Clare Lee & Anthony Baran CAESAR sorties Clare Lee & Anthony Baran © Crown copyright 2005

CAESAR Cirrus and Anvils: European Satellite and Airborne Radiation measurements project Main Aims: Study radiative and in-situ cirrus (frontal or convective) properties to improve representation in models 2 Options: Multi-frequency radiative properties of cirrus In-situ microphysics for radar intercomparison © Crown copyright 2005

Coincident observations Want flights in conjunction with: Satellite A-train – AQUA (AIRS), CloudSat (Radar), Calipso (Lidar) CloudSat orbit = AQUA orbit + ~1min Foot print = 1.4km (across track) x (2.5km along track) and/or Chilbolton radar facility © Crown copyright 2005

Chilbolton 94GHz radar on steerable mount Lidar, 3GHz radar, 35GHz radar plus standard insts on stand-by Met Office person at Chilbolton – VHF radio contact © Crown copyright 2005

Chilbolton Flight restrictions Danger areas/controlled airspace Chilbolton – can fly directly overhead, but in restricted way © Crown copyright 2005

A-train (AQUA overpass) 16 day repeat cycle Chilbolton suborbital overpasses (1302Z): Friday 5th Jan Sunday 21st Jan Tuesday 6th Feb © Crown copyright 2005

A-train (AQUA overpass) Chilbolton suborbital overpasses (0222Z): Monday 8th Jan Wednesday 24th Jan Friday 9th Feb On website: www.metresearch.com/wintex Or internally on P: drive © Crown copyright 2005

Option1 - radiative studies of cirrus Conditions: Frontal or convective cirrus Over sea or Chilbolton Clear sky below Ideally coincident with satellite overpass: A-train & ENVISAT Requirements: Measurement of cirrus remote sensing from below and above cirrus + orbits (view towards cloud) In-situ microphysics (e.g. Lagrangian spiral or straight & level runs) Measurements of atmosphere above and below cloud aircraft profiles drop sondes remote sensing from below and above (view away from cloud) Sea surface temperature (100ft run) © Crown copyright 2005

Option 1 – Radiative properties Drop sondes at max alt orbits 100ft Runs perpendicular to wind Advect with air mass ARIES & SWS to look in same direction, typically towards cloud © Crown copyright 2005

Lagrangian spiral instead to S&L runs Advecting with wind To continuously measure same air mass Runs above cloud cirrus fallspeed ~2 ms-1 For 10kft (3km) @ 2 ms-1 Take 25 mins 266m Lagrangian spiral descent Fall with the ice: Growth rate and changes at different levels Runs below cloud © Crown copyright 2005 ~ 5 – 10 km

Instruments (radiation) Critical ARIES SWS SID1 2DC Temp Humidity AVAPS Desirable MARSS TAFTS * SHIMS CPI * SID2 FFSSP 2DP CIPs Heimann Core chem (auto) © Crown copyright 2005

Instrument operators ARIES and SWS ARIES SWS Both instruments must point in the same direction as each other (except during cal) Majority of time towards cloud (or sea at 100ft) However, still need some data pointing away to characterise the atmos above and below the cloud (e.g. ~2 mins of 10 min run) Orbits both view towards cloud for whole time ARIES If still unstable for zenith view (shutter open) at high altitudes better to get 30 secs of good data in a 10 min run (with rest of time with shutter closed viewing cals or nadir) than all bad data – let SWS know viewing direction. SWS Zenith = 6 deg forward © Crown copyright 2005

Option 2 – Radar intercompaison/validation Conditions: Frontal or convective cirrus Clear sky preferred but not essential Radar critical - Chilbolton and/or CloudSat Over sea if only CloudSat Requirements: In-situ statistical properties (saw-tooth manoeuvres) No advection with wind Drop sondes Low remote sensing inst requirement N.B. Chilbolton – 94GHz steerable, all others zenith © Crown copyright 2005

CAESAR – radar intercomparison CloudSat wind Top view Chilbolton Trailing edge with Cu behind cirrus Leading edge Side view © Crown copyright 2005

CAESAR – radar intercomparison Side view Top view CloudSat Trailing edge with Cu behind Leading edge top base cirrus No advection – statistical sampling wind © Crown copyright 2005

Instruments (in-situ) Critical SID1 2DC 2DP CPI * FFSSP Temp Humidity Desirable SID2 CIPs AVAPS ARIES SWS MARSS TAFTS * SHIMS Heimann Core chem (auto) © Crown copyright 2005

Questions © Crown copyright 2005