OBR: Cloud Physics Research Phil Brown 11/12/12

Table of Contents Who we are and what we do Future activities: Coming soon to a field campaign near you....... Key instruments

Who we are – with 1st field campaigns  http://www.metoffice.gov.uk/research/foundation/observational-studies/cloud-physics Phil Brown First flight H335 RICO Steve Abel Richard Cotton INTACC Paul Barrett VOCALS Kirsty McBeath CONSTRAIN

What we do Ice-phase cloud processes deposition and aggregation growth (CONSTRAIN, PIK&MIX) ice nucleation Altitude Development of parametrizations of key microphysical processes drizzle / rain fallspeed aerosol activation and cloud droplet number ice crystal mass vs. size ice crystal fallspeed vs. size Mixed-phase cloud processes (CONSTRAIN, PIK&MIX) Altostratus structure and dynamics maintenance of supercooled water layers – turbulence / ice nucleation) Cold-air outbreak convection cellular structures and stratiform cloud breakup Observation comparisons with high-resolution model simulations Unified Model LES KiD Warm-cloud microphysics Aerosols and droplet numbers (VOCALS, COALESC) Drizzle and rain (RICO, VOCALS, COALESC) Temperature

Obtaining ice particle model parameters with in-situ aircraft observations Often requires unique flight path. Lagrangian descent following an evolving population of ice particles falling through the depth of cirrus. Measure just nucleated small ice crystals near top, to large snow aggregates near base. Extract directly from observations, model parameters that define the ice particle fall-speed as a function of size.

Ice bulk density as a function of particle size. Test current UM ice density function. Nevzorov TWC bulk water ‘truth’ Integrate PSD (with trial density) to derive predicted IWC. Improved ice density via mass-dimension relation: m(D)=0.0257 D2.0 for D>70μm Constant density 0.7 g cm-3 for D<70μm © Crown copyright Met Office

Future field campaigns COPE – Convective Precipitation Experiment (Jul/Aug 2013) Prestwick (Nov/Dec 2013) ICE-D – Ice in Clouds Experiment – Dust (Summer 2015?) NAMSTRABBA – Namibian Stratocumulus and Biomass-Burning Aerosols (Autumn 2015?)

Aims of COPE To study the production of precipitation in organized convective systems over SW England To improve the exploitation of data used for operational assimilation To improve the representation of microphysical processes in operational km-scale NWP Leading to the improvement of quantitative precipitation forecasts

COPE Background: Boscastle floods, 16 Aug 2004 Meteosat, high-res visible 1530Z 1130Z Convergence line over N.Cornwall Downdrafts triggering new convection 1330Z 1530Z

COPE Background: Boscastle floods, 16 Aug 2004 Golding et al COPE Background: Boscastle floods, 16 Aug 2004 Golding et al., 2005, Weather High accumulations resulted from intensity and duration of precipitation Slow-moving cells organized in along-wind lines These were not spectacular convective clouds – tops probably reaching -15 to -20C Significant involvement of both warm-rain and ice-phase processes New convection triggered by downdrafts

COPE Observations: What stuff? FGAM transportable X-band Doppler radar FAAM Plus: MO network radars (with dual-polarization and Doppler capability) additional radiosondes (Camborne and MRU mobile) Doppler lidar (MRU van) aerosol surface site (including our INCounter...) U.Wyoming King Air with WCR/WCL

Other campaigns Prestwick Nov/Dec 2013 ICE-D Summer 2015 Ice cloud characterisation in support of ISMAR Ice- and mixed-phase clouds around UK ICE-D Summer 2015 Cape Verde Mineral dust ice nucleation and impacts on convective clouds NAMSTRABBA Autumn 2015 Namibia Biomass-burning aerosols and impacts on stratocumulus

Key instruments IN counter TWC probe continuous-flow diffusion chamber currently under development TWC probe still a unique way to measure a variable that is conserved in the absence of precipitation CVI - Counterflow Virtual Impactor to provide alternative source of bulk ice mass to sample ice crystal residuals Microphysics suite Nevzorov – bulk water AIMMS-20 Winds / turbulence in supercooled clouds

Questions and answers