Mr Daniel-John Housley

PhD Outline:

There has been a steady improvement in the accuracy of weather forecasts over the past 50 years, from a rather crude prognosis of 1-2 days ahead to today’s ability to provide accurate forecasts over several days. This advance has been underpinned by two main factors – the development of numerical weather forecasting models and the much improved observational capacity, particularly from satellites. The science of meteorology is well understood on the synoptic scale and the balanced flow that dominates the dynamics on these scales allows different variables in the models to be linked to one another and related to measurements. However, this does not apply for the fine-scale forecasts that are currently coming on stream, and we need a new generation of observations to match the progress being made in modeling.

One promising avenue for obtaining better measurements is the use of remote-sensing vertical profiling devices - basically radars, lidars or passive radiometers. These operate automatically, and by measuring continuously the limitation of a fixed location is significantly reduced (basically, the motion of the atmosphere over the measurements extends their value). Potentially, there is a powerful synergy between the different measurement types which could provide further data (e.g. high-resolution temperature and humidity profiles) of enormous practical value (e.g. Klaus et al 2006). However, this requires fundamental improvements in our understanding of the measurement processes and of atmospheric physics on very small scales.

At the core of this project is the UK MST radar at Capel Dewi, Aberystwyth. This is a VHF radar measuring the Doppler spectrum of returned echoes from the atmosphere between about 2 and 20 km altitude. The radar echo power is a function of humidity and temperature gradients, and recent work has demonstrated a sensitivity to clouds and precipitation.

The University of Manchester is responsible for a UHF wind profiler, which works on the same principle as the VHF radar but at a much shorter wavelength. Research at the Met Office has shown that humidity profiles at high resolution may be derived from a combination of UHF radar and microwave radiometer, serving as a useful starting point for the current project.

The overall aims of this PhD project are as follows:

1. establish the factors that influence the echo power of the MST radar and develop a quantitative model relating the echo power to atmospheric parameters, taking into account the fundamentals of radio physics and the existing measurement data base

2. using 1), derive temperature and humidity profiles using the radar and ancillary data.

3. Establish what quantitative information on cloud structure may be derived from the radar

4. Extend these results to UHF profiling radars

5. evaluate how this information may be used to constrain numerical models

   
   

Current Work:

THAW Campaign

The 2009 Temperature, Humidity and Winds (THAW) campaign was a multi instrument field project that ran over a two week period in from the 23^rd of November through the 4^th of December 2009. The main objectives of the THAW project are to increase understanding in the area of radar return echoes from clear-sky phenomena. Thus the campaign was conducted to obtain the relevant data by measuring the fine-scale vertical temperature structure in the vicinity of the tropopause for the purpose of validation and testing of a radar reflection and scattering models that are in development at Manchester. The long term goal of this research is being able to retrieve temperature and humidity profiles from the MST radar.

The project's highlights included flights from the Bae 146 FAAM aircraft through the tropopause region during a low tropopause event, this is unique as the aircraft does not commonly attain such altitudes and thus measurements in this region using the FAAM aircraft are not usually conducted. Slow tight spiral descents were flown at 500 ft/min (150 m/s) over the radar facility and instruments co-located with the MST radar were used to retrieve temperature and humidity profiles, this included the daily launching of multiple radiosondes, and the operation of the 3-channel water vapour Raman lidar present at the MST facility.

Past Projects:

SAOZ Instrument Analysis

Using Differential Optical Absorption Spectrometry allowing the retrieval of daily ozone and NO2 total columns at sunrise and sunset, as well as total water vapour and oxygen dimmer and the detection of Polar Stratospheric Clouds (PSC) and volcanic aerosols. 

MPhys Projects: 

01/2008-06/2008
GEANT4 simulation of the FP420 upgrade for ATLAS

09/2007-01/2008
Monte-Carlo Simulations of Non-Equilibrium Critical Dynamics 

Dynamics, Remote sensing, Radar, Lidar, Radiosondes, Clear-air echoes, SAOZ

THESIS