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= The CLaMS sedimentation module sedi =

==  The program sedi ==

The program sedi calculates the trajectories of individual
NAT-particles. Horizontal motion is given from the wind fields whereas
vertical motion (sedimantation) is calculated from the settling
velocity of the particles. Dynamical uptake and release of HNO3
from/into the gas phase are calculated. For that the output for the
nearest neighbors of the chemistry simulation is interpolated to the
particle trajectory locations. The HNO3 field in the chemisty output
file is then adjusted according to Denitrification and
Renitrification.


== Update of programm sedi (March 2012) ==

The program sedi was updated in March 2012 to adapt to new developments of CLaMS

 * Integraton of the NAT nucleation (pos_sedi) into the sedi programme
 * Usage of the identical vertical (zeta) levels defined by pos_area for the air parcels
 * Definition of a factor giving the ratio of nucleated particle parcels per air parcels
 * Possibility to include a complex parametrisation of NAT nucleation rates developed by Ines Engel (ETHZ)




== Input files ==

The program sedi needs the following input files with the information of the particles:

The first '''sedi.nc''' is the last days' output and contains position and parameters of the NAT accumulated surviving particles. 

To run the model, one further needs the file '''bgr_sedi.nc''' that contains  hourly HNO3 and H2O output for the chem simulation.

From the '''init*.nc''' file, the vertical grid and the numbers of air parcels per grid '''of the first day of simulation''' is read. 
This is needed to adapt for changes in the number of air parcels in a level over the course of the simulation.

The file '''sedi.inp''' controls the run of sedi and includes all necessary files.

The file '''add_sedi.nc''' (output of pos_sedi) in not needed anymore. 

Changes of HNO3 will be written into the '''chem*.nc''' file. If present, the maximum NAT supersaturation SNATmax and the corresponding temperature Tmin can be read in to define the NAT nucleation rate after Ines Engel et al.

==  The (old) program pos_sedi 	 (now unnecessary) ==

The programm pos_sedi creates a set of newly nucleated particles equally 
distributed over the area where T < T_NAT. 

Levels and resolution are comparable to the program '''pos_area'''

It is advised to use this for particle nucleation as the positions
should be independent of the positions of the CLaMS air parcels.

An effective nucleation rate must be calculated from the ratio of 
particle parcels per air parcel.

=== Examples for Resolution/Aspect Ratio (Grooß et al., 2005, Winter 2002/03): ===

|| CLaMS    || Resolution pos_sedi|| NAT desity[m^-3]||Nucleation Rate||
||100km/250 || 66.7km/300 || 47 || 7.8×10−6 cm−3 h−1||
||	    || || 20 ||3.3×10−6 cm−3 h−1||