**Protocol Further Details on AeroCom protocol**

**WHAT
WE ABSOLUTELY NEED FROM AEROCOM MODEL CONTRIBUTORS**

=======================================================

1) Enough info on your model grid (area and vertical coordinate
info)

to reconstruct budgets, zonal plots and area means

Communicate with us on the vertical grid info available for
your model.

2) Info on any specific deviation from the protocol and/or
units given there.

Establish a corresponding ascii list.

3) Info on exact
units for Sulfur and Carbon compound

We prefer kgS and kgC instead of kg !!!

Please indicate also the Carbon-to-ParticulateOrganicMatter
conversion factor.

4) Additional info
on Sulfur/Sulfate emissions

Did you include gas-phase and liquid-phase sulfur production?

What do you mean by "emission of SO4"?

See also new suggestions in protocol-addup for differentiating
emissions

5) Info on eventual
Carbon or Sulfur production terms above surface level.

6) A check on whether
you did use the unit of kg/m2 (or eventually kg/kg or kg/m3)
for

Monthly vertical resolved dry mass loads etc.

Did you use kg/m2/*month?* (...we will take care of
correcting for months of different length!)

7) **Aerosol
optical depth per species for aerosol internal mixtures**

A check on how you compute the contribution of a given aerosol
species to total aerosol optical depth if you have internal
mixtures in the model:

Procedure recommended
during AEROCOM workshop: Compute volume fraction of aerosol
species in aerosol particle volume (without water!!) and retrieve
with that fraction the aerosol optical depth for a given species.
Apply the following densities for the major species (Dust
= 2650 kg/m3 / Sea salt = 1600 / Sulfate = 1769 / Black Carbon
= 1500 / Particulate organic matter = 1500 )

**WHAT
WE WISH TO HAVE FROM FROM AEROCOM MODEL CONTRIBUTORS**

=======================================================

( we recognise that this might not be possible within your
time frame)

1) A list of your
variable names (which correspond to protocol variables),

(at best put into the excel file of the protocol, see above)

2) That you apply
the protocol_addup to experiment B

and also to experiment A (if possible)

3) Further info
on your model

Is there a model website to connect to?

Info on aerosol dynamics, transport and removal process formulation.

(Stefan Kinne will collect the info and produce overview tables)

**For
info: How processing of model data files is done**

=======================================================

NCO data pre-processing

========================

Your variables are renamed by an nco script to fit our nomenclature
(see protocol),

(NCO web site
!!)

NCO commands are
also used to produce eg annual or monthly averages.

The indexing of
the model grid is different for different model,

this is taken care of by these scripts.

IDL pre-processing:

========================

A setup routine is prepared for each model.

Any variable not having the units asked for in the protocol
is converted.

Please find details on the calculations below.

Sometimes arrays need to be transposed to fit idl-array conventions.

IDL Calculations

========================

Columnload

----------

From the 3D Field of Load [kg/m2]: Sum over the height

Columnload=Sum_height(Load)

Some of you have
given a 3D Conc field instead of a 3D Load field.

From the 3D Field of Conc [kg/m3]: Integration over the height

Load=Integral_height(Conc*dh)

Concentrations

--------------

conversion from 3D Field of Load [kg/m2] to 3D field of Conc
[kg/m3]:

multiplication with the grid box height dh: Conc=Load*dh

conversion from
Conc to mass mixing ratio MMR: division with density of air
rho

MMR=Conc/rho

Means

-----

Load [kg/m2]: area weighted mean

Load_Mean=Sum(Load*area)/Sum(area)

Conc [kg/m3]: volume
weighted mean

Conc_Mean=Sum(Conc*volume)/Sum(volume)

Mass Mixing Ratio
MMR [kg/kg]: mass weighted mean

MMR_Mean=Sum(MMR*airmass)/Sum(airmass)

Volume Mixing Ratio
VMR [m3/m3]: volume weighted mean

VMR_Mean=Sum(VMR*volume)/Sum(volume)

Budgets

-------

Calculation of total load load_tot and fluxes flux_tot in
the model domain

load_tot=sum(load*area)

flux_tot=sum(flux*area)

height of a grid box dh [m] to calculate the volume from area
and height

------------------------------------------------------------------------

dh can be calculated from dh=pdel/rho/g

where pdel is a 3D field of the pressure gradient of the grid
box,

rho a 3D field of the density [kg/m3],

g the gravity constant 9.81

rho can be derived
from rho=pmid/temp/287

where pmid is a 3D field of the pressure of the grid box [Pa],

temp a 3D field of the temperature [K]

mass per grid box

-----------------

airmass can be calculated from airmass=pdel/g*area

where pdel is a 3D field of the pressure gradient of the grid
box,

area is a 2D field of area of grid box [m2]

g the gravity constant 9.81

horizontal cross sections at certain pressure levels or vertical
cross sections of 3D fields

------------------------------------------------------------------------

For these plots we need vertical information on grid.

pmid pressure the
grid cell center [Pa]

for sigma-p-coordinates pmid=sigma*(p_surf-p_top)+p_top

for hybrid sigma-p-coordinates phalflevel= Ak + Bk*p_surf

height h [m] (optional)

h can be derived from h(k)=h(k-1)+dh where k is the model
level index

the height h0 of the lowest level (orogrophy) needs to be
known

**For
info: Review of equivalent formulations to obtain grid info**

=======================================================

area

----

2D field of area of grid box [m2]

height of a grid box (to calculate the volume from area and
height)

--------------------

3D field dh height of a grid boxes [m]

or 3D field of
the pressure gradient of the grid box pdel [Pa],

3D field of the density rho [kg/m3],

or 3D field of
the pressure gradient of the grid box pdel [Pa],

3D field of the pressure in the grid box pmid [Pa],

a 3D field of the temperature [K]

airmass

-------

3D field airmass of grid box [kg]

or 3D field of
the pressure gradient of the grid box pdel [Pa],

3D field of the temperature temp [K]

pressure

--------

3D field of pressure [Pa]

for sigma coordinates

or 3D field of sigma

2D field of surface pressure [Pa]

2D field of top pressure [Pa]

for sigma-pressure-hybrid
coordinates ???

height (optional)

------

3D field of height [m]

or 3D field of height of surface level h0 [m]