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Christopher Nankervis (B.Sc Hons, Meteorology 2005) [CV]

Contact:  c.j.nankervis@sms.ed.ac.uk
Tel: 0131 6505103 (Crew Attic PG-suite)

- A little about me -

I am a fourth year Meteorology postgraduate student based in the Institute of Atmospheric and Environmental Sciences at the University of Edinburgh King's Buildings. I form part of the Global Change Group. My PhD is funded by NERC and supervised by Dr. Hugh Pumphrey & Dr. David Stevenson. I am a forecasting hobbyist, and use GFS numerical weather forecasts of the rainfall, temperature, and weather up to 8 days ahead. I produced a seasonal forecast for the UK Winter of 2008/2009 by analysis of a blocking system over the UK during Summer 2008, which proved successful. I am in the process of developing a radiative transfer model for prediction of tropical longwave emission, and have worked on Andes induced cloud ice by tracing the Jet Stream using EOS MLS measurements.

 - *Free* Seasonal Forecast Guide -

"The Technophobe's Guide to Seasonal
Forecasting in the 21st Century"

- Climate Action -

PRESENT Climate Calculator <= Copenhagen Dec 7 - Dec 18 => FUTURE Climate Calculator

 

- PhD Content - Why Study Ice Clouds? -

Ice clouds are one of the most poorly understood entities in climate science. The formation of ice particulates in clouds, their micro-physical structure (size and shape) is so variable from location to location , on a micro-physical scale, that cloud classification and "bulk property" analysis is often used to characterise their radiative effects. The EOS MLS employs a microwave frequency model to determine the clear-sky emission which is expected or inferred from limb measurements of gaseous absorbers. If the signal at a sensitive frequency fluctuates wildly from the clear-sky emission expected from radiative transfer calculations, then the limb scan can be classified as "cloudy", and using spherical ice crystal assumptions an estimate of cloud ice can be predicted for vertically resolved levels of about 1.5km thickness. This detection is "useful" to the scientific community between the altitudes of 8km to 20km approximately.
Colocation allows comparisons between A-train instrument measurements undertaken onboard satellites on the same orbit. There are at present 8 satellite instruments in the A-Train formation. Longwave radiation flux measurements at the top-of-atmosphere (ToA) are useful for determining local and long term shifts in climate. A full understanding of exactly how ice water in tropical cumulonibus type clouds can affect this longwave emission is crucial to our understanding of present and future climate.

  • My PhD involves assessing the affect of ice clouds on the Earth's top-of-atmosphere longwave energy flux. In order to achieve this I make use of NASA A-train satellite data from two key satellites; Aura and Aqua, which follow precisely the same orbital path around 705km above the Earth's surface. I work closely with the Microwave Limb Sounder group (MLS).

- How Does the EOS MLS Instrument Work? -


The MLS instrument is extremely sensitive and is able to detect passive (natural) sources of microwave emission from many radiatively active trace gases on the limb (edge) of the Earth's atmosphere. In order to achieve this, the MLS instrument payload includes both a set of radio-telescopes and GHz and THz frequency detectors (radiance counters). By "mixing" the radiance signal, with a local oscillator of known frequency within a mixer, the difference between the received signal and the detection can be analysed by selection of spectrally isolated double-sideband frequencies. Double sideband refers to a dual-sided frequency perturbation detected either side of the spectral curve. The EOS MLS detectors are often able to distinguish between horizontally and vertically polarized microwave sources. Wide-band detectors allow for analysis lower in the atmosphere, where pressure broadening of the absorber band-width scales with pressure. Each band is sectioned into a set of frequency channels. The retrieved variable is determined using algorithms which relate the microwave radiance to the pure rotational energies of molecules, to estimate their average volume mixing ratio along the extensive horizontal limb of a scan. The mathematics of microwave inverse theory used by the MLS team is described in detail by Livesey et al., 2006.

The cloud ice detection functions differently to retrievals of atmospheric gases. An algorithm has been produced by the NASA JPL team that computes a forward model calculation of "expected" clear-sky radiance along the limb using MLS retrievals. If the observed radiant temperature i.e. the perturbation from the clear-sky radiance, often refered to as the cloudy-sky radiance, exceeds a certain threshold, then Ice Water Content (IWC) is computed as a linear regression function proportional to the perturbed signal, based on spherical particles and a suitable particle-size distribution. The algorithm functions well only for tropical cumulonimbus clouds, due to the poor detection of thin midlatitude and anvil outflow cirrus, due to the low signal to noise ratio and the different micro-physical processes and parameterisation schemes required for such detection. The cloud ice algorithm is described by Dong Wu et al., 2006.

My Thesis title is:

"Study into the Radiative and Dynamical
Effects of Ice Clouds Using Colocated A-Train
Satellite Observations"

Hobbies/ Skills ...

Interactive Data Language (IDL) Programming

Edinburgh University squash club: Training Thursday and Sunday

Climbing/mountaineering

Cycling: 280 cycling tour from Barra to Stornaway in the Outer Hebrides, and from Ullapool to Inverness (July, 2007), cycling around Edinburgh and Lothians

Skiing: Lessons at Hillend Ski centre, Midlothian. Les Deux Alpes, Febraury 2007

Website design & publishing - Forecast for the week ahead 2005 - 2008, seasonal forecast for Winter 2008/2009 and Summer 2009

- Future Plans / Diary -

  • James Lovelock talk - 7th April - Science Week
  • Meteorology 40th Aniversary (Reading University) - 5th to 6th May
  • Edinburgh University Firbush Conference Centre - 31st May to 2nd June
  • Wednesday 21 June 2006 at 5.30pm
    Discover Antarctica Lecture - The Antarctic Ice Sheet and Climate Change
    Dr Mike Bentley, Department of Geography, University of Durham, The Royal Society of Edinburgh
  • University of East Anglia (Norwich) - Student Meteorology Conference - 21st to 23rd August 2006
  • NERC NCAS Summer School for Atmospheric Scientists - Isle of Aran (6 - 16th September)
  • March 21st Global Change Symposium
  • March 22nd GeoSciences Poster Presentation - Opening by the Chief Executive of NERC
  • RMetSoc Student Assembly (Student & Main Conference), Edinburgh Conference Centre, Heriot Watt (September, 2007) - Presentator/Earth Observation Chair for Student conference
  • American Geophysical Union, San Francisco (California, USA) - December 10-15th, 2007 - POSTER COMPLETE
  • RMetSoc Student Conference, Manchester (Dalton Hall) - POSTER - September 3rd-5th, 2008
  • Models for Nature and Society: Should they be Trusted? - Royal Society of Edinburgh, 22 George St, Edinburgh - 11th September, 2008
  • Edinburgh University (GeoSciences) GradSchool Conference, Ben Wyvis Hotel, Invernes-shire, 30th Jan - 1st February, 2009 [Poster]

  • Ph.D Thesis Submitted [11th September, 2009]
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