992), correcting for 100% water vapor according to Sarmiento et al. JGR (1992).

The model is initialised with GLODAP observations of DIC, AlkalinityWorld Ocean Atlas 2009 NO3, PO4, SiO3, O2.
For the "biological" state variables we use the output of the previous model version:
Download restart files on the ORCA2 grid for 1948 from our OpenDAP server.

We force the model with NCEP reanalysis. The forcing files have been produced from data downloaded from the NOAA Earth System Research Laboratory. The data have been interpolated to the required grid using the INTERP tool which was downloaded from Laboratoire d'Océanographie Dynamique et de Climatologie.

  • for each YEAR: file ncep_bulk_YEAR.nc contains daily values for
    model variable NetCDF variable description units
    tatm air mean Daily Air temperature at 2 m degrees C
    hatm humidity mean Daily Humidity (see below) -
    vatm wspd mean Daily Windspeed at 10 m m/s
    catm cloud daily mean Total cloud cover -
    watm rain mean Daily Precipitation Rate kg/m2/s
  • for each YEAR: file taux_1d_YEAR.nc
    for each YEAR: file tauy_1d_YEAR.nc
    contain daily values for
    taux uflx Zonal wind stress N/m2
    tauy vflx Meridional wind stress N/m2
  • averaged : file /esdata/env/e031/Input/runoff_1m_nomask.nc contains monthly values for
    sorunoff sorunoff freshwater input from rivers and ice kg/m2/s
In NEMO, humidity is calculated offline:
The humidity values are calculated from the specific humidity at 2m (shum) using the following relationship:
humidity = (shum*pres)/(.622 +.378*shum/sat_p)
where:
pres is the air pressure and sat_p = 611*10(7.5(T-273.15)/(T-35.86))
In OPA8, the forcing files contained the specific humidity at 2m, the air temperature at 2 m (T), and the air pressure, and humidity was calculated online.

Download forcing files onwards on the ORCA2 grid from our OpenDAP server

The NEMO GCM is initialised with temperature and salinity from WOA 2009.
The LIM ice model is initialised with ice cover fraction, ice thickness and snow thickness from GIOMAS.
Download restart files on the ORCA2 grid for 1948 from our OpenDAP server.

 

Results

 

Internal

 

Documentation stored on ADA (UEA login required)