CLaMS (Chemical Lagrangian Model of the Stratosphere) is a modular chemistry transport model (CTM) system developed at Forschungszentrum Jülich, Germany. 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 SCOUT-O3, and RECONCILE with a focus on simulating ozone depletion and water vapour transport.
Major strengths of CLaMS in comparison to other CTMs are
- its applicability for reverse domain filling studies
- its anisotropic mixing scheme
- its integrability with arbitrary observational data
- its comprehensive chemistry scheme
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Science Today: Nudibranchs | California Academy of Sciences
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El Sorprendente Mundo De Los Microorganismos DOCUMENTALES DE CIENCIA,DISCOVERY,NATIONAL GEOGRAPHIC
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Sedimentary Rocks
Transcription
(music) Have you ever thought of slugs as beautiful? Marine biologist Marta Pola does. Especially the ones called nudibranchs. She saw her first one on a college field trip to the south coast of Spain. They brought back from the sea a lot of different animals for the students to look at the surface and under the microscopes. There was when I saw my first sea slug moving under the microscope and I just fell in love for them. They were great-- it was moving around, very, very bright color, and I didn't know what was it? But I did know that I wanted to study them and if possible, to study them for a living. Nudibranchs, or sea slugs, are related to snails. Like them, they have a mouthpart called a radula-- it's rough surfaces studded with tiny teeth for scraping off bits of food. Nudibranchs eat sponges, jellies, crustaceans, and even other nudibranchs. But without a shell for protection, how do nudibranchs avoid becoming a meal themselves? The ones that eat jellyfish get something more than just food from their prey. The ones that feed on cnidarians like jellies-- jellies have stinging cells for defending themselves. But what nudibranchs do, is they are capable to acquire the stinging cells which are called nematocysts and they transform these nematocysts into a tiny sac that they have on the tip of their cerata. Predators that touch the cerata get a jolt when the stinging cells inside are released. And a nudibranch's brilliant colors and patterns aren't just pretty to look at. Those colors actually have a really important mission, which is to advertise to the predator that they are toxic. They are distasteful and they have poison. But Marta says that some nudibranchs can be a challenge to find. Not all nudibranchs have this spectacular coloration, but some of them actually are really difficult to find because they have colors that camouflage in the substrate in which they are found. And it's almost impossible to find-- we can spend almost all of a 60-minute dive just trying to find nudibranchs under a couple of rocks. With so many places to hide even nudibranchs with flashy colors are not always easy to see. Each time Marta goes to the Philippine Islands for her research, she isn't surprised to discover more new species. Actually, we went back to the Philippines and we found 97 species that were not known from the Philippines. Of these 97 species, at least 60 species were completely unknown to science. Because so much is unknown about their diversity and their importance in coral reef ecosystems, for Marta, the beauty of nudibranchs is more than just skin deep. Nudibranchs are interesting to study, not only because they are gorgeous and they are very diverse, they are very good indicators of the environment. They may also chemical compounds that could be useful in making pharmaceuticals. Maybe the cure for cancer is in one of these guys and it's sitting there waiting to be discovered.
CLaMS gridding
Unlike other CTMs (e.g. SLIMCAT, REPROBUS), CLaMS operates on a Lagrangian 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 path that an air parcels traces in space is called a trajectory. A specialised mixing scheme ensures that physically realistic diffusion is imposed on an ensemble of trajectories in regions of high wind shear.
CLaMS operates on arbitrarily resolved horizontal grids. The space coordinates are latitude, longitude and potential temperature.
CLaMS hierarchy
CLaMS is composed of four modules and several preprocessors. The four modules are
- a trajectory module
- a box chemistry module
- a Lagrangian mixing module
- 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 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, ERA-40
- United Kingdom Met Office (UKMO)
- 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
External links
References
The details of the model CLaMS are well documented and published in the scientific literature.
- Formulation of advection and mixing by McKenna et al., 2002a
- Formulation of chemistry-scheme and initialisation by McKenna et al., 2002b
- McKenna, Daniel S.; Konopka, Paul; Grooß, Jens-Uwe; Günther, Gebhard; Müller, Rolf; Spang, Reinhold; Offermann, Dirk; Orsolini, Y. (2002-08-27). "A new Chemical Lagrangian Model of the Stratosphere (CLaMS) 1. Formulation of advection and mixing" (PDF). Journal of Geophysical Research: Atmospheres. 107 (D16): ACH 15–1. Bibcode:2002JGRD..107.4309M. doi:10.1029/2000jd000114. ISSN 2156-2202.
- Comparison of the chemistry module with other stratospheric models by Krämer et al., 2003
- Calculation of photolysis rates by Becker et al., 2000
- Extension to 3-dimension model version by Konopka et al., 2004
- Lagrangian sedimentation by Grooß et al., 2005
This page was last edited on 3 January 2022, at 17:33