Imperial College London

Dr Jonathan E Murray

Faculty of Natural SciencesDepartment of Physics

Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7662j.murray

 
 
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Location

 

710aHuxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

31 results found

Eckardt FD, Bekiswa S, Von Holdt JR, Jack C, Kuhn NJ, Mogane F, Murray JE, Ndara N, Palmer ARet al., 2020, South Africa's agricultural dust sources and events from MSG SEVIRI, AEOLIAN RESEARCH, Vol: 47, ISSN: 1875-9637

Journal article

Murray JE, Brindley HE, Fox S, Bellisario C, Pickering JC, Fox C, Harlow C, Smith M, Anderson D, Huang X, Chen X, Last A, Bantges Ret al., 2020, Retrievals of high latitude surface emissivity across the infrared from high altitude aircraft flights, Journal of Geophysical Research: Atmospheres, Vol: 125, Pages: 1-16, ISSN: 2169-897X

We present retrievals of infrared spectral surface emissivities spanning the far and mid infrared from aircraft observations over Greenland, taken at an altitude of 9.2 km above sea level. We describe the flight campaign, available measurements and the retrieval method. The principal barriers to reducing uncertainty in the emissivity retrievals are found to be instrumental noise and our ability to simultaneously retrieve the underlying surface temperature. However, our results indicate that using the instrumentation available to us it is possible to retrieve emissivities from altitude with an uncertainty of ~ 0.02 or better across much of the infrared. They confirm that the far‐infrared emissivity of snow and ice surfaces can depart substantially from unity, reaching values as low as 0.9 between 400‐450 cm‐1. They also show good consistency with retrievals from the same flight made from near‐surface observations giving confidence in the methodology used and the results obtained for this more challenging viewing configuration. To the best of our knowledge, this is the first time that far‐infrared surface emissivity has been retrieved from altitude and demonstrates that the methodology has the potential to be extended to planned satellite far‐infrared missions.

Journal article

Bantges RJ, Brindley HE, Murray JE, Last AE, Russell JE, Fox C, Fox S, Harlow C, O'Shea SJ, Bower KN, Baum BA, Yang P, Oetjen H, Pickering JCet al., 2020, A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid- and far-infrared, Atmospheric Chemistry and Physics, Vol: 20, Pages: 12889-12903, ISSN: 1680-7316

Measurements of mid- to far-infrared nadir radiances obtained from the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 aircraft during the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) are used to assess the performance of various ice cloud bulk optical property models. Through use of a minimization approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty, but they are unable to simultaneously match the observations over the far-infrared frequency range. When both mid- and far-infrared observations are used to minimize residuals, first-order estimates of the spectral flux differences between the best-performing simulations and observations indicate a compensation effect between the mid- and far-infrared such that the absolute broadband difference is < 0.7 W m−2. However, simply matching the spectra using the mid-infrared (far-infrared) observations in isolation leads to substantially larger discrepancies, with absolute differences reaching ∼ 1.8 (3.1) W m−2. These results show that simulations using these microphysical models may give a broadly correct integrated longwave radiative impact but that this masks spectral errors, with implicit consequences for the vertical distribution of atmospheric heating. They also imply that retrievals using these models applied to mid-infrared radiances in isolation will select cirrus optical properties that are inconsistent with far-infrared radiances. As such, the results highlight the potential benefit of more extensive far-infrared observations for the assessment and, where necessary, the improvement of current ice bulk optical models.

Journal article

Bantges R, Brindley H, Russell J, Murray J, Last A, fox C, fox S, harlow C, o'shea S, bower K, baum B, yang P, oetjen H, Pickering Jet al., 2020, A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid-and far-infrared, Publisher: Atmospheric Chemistry and Physics. Discussion. Copernicus Publications

Measurements of mid- to far-infrared nadir radiances obtained from the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft during the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) are used to assess the performance of various ice cloud bulk optical (single-scattering) property models. Through use of a minimisation approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty but are unable to simultaneously match the observations over the far-infrared frequency range. When both mid and far-infrared observations are used to minimise residuals, first order estimates of the flux differences between the best performing simulations and observations indicate a strong compensation effect between the mid and far infrared such that the absolute broadband difference is < 0.7 W m−2. However, simply matching the spectra using the mid-infrared observations in isolation leads to substantially larger discrepancies, with absolute differences reaching ~ 1.8 W m−2. These results highlight the benefit of far infrared observations for better constraining retrievals of cirrus cloud properties and their radiative impact, and provide guidance for the development of more realistic ice cloud optical models.

Working paper

Bellisario C, Brindley H, Murray J, Last A, Pickering J, Chawn Harlow R, Fox S, Fox C, Newman S, Smith M, Anderson D, Huang X, Chen Xet al., 2017, Retrievals of the Far Infrared surface emissivity over the Greenland Plateau using the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS)., Journal of Geophysical Research, Vol: 122, Pages: 12152-12166, ISSN: 0148-0227

The Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) measured near surface upwelling and downwelling radiances within the far infrared (FIR) over Greenland during two flights in March 2015. Here we exploit observations from one of these flights to provide in-situ estimates of FIR surface emissivity, encompassing the range 80-535 cm-1. The flight campaign and instrumental set-up is described as well as the retrieval method, including the quality control performed on the observations. The combination of measurement and atmospheric profile uncertainties means that the retrieved surface emissivity has the smallest estimated error over the range 360-535 cm-1, (18.7-27.8 μm), lying between 0.89 and 1 with an associated error which is of the order ± 0.06. Between 80 and 360 cm-1, the increasing opacity of the atmosphere, coupled with the uncertainty in the atmospheric state, means that the associated errors are larger and the emissivity values cannot be said to be distinct from 1. These FIR surface emissivity values are, to the best of our knowledge, the first ever from aircraft-based measurements. We have compared them to a recently developed theoretical database designed to predict the infrared surface emissivity of frozen surfaces. When considering the FIR alone, we are able to match the retrievals within uncertainties. However, when we include contemporaneous retrievals from the mid infrared (MIR), no single theoretical representation is able to capture the FIR and MIR behaviour simultaneously. Our results point towards the need for model improvement and further testing, ideally including in-situ characterisation of the underlying surface conditions.

Journal article

Murray JE, Brindley HE, Bryant RG, Russell JE, Jenkins KF, Washington Ret al., 2016, Enhancing weak transient signals in SEVIRI false color imagery: Application to dust source detection in southern Africa, Journal of Geophysical Research: Atmospheres, Vol: 121, Pages: 10199-10219, ISSN: 2169-897X

A method is described to significantly enhance the signature of dust events using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI). The approach involves the derivation of a composite clear-sky signal for selected channels on an individual time-step and pixel basis. These composite signals are subtracted from each observation in the relevant channels to enhance weak transient signals associated with either (a) low levels of dust emission, or (b) dust emissions with high salt or low quartz content. Different channel combinations, of the differenced data from the steps above, are then rendered in false color imagery for the purpose of improved identification of dust source locations and activity. We have applied this clear-sky difference (CSD) algorithm over three [globally significant] source regions in southern Africa: the Makgadikgadi Basin, Etosha Pan, and the Namibian and western South African coast. Case study analyses indicate three notable advantages associated with the CSD approach over established image rendering methods: (i) an improved ability to detect dust plumes, (ii) the observation of source activation earlier in the diurnal cycle, and (iii) an improved ability to resolve and pinpoint dust plume source locations.

Journal article

Bantges RJ, Brindley HE, Chen XH, Huang XL, Harries JE, Murray JEet al., 2016, On the detection of robust multi-decadal changes in the Earth’s Outgoing Longwave Radiation spectrum, Journal of Climate, Vol: 29, Pages: 4939-4947, ISSN: 1520-0442

Differences between Earth’s global mean all-sky outgoing longwave radiation spectrum as observed in 1970 [Interferometric Infrared Spectrometer (IRIS)], 1997 [Interferometric Monitor for Greenhouse Gases (IMG)], and 2012 [Infrared Atmospheric Sounding Instrument (IASI)] are presented. These differences are evaluated to determine whether these are robust signals of multidecadal radiative forcing and hence whether there is the potential for evaluating feedback-type responses. IASI–IRIS differences range from +2 K in the atmospheric window (800–1000 cm−1) to −5.5 K in the 1304 cm−1 CH4 band center. Corresponding IASI–IMG differences are much smaller, at 0.2 and −0.8 K, respectively. More noticeably, IASI–IRIS differences show a distinct step change across the 1042 cm−1 O3 band that is not seen in IASI–IMG comparisons. This step change is a consequence of a difference in behavior when moving from colder to warmer scenes in the IRIS data compared to IASI and IMG. Matched simulations for the relevant periods using ERA reanalyses mimic the spectral behavior shown by IASI and IMG rather than by IRIS. These findings suggest that uncertainties in the spectral response of IRIS preclude the use of these data for quantitative assessments of forcing and feedback processes.

Journal article

Green PD, Newman SM, Beeby RJ, Murray JE, Pickering JC, Harries JEet al., 2012, Recent advances in measurement of the water vapour continuum in the far-infrared spectral region, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 370, Pages: 2637-2655, ISSN: 1364-503X

Journal article

Blackie D, Murray JE, Blackwell-Whitehead R, Thorne AP, Pickering JC, Willey BRet al., 2011, A zero-dispersion monochromator and two-beam output for UV Fourier transform absorption spectrometry, JOURNAL OF INSTRUMENTATION, Vol: 6, ISSN: 1748-0221

Journal article

Cox CV, Harries JE, Taylor JP, Green PD, Baran AJ, Pickering JC, Last AE, Murray JEet al., 2010, Measurement and simulation of mid- and far-infrared spectra in the presence of cirrus, QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 136, Pages: 718-739, ISSN: 0035-9009

Journal article

Cox CV, Murray JE, Taylor JP, Green PD, Pickering JC, Harries JE, Last AEet al., 2007, Clear-sky far-infrared measurements observed with TAFTS during the EAQUATE campaign, September 2004, QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 133, Pages: 273-283, ISSN: 0035-9009

Journal article

Yoshino K, Thorne AP, Murray JE, Cheung ASC, Wong AL, Imajo Tet al., 2006, The application of a vacuum-ultraviolet Fourier transform spectrometer and synchrotron-radiation source to measurements of bands of NO. VII. The final report, JOURNAL OF CHEMICAL PHYSICS, Vol: 124, ISSN: 0021-9606

Journal article

Cheung ASC, Wong AL, Lo DHY, Leung KWS, Yoshino K, Thorne AP, Murray JE, Imajo T, Ito K, Matsui Tet al., 2003, Application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of. VI. The epsilon(0,0) band of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 119, Pages: 8373-8378, ISSN: 0021-9606

Journal article

Matsui T, Cheung ASC, Leung KWS, Yoshino K, Parkinson WH, Thorne AP, Murray JE, Ito K, Imajo Tet al., 2003, High resolution absorption cross-section measurements of the Schumann-Runge bands of O-2 by VUV Fourier transform spectroscopy, JOURNAL OF MOLECULAR SPECTROSCOPY, Vol: 219, Pages: 45-57, ISSN: 0022-2852

Journal article

Rufus J, Yoshino K, Thorne AP, Murray JE, Imajo T, Ito K, Matsui Tet al., 2002, The application of a vacuum ultraviolet Fourier transform spectrometer and synchrotron radiation source to measurements of: V. The beta(11,0) band of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 117, Pages: 10621-10626, ISSN: 0021-9606

Journal article

Cheung ASC, Lo DHY, Leung KWS, Yoshino K, Thorne AP, Murray JE, Ito K, Matsui T, Imajo Tet al., 2002, The application of a vacuum ultraviolet Fourier transform spectrometer and synchrotron radiation source to measurements of: IV. The beta(6,0) and gamma(3,0) bands of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 116, Pages: 155-161, ISSN: 0021-9606

Journal article

Green P, Murray J, Harries J, Last A, Pickering Jet al., 2002, Clear-sky radiance measurements from the far-ir tafts instrument during emerald 2001, Boston, 11th conference on atmospheric radiation, Ogden, Utah, 3 - 7 June 2002, Publisher: American Meteorological Society, Pages: 94-95

Conference paper

Rufus J, Yoshino K, Esmond JR, Thorne AP, Murray JE, Imajo T, Ito K, Matsui Tet al., 2001, The application of a vacuum ultraviolet Fourier transform spectrometer and synchrotron radiation source to measurements of the III epsilon(1,0) band of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 115, Pages: 3719-3723, ISSN: 0021-9606

Journal article

Murray JE, Canas AA, 2001, Observing the radiative properties of clear and cloudy skies in the far infrared, 14-120 mu m, using the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS), Conference on Fourier Transform Spectroscopy, Publisher: OPTICAL SOC AMERICA, Pages: 20-23, ISSN: 1094-5695

Conference paper

Pickering JC, Thorne AP, Murray JE, Litzen U, Johansson S, Zilio V, Webb JKet al., 2000, Accurate laboratory wavelengths of some ultraviolet lines of Cr, Zn and Ni relevant to time variations of the fine structure constant, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 319, Pages: 163-167, ISSN: 0035-8711

Journal article

Imajo T, Yoshino K, Esmond JR, Parkinson WH, Thorne AP, Murray JE, Learner RCM, Cox G, Cheung ASC, Ito K, Matsui Tet al., 2000, The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of: II. The delta(1,0) band of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 112, Pages: 2251-2257, ISSN: 0021-9606

Journal article

Yoshino K, Thorne AP, Murray JE, Ito K, Matsui T, Leung KWS, Cheung ASC, Imajo Tet al., 2000, The application of a VUV-FT spectrometer and synchrotron radiation source to measurements of the NO and O-2 bands at 295 K, PHYSICS AND CHEMISTRY OF THE EARTH PART C-SOLAR-TERRESTIAL AND PLANETARY SCIENCE, Vol: 25, Pages: 199-201, ISSN: 1464-1917

Journal article

Dooley PM, Lewis BR, Gibson ST, Baldwin KGH, Cosby PC, Price JL, Copeland RA, Slanger TG, Thorne AP, Murray JE, Yoshino Ket al., 1998, A comparative high-resolution study of predissociation linewidths in the Schumann-Runge bands of O-2, JOURNAL OF CHEMICAL PHYSICS, Vol: 109, Pages: 3856-3867, ISSN: 0021-9606

Journal article

Yoshino K, Esmond JR, Parkinson WH, Thorne AP, Murray JE, Learner RCM, Cox G, Cheung ASC, Leung KWS, Ito K, Matsui T, Imajo Tet al., 1998, The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of: I. The beta(9,0) band of NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 109, Pages: 1751-1757, ISSN: 0021-9606

Journal article

Mossavati R, Kellock S, Mueller J, Harries JE, Murray JE, Sawyer E, Caldwell M, Oliver M, Delderfield J, Sandford Met al., 1998, Geostationary earth radiation budget, Conference on Satellite Remote Sensing of Clouds and the Atmosphere II, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, Pages: 125-135, ISSN: 0277-786X

Conference paper

YOSHINO K, ESMOND JR, MURRAY JE, PARKINSON WH, THORNE AP, LEARNER RCM, COX Get al., 1995, BAND OSCILLATOR-STRENGTHS OF THE HERZBERG-I BANDS OF O-2, JOURNAL OF CHEMICAL PHYSICS, Vol: 103, Pages: 1243-1249, ISSN: 0021-9606

Journal article

Learner RCM, Thorne AP, Murray JE, Semeniuk JIet al., 1995, UV Fourier transform spectroscopy of emission line spectra, Laboratory and Astronomical High Resolution Spectra, Vol: 81, Pages: 227-228

Journal article

Learner RCM, Thorne AP, Murray JE, Semeniuk JIet al., 1995, UV Fourier transform spectroscopy of emission line spectra, Laboratory and Astronomical High Resolution Spectra, Vol: 81, Pages: 227-228

Journal article

YOSHINO K, MURRAY JE, ESMOND JR, SUN Y, PARKINSON WH, THORNE AP, LEARNER RCM, COX Get al., 1994, FOURIER-TRANSFORM SPECTROSCOPY OF THE HERZBERG-I BANDS OF O-2, CANADIAN JOURNAL OF PHYSICS, Vol: 72, Pages: 1101-1108, ISSN: 0008-4204

Journal article

MURRAY JE, YOSHINO K, ESMOND JR, PARKINSON WH, SUN Y, DALGARNO A, THORNE AP, COX Get al., 1994, VACUUM-ULTRAVIOLET FOURIER-TRANSFORM SPECTROSCOPY OF THE DELTA(0,0) AND BETA(7,0) BANDS OF NO, JOURNAL OF CHEMICAL PHYSICS, Vol: 101, Pages: 62-73, ISSN: 0021-9606

Journal article

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