Overview

Recent decades have seen unprecedented changes in sea ice thickness and extent, in ocean and atmosphere temperatures and circulation, and in greenhouse atmospheric constituents across the North Atlantic Climate System. Not only such changes directly affect the UK climate, weather and air quality but also, via tele-connections, they drive changes further afield with major economic impacts on agriculture, fisheries, water, energy, transport and health worldwide.

Accurate predictions of climate and numerical weather models are still jeopardized by large uncertainties  related to the inadequate way clouds and their radiative properties are represented and to accurate knowledge of precipitation intensity and accumulation (IPCC 2013, see online at www.ipcc.ch).

One key to unravelling the complexity of cloud and precipitation feedbacks lies in clarifying the association between atmospheric circulation regimes, cloudiness and precipitation. Diabatic processes, and especially latent heat release due to the condensation of water vapour, can have a profound impact upon the development of extratropical cyclones by directly affecting storm dynamics and shaping the extratropical circulation, e.g. through the generation of vorticity, which are believed to contribute to a longer life span for precipitation systems and to heavy rainfall. Recent satellite measurements have the potential to improve our understanding of diabatic effects of clouds and precipitation. Specifically the Global Precipitation Measurement (GPM), launched by NASA and JAXA in February 2014 (http://gpm.nasa.gov) offer the unprecedented opportunity with its constellation of satellites to provide the next generation of space-borne precipitation measurements with better sampling (3-hourly over a specific location), higher accuracy (with a Ku-Ka band radar), finer spatial resolution (up to 0.1o x 0.1o), and greater coverage (from the tropics to high latitudes)  than ever before (Fig. 1).  By exploiting satellite retrieval schemes that depend  on some type of cloud-resolving model latent heat products have been routinely produced by the GPM Science Team since the beginning of the mission [1].

Similarly, since its launch in 2006, CloudSat (http://cloudsat.atmos.colostate.edu/) has added a ‘‘new dimension’’ to cloud and precipitation retrievals from space-based platforms providing for the first time a tool to assess vertical distributions of the properties of most types of clouds around the planet using reflectivity measurements from the 94 GHz Cloud Profiling Radar (CPR). Vertically resolved radiative flux and heating rate data set which are consistent with observed reflectivities from the CloudSat’s CPR are available as Level 2 FLXHR product [2,].

Tropical storm Kate as observed by the GPM core observatory on November 11, 2015. A 3-D cross section by GPM's Radar (DPR Ku Band) through Kate's weak eye shows intense storms swirling around the northern side of the tropical cyclone with precipitation exceeding 80 mm  per hour.

Methodology

The PhD student will first become acquainted with CloudSat and GPM satellite data and products. He/she will analyze the variability of latent and radiative heating structures of precipitation systems over the Atlantic for various types of precipitating system (e.g. convective, stratiform and shallow).

He/she will then identify discrepancies in estimates of diabatic heating profiles associated with precipitation based on satellite observations and microphysics and those derived from the thermodynamics of the large-scale environment and from numerical weather and climate model outputs (e.g. standard CMIP5 simulations but also some high resolution simulations which are available in Reading). He/she will try to identify and attribute causes for such discrepancies and improve our understanding of the interaction of atmospheric heating with large-scale dynamics.

Training and Skills

This project offers the candidate an excellent opportunity to develop novel remote sensing techniques, to work with the latest generation of satellite products,  weather and climate numerical models. Applicants should have a science degree with an engineer, physical or  mathematical background. Programming skills in matlab/idl/Python/C/Java/C++ and background studies in remote sensing, numerical computation are beneficial. CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research  themes.

Timeline

Year 1: The student will analyse products from the GPM and the CloudSat mission over the Atlantic ocean (characterization of the vertical structure of of latent and radiative heating).

Year 2: The student will liase with partners at Univerity of Reading to assess the model ability to

represent clouds and precipitation and their corresponding 4D structure of latent and radiative heating.

Year 3: The perfromances of the models over the Atlanic Ocean will be tested. Different horizontal resolutions and convection parametrization schemes will be considered to identify model deficiencies.

Partners and collaboration (including CASE)

A close collaboration between the Leicester Earth Observation Science group and the University of Reading (co-supervisor Prof Allan) is at the core of this project. Dr Battaglia is a cloud and precipitation microwave remote sensing expert with more than 50 co-authored papers and more than 16 years of experience in the field. He is Member of the NASA Precipitation Measuring Mission Science Team and he has connection with the scientists developing the GPM Latent Heat products (group led by Dr Tao). Dr Michael Barkley is Lecturer in Climate Change Adaptation and a past NERC Fellow. Prof Allan is Professor of Climate Science at the Department of Meteorology, in the University of Reading with expertise in assessing the realism of climate prediction models by exploiting Earth Observation remote sensing data. The student will benefit from technical support and use of facilities of the Leicester Space Research Center.

Further Details

For further information please contact Dr. A. Battaglia, ab474@le.ac.uk