UK COPS: Convection and Transport in Complex Terrain CATICT

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UK COPS Convection and Transport in Complex
Terrain (CATICT)
Alan Blyth and Stephen Mobbs
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Layout of CATICT Instruments
Valley
Rhine
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What Don't We Understand?

• How to accurately predict thermally driven flows.
  The fluid dynamics is represented reasonably well
  but the crucial surface exchanges of heat and
  moisture which drive the flow are not.
• How deep convective cells interact with the
  boundary layer and therefore how does air get
  drawn up into deep convective cells over the
  mountains?
• How biogenic and anthropogenic aerosols regulate
  the growth activation of cloud condensation
  nuclei ice nuclei and thereby control clouds
  and precipitation.
• How does deep orographic convection influence
  regional scale redistribution of aerosols
  chemical species?

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CATICT Questions and Objectives
How do orographic flows generate the horizontal
convergence necessary for development of deep
convective cells? OBJ1 To quantify the inflow to
orographically-locked convective cells along two
lines, one along a valley in the mountain range
(the valley route) and one directly over the
mountains (the direct route), following the
evolution through the life-cycles of the
cells. OBJ2 To quantify the relative roles of
valley and non-valley inflows in
orographically-locked convective cells over a
range of tropospheric conditions (stability, wind
structure) and through the life-cycles of the
cells. OBJ3 To determine the factors controlling
whether anabatic up-valley and up-mountain-range
flows are trapped or penetrate the free
troposphere. OBJ4 To determine the critical
factors (e.g. surface fluxes, resolution,
stability) affecting the ability of the Met
Office UM to reproduce the observed inflows to
orographically-locked convection.
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CATICT Questions and Objectives
How are aerosols and short-lived chemical species
lifted by these orographic flows from the surface
into the free troposphere in complex
terrain? OBJ5 To quantify the boundary-layer
fluxes of aerosols into orographically-locked
convective cells through the valley and direct
routes. OBJ6 To determine the role of
boundary-layer convective elements (thermals,
detrainment mechanisms, clouds) in mixing
aerosols into the free troposphere. OBJ7 To
determine the factors affecting the ability of
the Met Office UM to reproduce the observed
fluxes of aerosols and chemical species into
orographically-locked convection. OBJ8 To
determine the evolution of both short and
long-lived chemical species (e.g. isoprene,
ozone) in the convective boundary layer and to
relate these to air mass history.
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CATICT Questions and Objectives
How does the orographic convection and
precipitation depend on aerosols and the
microphysics and dynamics of the clouds? OBJ9 To
quantify the aerosol distributions and
composition in cloud inflow and in the cloud
environment which are needed for cloud models.
OBJ10 To determine the important microphysical
and dynamical processes responsible for the
development of precipitation in the orographic
clouds. OBJ11 To test the ability of cloud
resolving models to reproduce the observed cloud
microphysics, dynamics and precipitation and the
response of these to the variability in measured
aerosol properties. OBJ12 To determine, by
comparing models with observations, how the
orographic cumulus congestus clouds process the
aerosols, thereby influencing the aerosols
ingested into the clouds.
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CATICT Questions and Objectives
What influence do orographically-locked
convective systems have on the regional-scale
redistribution of aerosols and chemical species
and hence on the further development of
precipitation and air quality? OBJ13 To quantify
the concentrations of aerosols and trace chemical
species upwind and downwind of orographic
convection in the free troposphere. OBJ14 To
determine the factors affecting the ability of
the Met Office UM to reproduce the
upwind--downwind changes in aerosol concentration
across orographic convection.
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Possible CATICT Instruments
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FAAM BAe 146 Aircraft
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FAAM BAe 146 Aircraft Instruments
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