|
Funded by UK NERC
People: John Plane, Martyn Chipperfield, Wuhu Feng, Erin Dawkins
Description:
Changes in the mesosphere are an important signal of climate change, and
there is increasing evidence that accurate Simulations of changes to the
Earth's climate require models with a well resolved and accurate
stratosphere and mesosphere. Metal species in the upper atmosphere offer a
unique way of observing this region and accuracy of climate models in this
domain. The major source of metals in the upper atmosphere is the ablation
of the roughly 50 tonnes of interplanetary dust that enters each day from space.
This gives rise to the layer of metal atoms and ions that occur globally in
the upper mesosphere/lower thermosphere (MLT) region between about 75 and
120 km. The purpose of this NERC funded project is to insert the chemistry
of four metals - Na, Fe, Ca and Mg - into a global chemistry-climate model NCAR WACCM in
order to use these layers as probes of chemistry and dynamics in the MLT,
and to examine the response of the metal layers to the solar cycle, solar
proton events, noctilucent clouds and climate change in the middle
atmosphere.
Here are five objectives of this project:
- 1)
Determine the ablation flux profiles of individual meteoric metal
atoms and ions as a function of altitude, latitude, time-of-day,
season and solar cycle; our project partner Dr. Diego Janches will
work out based on the look up tables of the elemental ablation
profiles for Na, Fe, Ca, Mg and Si produced from Leeds CABMOD model.
- 2)
Obtain a near-global data set on the Na, Fe, Ca and K metal atom
and ion using UV-NIR dayglow
observations with the limb-scanning SCIAMACHY spectrometer on ENVISAT
- 3)
Assess the importance of dynamical transport caused by dissipating
gravity waves on minor constituents in the MLT. Does this need to be
parameterised in General Circulation Models?
- 4)
Develop the first global model of the meteoric metals by inserting the
chemistry of Na, Fe, Ca and Mg into the Whole Atmosphere Chemistry
Model (WACCM) with project partner Dr. Dan Marsh Validate by
comparison with lidar and satellite observations.
- 5)
Investigate the likely impact of the solar cycle and climate change on
the MLT distributions of all four metals. Investigate the impact of
the resolved and improved mesosphere on stratospheric ozone and
climate.
Link to Leeds 4M workshop 16-18th May 2011
|
