1. © Crown copyright Met Office MEVALI Detachment Brief Chawn Harlow, FAAM, 20/10/11

2. © Crown copyright Met Office Collaborators Richard Essery, University of Edinburgh Mel Sandells, Mark Richardson, and Robert Gurney of NCEO Jouni Pullianen of FMI FAAM and Met Office aircraft crew taking part.

3. © Crown copyright Met Office Contents Science MEVALI Cloud Physics Campaign

4. © Crown copyright Met Office Motivation Hope to assimilate satellite microwave data over land Provide atmospheric temp and humidity profile information. Need emissivity information derived from models and satellite observations. New snow module to be included in Met Office surface component JULES Couple fast regression based microwave radiative transfer model to JULES snow module. First need to validate complex snow radiative transfer models in 20 to 200 GHz range.

5. © Crown copyright Met Office T n =T a +  s T s exp(-  )+(1-  s )T d exp(-  ) T d =T z exp(-  )+T a Reflected atmospheric and surface emission

6. © Crown copyright Met Office MEMLS Chief emissivity model being evaluated. Microwave Emissivity Model of Layered Snowpacks Mult-layer, multiple scattering radiative transfer model with empirically derived scattering coefficients. Evaluated on frequency range: 5 to 100 GHz. Purpose of CLPX-II and MEVALI to extend to 200 GHz.

7. © Crown copyright Met Office MEMLS (cont'd) Input profile: density, temp., correlation length, wetness, layer thicknesses. Aux. Inputs: freq and look angle. Outputs: emissivity CLPX-II and MEVALI are opportunities to test MEMLS with observations of the outputs (aircraft measurements of emissivities) and collocated snow pit data.

8. © Crown copyright Met Office Goals for MEVALI simulation of grain size depth profiles most difficult demand on snow module. Field data will provide pit profiles distributed in time and space. With distributed met data can evaluate snow modules that generate snow profiles of temperature, grain size, density, wetness, etc. (Essery) With observed microwave and IR brightness temperatures can evaluate snow microwave radiative transfer routines (Harlow). Evaluation of snow RT carried out at frequencies above 100 GHz. Measurements on the ground of grain and temp profiles Measurements of brightness temperatures with MARSS, ARIES and Heimann. Dropsondes key for modelling absorption of atmospheric profile

9. © Crown copyright Met Office MEVALI vs. CLPX-II MEVALI focuses on Lake Ice much less spatial variability than tundra of CLPX-II Snow pit measurements at MEVALI provide better measurements of grain size than CLPX-II CLPX-II went a great way to extension of MEMLS to 200 GHz. MEVALI more idealized providing more rigid constraints.

10. © Crown copyright Met Office MEVALI Sortie outline Transit to Lake Oranjarvi arriving at high level (~30 min). Drop two sondes during 10 min SLR. Low level work to sample emissivity (120 min) Focus on Lake Oranjarvi and SnowSCAT site. Translating racetrack to map area. Profile climb to Max Alt (30 min). Sonde dropping runs nearby sites sampled (30 min) Return to Kiruna(30 min; 4 hr 10 min total)

11. © Crown copyright Met Office

13. Cloud-physics flights Richard Cotton

14. © Crown copyright Met Office Wave cloud-Ice Nucleation studies: Can the number of ice particles formed by ice nucleation mechanisms be predicted if the aerosol feeding into the cloud is adequately characterised both physically and chemically? Cloud physics probes observe super-cooled liquid drops, small pristine ice crystals and larger snow aggregates. Model streamlines using observed wind and thermodynamic profiles. Input upwind aerosol.

15. © Crown copyright Met Office Cold-air outbreak: Low level stratiform cloud Open cell convection Runs below, in and above cloud. Cold northerly flow. Icing issues to resolve. Evolution of cloud during cold air outbreak. Stratiform => open cell convective.

16. © Crown copyright Met Office MEVALI: Mix of Science sorties Low level Lake (3-4 sorties) Cold air outbreaks (3-4 sorties) Wave clouds (<3 sorties) Clear skies IASI (<3) Cirrus studies (<3) VACAR over land (<3)

17. © Crown copyright Met Office Operating Areas Kiruna Sodankyla Wave clouds

18. © Crown copyright Met Office MEVALI Flying Clearances Operation over Norway, Sweden, Finland, and Norwegian and Barents Seas up to Svalbard. Low level clearances Sodankyla area is paramount. Clearance over Northern Sweden useful. 500’ over land if obtainable. Dropsonde clearances necessary for all operating areas.

19. © Crown copyright Met Office Conclusions Goal: to evaluate snow emissivity/RT models To allow future retrieval atmospheric profiles over land with AMSU and MHS Ability to retrieve emissivity with BAe-146 A basic outline of core sortie Brief presentation of alternative science plans.

20. © Crown copyright Met Office Questions and answers