Larry O'Neill

Associate Professor and Director of Oregon Climate Services

Office: 541-737-6396

Burt Hall

Burt Hall 332D

2651 SW Orchard Avenue

2651 SW Orchard Avenue
Corvallis, OR 97331

Profile Field Tabs

Brief Research Interests: 

Air-sea interactions, satellite meteorology and oceanography, atmospheric boundary layer and ocean mixed layer dynamics



Air-sea interactions, satellite meteorology and oceanography, atmospheric boundary layer and ocean mixed layer dynamics, Pacific Northwest and North Pacific weather, ocean, and climate variability.


Current Research

(1) The influence of air-sea interactions on climate variability of the North Pacific and North America. (2) Variability of surface winds over the ocean and their consequences for ocean circulation and air-sea heat and momentum exchange. (3) Influences of ocean currents and temperature on air-sea interactions. (4) Relationship between surface winds, sea surface height, and surface ocean currents. (5) Improving water supply and climate monitoring in Oregon and the Pacific Northwest. 



Ph.D. Oceanography, Oregon State University, 2007
B.S. Atmospheric Sciences, University of California at Davis, 2000


Courses Taught

  • OC 678: Satellite Oceanography/Ocean Remote Sensing
  • OEAS 530: Fluid Earth


Graduate Students

  • Emily Hayden (Ph.D., Physics of Oceans and Atmospheres, Atmospheric Sciences concentration)
  • Rose Una (M.S., Physics of Oceans and Atmospheres)


Current Science Working Groups and Advisory Committees

  • NASA's Ocean Vector Winds Science Team
  • Jet Propulsion Laboratory's PO.DAAC Users Working Group
  • NASA's Ocean Surface Topography Science Team
  • Co-Chair of US CLIVAR Working Group on Air-Sea Interactions
  • State of Oregon Water Supply Availability Committee and Drought Readiness Council
  • Oregon Climate Extremes Committee
  • Oregon Drought Monitor Advisory Committee

Peer-Reviewed Publications

Hayden, E. E., L. W. O'Neill, and S. F. Zippel, 2024: Atmospheric variability drives anomalies in the Bering Sea air-sea heat exchange. Submitted to Journal of Climate.

O'Neill, L. W., D. B. Chelton, E. Rodriguez, R. Samelson, and A. Wineteer, 2024: Feasibility of estimating sea surface height anomalies from surface ocean currents. Journal of Atmospheric and Oceanic Technology, In Press.

O’Neill, L. W., R. F. Milliff, and D. B. Chelton, 2024: Extratropical storms fundamentally shape the maritime surface wind climatology. Submitted to NPJ Climate and Atmospheric Sciences.

Jacobs, R., and L. W. O'Neill, 2024: Co-variability between the surface wind divergence and vorticity over the ocean. Remote Sensing, 16(3), 451, doi:10.3390/rs16030451.

Hayden, E. E., and L. W. O’Neill, 2024: Processes Contributing to Bering Sea Temperature Variability in the Late Twentieth and Early Twenty-First Century. Journal of Climate, 37, 41-58.

Rupp, D. E., L. W. O'Neill, E. Fleishman, P. C. Loikith, and D. Loomis, 2023: Response of gap wind-driven freezing rain and ice accretion to global warming. Climate Dynamics, doi:10.1007/s00382-023-06991-5.

Small, R. J., V. Rousseau, R. Parfitt, L. Laurindo, L. W. O’Neill, R. Masunaga, N. Schneider, and P. Chang, 2023: Near-surface wind convergence over the Gulf Stream – the role of SST revisited. Journal of Climate, 36, 5527–5548.

Seo, H., L. W. O'Neill, M. A. Bourassa, A. Czaja, K. Drushka, J. B. Edson, B. Fox-Kemper, I. Frenger, S. T. Gille, B. P. Kirtman, S. Minobe, A. G. Pendergrass, L. Renault, M. J. Roberts, N. Schneider, R. J. Small, A. Stoffelen, and Q. Wang, 2023: Ocean Mesoscale and Frontal-scale Ocean-Atmosphere Interactions and Influence on Large-scale Climate: A Review. Journal of Climate, 36, 1981–2013.

Cooley, K., M. Fewings, J. Lerczak, L. W. O'Neill, and K. Brown, 2022: Role of sea surface physical processes in mixed-layer temperature changes during summer marine heat waves in the Chile-Peru Current System. Journal of Geophysical Research Oceans, 127 (7).

Cullen, K. E., E. Shroyer, and L. W. O’Neill, 2022: Weakly nonlinear Ekman pumping in the Sri Lanka Dome and the Southwest Monsoon Current. Journal of Physical Oceanography, 52 (8), 1693-1703.

Seo, H., H. Song, L. W. O’Neill, M. Mazloff, and B. Cornuelle, 2021: Impacts of ocean currents on the South Indian Ocean extratropical storm track through the relative wind effect. Journal of Climate, 34 (22), 9093-9113.

Abatzoglou, J. T., D. E. Rupp, L. W. O’Neill, and M. Sadegh, 2021: Compound extremes drive the western Oregon wildfires of September 2020. Geophysical Research Letters, 48, e2021GL092520.

Painemal, D., A. F. Corral, A. Sorooshian, M. A. Brunke, S. Chellappan, V. A. Gorooh, S.-H. Ham, L. W. O’Neill, W. L. Smith Jr., G. Tselioudis, H. Wang, X. Zeng, and P. Zuidema, 2021: An overview of atmospheric features over the Western North Atlantic Ocean and North American East Coast – Part 2: Circulation, boundary layer, and clouds. Journal of Geophysical Research: Atmospheres, 126, e2020JD033423.

Phillips, B. K., and L. W. O’Neill, 2020: Observational Analysis of Extratropical Cyclone Interactions with Northeast Pacific Sea Surface Temperature Anomalies. Journal of Climate, 33, 6745-6763.

Samelson, R. M., L. W. O’Neill, D. B. Chelton, E. D. Skyllingstad, P. L. Barbour, and S. M. Durski, 2020: Surface stress and atmospheric boundary layer response to mesoscale SST structure in coupled simulations of the northern California Current System. Monthly Weather Review, 148, 259-287.

Farrar, J. T. et al., 2020: S-MODE: The Sub-Mesoscale Ocean Dynamics Experiment, IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020, pp. 3533-3536.

Skyllingstad, E. D., S. P. de Szoeke, and L. W. O'Neill, 2019: Modeling the transient response of tropical convection to mesoscale SST variations. Journal of Atmospheric Sciences, 76, 1227-1244.

O'Neill, L. W. , T. Haack, D. B. Chelton, and E. D. Skyllingstad, 2018: Reply to “Comments on ‘The Gulf Stream Convergence Zone in the Time-Mean Winds’”. Journal of Atmospheric Sciences, 75, 2151-2153.

O'Neill, L. W. , T. Haack, D. B. Chelton, and E. D. Skyllingstad, 2017: The Gulf Stream Convergence Zone in the time-mean winds. Journal of Atmospheric Sciences, 74, 2383-2412.

Hong, X., C. Reynolds, J. Doyle, P. May, and L. W. O'Neill, 2017: Assessment of Upper-Ocean Variability and the Madden-Julian Oscillation in Extended-Range Air-Ocean Coupled Mesoscale SimulationsDyn. Atmos. Oc., 78, 89-105.

Wentz, F. J., L. Ricciardulli, E. Rodriguez, B. Stiles, M. Bourassa, D. Long, R. Hoffman, A. Stoffelen, A. Verhoef, L. W. O’Neill, T. Farrar, D. Vandemark, A. Fore, S. Hristova-Veleva, J. Turk, R. Gaston, D. Tyler, 2017: Evaluating and Extending the Ocean Wind Climate Data Record. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 99, 1–21.

O'Neill, L. W., T. Haack, and T. Durland, 2015: Estimation of time-averaged surface divergence and vorticity from satellite ocean vector winds. Journal of Climate, 28, 7596–7620.

Gaube, P., D. B. Chelton, R. M. Samelson, M. G. Schlax, and L. W. O’Neill, 2015: Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping. Journal of Physical Oceanography, 45, 104–132.

Perlin, N., S. P. de Szoeke, D. B. Chelton, R. M. Samelson, E. D. Skyllingstad, and L. W. O'Neill, 2014: Modeling the Atmospheric Boundary Layer Response to Mesoscale Sea Surface Temperature Perturbations. Monthly Weather Review, 142, 4284-4307.

Hong, X., S. Wang, T. Holt, P. Martin, and L. O'Neill, 2013: Modulation of the Sea-Surface Temperature in the Southeast Pacific by the Atmospheric Low-Level Coastal Jet. J. Geophys. Res., 118, 1-20.

Painemal, D., P. Minnis, and L. W. O'Neill, 2013: The diurnal cycle of cloud top height and cloud cover over the Southeast Pacific as observed by GOES-10. Journal of Atmospheric Sciences, 70, 2393–2408.

Painemal, D., P. Minnis, J. K. Ayers, and L. W. O'Neill, 2012: GOES-10 microphysical retrievals in marine warm clouds: Multi-instrument validation and daytime cycle over the southeast Pacific. J. Geophys. Res., 117, D19212, doi:10.1029/2012JD017822.

O'Neill, L. W., D. B. Chelton, and S. K. Esbensen, 2012: Covariability of surface wind and stress responses to sea-surface temperature fronts. Journal of Climate, 25, 5916–5942.

O'Neill, L. W., 2012: Wind speed and stability effects on the coupling between surface wind stress and SST observed from buoys and satellite. Journal of Climate, 26, 1544-1569.

O'Neill, L. W., S. Wang, and Q. Jiang, 2011: Variability of the diurnal cycle of liquid water path over the southeast subtropical Pacific. Atmos. Chem. Phys. Disc., 11, 31159-31206.

Hong, X., C. Bishop, T. Holt, and L. O'Neill, 2011: Impact of sea surface temperature uncertainty on the western North Pacific subtropical high (WNPSH) and rainfall. Wea. Forecasting, 26, 371-387.

Wang, S., L. O'Neill, Q. Jiang, X. Hong, H. Jin, S. de Szoeke, W. Thompson, and X. Zheng, 2011: A regional real-time forecast of marine boundary layers during VOCALS-REx. Atmos. Chem. Phys., 465-477.

Jiang, Q., S. Wang, and L. W. O'Neill, 2010: Some insights into the characteristics and dynamics of the Chilean low-level coastal jet. Mon. Wea. Rev., 138, 3185-3206.

O'Neill, L. W., S. K. Esbensen, N. Thum, R. M. Samelson, and D. B. Chelton, 2010:  Dynamical analysis of the boundary layer and surface wind responses to mesoscale SST perturbations. J. Climate, 23, 559-581.

O'Neill, L. W., D. B. Chelton, and S. K. Esbensen, 2010: The effects of SST-induced wind speed and direction gradients on mid-latitude surface vorticity and divergence. J. Climate, 23, 255-281.

Song, Q., D. B. Chelton, S. K. Esbensen, N. Thum, and L. W. O'Neill, 2009: Coupling between sea surface temperature and low-level winds in mesoscale numerical models. J. Climate, 22, 146-164.

Small, R. J., S. de Szoeke, S. P. Xie, L. O'Neill, H. Seo, Q. Song, P. Cornillon, M. Spall, and S. Minobe, 2008: Air-sea interaction over ocean fronts and eddies. Dyn. Atmos. Oceans, 45, 274-319, doi:10.1016/j.dynatmoce.2008.01.001.

Samelson, R. M., E. D. Skyllingstad, D. B. Chelton, S. K. Esbensen, L. W. O'Neill, and N. Thum, 2006: A note on the coupling of wind stress and sea surface temperature. J. Climate, 19, 1557-1566.

O'Neill, L. W., D. B. Chelton, S. K. Esbensen, and F. J. Wentz, 2005: High-resolution satellite measurements of the atmospheric boundary layer response to SST variations along the Agulhas Return Current. J. Climate, 18, 2706-2723.

O'Neill, L. W., D. B. Chelton, S. K. Esbensen, 2003: Observations of SST-induced perturbations of the wind stress fields over the Southern Ocean on seasonal time-scales. J. Climate, 16, 2340-2354.


Technical Reports and Assessments

Bumbaco, K.A., C.L. Raymond, L.W. O’Neill, A. Mehta, and D.J. Hoekema, 2023: 2022 Pacific Northwest water year impacts assessment. A collaboration between the Office of the Washington State Climatologist, Climate Impacts Group, Oregon State Climatologist, Idaho Department of Water Resources, and NOAA National Integrated Drought Information System.

Fleishman, E., editor, 2023: Sixth Oregon Climate Assessment. Oregon Climate Change Research Institute, Oregon State University, Corvallis, Oregon.

Bumbaco, K. A., M. H. Rogers, L. W. O’Neill, D. J. Hoekema, and C. L. Raymond, 2022: 2021 Pacific Northwest Water Year Impacts Assessment. A collaboration between the Office of the Washington State Climatologist, Climate Impacts Group, Oregon State Climatologist, Idaho Department of Water Resources, and NOAA National Integrated Drought Information System.

Vescio, M. D., A. Bair, K. Gleason, D. McEvoy, L. W. O'Neill, B. Warren, 2022: State Climate Extremes Committee Memorandum: Oregon All Time Maximum Temperature Record Tied at Pelton Dam, OR and Moody Farms, OR

Dalton, M., and E. Fleishman, editors. 2021. Fifth Oregon Climate Assessment. Oregon Climate Change Research Institute, Oregon State University, Corvallis, Oregon.

Bumbaco, K. A., C. L. Raymond, L. W. O’Neill, D. J. Hoekema. 2021. 2020 Pacific Northwest Water Year Impacts Assessment. A collaboration between the Office of the Washington State Climatologist, Climate Impacts Group, Oregon State Climatologist, Idaho Department of Water Resources, and NOAA National Integrated Drought Information System.

Kessler, W. S., S. E. Wijffels, S. Cravatte, N. Smith, and Contributing Authors, 2019: Second Report of TPOS 2020. GOOS-234, 265 pp.

Farrar, J. T., L. W. O'Neill, N. Smith, and M. A. Bourassa, 2015: TPOS2020: An integrated observing system for 2020 and beyond (Response to NRC Decadal Survey in Earth Science and Applications from Space).

O'Neill, L. W., 2014: Comparison of surface ocean vector wind sampling from TAO buoys and satellite scatterometers. Report to the TPOS 2020 Committee.

Lindstrom, E., Bourassa, M., Chelton, D., Corlett, G., Durland, T., Farrar, T., Janssen, P., Lagerloef, G., Lee, T., Minnett, P., O’Neill, L., and Willis, J., 2014: Satellite Views of the Tropical Pacific. Report to the TPOS 2020 Committee.

Cronin, M. F., Bourassa, M., Clayson, C., Edson, J., Fairall, C., Feely, R., Kumar, K., Large, W., Mathis, J., McPhaden, M., O’Neill, L., Pinker, R., Takahashi, K., Tomita, H., Weller, R., Yu, L., and Zhang, C., 2014: Wind stress and air-sea fluxes observations: status, implementation and gaps. Report to the TPOS 2020 Committee.



Recent Outreach and Media Appearances

Seventy-Two Hours Under the Heat Dome. The New Yorker. Oct 11, 2021.

Fire season over for half of Oregon; eastern, southern regions need more rain. The Oregonian, Oct 6, 2021.

State says fire season over for half of Oregon. The Blue Mountain Eagle. Oct 6, 2021.

State climatologist speaks on what a dry spring, summer means for fall in Oregon. KVAL News, Sept 26, 2021.

Experts say more planning, resilience needed to protect against wildfires. Capital Press, Sept 22, 2021.

Oregon State University fire expert panel: Oregonians' mindset needs to expect, accept wildfires. The Eugene Register-Guard, Sept 21, 2021.

Oregon’s large wildfires of recent years seen by OSU experts as precursor for future seasons. KTVZ News. Sept 21, 2021.

Weekend soak brings more than an inch of rain to Salem, dry week ahead. Salem Statesman Journal, Sept 19, 2021.

Oregonians relieved for rain, but experts say drought isn't over. KEZI News, Sept 18, 2021.

La Niña could bring cold, wet weather through December, models predict. Bend Bulletin, Sept 18, 2021.

First significant rain in eight months forecasted for Salem this weekend. Salem Reporter, Sept 16, 2021.

Oregon to get major rain this weekend, likely to slow wildfires but not bust drought. Salem Statesman Journal, Sept 15, 2021.

Biden Tours Western Fire Center And Tells Firefighters, 'You Saved Lake Tahoe'. GPB News NPR. Sept. 13, 2021.

Wildfires rage late into season with hot, dry conditions, but lack bite of 2020 blazes: ‘We really dodged a bullet’. The Oregonian. Sept 12, 2021.

Prolonged Heat And Smoke Is Taking Its Toll On West Coast Residents. NPR Weekend Edition, Sept 12, 2021.

KOIN Podcast Special: Climate in Crisis. Sep 7, 2021.

Experts: Oregon seems to be in ‘perpetual drought’. AP News. Aug 26, 2021.

Oregon becoming less resilient to drought, experts say. Capital Press. Aug 25, 2021.

Ramp down starts for Wickiup as drought takes its toll. Bend Bulletin. Aug 20, 2021.

Temperatures soar as Washington and Oregon endure another major heatwave. The Guardian. Aug 13, 2021.

State climatologist: Oregon's second heat wave indicates troubling trend. Corvallis Gazette-Times. Aug 11, 2021.

Oregon declares state of emergency as another ‘extreme heatwave’ looms. The Guardian. Aug 11, 2021.

Central Oregon glaciers, snowpack feeling the heat of climate change. Bend Bulletin, Aug 3, 2021.

A drought like no other, NOAA scientist says. Capital Press, Aug 2, 2021.

5 counties at near record breaking drought levels. Natural Resource Report, Jul 14, 2021.

Portland’s new normal: Can we expect more deadly heat waves?. KOIN-6 News. Jul 13, 2021.

Extreme heat and drought hit Oregon. Oregon Public Broadcasting (OPB) Think Out Loud. July 8, 2021.

Extreme fire conditions converge ahead of holiday weekend, worrying experts: ‘The table is set’. The Oregonian. Jul 2, 2021.

Drought emergency in Lincoln County. Newport News-Times. Jun 30, 2021.

How climate change 'loads the dice' for heat waves. NBC News, June 29, 2021.

Global Warming Cauldron Boils Over in the Northwest in One of the Most Intense Heat Waves on Record Worldwide. Inside Climate News, June 29, 2021.

Here’s what’s causing record temperatures in the Pacific Northwest. Washington Post, Jun 29, 2021.

3 things to know about the record-smashing heat wave baking the Pacific Northwest. Science News. Jun 29, 2021.

Unprecedented Heat Wave in Pacific Northwest Driven by Climate Change. Scientific American, Jun 28, 2021.

Sunday was hottest day ever for mid-valley. Albany Democrat-Herald. Jun 28, 2021.

‘Historic, dangerous, prolonged and unprecedented’ heat wave swells over Pacific Northwest. Washington Post, June 26, 2021.

Pacific Northwest braces for historic heat wave, and experts say climate change could be to blame. ABC News. Jun 25, 2021.

US Pacific north-west braces for ‘unprecedented’ sweltering heatwave. The Guardian, Jun 25, 2021.

Parts Of Eastern And Central Oregon Experiencing Historic Drought Conditions. KLCC NPR. Jun 23, 2021.

Oregon fall firestorms cautionary tale in worsening drought. Associated Press, June 3, 2021.

Irrigators ask county to declare Deschutes in state of drought. Bend Bulletin, May 22, 2021.

Much of Oregon Is Already in Drought. Does That Mean the State Is Headed for Another Massive Wildfire Season? Willamette Week, May 4, 2021.

OSU researchers warn 2021 fire season may be even worse than 2020. Corvallis Gazette-Times. Apr 26, 2021.

OSU researchers look at conditions that led to September wildfires. KPTV Portland, OR. Apr 26, 2021.

Unprecedented combination of weather and drought conditions fueled Oregon’s September wildfires. OSU Newsroom, Apr 26, 2021.

Unprecedented combination of weather and drought conditions fueled Oregon's September wildfires. visual story, Apr 2021.

Dry conditions in Oregon portend another explosive fire season. Bend Bulletin, Apr 24, 2021.

Climate change impacts around (the) Bend. OSU-Cascades Science Pub Talk. Mar 16, 2021.

Climate change impact on Bend topic of OSU-Cascades Science Pub talk. Bend Bulletin, Mar 12, 2021.

Farmers watch and wait as reservoir levels inch higher. Bend Bulletin, Jan 6, 2021.

Climate Enabling Conditions and Drivers of the Western Oregon Wildfires of 2020. The Climate CIRCulator. Dec 2020.

Climate change heats up fire risk in Oregon's forests. Bend Bulletin, Nov 29, 2020.

Weekend storms get 2020 water year off to healthy start, but drought conditions remain, Bend Bulletin, Nov 16, 2020.

‘When the sparks just flew’: How power lines ignited dozens of Washington state fires during fierce Labor Day winds. Seattle Times, Nov 15, 2020.

Drying and dying: Drought conditions plague the Pacific Northwest. The UW Daily, Nov 3, 2020.

Today’s wildfire modeling ‘just sucks’ for flames fueled by climate change. High Country News, Oct 19, 2020.

Dry summer triples drought affected land in Deschutes County, Bend Bulletin, Oct 8, 2020.

Drought stirs fears of Dust Bowl near Madras. Bend Bulletin, Oct 8, 2020.

La Niña could make for big snow year. Bend Bulletin, Oct 3, 2020.

Climate change brings Santa Ana-like winds and explosive wildfires to Oregon. LA Times, Sept 10, 2020.

Don’t Forget the Climate: Droughts and hot temperatures affect Oregon’s communities. The Eugene Weekly. Aug 27, 2020.

Pacific Northwest Climate Change Network update on regional drought conditions. Aug 19, 2020.

Oregon is in Drought—Here’s How We Got There. The Climate CIRCulator. August 2020.

Drought may leave Central Oregon irrigation districts out of water this year. Bend Bulletin, Jun 16, 2020.

Drought Conditions in the West. Farm of the Future, Jun 15, 2020.

Drought Emerges Across the Pacific Northwest. Latest US Drought monitor report from the National Drought Mitigation Center. Jun 3, 2020.

This year’s snowfall is hard to predict, but signs point toward a warmer-than-average winter. Bend Bulletin, Oct 24, 2019.


Feature Story

How a life-long fascination is providing insight into Gulf Stream weather (May, 2017)