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Today's Topics:
1. Two fully-funded PhD positions - School of Chemistry,
University of Leeds (Erin Dawkins)
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Message: 1
Date: Tue, 29 Nov 2011 12:39:05 +0000
From: Erin Dawkins <erin_dawkins@hotmail.com>
Subject: [Met-jobs] Two fully-funded PhD positions - School of
Chemistry, University of Leeds
To: <met-jobs@lists.reading.ac.uk>,
<met-jobs-owner@lists.reading.ac.uk>
Message-ID: <BLU158-W12A867DF18C2ADA053E12AEDB30@phx.gbl>
Content-Type: text/plain; charset="windows-1252"
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 K?ln (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)
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