Dr. Linda Hirons

Dr Linda Hirons
NCAS-Climate Research Scientist

T: +44 (0)118 378 7497
E: l.c.hirons@reading.ac.uk
W: http://www.met.reading.ac.uk/~linda/

Room 128 (Harry Pitt)
Department of Meteorology
University of Reading
PO Box 243
Reading RG6 6BB, UK

Working Days: Mon - Wed

    RECENT NEWS:
  • NEW PROJECT: Our Global Challenges Research Fund (GCRF) African-SWIFT (African Science for Weather Information and Forecasting Techniques) project has started.
    The kickoff meeting took place in Dakar, Senegal in November 2017.

    • RECENT PAPERS:
    • Current IMPALA (Improving Model Processes of African cLimAte) project work within Future Climate for Africa (FCFA) has been submitted to Journal of Climate: Hirons, L. C., Turner, A. (2017) The impact of Indian Ocean mean-state biases on the representation of the East African short rains |
      Abstract

      The role of the Indian Ocean Dipole (IOD) in controlling interannual variability in the East African short rains, from October to December, is examined in the CMIP5 models and in detail in one particular climate model. In observations, a wet short-rains is associated with the positive phase of the IOD and anomalous easterly low-level flow across the equatorial Indian Ocean. A model’s ability to capture the teleconnection to the positive IOD is closely related to its representation of the mean-state. During the short-rains season, the observed low-level wind in the equatorial Indian Ocean is westerly. However, half of the models analysed exhibit mean-state easterlies across the entire basin. Specifically, those models that exhibit mean-state low-level equatorial easterlies in the Indian Ocean, rather than the observed westerlies, are unable to capture the latitudinal structure of moisture advection into East Africa during a positive IOD. Furthermore, the associated anomalous easterly surface wind stress causes upwelling in the eastern Indian Ocean enhances the zonal sea-surface temperature gradient between west and east and strengthens the positive IOD pattern, further amplifying the easterly wind stress. This positive Bjerknes coupled feedback is stronger in easterly mean-state models, which results in a wetter East African short rain precipitation bias in those models.


    • Future Weather project work has been submitted to Journal of Advances in Modeling Earth Systems (JAMES): Hirons, L.C., Klingaman, N.P. and Woolnough, S.J. (2017) The impact of air-sea interactions on the representation of tropical precipitation extremes |
      Abstract

      The impacts of air-sea interactions on the representation of tropical precipitation extremes are investigated using the Global Ocean Mixed Layer configuration of the Met Office Unified Model (MetUM-GOML). MetUM-GOML is compared to two atmosphere-only MetUM simulations driven by MetUM-GOML sea-surface temperatures (SSTs): one with 31-day running means (GA3-31d), the other with a repeating mean annual cycle. This allows separation of the effects of interannual SST variability from those of coupled feedbacks on shorter timescales. Crucially, all simulations have a consistent mean state with very small SST biases against present-day climatology.

      GA3-31d overestimates the frequency, intensity and persistence of extreme tropical precipitation relative to MetUM-GOML, likely due to excessive SST-forced precipitation variability. This implies that atmosphere-only attribution and time-slice experiments may overestimate the strength and duration of precipitation extremes. In MetUM-GOML, air-sea feedbacks damp extreme precipitation, likely through negative local thermodynamic feedbacks between convection, surface fluxes and SST.



      • CONSULTANCY:
      • I was commissioned by DfID (Department for International Development) to produce a series of reports on the impact of the 2015/16 El Niño and potential 2016/17 La Niña events on low- and middle-income countries across regions of Africa, Asia and the Middle East.


      ABOUT: I'm a Research Scientist in the National Centre for Atmospheric Science (NCAS)-Climate based in the Walker Institute within the Department of Meteorology.

      Here you can see my 2-page CV and a full list of my Publications.

      RESEARCH INTERESTS:
      • Drivers of climate variability and change in Africa
      • Sub-seasonal to seasonal variability in the Tropics, e.g., the Madden-Julian Oscillation (MJO), monsoon systems
      • The role of air-sea interactions in sub-seasonal climate variability
      • Climate services for Society

      • To find out more visit my Research page.



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