Cirrus Coupled Cloud- Radiation Experiment: Juliet Pickering, Jonathan Murray, Alan Last, Cathryn Cox, Helen Brindley Keith Bower, James Dorsey, Ian Crawford Joseph Ulanowski, Chris Stopford, Jenna Thornton Anthony Baran – cirrus modelling ? (Stuart Newman) – ARIES mid IR 1

Overall goals: to understand the link between evolving ice cloud microphysical properties and the resulting radiative signatures of the cirrus, at the macrophysical scale, as seen from a remote sensing platform. an accurate parameterisation of cirrus optical properties in global climate modelling and NWP 2

Campaign objectives Radiative closure cirrus cloud-radiation experiments in northern and mid latitudes. 3 campaigns: Prestwick Nov ‘13, Goose Bay April ‘14, Prestwick winter ‘14/ ’15 radiance measurements μm from above, below and within an extensive layer of well developed cirrus. RH, T of column above and below cirrus Map the ice crystal particle size distribution, habit types and crystal complexity (including roughness, concavity etc) within cirrus layer 3

Why observe cirrus μm? Mean global coverage of ~30% (Wylie & Menzel 1999) Cirrus either cools or warms the upper atmosphere, depending on altitude, height, optical thickness, particle size, particle shape Radiative properties are not well understood particularly FIR. FIR contributes 27-35% of clear sky OLR (Sinha & Harries 1995) Modelling studies suggest cirrus induces strong changes in spectral fluxes, particularly in the FIR (Maestri and Rizzi 2003, Yang et al 2005) Previous cirrus studies (Cox et al, QJRMS 136,178, 2010) using in-situ measured radiances showed inconsistency in models between FIR and MIR. No campaign dataset exists combining broadband radiances with accurate cloud microphysics, and detailed atmospheric state measurements NWP models require more robust cirrus parameterization with consistency across the entire spectrum. 4

Radiative transfer model Thin cirrus Bulk extinction estimates using measured cloud properties Measured spectra Is particle scattering model/ parameterization consistent with data? Collaborate with A.Baran on improving & testing models Improved parameterisation of cloud scattering sunlight Direct extinction measurement IWC, T Drop Sondes RH, T 5

Measurements summary Onboard FAAM: In situ gases and aerosols In situ cloud particle shapes and sizes, roughness IWC Bulk extinction Radiation: both solar and infrared, covering the spectrum 0.22 – 125 μm Active remote sensing of clouds (lidar, cloud radar) Drop sondes: RH, T profiles Novelty: these will be the first complete radiation measurements to be coupled with detailed cloud particle measurements (also first with anti-shattering particle probes ?) 6

Previously... EMERALD Darwin, Australia – 2002 Participants: Aberystwyth, Manchester, Imperial, DLR, ARA. lack of adequate RH & T profiles WINTEX UK 2005 (Cox et al 2010) – inadequate sampling of cloud and atmosphere RHUBC (NSA ARM) arctic cirrus measurements from ground – 2007 (N Humpage PhD Thesis 2010) no in-situ particle measurements, problem with small ice CAESAR years particle shattering, cabling/noise issues 7

Instrumentation for CIRCCREX Radiometers TAFTS FIR ARIES IR SWS Short wave ISMAR? MARSS? μwave Hygrometers (GE, Nevzorov, FWVS, WVSS-II etc) Other GPS,Radar alt., Thermometers Mini Lidar (aerosol profiles) AVAPS dropsondes Cloud Physics FAAM: 2DC + anti shatter (50-800μm) CDP (1-75μm), CIP15 (15 – 930 μm), CIP100 (100 – 6200 μm) BCP, BCPOL Nephelometer ?? Hertfordshire: SID3 (1-50 μm), or SID2(if SID3 not working) Manchester: SPEC-CPI ( μm) 2DS ( μm) (+ anti shatter) [SPEC 3VCPI (7 – 2300 μm) (not avail)] (CAPS-CAS- DPOL (being repaired?)leave out because of drag) 8

Sorties (taken from FAAM form) A typical sortie would involve a transit to the operational area, arriving at an altitude that would help verify the cirrus layer base height and thickness, with a probable sonde release. A profile to the sea surface, followed by a short and level run and determination of the sea condition/temperature, before returning to just below the cloud (cirrus) base for a run below the cloud layer. Successive runs within the cloud ascending between runs to map the microphysical structure of the cloud layer. Runs above the cloud top, preferably in conjunction with a satellite overpass with a few additional sonde launches. A profile back down through the cloud or Lagrangian spiral, with additional run(s) below the cloud, time permitting. 9

Sorties…Plus: at least one science flight to perform a descent at the same speed as the fall speed of ice crystals. Here, we want to measure the spectrum as the PSD evolves through aggregation processes, as this will be a measure of the PSD through interferometry (this aspect is new and was stated in the NERC proposal). This will take a long time so will require one flight the other flights can be as normal as previously stated. 10

Use derivatives of the macrophysical and microphysical state, including ice water content and temperature, as input into state-of-the-art scattering model codes and cirrus parameterisations, whose output (via a radiative transfer model) will be critically validated against the radiance measurements throughout the sub-mm, infrared and visible spectrum. Sensitivity of the predicted radiance to PSD, habit types, aggregate and ensemble models, crystal complexity will be investigated by reference to the microphysical datasets. Exploit campaign datasets and constraint of cloud microphysical and radiative uncertainties in case studies to facilitate improvement of cirrus scattering models allowing a self-consistent and physically-based parameterisation of the ice crystal scattering properties. Through case studies using northern and mid-latitude campaign datasets, test the ice crystal scattering models and the coupled cloud-radiation parameterization by running the high-resolution version of the MO Unified Model (UM) at 1.0km resolution, with a view to incorporating the new parameterisations into the widely used UM. Further information : Testing of cirrus models/parameterizations. We plan to: 11

Issues/questions for discussion? Any instrument clashes? Or drag limitations to our instrument needs? (slide 8) Who is replacing Stuart Newman wrt ARIES? Do we need both the SID2 and SID3 at same time? (question for Herts.) 12

Spare slides 13

Imperial CollegeTAFTS instrument Martin-Puplett polarizing FTS Spectral range: 80 – 800 cm -1 (12 – 125 µm) Resolution: 0.12 cm -1 Observes both nadir and zenith radiation Scan time: 2 seconds 4 on-board BBs for calibration 14

02/12/2002 lidar plot Lidar used to determine height and thickness of the cirrus layer – used in real time to determine Egrett flight path 15

Example down welling spectra from the EMERALD II campaign Darwin, Australia Dec 2002 This data proved difficult to interpret due to insufficient information of the atmospheric state 16