Dr. Linda Hirons

I'm a Research Scientist in the National Centre for Atmospheric Science (NCAS)-Climate.

Current Projects | Policy Consultancy | Past Projects | Thesis

Current Research Projects

  • African-SWIFT: African Science for Weather Information and Forecasting Techniques (2017- )

  • The Global Challenges Research Fund (GCRF) African-SWIFT project will:

    • Make fundamental research advances to significantly improve weather forecasts in Africa, and the tropics more generally, from the hourly to the seasonal timescale.
    • Build the operational capability of the African forecast agencies; deliver state-of-the-art forecasting tools; and improve links and communication with forecast users.
    • Assist African partners in developing capacity for sustained training of forecasters, in partnership with African academic institutions and international agencies to yield ongoing forecasting improvements in the coming decades.
    • Ensure results are translatable beyond the partner countries to other nations of Africa and the developing world more widely.
    • Deliver an impact felt by many millions of ordinary African people, and by large public and private-organisations across sectors from aviation to agriculture, energy, water and emergency response.
    GCRF African-SWIFT Overview

    Accurate weather forecasting is an essential tool of modern society, which brings benefit to people's safety and livelihoods, along with country-wide economic development and prosperity. The Global Challenges Research Fund (GCRF) African Science for Weather Information and Forecasting Techniques (GCRF African-SWIFT) programme will develop sustainable African weather forecasting capability, to enhance the livelihood of African populations and improve the economies of their countries.

    In the UK we benefit from some of the best forecasting in the world and the UK Met Office is estimated to bring 3 billion of benefit to the UK economy every year. In Africa, the impacts of weather are much higher due to the severity of weather extremes such as storms, droughts and floods, and to the vulnerability of poor people. Comparable benefits to those seen in the UK are not yet possible in Africa without significant improvements in the skill and capability of the forecasts.

    GCRF African-SWIFT is a 7.8m programme of research and capability building funded by Research Councils UK that aims to tackle this problem by delivering a step change in African weather forecasting capability from hourly to seasonal timescales, and by building the research capability to continue those improvements into the future.

    The GCRF African-SWIFT consortium, led by the National Centre for Atmospheric Science (NCAS), builds upon existing partnerships between forecasting centres and universities in four African partner countries - Senegal, Ghana, Nigeria and Kenya - bringing together 5 UK partners (NCAS, University of Leeds, University of Reading, CEH, UK Met Office), 10 African Partners (ACMAD, ICPAC, ANACIM, UCAD, GMet, KNUST, NiMet, FUTA, KMet and University of Nairobi) and, as an advisory partner, the UN World Meteorological Organisation (WMO).

    Over the 4 year programme, the team of 25 UK and 45 African atmospheric scientists, social scientists and operational forecasters will undertake fundamental scientific research into the physics of tropical weather systems; evaluation and presentation of complex model and satellite data; and communication and exploitation of forecasts.

    The GCRF African-SWIFT team will work with forecast users across sectors from aviation to agriculture, energy, water and emergency response to understand how to tailor the provision and delivery of weather forecasts and to ensure improved response to high-impact events (e.g. onset of rains, heat-waves, dry spells, strong winds); rapid emergency response to extreme events, such as urban flooding and prolonged droughts; and increased resilience, through integration of weather prediction into strategies for response to climate change.

  • IMPALA: Improving Model Processes for African cLimAte (2015- )

  • The IMPALA project is part of the Future Climate for Africa (FCFA) program which aims to generate fundamentally new climate science focused on Africa, and to ensure that this science has an impact on human development across the continent.

    The IMPALA project, which is the pan-Africa part of FCFA, aims to deliver a step change in global climate model prediction capability for Africa. |
    IMPALA Overview

    This project will focus on a single climate model, the Met Office Unified Model, to improve its simulation of African climate through a better understanding and representation of weather and climate processes. This will result in reduced uncertainty in future projections of the African climate and provide valuable information to climate scientists and modellers within Africa and worldwide, and empower decision-makers with information that can be used to reduce risks and help protect the livelihoods of the most vulnerable.

    The project aims to tackle a major scientific hurdle that limits decision-makers from using climate information: current climate models have only a modest ability to capture African climate systems. Because of this, there is large uncertainty and low scientific confidence in important aspects of the projections for Africa’s climate in the next 5–40 years.

    The initiative aims to deliver a step change in global climate model capability that will reduce uncertainty and enable better informed evaluation of the robustness of future projections.

    The IMPALA project will develop, for the first time, a pan-African very high resolution model (grid-spacing of around 4km) to better capture key processes and local-scale weather phenomena including extremes, providing new understanding of the roles played by these processes in African climate variability and change. The improved knowledge and new simulations will be used by scientists in the four regional research projects (AMMA-2050, FRACTAL, HyCRISTAL and UMFULA) . This, in turn, will deliver more reliable information for decision-makers and scientists in a range of sectors including agriculture, urban and rural water resources, health and infrastructure management and renewable energy.

    Within the IMPALA project I am working with Dr. Andrew Turner on the understanding the major modes of global climate variabilty and the teleconnection pathways by which they drive African rainfall variability.

    Policy Consultancy Work

  • The historical impacts of La Niña (Feb 2016):

  • Comissioned by DfID to produce a report on the impact of historical La Niña events on 30+ low- and middle-income countries.

  • The impacts of El Niño 2015/2016: A monthly seasonal update (Oct 2015-Feb 2016):

  • Commissioned by DfID to produce monthly updates on the 2015/2016 El Niño event, including and outlook for the next 1-6 months using sub-seasonal and seasonal forecast data.

    | Nov 2015 | Dec 2015 | Jan 2016 | Feb 2016 | Mar 2016 |

  • The historical impacts of El Niño (Jul2015-Aug2015):

  • Commissioned by DfID (Department for International Development) to produce a report on the impact of historical El Niño events on 30+ low- and middle-income countries.

    Past Research Projects

  • Future Weather (2012-2016)

  • The Future Weather project examines how air-sea interactions affect sub-seasonal variability and the projections of changes in regional weather and climate extremes.

    The first phase of this project was focused on developing a near-globally coupled ocean mixed-layer model - MetUM-GOML. The MetUM-GOML comprises the MetUM Global Atmosphere (GA) and Global Land (GL) coupled to the MC-KPP ocean mixed-layer model. The configuration and validation of this model are described in a paper in Geoscientific Model Development.

  • Climate Science Services Partnership (CSSP)- China project (Oct 2014-Mar 2015):

  • Within the CSSP-China project I was focused on understanding drivers of sub-seasonal variability in the East Asian Summer Monsoon.

  • Bay of Bengal Boundary Layer Experiment (BoBBLE) (Jan-Mar 2015):

  • Within the BoBBLE project I was focused on understanding the process which control sub-seasonal monsoon variability in the Asian Summer monsoon.
    BoBBLE Summary

    The South Asian summer monsoon (June-September) provides 80% of the annual rainfall for over one billion people, many of whom depend on monsoon rains for subsistence agriculture and freshwater. It is critical to forecast accurately not only the seasonal rainfall, but also rainfall variations within the summer. Sub-seasonal "active" and "break" phases can last weeks, resulting in floods and droughts across broad areas of South Asia.

    Air-sea interactions are key to understanding and predicting monsoon behaviour. Ocean surface temperatures in the Bay of Bengal, east of India, remain very warm (above 28 C) throughout the summer. Evaporation from the Bay provides moisture and energy to monsoon depressions that form over the Bay and bring substantial rain to India. It is not understood how the Bay remains warm despite losing energy to these systems. Ocean temperature and salinity variations across the Bay are known to drive changes in rainfall over the Bay and surrounding land, but it is not clear how these arise or how they are maintained. This is particularly true for east-west variations in the southern Bay, a focus of this project. Although air-sea interactions are important to the monsoon, weather predictions are made with models of only the atmosphere. There is potential to improve monsoon forecasts by including well-represented air-sea interactions in models.

    The Bay of Bengal Boundary Layer Experiment (BoBBLE) proposes an observational campaign for the southern Bay, during the established monsoon (mid-June to mid-July). BoBBLE will deploy two ships, six ocean gliders and eight floats to collect an unprecedented range of oceanic and air-sea flux observations. The ships will occupy locations in the southwest and southeast Bay, as well as tracing east-west and north-south paths between those locations, measuring ocean temperature, salinity and currents. Two gliders (automated underwater vehicles) will accompany each ship, with two others between the ships, diving to 500 metres every 2 hours to measure temperature, salinity and currents. Diurnal variations in air-sea fluxes and ocean temperatures may affect the development of weather systems. A novel configuration of the gliders will allow computations of horizontal transports of heat and salt. The floats (automated submersibles) will be deployed in the Bay to measure the ocean to 2000 metres every 5 days. They will remain in the Bay after BoBBLE, enhancing the observing network. Ships and gliders will also measure ocean chlorophyll, which absorb sunlight and alter near-surface ocean temperature, influencing air-sea interactions.

    BoBBLE scientists will analyse these observations, along with routine datasets, to understand the evolution of conditions in the Bay and how they influence the atmosphere. Particular emphasis will be placed on estimating the uncertainty in existing datasets of air-sea fluxes by validating them against all available observations. The best-performing datasets will be used to improve estimates of air-sea exchanges and their variability on daily to decadal timescales, to calculate budgets of heat and freshwater fluxes in the Indian Ocean and the Bay, and to validate model simulations.

    A hierarchy of model simulations will reveal how conditions in the Bay are maintained and how air-sea interactions influence the monsoon. Simulations with an ocean model, forced by and validated against BoBBLE observations, will isolate the roles of air-sea fluxes (including the diurnal cycle), chlorophyll and horizontal transports in maintaining and recharging ocean structure after each weather system passage. Retrospective forecasts of the BoBBLE period with atmosphere-only and atmosphere-ocean coupled models will demonstrate how air-sea interactions influence monsoon rainfall predictions. Multi-decadal simulations will evaluate how air-sea interactions and coupled-model systematic errors influence daily-to-seasonal monsoon variability.

    PhD Thesis

    I completed my PhD at the University of Reading in 2012.

    My PhD Thesis focused on the representation of the Madden-Julian Oscillation (MJO) in the European Centre for Medium Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS). Modifications made to the model physics in 2007 resulted in significant advances in the representation of the MJO, and tropical variability more generally. The experiments I carried out atrributed these advances in the representation of the MJO to modifications to the entrainment rate in the convection scheme. Specifically, increasing the sensitivity of the deep convection scheme to environmental moisture was shown to modify the relationship between precipitation and moisture and improve the transition from shallow to deep convection in the model.

    This work has been written up in two papers: Part I describes the representation of the MJO and Part II the application of process-based diagnostics.

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