My group’sresearch can be briefly summarized in the following four areas: (1) developing the cutting-edge cloud retrieval techniques in ground-based remote sensing, 2) developing innovative methods to validate satellite cloud retrievals using ground-based results, (3) improving GCM/WRF and reanalyses simulated cloud, radiation and precipitation using surface-satellite data, and (4) investigating  the feedback processes of Arctic cloud-radiation on Arctic sea ice changes. These research efforts have been supported by DOE ARM/ASR, CMDV and CESM; NASA CERES, MAP, NEWS, CAN, EVC-1, ESS; NOAA GOES-R, MAAP and R2O; and NSF. My group consists of three  research faculty, 6 Ph.D students and 2 MS students.      

      (1) Ground-based Remote sensing of Clouds and Precipitation (Supported by DOE ARM/ASR, NOAA GOES_R and NSF projects)
      Developing new retrieving methods to retrieve cloud microphysical properties using ARM ground-based observations, and studying the seasonal and diurnal variations of clouds. (Supported by DOE ARM/ASR).

I have been working on the DOE ARM program since 1991. During my Ph.D study, a new method to retrieve low-level cloud microphysical properties was developed using a radiative transfer model and ground-based observations. These cloud retrievals have been widely used by DOE ARM (two ARM PI products) and NASA CERES (as ground truth to validate satellite results) projects.  Under the support of NOAA GOES-R and DOE ASR programs, my group has generated a hybrid precipitation product from a combination of NEXRAD radar and GOES satellite results over the continental USA. This newly generated product has been used to investigate the diurnal and life cycles of deep convective clouds and associated precipitation. These results have provided statistical information of clouds and precipitation for climate and forecast modelers to improve their climate precipitation and severe weather forecasting.

Related Results

      ARM SGP site
      ARM NSA site
      ARM AMF-AZORES site

Related Publications

      -- Dong, X., B. Xi, A. Kennedy, P. Minnis and R. Wood, 2013: A 19-month of Marine Aerosol-Cloud-Radiation Properties derived from DOE ARM AMF deployment at the Azores: Part I: Cloud Fraction and Single-layered MBL cloud Properties. Submitted to J. Clim.
      -- Kennedy, A., X. Dong, and B. Xi, 2013: Cloud Fraction at the ARM SGP Site: Instrument and Sampling Considerations from 14 years of ARSCL . Theor. Appl. Climatol. DOI:10.1007/s00704-013-0853-9.
     -- Huang, D., C. Zhao, M. Dunn, X. Dong , G.G. Mace, M.P. Jensen, S. Xie, and Y. Liu, 2012: An Intercomparison of Radar-Based Liquid Cloud Microphysics Retrievals and Implication for Model Evaluation Studies . Atmospheric Measurement Techniques, 5, 1409-1424, doi:10.5194/amt-5-1409-2012.
     -- Dong, X. , B. Xi, K.Crosby, C.N.Long, R.Stone, 2010: A 10 year climatology of Arctic cloud fraction and radiative forcing at Barrow, Alaska J. Geophys. Res. D12124, doi:10.1029/2009JD013489.
      --Xi, B., X. Dong, , P.Minnis, M. Khaiyer, 2009: A 10-yr climatology of cloud cover and vertical distribution from both surface and GOES observations over DOE ARM SGP site, J. Geophys. Res. 115,D12124, doi:10.1029/2009JD012800.
      -- Dong, X. , B. Xi, and P. Minnis, 2006: A climatology of midlatitude continental clouds from ARM SGP site. Part II: Cloud fraction and surface radiative forcing . J. Climate. 19 , 1765-1783.
      -- Dong X. , P. Minnis, B. Xi, 2005: A climatology of midlatitude stratus clouds from ARM SGP site: Part I:Macrophysical, microphysical and radiative properties . J. Climate. 18 , 1391-1410.
      -- Dong X. , and G.G. Mace, 2003: Profiles of Low-level Stratus Cloud Microphysics Deduced from Ground-based Measurements . J. Atmos and Oceanic Tech . 20 ,42-53.
      -- Dong X. , and G.G. Mace, 2003: Arctic Stratus Cloud Properties and Radiative Forcing Derived From Ground-Based Data Collected Near Point Barrow, Alaska . J. of Climate , 16. 445-461.       -- Dong X. , P. Minnis, G.G. Mace, W.L. Smith Jr, M. Poellt, R. Marchand, and Anita D. Rapp, 2002: Comparison of stratus cloud properties deduced from surface, GOES, and aircraft data during the March 2000 ARM Cloud IOP . J. Atmos. Sci . 59, 3265-3284.
      -- Dong X. , G.G.Mace, P.Minnis, and D.F. Young, 2001: Arctic Stratus Cloud Properties and Their Effect on the Surface Radiation Budget: Selected Cases from FIRE ACE . JGR FIRE special issue . J. Geophys. Res. 106, 15,297-15,312.
      -- Dong X. , P. Minnis, T. P. Ackerman, E. E. Clothiaux, G. G. Mace, C. N. Long, and J. C. Liljegren, 2000: A 25-month Database of Stratus Cloud Properties Generated from Ground-based Measurements at the ARM SGP Site . J. Geophys. Res . 105, 4529-4538.
      -- Dong X. , T.P. Ackerman, and E.E. Clothiaux, 1998: Parameterizations of Microphysical and Radiative Properties of Boundary Layer Stratus from Ground-based measurements . J. Geophys. Res . 102, 31,681-31,393.
      -- Dong X. , T.P. Ackerman, E.E. Clothiaux, Pilewskie, and Y. han, 1997: Microphysical and Radiative Properties of Stratiform Clouds Deduced from Ground-based Measurements . J. Geophys. Res , 102, 23829-23843.

      (2) Validation of Satellite Cloud Retrievals (Supported by NASA CERES porject)
Started at 1996, I have been working on the NASA CERES project to validate the satellite retrieved cloud properties using the ground-based results and aircraft in situ measurements. From this study, we have addressed some fundamental issues or answered some scientific questions. For example, how well the ARM point observations represent a large area? If both satellite and surface observe and retrieve cloud properties are correct, do they agree each other? If so (not), why (not)? Do the passive remote sensors (MODIS/GOES) and active remote sensors (radar-lidar) observe the same type of clouds (vertically), even from the same radar-lidar sensors, do ARM (surface) and CloudSat/CALIPSO (satellite) have the same vertical distribution of clouds?        

Related Results

      Presentations at CERES Science Team meetings

Related Publications

      --Xi, B., X. Dong, P. Minnis, and S. Sun-Mack, Validation of satellite-retrieved MBL cloud properties using DOE AMF measurements at the Azores. In preparation for JGR.
      --Xi, B., X. Dong, , P.Minnis, M. Khaiyer, 2009: A 10-yr climatology of cloud cover and vertical distribution from both surface and GOES observations over DOE ARM SGP site, J. Geophys. Res. 115,D12124, doi:10.1029/2009JD012800.
      -- Dong, X. , B. Wielicki, B. Xi, Y. Hu, G. G. MACE, S. Benson, 2008: Using Observations of Deep Convective Systems to Constrain Atmospheric Column Absorption in the Optically Thick Limit . J. Geophys. Res. .Vol. 113,D10206, doi:10.1029/2007JD009769.
      -- Dong, X. ,P. Minnis, B. Xi, S. Sun-Mack, and Y. Chen, 2008: Comparison of CERES-MODIS stratus cloud properties using ground-based measurements at the DOE ARM SGP site . J. Geophys. Res. , Vol. 113 ,D03204,doi:10.1029/2007JD008438.
      -- Patrick, M., Patrick, H., Sunny, S., Qing, T, Yan, C, Ricky, B, Sharon, G, Xiquan, D, Baike, X: A Multi-Year Data Set of Cloud Properties Derived for CERES from Aqua, Terra, and TRMM. IGARSS 2006: 1780-1783.
      -- Dong X. , P. Minnis, G.G. Mace, W.L. Smith Jr, M. Poellt, R. Marchand, and Anita D. Rapp, 2002: Comparison of stratus cloud properties deduced from surface, GOES, and aircraft data during the March 2000 ARM Cloud IOP . J. Atmos. Sci . 59, 3265-3284.

      (3) Evaluation of GCM/SCM/WRF and Reanalysis Results (Supported by NASA MAP and CAN, NOAA MAPP and R2O projects).      

Although many improvements have been made in CMIP5, aerosols, clouds, radiation and precipitation remain a significant source of uncertainty in GCMs. We compared 28 CMIP5 model simulated CF, CWP, TOA radiation budget with NASA satellite products and found that most of GCMs underpredicted CFs with a relatively large spread of cloud radiative forcings. Our studies have systematically evaluated 28 CMIP5 simulated CF, CWP and CRFs, which will certainly help mitigate the errors in future versions of CMIP, and thus the IPCC AR6. My group also developed an algorithm to identify the width of the ITCZ and compared model ITCZ representations to observations from TRMM and GPCP. These results have drawn the NASA MAP program manager Dr. David Considine’s attention, and be recommended as highlights for NASA HQ monthly reports and Jack Kaye’s presentation. My group is also evaluating the DOE new climate model, NOAA NWS simulated precipitation and NOAA reanalyses using satellite-surface observations.     

Related Results

      Presentations at different scientific meetings

Related Publications

      -- Dolinar, E., X. Dong, B. Xi, and, J. Jiang: Evaluation of CMIP 5 GCMs simulated Cloud fraction and TOA Radiation Budgets using NASA satellite observations. In preparation for JGR.
      -- Stanfield, R., X. Dong, B. Xi, A. Gel Genio, P. Minnis, and J. Jiang, 2013: Assessment of NASA GISS CMIP5 and post-CMIP5 Simulated Clouds and TOA Radiation Budgets Using Satellite Observations: Part I: Cloud fraction and properties. Submitted to J. Clim.
      --Kennedy, A., X. Dong, , B. Xi, P.Minnus, A. Del Genio, M.M. Khaiyer, and A. Wolf, 2009: Evaluation of NASA GISS Single Column Model Simulated Clouds Using Combines Surface and Satellite Observation. J. Climate. doi:10.1175/2010JCLI3353.1.
      -- Kennedy, A.D., X. Dong , B. Xi. S. Xie, Y. Zhang, and J. Chen, 2011: A Comparison of MERRA and NARR Reanalysis Datasets with the DOE ARM SGP Continuous Forcing data. J. Clim. 24, 4541-4557.
      -- Zib, B., X. Dong , B. Xi, and A. Kennedy, 2011: Evaluation and Intercomparison of Cloud Fraction and Radiative Fluxesin Recent Reanalyses over the Arctic using BSRN Surface Observations. J. Climate, 25, 2291-2305.      

      --Stenz, R., X. Dong, B. Xi, and B. Kuligowski, Assessment of SCaMPR and NEXRAD Q2 precipitation estimates using Oklahoma Mesonet observations. Submitted to J. Hydrometeorology.
      -- Wu, D., X. Dong , B. Xi, Z. Feng, A. Kennedy, G. Mullendore, M. Gilmore, and W-K Tao, 2013: Impacts of microphysical scheme on convective and stratiform characteristics in two high precipitation squall line events. JGR, 118, D50798, doi:10.1002/2013JGRD.50798.
      -- Feng, Z. X. Dong , B. Xi, S. McFarlane, A. Kennedy, B. Lin, and P. Minnis, 2012: Life Cycle of Mid-Latitude Deep Convetive Systems in a Lagrangian Framework . JGR. 117, D23201, doi:10.1029/2012JD018362.
      -- Feng,Z., X, Dong , B. Xi, C. Schumacher, P. Minnis, and M. Khaiyer, 2011: TOA Radiation Budget of Convective Core/Stratiform Rain and Anvils from Deep Convective Systems. JGR,Vol 116, D23202, doi10.1029/2011JD16451.
      -- Feng,Z., X.Dong, , B. Xi, 2009: A Method to Merge WSR-88D Data with ARM SGP Millimeter Cloud Radar Data by Studying Deep Convective Systems. J. Atmos.Oceanic.Technol. Vol. 26, 958-971.

      (4) Investigating the feedback processes of Arctic cloud-radiation on Arctic Sea ice Changes (Supported by NASA NEWS project and NESSF). 

 The cloud-radiation feedback has a large impact on Arctic sea ice long-term trend and variability. The important findings from our research are about dynamical and physical mechanisms on early and late initial melting of Arctic sea ice, as well as how the cloud-radiation feedback processes affect Arctic sea ice variations. The results from our recent papers are promising and innovative, which will help to improve the Arctic sea ice seasonal forecast, and certainly benefit broader cryosphere and polar meteorology community as well as promote the sustainability in the Arctic. 

Related Publications

      -- Dong, X. , B. Zib, B. Xi, Y. Deng, X, Zhang, B. Lin, and C.N. Long 2014: Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996 . Climate Dynamics, DOI:10.1007/s00382-013-1920-8

Huang, Y., X. Dong, B. Xi, E. Dolinar, R. Stanfield, 2017a: The footprints of 16-year trends of Arctic springtime cloud and radiation properties on September sea-ice retreat. JGR. 122, 2179-2193. DOI: 10.1002/2016JD026020


Huang Y, X, Dong, B. Xi, E.K. Dolinar, R.E. Stanfield and S. Qiu, 2017b: Quantifying the uncertainties of reanalyzed Arctic cloud and radiation properties using satellite-surface observations: J. Clim., 8007-8029, 30, 10.1175/JCLI-D-16-0722.1


Huang, Y., X. Dong, B. Xi and Y. Deng, 2018: A Survey of the Atmospheric Physical and Dynamical Processes Key to the Onset of Arctic Sea Ice Melting in Spring. Clim Dyn. 


Huang, Y., X. Dong et al., 2019: Thicker clouds, warmer air, accelerated Arctic sea ice decline: The atmosphere-sea ice interactions in spring. Accepted by GRL.   

      (5) Aerosol Properties & Interactions with Clouds
 Classifying and investigating Aerosol physical and chemical properties using surface-satellite and aircraft in situ measurements, as well as model simulations. Studying aerosol indirect effect on cloud microphysical properties (Supported by NASA and DOE ASR projects).

Related Publications

        -- Dai, T., D. Goto, X. Dong , and T Nakajima, 2013: Simulation of aerosol optical properties using a global three-dimensional aerosol model and its comparison with measurements. Accepted by Atmospheric Environemnt.
        -- Logan, T., B. Xi, X. Dong, K. Giannechini, and A. Kennedy, 2013, Aerosol transport and optical properties of the 2012 North American wildfire. Submitted to ACP.
        -- Logan, T., B. Xi, X. Dong, 2013, A Comparison of the Mineral Dust Absorptive Properties between Two Asian Dust Events . Atmosphere 2013, 4(1), 1-16; doi:10.3390/atmos4010001
        -- Logan, T., B. Xi, X. Dong , Z. Li, and M. Cribb, 2013: Discerning the Regional and Seasonal Variation of Asian Aerosols Using Absorption Spectral Variation . Atmos. Chem. Phys, 13, 2253-2265.
        -- Logan, T., B. Xi, X. Dong , R. Obrecht, Z. Li, M. Cribb, E. Browell, and A. Clarke, 2010: A study of Asian Dust Plumes using Satellite, Surface, and Aircraft Measurementsduring the INTEX-B Field Experiment. J. Geophys. Res. 115, D12124, doi:10.1029/2010JD014134.
        -- Garrett, T.J., C. Zhao, X. DONG , G.G. Mace, and P.V. Hobbs, 2004: Effects of Long-Range Pollution Transport on North American Arctic Stratus . Geophys. Res. Lett. 31, doi:10.1029/2004GL019928.
        -- Penner, J.E., X.Dong , Y. Chen, 2004: Observational evidence for a change in radiative forcing due to the indirect aerosol effect . Nature , 427, 231-234.