Brief Description

Climate Models used by UKCA

The UKCA model runs within the Hadley Centre version of the Unified Model. There are a number of different versions of this climate model at a number of resolutions which are used for UKCA development.

UM Version	Model	Horizontal Resolution	Vertical Levels	Model Top	Scheme Used
6.1	HadGAM1a	N48 (2.5°×3.75°)	L60	~84km	Tropospheric Chemistry
6.1	HadGAM2	N48	L60	~84km	Stratospheric Chemistry
6.6.4	HadGEM2-ES	N96	L38	~40km	Hadley Centre Earth System Model
7.1	HadGEM3-A	N96 (1.25°×1.875°)	L38	~40km	Tropospheric Chemistry
7.3	HadGEM3-A r2.0	N96	L38	~40km	Tropospheric Chemistry
7.3	HadGEM3-A r2.0	N96	L63	~40km	Tropospheric Chemistry
7.3	HadGEM3-A r2.0	N96	L85	85km	Stratospheric Chemistry
7.3	HadGEM3-A r2.0	N48	L60	~84km	Stratospheric Chemistry
7.3	HadGEM3-AO r2.0	N48	L60	~84km	QUEST Earth System Model

UKCA: Currently Available Chemistry Schemes

• Standard Tropospheric Chemistry
• Tropospheric Chemistry with Isoprene
• Extended Tropospheric Chemistry (ExtTC)
• Regional Air Quality (RAQ) Chemistry
• Standard Stratospheric Chemistry
• Chemistry of the Stratosphere and Troposphere

UKCA Aerosol Scheme: GLOMAP-mode

• Brief summary of GLOMAP-mode: global size-resolved aerosol microphysics
• GLOMAP-mode in UKCA linked to Tropospheric Chemistry (StdTrop)
• GLOMAP-mode in UKCA linked to Tropospheric Chemistry (IsopTrop)
• GLOMAP-mode in UKCA linked to Stratospheric Chemistry (StratChem)
• GLOMAP-mode in UKCA linked to whole-atmosphere chemistry (CheST)
• Direct effect from GLOMAP-mode aerosol to the Edwards-Slingo radiation scheme
• First indirect effect from GLOMAP-mode aerosol to the Edwards-Slingo radiation scheme

Nudging

• Description of the nudged version of UKCA: This describes the nudged version of the model which is constrained to meteorological analysis data, allowing hindcasts and comparisons to episodic data-sets.

UKCA Development Timeline

If you are interested in using UKCA, and there is a particular piece of functionality that you would like or need, but are not sure if it is available, please contact Luke Abraham for further information.

Short-Term Development

• Stratospheric Chemistry at UM7.3 HadGEM3-A (N96L85 and N48L60) - Luke Abraham
• ASAD Flux Diagnostics at UM7.3 - Luke Abraham
• Improved representation of isoprene oxidation at UM6.1 - Alex Archibald
• Chemistry of Stratosphere and Troposphere - CheST at UM7.3 - Alex Archibald
• Flight track emulator to compare to campaign data at UM7.3 - Paul Telford
• Fast-JX photolysis code validation at UM7.3 - Paul Telford
• Emissions Profiling from ExTC at 7.3- Paul Telford & Maria Russo
• Interactive biogenic emissions from ExTC at 7.3- Paul Telford

Medium-Term Development

• HadGEM3-AO UKCA - Luke Abraham
• Satellite emulator, including averaging kernels, to improve validation at UM7.3 - Paul Telford
• Couple mode aerosols and fast-jx code at UM7.3 - Paul Telford and ?
• Shift UKCA emissions from Section 0 (user-defined) to Section 34 - Mohit Dalvi Sec34 emissions
• Extend Weseley scheme dry deposition to match 2D scheme - Paul Telford

Long-Term Development

• Coupled UKCA Stratosphere-Troposphere Chemistry with MODE

UKCA: Model Outline

Development of UKCA consists of the following subprojects:

Tropospheric model development

• HadGEM3 at N96L63 and HadGEM2-ES at N96L38
• Tropospheric Configuration of UKCA (Fiona M. O’Connor)

Stratospheric model development

• HadGEM3 at N96L85/N48L60
• Coupled stratospheric chemistry

Aerosols

• New aerosol species and microphysics
• Aerosol chemistry
• Integrated Climate Programme report (Mar10) comparing CLASSIC and GLOMAP-mode in HadGEM3File:ICP reportM3 2v3.pdf.
• Integrated Climate Programme report (Mar11) describing latest UKCA developments for HadGEM3File:UKCA ICP Mar11.pdf.
• Scoping document for HadGEM3 recommends including GLOMAP-mode in UKCA for HadGEM3File:HadGEM3ES scoping v1.1.pdf.
• Coupling of GLOMAP-mode aerosol to UM radiation scheme File:UKCA RADAER.pdf.

Aerosols Cloud Coupling

Aerosol Cloud Coupling: the modal UKCA scheme [Mann et al., 2010] has been coupled by Oxford and the MetOffice to the PC2 cloud scheme [Wilson et al., 2008] via an explicit Köhler theory based activation scheme [Abdul-Razzak & Ghan, 2000].

• Features:
  • Sub-grid scale probability density function for updraft velocities coupled to turbulent kinetic energy
  • Coupling to cloud radiative properties (i.e. cloud albedo effects)
  • Coupling to precipitation formation scheme (i.e. cloud lifetime effects)
• Publications:
  • West et al. (in preparation)

New features

• Coupled chemistry, aerosols and climate model
• Based on new dynamics
• Combined troposphere-stratosphere chemistry
• Improved aerosol microphysics and chemistry
• Capability to interact with surface, radiation and biosphere
• Modular structure