GLOMAP MnP Representation

TL;DR

                               +------------------------------------------+
                               |             Nucleation Mode              |
                               +------------------------------------------+
                               |                                          |
                               |             (No MPs allowed)             |
                               | MPs not emitted here due to size (>5 µm) |
                               |                                          |
                               +------------------------------------------+
                                             |                      |

                                            \|/                    \|/
                                      +-------------+          +----------+
                                      |  Fragments  |          |  Fibers  |
                                      +-------------+          +----------+
                                             |                      |

                                             |       emittion       |

                            +- - - - - - - - + - - - - - - - -+     |

                            |                                 |     |

                           \|/                               \|/   \|/
+-------------------------------------------------------------------------+
|                          Insoluble Modes                                |
+-------------------------------------------------------------------------+
|                                                          |              |
|         coagulation                 coagulation          |              |
| Aitken -------------> Accumulation -------------> Coarse | Super-Coarse |
|            growth                      growth            |              |
|                                                          |              |
+----------------------------------------------------------+--------------+
                            |

                            |
            aging / condensation (soluble coating)
                            |

                           \|/
+----------------------------------------------------------+
|                       Soluble Modes                      |
+----------------------------------------------------------+
|                                                          |
|         coagulation                 coagulation          |
| Aitken -------------> Accumulation -------------> Coarse |
|            growth                      growth            |
|                                                          |
+----------------------------------------------------------+

Figure 1. Scheme of the GLOMAP MnP representation. (Check Terminology for definitions of modes and MnP particle types) In UKESM1.1, microplastics are added to GLOMAP as fragments and fibres. Fragments enter all insoluble modes (except nucleation); fibres only the super-coarse mode. Fragments can age into soluble modes. All particles undergo dry and wet deposition.

Explanation

• Emission: MPs are emitted directly into all insoluble modes except nucleation.

• Super-coarse insoluble mode has no pathway to soluble modes via aging.

• Aging process: Involves accumulation of soluble species (e.g., sulfate) forming 10+ monolayers, enabling CCN activation.

• Coagulation occurs across modes and alters particle size and lifetime.

• Deposition: All modes are subject to dry and wet deposition.

  • Soluble particles are more efficiently removed via wet deposition due to CCN activation.

• Limitations: Fibres currently modeled as spherical, which underrepresents their atmospheric lofting. This is a known area for future improvement.

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