met-jobs@lists.reading.ac.uk
November 2011
Message 97

[Periods|Index by:DateThreadSubjectAuthor|Date:PreviousNext|Thread:(Previous)(Next)|List Information]

[Met-jobs] Two fully-funded PhD positions - School of Chemistry, University of Leeds

From Erin Dawkins <erin_dawkins@hotmail.com>
To <met-jobs@lists.reading.ac.uk>, <met-jobs-owner@lists.reading.ac.uk>
Date Tue, 29 Nov 2011 12:39:05 +0000

Posted on behalf of Prof John Plane.

Two fully-funded PhD opportunities related to the study of cosmic dust.

******
1. PhD title: 'Impacts of meteoric smoke in the stratosphere and upper troposphere'
Supervised by: Prof J. Plane and Dr B J Murray

The amount of cosmic dust entering the earth’s atmosphere is highly uncertain: estimates range from about 10 to 270 tonnes per day globally. Most of the dust particles enter the atmosphere at very high speeds (12 - 72 km s-1), causing the particles to undergo meteoric ablation. The resulting vapours of iron, magnesium and silicon become oxidised and then condense over several days to form nanometre-size particles termed meteoric smoke.

The purpose of this project is to investigate the impacts of smoke particles in the middle atmosphere. These impacts include reaction in the mesosphere and upper stratosphere with acidic gases such as sulphuric, nitric and hydrochloric acid. The smoke may also act as condensation nuclei for sulphuric acid droplets in the middle stratosphere. A major focus of the project will be the role of meteor smoke in crystallising sulphuric acid and nitric acid droplets in the lower stratosphere and upper troposphere (i.e. enhancing the freezing of polar stratospheric clouds), and determining the resulting effect on stratospheric O3. Laboratory experiments using an optical microscope with Raman spectroscopy will be used to study droplets containing meteoric smoke analogues (made using the “lab-on-the-chip” microfluidics technique) under stratospheric conditions.

The results from these experiments will then be incorporated into a chemistry-climate model of the whole atmosphere. Comparison with observations of the meteoritic material in sulphuric acid droplets will be used to constrain the cosmic dust flux. This model will be used to simulate changes to O3 as the stratosphere cools through the 21st Century, and also to explore how meteoric smoke may interfere with a proposed geo-engineering climate solution which involves pumping sulphur dioxide into the stratosphere.

The studentship will involve: experimental work using Raman microscopy and the microfluidics technique to generate nanoparticles; and atmospheric modelling using a microphysical mass advection model coupled to a leading chemistry-climate model. An appropriate background would be a first degree in chemistry, physics or atmospheric science.

The student will join a large research team studying the evolution of cosmic dust from the outer solar system to the earth’s surface. The team consists of 4 senior staff members, 5 post-docs and 2 PhD students at Leeds, as well as 10 remote members in the US and Germany.


******
2. PhD title: 'Meteoric ions in planetary atmospheres'
Supervised by Prof J. Plane

Interplanetary dust particles are produced by the sublimation of dust from comets, and collisions between asteroids. When these particles enter a planetary atmosphere, high velocity collisions with atmospheric molecules lead to rapid heating, melting and evaporation – a process termed meteoric ablation. The purpose of this project is to carry out a comparative study of the effects of meteoric ablation in the atmospheres of Mars, Venus and Titan. Ablation provides a source of metals such as Fe, Mg and Na, which ionize readily. The resulting layers of metallic ions have been detected recently on Mars and Venus by radio occultation measurements with orbiting spacecraft, and similar layers are expected to occurs about 500 km above the surface of Titan.

The project will involve constructing a new laboratory apparatus to study the rates at which metallic molecular ions are neutralised by electrons (a type of reaction known as dissociative recombination). These reactions control the atmospheric lifetimes of metallic ions, and so their rates are essential information for modelling metal ion chemistry. The experimental results will then be input into models of the middle atmospheres of these four solar system bodies. These models will be coupled to an astronomical model of the Zodiacal Cloud and a model of meteoric ablation, in order to estimate the rates of meteoric ablation in each atmosphere. The model predictions will then be compared with satellite observations of ion layers, through collaborations with Boston University and the University of Köln (where the student will make short-term research visits).

The studentship will involve: experimental reaction kinetics of ion-molecule reactions; the option to carry out fundamental theoretical calculations on these reactions; and the development of atmospheric models of three solar system bodies. An appropriate background would be a first degree in chemistry, physics, astronomy or atmospheric science.

The student will join a large research team studying the evolution of cosmic dust from the outer solar system to the earth’s surface. The team consists of 4 senior staff members, 5 post-docs and 2 PhD students at Leeds, as well as 10 remote members in the US and Germany.


******
For further information and enquiries, please contact: Prof John Plane (j.m.c.plane@leeds.ac.uk)


Attachment: CODITA PhD student 1 advert.docx
Description: application/vnd.openxmlformats-officedocument.wordprocessingml.document

Attachment: CODITA PhD student 2 advert.docx
Description: application/vnd.openxmlformats-officedocument.wordprocessingml.document



Go to: Periods · List Information · Index by: Date (or Reverse Date), Thread, Subject or Author.