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CLaMS (Chemical Lagrangian Model of the Stratosphere) is a modular chemistry transport model (CTM) system developed at Research Centre Jülich
Jülich Research Centre

Forschungszentrum J?lich GmbH is a member of the Helmholtz-Gemeinschaft or Hermann von Helmholtz Association of National Research Centres and is one of the largest interdisciplinary research centres in Europe....
, Germany
Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
. CLaMS was first described by McKenna et al (2000a,b) and was expanded into three dimensions by Konopka et al (2004). CLaMS has been employed in recent European field campaigns THESEO, EUPLEX, TROCCINOX and SCOUT-O3 with a focus on simulating ozone depletion
Ozone depletion

Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total volume of ozone in Earth stratosphere since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period....
 and water vapour transport.

Major strengths of CLaMS in comparison to other CTMs are
  1. its applicability for reverse domain filling studies
  2. its anisotropic mixing scheme
  3. its integrability with arbitrary observational data
  4. its comprehensive chemistry scheme


CLaMS gridding
Unlike other CTMs (e.g.






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CLaMS (Chemical Lagrangian Model of the Stratosphere) is a modular chemistry transport model (CTM) system developed at Research Centre Jülich
Jülich Research Centre

Forschungszentrum J?lich GmbH is a member of the Helmholtz-Gemeinschaft or Hermann von Helmholtz Association of National Research Centres and is one of the largest interdisciplinary research centres in Europe....
, Germany
Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
. CLaMS was first described by McKenna et al (2000a,b) and was expanded into three dimensions by Konopka et al (2004). CLaMS has been employed in recent European field campaigns THESEO, EUPLEX, TROCCINOX and SCOUT-O3 with a focus on simulating ozone depletion
Ozone depletion

Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total volume of ozone in Earth stratosphere since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period....
 and water vapour transport.

Major strengths of CLaMS in comparison to other CTMs are
  1. its applicability for reverse domain filling studies
  2. its anisotropic mixing scheme
  3. its integrability with arbitrary observational data
  4. its comprehensive chemistry scheme


CLaMS gridding


Unlike other CTMs (e.g. SLIMCAT, REPROBUS), CLaMS operates on a Lagrangian
Lagrangian

The Lagrangian, , of a dynamical system is a function that summarizes the dynamics of the system. It is named after Joseph Louis Lagrange. The concept of a Lagrangian was originally introduced in a reformulation of classical mechanics known as Lagrangian mechanics....
 model grid (see section about model grids in general circulation model): an air parcel is described by three space coordinates and a time coordinate. The time evolution
Time evolution

Time evolution is the change of state brought about by the passage of time, applicable to systems with internal state . In this formulation, time is not required to be a continuous parameter, but may be discrete time or even wiktionary:finite....
 path that an air parcels traces in space is called a trajectory
Trajectory

Trajectory is the path of a moving object that it follows through space. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit - the path of a planet, an asteroid or a comet as it travels around a central mass....
. A specialised mixing scheme ensures that physically realistic diffusion
Diffusion

Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion....
 is imposed on an ensemble of trajectories in regions of high wind shear
Wind shear

Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind wind speed and wind direction over a relatively short distance in the Earth's atmosphere....
.

CLaMS operates on arbitrarily resolved horizontal grids. The space coordinates are latitude
Latitude

Latitude, usually denoted symbolically by the Greek letter phi gives the location of a place on Earth north or south of the equator. Lines of Latitude are the horizontal lines shown running east-to-west on maps ....
, longitude
Longitude

Longitude , symbolized by the Greek character lambda , is the geographic coordinate most commonly used in cartography and global navigation for east-west measurement....
 and potential temperature
Potential temperature

The potential temperature of a Air parcel of fluid at pressure is the temperature that the parcel would acquire if Adiabatic process brought to a standard reference pressure , usually 1000 millibars....
.

CLaMS Hierarchy


CLaMS is composed of four modules and several preprocessors. The four modules are
  1. a trajectory module
  2. a box chemistry module
  3. a Lagrangian mixing module
  4. a Lagrangian sedimentation scheme


Trajectory module

Integration of trajectories with 4th order Runge-Kutta method, integration time step 30 minutes. Vertical displacement of trajectories is calculated from radiation budget.

Box chemistry module


Chemistry is based on the ASAD chemistry code of the University of Cambridge. More than 100 chemical reactions involving 40+ chemical species are considered. Integration time step is 10 minutes, species can be combined into chemical families to facilitate integration. The module includes a radiative transfer model for the determination of photolysis rates. The module also includes heterogeneous reactions on NAT, ice and liquid particle surfaces.

Lagrangian mixing

Mixing is based on grid deformation of quasi uniform air parcel distributions. The contraction or elongation factors of the distances to neighboring air parcels are examined: if a critical elongation (contraction) is reached, new air parcels are introduced (taken away). This way, anisotropic diffusion is simulated in a physically realistic manner.

Lagrangian sedimentation


Lagrangian sedimentation is calculated by following individual nitric acid trihydrate (NAT) particles that may grow or shrink by the uptake or release of HNO3 from/to the gas phase. These particle parcels are simulated independently from the Lagrangian air parcels. Their trajectories are determined using the horizontal winds and their vertical settling velocity that depends on the size of the individual particles. NAT particles are nucleated assuming a constant nucleation rate and they evaporate where temperatures grow too high. With this, a vertical redistribution of HNO3 (denitrification and renitrification) is determined.

CLaMS data sets


A chemical transport model
Chemical transport model

A chemical transport model is a type of computer simulation which typically simulatesatmospheric chemistry ....
 does not simulate the dynamics of the atmosphere. For CLaMS, the following meteorological data sets have been used
  • European Centre for Medium-Range Weather Forecasts (ECMWF), Predictions, Analyses, ERA-15, ERA40
  • United Kingdom Meteorological Office (UKMO
    UKMO

    UKMO may refer to* The Met Office * The proposed UK Music Office in New York ...
    )
  • European Centre Hamburg Atmospheric Model (ECHAM4), in the DLR version


To initialize the chemical fields in CLaMS, data from a large variety of instruments have provided data.
  • on satellite (CRISTA, MIPAS, MLS, HALOE, ILAS, ...),
  • on aircraft and balloons (HALOX, FISH, Mark IV, BONBON...)


If no observations are present, the chemical fields can be initialised from two-dimensional chemical models, chemistry-climate models, climatologies, or from correlations between chemical species or chemical species and dynamical variables.

See also


  • Forschungszentrum Jülich
  • Ozone depletion
    Ozone depletion

    Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total volume of ozone in Earth stratosphere since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period....
  • Meteorology
    Meteorology

    Meteorology is the interdisciplinary scientific study of the Earth's atmosphere that focuses on weather processes and forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century....


External links


  • [https://scout-o3.icg.kfa-juelich.de/SCOUT-O3/SCOUT-O3 Current field campaign SCOUT-O3]