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Atmospheric Science & Global Change

Staff information


Samson Hagos

Earth Systems Analysis & Modeling
Earth Scientist
Pacific Northwest National Laboratory
PO Box 999
MSIN: K9-30
Richland, WA 99352


Dr. Hagos earned his PhD in Atmospheric Sciences in 2008 from Cornell University and was a Postdoctoral Research Associate at the University of Miami, Rosenstiel School of Marine and Atmospheric Sciences before joining PNNL in 2009.

Research Interests

  • Dr. Hagos’ research interests are focused on understanding and modeling of precipitation processes over a wide range of spatio-temporal scales, from the life-cycles of individual convective cells, to tropical intra-seasonal oscillations, atmospheric rivers and inter-annual to multi-decadal variations of monsoon systems.

Education and Credentials

  • PhD Atmospheric Sciences Cornell University Ithaca NY
  • MS Atmospheric Sciences Cornell University Ithaca NY
  • BS Physics University of Asmara Asmara Eritrea

Affiliations and Professional Service

  • Member American Meteorological Society
  • Member American Geophysical Union
  • Member European Geosciences Union
  • Member AGU Fall Meeting Program Committee
  • Member AMS Climate Variability Committee
  • Member World Meteorological Organization MJO Task Force
  • Member US CLIVAR Process Studies and Model Improvement Panel

Awards and Recognitions

  • American Meteorological Society Clarence Leroy Meisinger Award

PNNL Publications


  • Balaguru K., G. Foltz, L. Leung, S.M. Hagos, and D.R. Judi. 2018. "On the use of ocean dynamic temperature for hurricane intensity forecasting." Weather and Forecasting 33, no. 2:411-418. PNNL-SA-129386. doi:10.1175/WAF-D-17-0143.1
  • Burleyson C.D., S.M. Hagos, Z. Feng, B. Kerns, and D. Kim. 2018. "Large-scale Environmental Characteristics of MJOs that Strengthen and Weaken Over the Maritime Continent." Journal of Climate 31, no. 14:5731-5748. PNNL-SA-128529. doi:10.1175/JCLI-D-17-0576.1
  • Foltz G., K. Balaguru, and S.M. Hagos. 2018. "Interbasin Differences in the Relationship Between SST and Tropical Cyclone Intensification." Monthly Weather Review 146, no. 3:853-870. PNNL-SA-126415. doi:10.1175/MWR-D-17-0155.1
  • Hagos S.M., J.A. Ijampy, F. Sima, S. Francis, and Z. Feng. 2018. "West Africa [in "State of the Climate in 2017"]." Bulletin of the American Meteorological Society 99, no. 8:S214 - S216. PNNL-SA-138430. doi:10.1175/2018BAMSStateoftheClimate.1
  • Hagos S.M., L. Leung, C. Zhao, Z. Feng, and K. Sakaguchi. 2018. "How do microphysical processes influence large-scale precipitation variability and extremes?." Geophysical Research Letters 45, no. 3:1661-1667. PNNL-SA-130576. doi:10.1002/2017GL076375
  • Hagos S.M., Z. Feng, R.S. Plant, R.A. Houze, and H. Xiao. 2018. "A stochastic framework for modeling the population dynamics of convective clouds." Journal of Advances in Modeling Earth Systems 10, no. 2:448-465. PNNL-SA-130047. doi:10.1002/2017MS001214


  • Gao Y., L. Leung, C. Zhao, and S.M. Hagos. 2017. "Sensitivity of U.S. Summer Precipitation to Model Resolution and Convective Parameterizations Across Gray Zone Resolutions." Journal of Geophysical Research. D. (Atmospheres) 122, no. 5:2714-2733. PNNL-SA-120761. doi:10.1002/2016JD025896
  • Hagos S.M., J.A. Ijampy, F. Sima, S. Francis, and Z. Feng. 2017. "West Africa [in State of the Climate in 2016]." Bulletin of the American Meteorological Society 98, no. 8:S193-S195. PNNL-SA-128495. doi:10.1175/2017BAMSStateoftheClimate.1
  • Yang Q., L. Leung, J. Lu, Y. Lin, S.M. Hagos, K. Sakaguchi, and Y. Gao. 2017. "Exploring the effects of a nonhydrostatic dynamical core in high-resolution aquaplanet simulations." Journal of Geophysical Research. D. (Atmospheres) 122, no. 6:3245-3265. PNNL-SA-124394. doi:10.1002/2016JD025287


  • Ahmed F., C. Schumacher, Z. Feng, and S.M. Hagos. 2016. "A retrieval of tropical latent heating using the 3D structure of precipitation features." Journal of Applied Meteorology and Climatology 55, no. 9:1965-1982. PNNL-SA-107838. doi:10.1175/JAMC-D-15-0038.1
  • Boone A., Y. Xue, F. de Sales, R.E. Comer, S.M. Hagos, S. Mahanama, and K. Schiro, et al. 2016. "The regional impact of Land-Use Land-cover Change (LULCC) over West Africa from an ensemble of global climate models under the auspices of the WAMME2 project." Climate Dynamics 47, no. 11:3547-3573. PNNL-SA-111780. doi:10.1007/s00382-016-3252-y
  • Burleyson C.D., Z. Feng, S.M. Hagos, J.D. Fast, L. Machado, S.T. Martin, and S.T. Martin. 2016. "Spatial Variability of the Background Diurnal Cycle of Deep Convection around the GoAmazon2014/15 Field Campaign Sites." Journal of Applied Meteorology and Climatology 55, no. 7:1579-1598. PNNL-SA-111694. doi:10.1175/JAMC-D-15-0229.1
  • Feng Z., L. Leung, S.M. Hagos, R.A. Houze, C.D. Burleyson, and K. Balaguru. 2016. "More frequent intense and long-lived storms dominate the springtime trend in central U.S. rainfall." Nature Communications 7. PNNL-SA-122022. doi:10.1038/ncomms13429
  • Hagos S.M., C. Zhang, Z. Feng, C.D. Burleyson, C. DeMott, B. Kerns, and J. Benedict, et al. 2016. "The impact of the diurnal cycle on the propagation of Madden-Julian Oscillation convection across the Maritime Continent." Journal of Advances in Modeling Earth Systems 8, no. 4:15521564. PNNL-SA-118613. doi:10.1002/2016MS000725
  • Hagos S.M., J.A. Ijampy, F. Sima, S. Francis, and Z. Feng. 2016. "West Africa [in ”State of the Climate in 2015”]." Bulletin of the American Meteorological Society 97, no. 8 Special Supplement:188-189. PNNL-SA-119982. doi:10.1175/2016BAMSStateoftheClimate.1
  • Hagos S.M., L.R. Leung, J. Yoon, J. Lu, and Y. Gao. 2016. "A Projection of Changes in Landfilling Atmospheric River Frequency and Extreme Precipitation over Western North America from the Large Ensemble CESM Simulations." Geophysical Research Letters 43, no. 3:1357-1363. PNNL-SA-115451. doi:10.1002/2015GL067392
  • Hagos S.M., Z. Feng, C.D. Burleyson, C. Zhao, M. Martini, and L.K. Berg. 2016. "Moist process biases in simulations of the Madden-Julian Oscillation episodes observed during the AMIE/DYNAMO field campaign." Journal of Climate 29, no. 3:1091-1107. PNNL-SA-110414. doi:10.1175/JCLI-D-15-0349.1
  • Qian Y., H. Yan, L.K. Berg, S.M. Hagos, Z. Feng, B. Yang, and M. Huang. 2016. "Assessing impacts of PBL and surface layer schemes in simulating the surface-atmosphere interactions and precipitation over the tropical ocean using observations from AMIE/DYNAMO." Journal of Climate 29, no. 22:8191-8210. PNNL-SA-114620. doi:10.1175/JCLI-D-16-0040.1
  • Sakaguchi K., J. Lu, L. Leung, C. Zhao, Y. Li, and S.M. Hagos. 2016. "Sources and Pathways of the Upscale Effects on the Southern Hemisphere Jet in MPAS-CAM4 Variable-Resolution Simulations." Journal of Advances in Modeling Earth Systems 8, no. 4:1786-1805. PNNL-SA-120998. doi:10.1002/2016MS000743
  • Tao W., Y.N. Takayabu, S. Lang, S. Shige, W.S. Olson, A. Hou, and G. Skofronick-Jackson, et al. 2016. "TRMM Latent Heating Retrieval: Applications and Comparisons with Field Campaigns and Large-Scale Analyses." In Meteorological Monographs. 2.1-2.34. Boston, Massachusetts:American Meteorological Society. PNNL-SA-103710. doi:10.1175/AMSMONOGRAPHS-D-15-0013.1
  • Xue Y., F. de Sales, W. Lau, A. Boone, K. Kim, C. Mechoso, and G. Wang, et al. 2016. "West African monsoon decadal variability and surface-related forcings: Second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)." Climate Dynamics 47, no. 11:3517-3545. PNNL-SA-112235. doi:10.1007/s00382-016-3224-2
  • Zhao C., L.R. Leung, S. Park, S.M. Hagos, J. Lu, K. Sakaguchi, and J. Yoon, et al. 2016. "Exploring the impacts of physics and resolution on aqua-planet simulations from a non-hydrostatic global variable-resolution modeling framework." Journal of Advances in Modeling Earth Systems 8, no. 4:1751-1768. PNNL-SA-118452. doi:10.1002/2016MS000727


  • Chen Q., J. Fan, S.M. Hagos, W.I. Gustafson, and L.K. Berg. 2015. "Roles of Wind Shear at Different Vertical Levels: Cloud System Organization and Properties." Journal of Geophysical Research. D. (Atmospheres) 120, no. 13:6551-6574. PNNL-SA-98941. doi:10.1002/2015JD023253
  • Feng Z., S.M. Hagos, A. Rowe, C.D. Burleyson, M. Martini, and S. de Szoeke. 2015. "Mechanisms of Convective Cloud Organization by Cold Pools over Tropical Warm Ocean during the AMIE/DYNAMO Field Campaign." Journal of Advances in Modeling Earth Systems 7, no. 2:357-381. PNNL-SA-105094. doi:10.1002/2014MS000384
  • Gao Y., J. Lu, L.R. Leung, Q. Yang, S.M. Hagos, and Y. Qian. 2015. "Dynamical and thermodynamical modulations of future changes in landfalling atmospheric rivers over North America." Geophysical Research Letters 42, no. 17:7179-7186. PNNL-SA-110116. doi:10.1002/2015GL065435
  • Hagos S.M., J.A. Ijampy, F. Sima, and S. Francis. 2015. "West Africa [in "State of the Climate in 2014"]." Bulletin of the American Meteorological Society 96, no. 7:S185-S187. PNNL-SA-110969. doi:10.1175/2015BAMSStateoftheClimate.1
  • Hagos S.M., L.R. Leung, Q. Yang, C. Zhao, and J. Lu. 2015. "Resolution and Dynamical Core Dependence of Atmospheric River Frequency in Global Model Simulations." Journal of Climate 28, no. 7:2764-2776. PNNL-SA-104683. doi:10.1175/JCLI-D-14-00567.1
  • Lu J., G. Chen, L.R. Leung, D.A. Burrows, Q. Yang, K. Sakaguchi, and S.M. Hagos. 2015. "Toward the Dynamical Convergence on the Jet Stream in Aquaplanet AGCMs." Journal of Climate 28, no. 17:67636782. PNNL-SA-111542. doi:10.1175/JCLI-D-14-00761.1
  • Sakaguchi K., L.R. Leung, C. Zhao, Q. Yang, J. Lu, S.M. Hagos, and S. Rauscher, et al. 2015. "Exploring a Multi-resolution Approach Using AMIP Simulations." Journal of Climate 28, no. 14:55495574. PNNL-SA-106250. doi:10.1175/JCLI-D-14-00729.1
  • Taraphdar S., L.R. Leung, and S.M. Hagos. 2015. "Linkages of Remote Sea Surface Temperatures and Atlantic Tropical Cyclone Activity Mediated by the African Monsoon." Geophysical Research Letters 42, no. 2:572-578. PNNL-SA-105745. doi:10.1002/2014GL062600
  • Xiao H., W.I. Gustafson, S.M. Hagos, C. Wu, and H. Wan. 2015. "Resolution-dependent behavior of subgrid-scale vertical transport in the Zhang-McFarlane convection parameterization." Journal of Advances in Modeling Earth Systems 7, no. 2:537-550. PNNL-SA-103534. doi:10.1002/2014MS000356


  • Hagos S.M., L.R. Leung, W.I. Gustafson, and B. Singh. 2014. "Eddy Fluxes and Sensitivity of the Water Cycle to Spatial Resolution in Idealized Regional Aquaplanet Model Simulations." Climate Dynamics 42, no. 3-4:931-940. PNNL-SA-90821. doi:10.1007/s00382-013-1857-y
  • Hagos S.M., L.R. Leung, Y. Xue, A. Boone, F. de Sales, N. Neupane, and M. Huang, et al. 2014. "Assessment of Uncertainties in the Response of the African Monsoon Precipitation to Land Use change simulated by a regional model." Climate Dynamics 43, no. 9-10:2765-2775. PNNL-SA-96599. doi:10.1007/s00382-014-2092-x
  • Hagos S.M., Z. Feng, C.D. Burleyson, K. Lim, C.N. Long, D. Wu, and G. Thompson. 2014. "Evaluation of convection-permitting model simulations of cloud populations associated with the Madden-Julian Oscillation using data collected during the AMIE/DYNAMO field campaign." Journal of Geophysical Research. D. (Atmospheres) 119, no. 21:12,05212,068. PNNL-SA-100601. doi:10.1002/2014JD022143
  • Hagos S.M., Z. Feng, K. Landu, and C.N. Long. 2014. "Advection, Moistening, and Shallow-to-deep Convection Transitions During the Initiation and Propagation of Madden-Julian Oscillation." Journal of Advances in Modeling Earth Systems 6, no. 3:938-949. PNNL-SA-97931. doi:10.1002/2014MS000335
  • Landu K., L.R. Leung, S.M. Hagos, V. Vinoj, S. Rauscher, T. Ringler, and M. Taylor. 2014. "The Dependence of ITCZ Structure on Model Resolution and Dynamical Core in Aquaplanet Simulations." Journal of Climate 27, no. 6:23752385. PNNL-SA-95463. doi:10.1175/JCLI-D-13-00269.1


  • Hagos S.M., L.R. Leung, S. Rauscher, and T. Ringler. 2013. "Error Characteristics of Two Grid Refinement Approaches in Aquaplanet Simulations: MPAS-A and WRF." Monthly Weather Review 141, no. 9:3022-3036. PNNL-SA-92096. doi:10.1175/MWR-D-12-00338.1
  • Hagos S.M., Z. Feng, S.A. McFarlane, and L.R. Leung. 2013. "Environment and the Lifetime of Tropical Deep Convection in a Cloud-Permitting Regional Model Simulation." Journal of the Atmospheric Sciences 70, no. 8:24092425. PNNL-SA-90832. doi:10.1175/JAS-D-12-0260.1
  • Lee T., X. Tong, H. Shen, P.C. Wong, S.M. Hagos, and L.R. Leung. 2013. "Feature Tracking and Visualization of Madden-Julian Osciallation in Climate Simulation." IEEE Computer Graphics and Applications 33, no. 4:29-37. PNNL-SA-94719. doi:10.1109/MCG.2013.36
  • O'Brien T.A., F. Li, W.D. Collins, S. Rauscher, T. Ringler, M. Taylor, and S.M. Hagos, et al. 2013. "Observed Scaling in Clouds and Precipitation and Scale Incognizance in Regional to Global Atmospheric Models." Journal of Climate 26, no. 23:93139333. PNNL-SA-95766. doi:10.1175/JCLI-D-13-00005.1


  • Hagos S.M., and L.R. Leung. 2012. "Large-scale Environmental Variables and Transition to Deep Convection in Cloud Resolving Model Simulations: A Vector Representation." Journal of Advances in Modeling Earth Systems 4. PNNL-SA-80961. doi:10.1029/2012MS000155
  • Hagos S.M., and L.R. Leung. 2012. "On the relationship between uncertainties in tropical divergence and the hydrological cycle in global models." Journal of Climate 25, no. 1:381-391. PNNL-SA-77638. doi:10.1175/JCLI-D-11-00058.1


  • Hagos S.M., and L.R. Leung. 2011. "Moist thermodynamics of the Madden-Julian Oscillation in a cloud resolving simulation." Journal of Climate 24, no. 21:55715583. PNNL-SA-76338. doi:10.1175/2011JCLI4212.1
  • Hagos S.M., L.R. Leung, and J. Dudhia. 2011. "Thermodynamics of the Madden-Julian Oscillation in a Regional Model with Constrained Moisture." Journal of the Atmospheric Sciences 68, no. 9:1974-1989. PNNL-SA-73333. doi:10.1175/2011JAS3592.1
  • Zhao C., X. Liu, L.R. Leung, and S.M. Hagos. 2011. "Radiative impact of mineral dust on monsoon precipitation variability over West Africa." Atmospheric Chemistry and Physics 11, no. 5:1879-1893. PNNL-SA-76065. doi:10.5194/acp-11-1879-2011


  • Hagos S.M. 2010. "Building Blocks of Tropical Diabatic Heating." Journal of the Atmospheric Sciences 67, no. 7:2341-2354. PNNL-SA-71870. doi:10.1175/2010JAS3252.1
  • Hagos S.M., and C. Zhang. 2010. "Diabatic heating, divergent circulation and moisture transport in the African monsoon system." Quarterly Journal of the Royal Meteorological Society 136, no. S1:411-425. PNNL-SA-70976. doi:10.1002/qj.538
  • Hagos S.M., C. Zhang, W. Tao, S. Lang, Y.N. Takayabu, S. Shige, and M. Katsumata, et al. 2010. "Estimates of Tropical Diabatic Heating Profiles: Commonalities and Uncertainties." Journal of Climate 23, no. 3:542-558. PNNL-SA-70981. doi:10.1175/2009JCLI3025.1
  • Zhang C., J. Ling, S.M. Hagos, W. Tao, S. Lang, Y.N. Takayabu, and S. Shige, et al. 2010. "MJO Signals in Latent Heating: Results from TRMM Retrievals." Journal of the Atmospheric Sciences 67, no. 11:34883508. PNNL-SA-74067. doi:10.1175/2010JAS3398.1

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