Dr Penny Holliday

Marine Physics and Ocean Climate
+44 (0)23 8059 6206


My research has centred on physical processes in the high latitude North Atlantic Ocean.  In particular I am interested in the mechanisms that drive the variability that we observe in the gyre and overturning circulation in the subpolar region (broadly speaking the ocean between Canada, Greenland, Iceland and north-west Europe).  The areas of research that I am working on include year-to-year changes in the amount of heat, freshwater and carbon carried in the subpolar currents, the causes and effects of variability of Arctic freshwater in the subpolar region and the impact of physical variability on ecosystems.

I'm NOC Principal Investigator for the Extended Ellett Line programme, which is a long-running project (started in 1975) observing and understanding the ocean west of Britain.  

I'm project leader for the UK OSNAP project, which is part of an international programme to directly observe the subpolar gyre and overturning circulation and property transports. 


Committee and Board Memberships: 

Member of the OSNAP Steering Committee and OSNAP Data Products Working Group

Member of the ICES Working Group on Oceanic Hydrography




Johnson, Clare; Sherwin, Toby; Cunningham, Stuart; Dumont, Estelle; Houpert, Loïc; Holliday, N. Penny. 2017 Transports and pathways of overflow water in the Rockall Trough. Deep Sea Research Part I: Oceanographic Research Papers, 122. 48-59.10.1016/j.dsr.2017.02.004
Benetti, M.; Reverdin, G.; Lique, C.; Yashayaev, I.; Holliday, N.P.; Tynan, E.; Torres-valdes, S.; Lherminier, P.; Tréguer, P.; Sarthou, G.. 2017 Composition of freshwater in the spring of 2014 on the southern Labrador shelf and slope. Journal of Geophysical Research: Oceans, 122 (2). 10.1002/2016JC012244
Lozier, M. Susan; Bacon, Sheldon; Bower, Amy S.; Cunningham, Stuart A.; de Jong, M. Femke; de Steur, Laura; deYoung, Brad; Fischer, Jürgen; Gary, Stefan F; Greenan, Blair J.W.; Heimbach, Patrick; Holliday, Naomi P.; Houpert, Loïc; Inall, Mark E.; Johns, William E.; Johnson, Helen L.; Karstensen, Johannes; Li, Feili; Lin, Xiaopei; Mackay, Neill; Marshall, David P.; Mercier, Herlé; Myers, Paul G.; Pickart, Robert S.; Pillar, Helen R.; Straneo, Fiammetta; Thierry, Virginie; Weller, Robert A.; Williams, Richard G.; Wilson, Chris; Yang, Jiayan; Zhao, Jian; Zika, Jan D.. 2017 Overturning in the Subpolar North Atlantic Program: a new international ocean observing system. Bulletin of the American Meteorological Society, 98 (4). 737-752.10.1175/BAMS-D-16-0057.1
Main, C.E.; Yool, A.; Holliday, N.P.; Popova, E.E.; Jones, D.O.B.; Ruhl, H.A.. 2017 Simulating pathways of subsurface oil in the Faroe–Shetland Channel using an ocean general circulation model. Marine Pollution Bulletin, 114 (1). 315-326.10.1016/j.marpolbul.2016.09.041
Humphreys, Matthew P.; Griffiths, Alex M.; Achterberg, Eric P.; Holliday, N. Penny; Rerolle, Victoire M.C.; Menzel Barraqueta, Jan-Lukas; Couldrey, Matthew P.; Oliver, Kevin I.C.; Hartman, Susan; Esposito, Mario; Boyce, Adrian J.. 2016 Multidecadal accumulation of anthropogenic and remineralized dissolved inorganic carbon along the Extended Ellett Line in the northeast Atlantic Ocean. Global Biogeochemical Cycles, 30 (2). 293-310.10.1002/2015GB005246
Marzocchi, Alice; Hirschi, Joël J.-M.; Holliday, N. Penny; Cunningham, Stuart A.; Blaker, Adam T.; Coward, Andrew C.. 2015 The North Atlantic subpolar circulation in an eddy-resolving global ocean model. Journal of Marine Systems, 142. 126-143.10.1016/j.jmarsys.2014.10.007
Prieto, E.; González-Pola, C.; Lavín, A.; Holliday, N.P.. 2015 Interannual variability of the northwestern Iberia deep ocean: Response to large-scale North Atlantic forcing. Journal of Geophysical Research: Oceans, 120 (2). 832-847.10.1002/2014JC010436
Holliday, N.P.; Cunningham, S.A.; Johnson, C.; Gary, S.F.; Griffiths, C.; Read, J.F.; Sherwin, T.. 2015 Multidecadal variability of potential temperature, salinity, and transport in the eastern subpolar North Atlantic. Journal of Geophysical Research: Oceans, 120 (9). 5945-5967.10.1002/2015JC010762
Fischer, J.; Karstensen, J.; Zantopp, R.; Visbeck, M.; Biastoch, A.; Behrens, E.; Böning, C.W.; Quadfasel, D.; Jochumsen, K.; Valdimarsson, H.; Jónsson, S.; Bacon, S.; Holliday, N.P.; Dye, S.; Rhein, M.; Mertens, C.. 2015 Intra-seasonal variability of the DWBC in the western subpolar North Atlantic. Progress in Oceanography, 132. 233-249.10.1016/j.pocean.2014.04.002
Holliday, Penny. 2014 Autobiography. Oceanography, 27 (4 Suppl.), supplement Women in Oceanography: a decade later. p138.
Bacon, Sheldon; Marshall, Abigail; Holliday, N. Penny; Aksenov, Yevgeny; Dye, Stephen R.. 2014 Seasonal variability of the East Greenland Coastal Current. Journal of Geophysical Research: Oceans, 119 (6). 3967-3987.10.1002/2013JC009279
Henson, Stephanie A.; Painter, Stuart C.; Holliday, N. Penny; Stinchcombe, Mark C.; Giering, Sarah L.C.. 2013 Unusual subpolar North Atlantic phytoplankton bloom in 2010: Volcanic fertilisation or North Atlantic Oscillation? Journal of Geophysical Research: Oceans, 118 (10). 4771-4780.10.1002/jgrc.20363
Hughes, S.; Holliday, N.P.; Gaillard, F.; ICES Working Group on Oceanic Hydrography, .. 2012 Variability in the ICES/NAFO region between 1950 and 2009: observations from the ICES Report on Ocean Climate. ICES Journal of Marine Science, 69 (5). 706-719.10.1093/icesjms/fss044
Holt, Jason; Hughes, Sarah; Hopkins, Joanne; Wakelin, Sarah L.; Holliday, N. Penny; Dye, Stephen; González-Pola, César; Hjøllo, Solfrid Sætre; Mork, Kjell Arne; Nolan, Glen; Proctor, Roger; Read, Jane; Shammon, Theresa; Sherwin, Toby; Smyth, Tim; Tattersall, Graham; Ward, Ben; Wiltshire, Karen Helen. 2012 Multi-decadal variability and trends in the temperature of the northwest European continental shelf: A model-data synthesis. Progress in Oceanography, 106. 96-117.10.1016/j.pocean.2012.08.001
Sherwin, Toby J.; Read, Jane F.; Holliday, N. Penny; Johnson, C.. 2012 The impact of changes in North Atlantic Gyre distribution on water mass characteristics in the Rockall Trough. ICES Journal of Marine Science, 69 (5). 751-757.10.1093/icesjms/fsr185
Stanford, J.D.; Rohling, E.J.; Bacon, S.; Holliday, N.P.. 2011 A review of the deep and surface currents around Eirik Drift, south of Greenland: Comparison of the past with the present. Global and Planetary Change, 79. 244-254.10.1016/j.gloplacha.2011.02.001
Hughes, S.L.; Holliday, N.P.; Kennedy, J.; Berry, D.I.; Kent, E.C.; Sherwin, T.; Dye, S.; Inall, M.; Shammon, T.; Smyth, T.. 2010 Temperature (air and sea). MCCIP Annual Report Card 2010-11, MCCIP Science Review. 16p.
Montagnes, David J.S.; Allen, John T.; Brown, Louise; Bulit, Celia; Davidson, Russell; Fielding, Sophie; Heath, Mike; Holliday, N. Penny; Rasmussen, Jens; Sanders, Richard; Waniek, Joanna; Wilson, David I.. 2010 Role of ciliates and other microzooplankton in the Irminger Sea (NW Atlantic Ocean). Marine Ecology Progress Series, 411. 101-115.10.3354/meps08646
Aksenov, Yevgeny ; Bacon, Sheldon; Coward, Andrew C.; Holliday, N. Penny . 2010 Polar outflow from the Arctic Ocean: A high resolution model study. Journal of Marine Systems, 83 (1-2). 14-37.10.1016/j.jmarsys.2010.06.007
Holliday, N.P.; Hughes, S.L.; Dye, S.; Inall, M.; Read, J.; Shammon, T.; Sherwin, T.; Smyth, T.. 2010 Salinity. MCCIP Annual Report Card 2010-11, MCCIP Science Review. 10p.
Holliday, N.P.; Bacon, S.; Allen, J.T.; McDonagh, E.L.. 2009 Circulation and transport in the western boundary currents at Cape Farewell, Greenland. Journal of Physical Oceanography, 39 (8). 1854-1870.10.1175/2009JPO4160.1
Hughes, S.; Holliday, N.P.; Colbourne, E.; Ozhigin, V.; Valdimarsson, H.; Østerhus, S.; Wiltshire, K.. 2009 Comparison of in situ time-series of temperature with gridded sea surface temperature datasets in the North Atlantic. ICES Journal of Marine Science, 66 (7). 1467-1479.10.1093/icesjms/fsp041
Heath, M.R.; Rasmussen, J.; Ahmed, Y.; Allen, J.; Anderson, C.I.H.; Brierley, A.S.; Brown, L.; Bunker, A.; Cook, K.; Davidson, R.; Fielding, S.; Gurney, W.S.C.; Harris, R.; Hay, S.; Henson, S.; Hirst, A.G.; Holliday, N.P.; Ingvarsdottir, A.; Irigoien, X.; Lindeque, P.; Mayor, D.J.; Montagnes, D.; Moffat, C.; Pollard, R.; Richards, S.; Saunders, R.A.; Sidey, J.; Smerdon, G.; Speirs, D.; Walsham, P.; Waniek, J.; Webster, L.; Wilson, D.. 2008 Spatial demography of Calanus finmarchicus in the Irminger Sea. Progress in Oceanography, 76 (1). 39-88.10.1016/j.pocean.2007.10.001
Holliday, N.P.; Hughes, S.L.; Bacon, S.; Beszczynska-Möller, A.; Hansen, B.; Lavin, A.; Loeng, H.; Mork, K.A.; Østerhus, S.; Sherwin, T.; Walczowski, W.. 2008 Reversal of the 1960s to 1990s freshening trend in the northeast North Atlantic and Nordic Seas. Geophysical Research Letters, 35. L03614.10.1029/2007GL032675
Holliday, N.P.; Kennedy, J.; Kent, E.C.; Marsh, R.; Hughes, S.L.; Sherwin, T.; Berry, D.I.. 2008 Scientific review - sea temperature. Marine Climate Changes Impact Annual Report Card 2008.
Holliday, N.P.; Hughes, S.L.; Shammon, T.; Sherwin, T.. 2008 Scientific review - ocean salinity. Marine Climate Change Impacts Annual Report Card 2008.
Lauderdale, Jonathan M.; Bacon, Sheldon; Naveira Garabato, Alberto C.; Holliday, N.Penny. 2008 Intensified turbulent mixing in the boundary current system of southern Greenland. Geophysical Research Letters, 35. L04611.10.1029/2007GL032785
Montagnes, David J.S.; Allen, John T.; Brown, Louise; Bulit, Celia; Davidson, Russell; Diaz-Avalos, Carlos; Fielding, Sophie; Heath, Mike; Holliday, Naomi P.; Rasmussen, Jens; Sanders, Richard; Waniek, Joanna J.; Wilson, David. 2008 Factors controlling the abundance and size distribution of the phototrophic ciliate Myrionecta rubra in open waters of the North Atlantic. Journal of Eukaryotic Microbiology, 55 (5). 457-465.10.1111/j.1550-7408.2008.00344.x
Holliday, N.P.; Meyer, A.; Bacon, S.; Alderson, S.; de Cuevas, B.. 2007 The retroflection of part of the East Greenland Current at Cape Farewell. Geophysical Research Letters, 34 (7). L07609.10.1029/2006GL029085
Castellani, C.; Irigoien, X.; Harris, R.P; Holliday, N.P.. 2007 Regional and temporal variation of Oithona spp. biomass, stage structure and productivity in the Irminger Sea, North Atlantic. Journal of Plankton Research, 29 (12). 1051-1070.10.1093/plankt/fbm079
Polyakov, I.; Timokhov, L.; Dmitrenko, I.; Ivanov, V.; Simmons, H.; Beszcynska-Moeller, A.; Dickson, R.; Fahrbach, E.; Fortier, L.; Gascard, J.; Hoeleman, J.; Holliday, N.P.; Hansen, E.; Mauritzen, C.; Piechura, J.; Pickart, R.; Schauer, U.; Steele, M.; Walczowski, W.. 2007 Observational program tracks Arctic Ocean transition to a warmer state. EOS, Transactions, American Geophysical Union, 88 (40). 398-399.
Yashayaev, Igor; van Aken, Hendrik M.; Holliday, N. Penny; Bersch, Manfred. 2007 Transformation of the Labrador Sea water in the subpolar North Atlantic. Geophysical Research Letters, 34 (22). L22605.10.1029/2007GL031812
Holliday, N.P.; Waniek, J.; Davidson, R.; Wilson, D.; Brown, L.; Sanders, R.; Pollard, R.T.; Allen, J.T.. 2006 Large-scale physical controls on phytoplankton growth in the Irminger Sea. Part 1: Hydrographic zones, mixing and stratification. Journal of Marine Systems, 59 (3-4). 201-218.10.1016/j.jmarsys.2005.10.004
Hughes, S.L.; Holliday, N.P.. 2006 The ICES Report on Ocean Climate 2005. CLIVAR Exchanges, 11 (3). 26-27.
Hughes, S.L.; Holliday, Naomi P.. 2006 The ICES Report on Ocean Climate 2005. GLOBEC International Newsletter, 12 (2). p.13.
Holliday, N.P.; Yelland, M.Y.; Pascal, R.; Swail, V.; Taylor, P.K.; Griffiths, C.R.; Kent, E.C.. 2006 Were extreme waves in the Rockall Trough the largest ever recorded? Geophysical Research Letters, 33 (5). L05613.10.1029/2005GL025238
Waniek, Joanna J.; Holliday, N.P.; Davidson, R.; Brown, L.; Henson, S.A.. 2005 Freshwater control of onset and species composition of Greenland shelf spring bloom. Marine Ecology - Progress Series, 288. 45-57.10.3354/meps288045
Hydes, D.J.; Gowen, R.J.; Holliday, N.P.; Shammon, T.; Mills, D.. 2004 External and internal control of winter concentrations of nutrients (N, P and Si) in north-west European shelf seas. Estuarine Coastal and Shelf Science, 59 (1). 151-161.10.1016/j.ecss.2003.08.004
Pollard, R.T.; Read, J.F.; Holliday, N.P.; Leach, H.. 2004 Water masses and circulation pathways through the Iceland Basin during Vivaldi 1996. Journal of Geophysical Research, 109 (C4). C04004.10.1029/2003JC002067
Turrell, W.R.; Holliday, N.P.. 2003 The ICES Annual Ocean Climate Status Summary: 2000/2001. ICES Marine Science Symposia, 219. 309-310.
Holliday, N.P.. 2003 Air-sea interaction and circulation changes in the northeast Atlantic. Journal of Geophysical Research, 108 (C8). art. no.3259.10.1029/2002JC001344
Read, J.F.; Pollard, R.T.; Holliday, N.P.; Allen, J.T.; Leach, H.. 2002 FISHES 2001 and Vivaldi 1996: two recent surveys of the subpolar northeast Atlantic (abstract of paper presented at ASLO/AGU Ocean Sciences Meeting, Honolulu, HI, 11-15 Feb 2002). EOS: Transactions American Geophysical Union, 83 (4 Supplement). p.OS80.
Holliday, P.. 2001 SALTS: latest float deployments in the N E Atlantic. Challenger Wave, May 2001. p.2.
Reid, P.C.; Holliday, N.P.; Smyth, T.J.. 2001 Pulses in the eastern margin current and warmer water off the north west European shelf linked to North Sea ecosystem changes. Marine Ecology - Progress Series, 215. 283-287.
Holliday, N.P.. 2001 Countdown to the final issue of the WOCE global data. International WOCE Newsletter, No.41. 3-4.
Holliday, N.P.; Pollard, R.T.; Read, J.F.; Leach, H.. 2000 Water mass properties and fluxes in the Rockall Trough, 1975-1998. Deep-Sea Research I, 47 (7). 1303-1332.10.1016/S0967-0637(99)00109-0


Holliday, N.P.; et al, .. 2016 RRS Discovery Cruise DY054, 27 Jul - 17 Aug 2016, Reykjavik to Southampton. OSNAP 2016 mooring refurbishment cruise, Leg 2. Southampton, National Oceanography Centre, 77pp. (National Oceanography Centre Cruise Report 40)
Holliday, N.P.; et al, .. 2015 RRS Discovery Cruise DY031, 28 May - 18 Jun 2015, Southampton to Liverpool. The 40th Anniversary Extended Ellett Line. Southampton, National Oceanography Centre, 72pp. (National Oceanography Centre Cruise Report 34)
King, B.A.; Holliday, N.P.; et al, .. 2015 RRS James Clark Ross Cruise 302, 06 Jun - 21 Jul 2014. The 2015 RAGNARRoC, OSNAP AND Extended Ellett Line cruise report. Southampton, National Oceanography Centre, 76pp. (National Oceanography Centre Cruise Report 35)
Holliday, N.P.; Gary, S.. 2014 State of the eastern North Atlantic subpolar gyre: The Extended Ellett Line Programme Annual Report No. 2. Southampton, National Oceanography Centre, 19pp. (National Oceanography Centre Research and Consultancy Report, 43)
Holliday, N.P.; Cunningham, S.; Griffiths, C.. 2013 State of the eastern North Atlantic subpolar gyre: The Extended Ellett Line Programme Annual Report No. 1. Southampton, National Oceanography Centre, 15pp. (National Oceanography Centre Research and Consultancy Report, 36)
Hughes, Sarah L.; Holliday, Naomi P.. 2007 ICES report on ocean climate 2006. Copenhagen, Denmark, International Council for the Exploration of the Seas, 57pp. (ICES Cooperative Research Report 289 Special Issue)
Hughes, Sarah L.; Holliday, Naomi P.. 2006 ICES report on ocean climate 2005. Copenhagen, Denmark, International Council for the Exploration of the Seas, 47pp. (ICES Cooperative Research Report 280)
Holliday, N.P.; Griffiths, C.R.. 2000 RRS Discovery Cruise 245, 27 Jan-20 Feb 2000. A hydrographic section from Scotland to Iceland. Southampton, UK, Southampton Oceanography Centre, 80pp. (Southampton Oceanography Centre Cruise Report 29)

Book section

Dye, Stephen; Hughes, Sarah L.; Tinker, Jonathan; Berry, David I.; Holliday, N. Penny; Kent, Elizabeth C.; Kennington, Kevin; Inall, Mark; Smythe, Tim; Nolan, Glenn; Lyons, Kieran; Adres, Olga; Beszczynska-Möller, Agnieszka . 2013 Impacts of climate change on temperature (air and sea). In: Baxter, J.M.; Buckley, P.J.; Wallace, C.J., (eds.)Marine Climate Change Impacts Partnership Science Review 2013. Lowestoft, UK, MCCIP Secretariat, 12pp.
Holliday, N.P.; Bacon, S.; Aksenov, Y.; de Cuevas, B.; Colbourne, E.; Lee, C.; Curry, B.; de Steur, L.; Hansen, E.. 2012 Reduction in Arctic Ocean Freshwater transport. In:2012 Ocean Sciences Meeting 20-24 February 2012 Salt Lake City, Utah, USA, Abstracts Book. Waco, Texas, Oceanography Society/ASLO/AGU, p198-10166.
Holliday, Penny. 2012 Story Board 3: Riding the storm in the North Atlantic. In: Dwer, Ned, (ed.)The Status of Ireland's Climate, 2012. Wexford, Ireland, Environmental Protection Agency, 71-72, 147pp. (CCRP Report, 26).
Holliday, N.P.; Quante, M.; Sherwin, T.; Nolan, G.; Mork, K.A.; Cannaby, H.; Berry, D.I.. 2011 North Atlantic circulation and atmospheric forcing. In: Reid, P.C.; Valdes, L., (eds.)ICES Status Report on Climate Change in the North Atlantic. Copenhagen, International Council for the Exploration of the Sea, 8-20, 262pp. (ICES Cooperative Research Report 310).
Holliday, N.P.; Hughes, S.L.; Borenas, K.; Feistel, R.; Gaillard, F.; Lavin, A.; Loeng, H.; Mork, K.A.; Nolan, G.; Quante, M.; Somavilla, R.. 2011 Long-term physical variability in the North Atlantic Ocean. In: Reid, P.C.; Valdes, L., (eds.)ICES Status Report on Climate Change in the North Atlantic. Copenhagen, International Council for the Exploration of the Sea, 21-46, 262pp. (ICES Cooperative Research Report 310).
Holliday, N.P.; Hughes, S.L.; Quante, M.; Rudels, B.. 2011 Sea Level Rise and Changes in Arctic Sea-ice. In: Reid, P.C.; Valdes, L., (eds.)ICES Status Report on Climate Change in the North Atlantic. Copenhagen, International Council for the Exploration of the Sea, 47-58, 262pp. (ICES Cooperative Research Report 310).
Holliday, N.P.; Valdimarsson, H.; Nolan, G.; Hughes, S.L.; Lavin, A.; Østerhus, S.; Sherwin, T.; Trofimov, A.. 2010 The ICES Working Group on Oceanic Hydrography: Building on Over 100 Years of North Atlantic Observations. In: Hall, J.; Harrison, D.E.; Stammer, D., (eds.)Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society, Vol. 2. Noordwijk, The Netherlands, European Space Agency, 501-507. (ESA Special Publication, WPP-306).
Yelland, M.; Holliday, N.; Skjelvan, I.; Østerhus, S.; Conway, T.. 2010 Continuous Observations From the Weather Ship Polarfront at Station Mike. In: Hall, J.; Harrison, D.E.; Stammer, D., (eds.)Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society, Annex. Noordwijk, The Netherlands, European Space Agency. (ESA Special Publication, WPP-306).
Yashayaev, Igor; Holliday, N.Penny; Bersch, Manfred; van Aken, Hendrik M.. 2008 The history of the Labrador Sea Water: production, spreading, transformation and loss. In: Dickson, R.R.; Meincke, J.; Rhines, P., (eds.)Arctic-Subarctic Ocean Fluxes. Berlin, Springer, 569-612, 736pp.
Holliday, Naomi P.; Griffiths, Colin; Read, J.F.; Sherwin, T.. 2006 Rockall Trough and Iceland Basin (Area 5 Report). In:ICES Working Group on Oceanic Hydrography Annual Meeting, Galway, Ireland, 19-22 April 2006. Copenhagen, Denmark, International Council for the Exploration of the Seas, 65-71, 156pp.
Holliday, N.P.; Pollard, R.T.; Griffiths, G.. 2003 A comparison of simultaneous measurements from shipboard VM-150 and OS-75 acoustic Doppler current profilers. In:Proceedings of the IEEE/OES Seventh Working Conference on Current Measurement. USA, Institution of Electrical and Electronics Engineers, 191-196.
Holliday, N.P.; Nolan, G.D.. 2002 Changes in warm water through-flow in the Rockall Trough: results of a 26 year time series of oceanographic data. In: Convery, F.; Feehan, J., (eds.)Achievement and Challenge: Rio+10 and Ireland. Dublin, Eire, Environmental Institute, University College Dublin, 393-396.