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Volumn 16, Issue 4, 2015, Pages 1752-1772

A particle batch smoother approach to snow water equivalent estimation

Author keywords

[No Author keywords available]

Indexed keywords

DATA ASSIMILATION; ENSEMBLE FORECASTING; ESTIMATION METHOD; RIVER BASIN; SENSITIVITY ANALYSIS; SMOOTHING; SNOW WATER EQUIVALENT;

EID: 84930960933     PISSN: 1525755X     EISSN: 15257541     Source Type: Journal    
DOI: 10.1175/JHM-D-14-0177.1     Document Type: Article
Times cited : (93)

References (46)
  • 1
    • 0036475447 scopus 로고    scopus 로고
    • A tutorial on particle filters for online nonlinear/non-Gaussian Bayesian tracking
    • Arulampalam, M. S., S. Maskell, N. Gordon, and T. Clapp, 2002: A tutorial on particle filters for online nonlinear/non-Gaussian Bayesian tracking. IEEE Trans. Signal Process., 50, 174-188, doi:10.1109/78.978374.
    • (2002) IEEE Trans. Signal Process. , vol.50 , pp. 174-188
    • Arulampalam, M.S.1    Maskell, S.2    Gordon, N.3    Clapp, T.4
  • 3
    • 27844501665 scopus 로고    scopus 로고
    • Potential impacts of a warming climate on water availability in snowdominated regions
    • Barnett, T. P., J. C. Adam, and D. P. Lettenmaier, 2005: Potential impacts of a warming climate on water availability in snowdominated regions. Nature, 438, 303-309, doi:10.1038/nature04141.
    • (2005) Nature , vol.438 , pp. 303-309
    • Barnett, T.P.1    Adam, J.C.2    Lettenmaier, D.P.3
  • 4
    • 79960903616 scopus 로고    scopus 로고
    • Representing spatial variability of snow water equivalent in hydrologic and land-surface models: A review
    • Clark, M. P., and Coauthors, 2011: Representing spatial variability of snow water equivalent in hydrologic and land-surface models: A review. Water Resour. Res., 47, W07539, doi:10.1029/2011WR010745.
    • (2011) Water Resour. Res. , vol.47 , pp. W07539
    • Clark, M.P.1
  • 5
    • 0031981735 scopus 로고    scopus 로고
    • Estimating the spatial distribution of snow in mountain basins using remote sensing and energy balance modeling
    • Cline, D. W., R. C. Bales, and J. Dozier, 1998: Estimating the spatial distribution of snow in mountain basins using remote sensing and energy balance modeling. Water Resour. Res., 34, 1275-1285, doi:10.1029/97WR03755.
    • (1998) Water Resour. Res. , vol.34 , pp. 1275-1285
    • Cline, D.W.1    Bales, R.C.2    Dozier, J.3
  • 6
    • 84888083698 scopus 로고    scopus 로고
    • Analysis of subpixel snow and ice extent over the extratropical Andes using spectral unmixing of historical Landsat imagery
    • Cortés, G., M. Girotto, and S. A. Margulis, 2014: Analysis of subpixel snow and ice extent over the extratropical Andes using spectral unmixing of historical Landsat imagery. Remote Sens. Environ., 141, 64-78, doi:10.1016/j.rse.2013.10.023.
    • (2014) Remote Sens. Environ. , vol.141 , pp. 64-78
    • Cortés, G.1    Girotto, M.2    Margulis, S.A.3
  • 7
    • 0032698090 scopus 로고    scopus 로고
    • An improved parameterization for estimating effective atmospheric emissivity for use in calculating daytime downwelling longwave radiation
    • Crawford, T. M., and C. E. Duchon, 1999: An improved parameterization for estimating effective atmospheric emissivity for use in calculating daytime downwelling longwave radiation. J.Appl. Meteor., 38, 474-480, doi:10.1175/1520-0450(1999)038,0474: AIPFEE.2.0.CO;2.
    • (1999) J.Appl. Meteor. , vol.38 , pp. 474-480
    • Crawford, T.M.1    Duchon, C.E.2
  • 8
    • 77953350645 scopus 로고    scopus 로고
    • Satellite-scale snow water equivalent assimilation into a high-resolution land surface model
    • De Lannoy, G. J., R. H. Reichle, P. R. Houser, K. R. Arsenault, N. E. Verhoest, and V. R. Pauwels, 2010: Satellite-scale snow water equivalent assimilation into a high-resolution land surface model. J. Hydrometeor., 11, 352-369, doi:10.1175/2009JHM1192.1.
    • (2010) J. Hydrometeor. , vol.11 , pp. 352-369
    • De Lannoy, G.J.1    Reichle, R.H.2    Houser, P.R.3    Arsenault, K.R.4    Verhoest, N.E.5    Pauwels, V.R.6
  • 9
    • 12144259051 scopus 로고    scopus 로고
    • Winter orographic precipitation ratios in the Sierra Nevada-Large-scale atmospheric circulations and hydrologic consequences
    • Dettinger, M., K. Redmond, and D. Cayan, 2004: Winter orographic precipitation ratios in the Sierra Nevada-Large-scale atmospheric circulations and hydrologic consequences. J. Hydrometeor., 5, 1102-1116, doi:10.1175/JHM-390.1.
    • (2004) J. Hydrometeor. , vol.5 , pp. 1102-1116
    • Dettinger, M.1    Redmond, K.2    Cayan, D.3
  • 10
    • 80455174840 scopus 로고    scopus 로고
    • Mountain hydrology, snow color, and the fourth paradigm
    • Dozier, J., 2011: Mountain hydrology, snow color, and the fourth paradigm. Eos, Trans. Amer. Geophys. Union, 92, 373-375, doi:10.1029/2011EO430001.
    • (2011) Eos, Trans. Amer. Geophys. Union , vol.92 , pp. 373-375
    • Dozier, J.1
  • 11
    • 54949107294 scopus 로고    scopus 로고
    • Time-space continuity of daily maps of fractional snow cover and albedo from MODIS
    • Dozier, J., T. H. Painter, K. Rittger, and J. E. Frew, 2008: Time-space continuity of daily maps of fractional snow cover and albedo from MODIS. Adv. Water Resour., 31, 1515-1526, doi:10.1016/j.advwatres.2008.08.011.
    • (2008) Adv. Water Resour. , vol.31 , pp. 1515-1526
    • Dozier, J.1    Painter, T.H.2    Rittger, K.3    Frew, J.E.4
  • 12
    • 34548612503 scopus 로고    scopus 로고
    • Correcting first-order errors in snow water equivalent estimates using a multifrequency, multiscale radiometric data assimilation scheme
    • Durand, M., and S. A. Margulis, 2007: Correcting first-order errors in snow water equivalent estimates using a multifrequency, multiscale radiometric data assimilation scheme. J. Geophys. Res., 112, D13121, doi:10.1029/2006JD008067.
    • (2007) J. Geophys. Res. , vol.112 , pp. D13121
    • Durand, M.1    Margulis, S.A.2
  • 13
    • 58149269123 scopus 로고    scopus 로고
    • A Bayesian approach to snow water equivalent reconstruction
    • Durand, M., N. Molotch, and S. Margulis, 2008: A Bayesian approach to snow water equivalent reconstruction. J. Geophys. Res., 113, D20117, doi:10.1029/2008JD009894.
    • (2008) J. Geophys. Res. , vol.113 , pp. D20117
    • Durand, M.1    Molotch, N.2    Margulis, S.3
  • 14
    • 1542442239 scopus 로고    scopus 로고
    • Snow water equivalent interpolation for the Colorado River basin from snow telemetry (SNOTEL) data
    • Fassnacht, S. R., K. A. Dressler, and R. C. Bales, 2003: Snow water equivalent interpolation for the Colorado River basin from snow telemetry (SNOTEL) data. Water Resour. Res., 39, 1208, doi:10.1029/2002WR001512.
    • (2003) Water Resour. Res. , vol.39 , pp. 1208
    • Fassnacht, S.R.1    Dressler, K.A.2    Bales, R.C.3
  • 15
    • 65349094020 scopus 로고    scopus 로고
    • Comparison of algorithms for incoming atmospheric longwave radiation
    • Flerchinger, G. N., W. Xaio, D. Marks, T. J. Sauer, and Q. Yu, 2009: Comparison of algorithms for incoming atmospheric longwave radiation. Water Resour. Res., 45, W03423, doi:10.1029/2008WR007394.
    • (2009) Water Resour. Res. , vol.45 , pp. W03423
    • Flerchinger, G.N.1    Xaio, W.2    Marks, D.3    Sauer, T.J.4    Yu, Q.5
  • 17
    • 84906015758 scopus 로고    scopus 로고
    • Examining spatial and temporal variability in snow water equivalent using a 27 year reanalysis: Kern River watershed, Sierra Nevada
    • Girotto, M., G. Cortés, S. A. Margulis, and M. Durand, 2014a: Examining spatial and temporal variability in snow water equivalent using a 27 year reanalysis: Kern River watershed, Sierra Nevada. Water Resour. Res., 50, 6713-6734, doi:10.1002/2014WR015346.
    • (2014) Water Resour. Res. , vol.50 , pp. 6713-6734
    • Girotto, M.1    Cortés, G.2    Margulis, S.A.3    Durand, M.4
  • 18
    • 84901828971 scopus 로고    scopus 로고
    • Probabilistic SWE reanalysis as a generalization of deterministic SWE reconstruction techniques
    • Girotto, M., S. A. Margulis, and M. Durand, 2014b: Probabilistic SWE reanalysis as a generalization of deterministic SWE reconstruction techniques. Hydrol. Processes, 28, 3875-3895, doi:10.1002/hyp.9887.
    • (2014) Hydrol. Processes , vol.28 , pp. 3875-3895
    • Girotto, M.1    Margulis, S.A.2    Durand, M.3
  • 19
    • 84885126440 scopus 로고    scopus 로고
    • Snow water equivalent in the Sierra Nevada: Blending snow sensor observations with snowmelt model simulations
    • Guan,B., N. Molotch, D.Waliser, S. Jepsen, T. Painter, and J.Dozier, 2013: Snow water equivalent in the Sierra Nevada: Blending snow sensor observations with snowmelt model simulations. Water Resour. Res., 49, 5029-5046, doi:10.1002/wrcr.20387.
    • (2013) Water Resour. Res. , vol.49 , pp. 5029-5046
    • Guan, B.1    Molotch, N.2    Waliser, D.3    Jepsen, S.4    Painter, T.5    Dozier, J.6
  • 21
    • 33947676794 scopus 로고    scopus 로고
    • Completion of the 2001 National Land Cover Database for the conterminous United States
    • Homer, C., and Coauthors, 2007: Completion of the 2001 National Land Cover Database for the conterminous United States. Photogramm. Eng. Remote Sensing, 73 (4), 337-341.
    • (2007) Photogramm. Eng. Remote Sensing , vol.73 , Issue.4 , pp. 337-341
    • Homer, C.1
  • 22
    • 84863419876 scopus 로고    scopus 로고
    • Interannual variability of snowmelt in the Sierra Nevada and Rocky Mountains, United States: Examples from two alpine watersheds
    • Jepsen, S. M., N. P. Molotch, M. W. Williams, K. E. Rittger, and J. O. Sickman, 2012: Interannual variability of snowmelt in the Sierra Nevada and Rocky Mountains, United States: Examples from two alpine watersheds. Water Resour. Res., 48, W02529, doi:10.1029/2011WR011006.
    • (2012) Water Resour. Res. , vol.48 , pp. W02529
    • Jepsen, S.M.1    Molotch, N.P.2    Williams, M.W.3    Rittger, K.E.4    Sickman, J.O.5
  • 23
    • 36549032118 scopus 로고    scopus 로고
    • A prototype AMSR-E global snow area and snow depth algorithm
    • Kelly, R. E., A. T. Chang, L. Tsang, and J. L. Foster, 2003: A prototype AMSR-E global snow area and snow depth algorithm. IEEE Trans. Geosci. Remote Sens., 41, 230-242, doi:10.1109/TGRS.2003.809118.
    • (2003) IEEE Trans. Geosci. Remote Sens. , vol.41 , pp. 230-242
    • Kelly, R.E.1    Chang, A.T.2    Tsang, L.3    Foster, J.L.4
  • 24
    • 84864410106 scopus 로고    scopus 로고
    • Potential for hydrologic characterization of deep mountain snowpack via pass microwave remote sensing in the Kern River basin, Sierra Nevada, USA
    • Li, D., M. Durand, and S. A. Margulis, 2012: Potential for hydrologic characterization of deep mountain snowpack via pass microwave remote sensing in the Kern River basin, Sierra Nevada, USA. Remote Sens. Environ., 125, 34-48, doi:10.1016/j.rse.2012.06.027.
    • (2012) Remote Sens. Environ. , vol.125 , pp. 34-48
    • Li, D.1    Durand, M.2    Margulis, S.A.3
  • 25
    • 84867870419 scopus 로고    scopus 로고
    • Simulation of snow distribution and melt under cloudy conditions in an alpine watershed
    • Li, H.-Y., and J. Wang, 2011: Simulation of snow distribution and melt under cloudy conditions in an alpine watershed. Hydrol. Earth Syst. Sci., 15, 2195-2203, doi:10.5194/hess-15-2195-2011.
    • (2011) Hydrol. Earth Syst. Sci. , vol.15 , pp. 2195-2203
    • Li, H.-Y.1    Wang, J.2
  • 26
    • 1842739386 scopus 로고    scopus 로고
    • Representing subgrid snow cover heterogeneities in regional and global models
    • Liston, G. E., 2004: Representing subgrid snow cover heterogeneities in regional and global models. J. Climate, 17, 1381-1397, doi:10.1175/1520-0442(2004)017,1381:RSSCHI.2.0.CO;2.
    • (2004) J. Climate , vol.17 , pp. 1381-1397
    • Liston, G.E.1
  • 27
    • 78049269527 scopus 로고    scopus 로고
    • Relationships between barrier jet heights, orographic precipitation gradients, and streamflow in the northern Sierra Nevada
    • Lundquist, J. D., J. R. Minder, P. J. Neiman, and E. Sukovich, 2010: Relationships between barrier jet heights, orographic precipitation gradients, and streamflow in the northern Sierra Nevada. J. Hydrometeor., 11, 1141-1156, doi:10.1175/2010JHM1264.1.
    • (2010) J. Hydrometeor. , vol.11 , pp. 1141-1156
    • Lundquist, J.D.1    Minder, J.R.2    Neiman, P.J.3    Sukovich, E.4
  • 28
    • 62249109379 scopus 로고    scopus 로고
    • Reconstructing snow water equivalent in the Rio Grande headwaters using remotely sensed snow cover data and a spatially distributed snowmelt model
    • Molotch, N. P., 2009: Reconstructing snow water equivalent in the Rio Grande headwaters using remotely sensed snow cover data and a spatially distributed snowmelt model. Hydrol. Processes, 23, 1076-1089, doi:10.1002/hyp.7206.
    • (2009) Hydrol. Processes , vol.23 , pp. 1076-1089
    • Molotch, N.P.1
  • 29
    • 29944442652 scopus 로고    scopus 로고
    • Scaling snow observations from the point to the grid element: Implications for observational network design
    • Molotch, N. P., and R. C. Bales, 2005: Scaling snow observations from the point to the grid element: Implications for observational network design. Water Resour. Res., 41, W11421, doi:10.1029/2005WR004229.
    • (2005) Water Resour. Res. , vol.41 , pp. W11421
    • Molotch, N.P.1    Bales, R.C.2
  • 30
    • 84954358194 scopus 로고    scopus 로고
    • Estimating the distribution of snow water equivalent using remotely sensed snow cover data and a spatially distributed snowmelt model: A multi-resolution, multi-sensor comparison
    • Molotch, N. P., and S. A. Margulis, 2008: Estimating the distribution of snow water equivalent using remotely sensed snow cover data and a spatially distributed snowmelt model: A multi-resolution, multi-sensor comparison. Adv. Water Resour., 31, 1503-1514, doi:10.1016/j.advwatres.2008.07.017.
    • (2008) Adv. Water Resour. , vol.31 , pp. 1503-1514
    • Molotch, N.P.1    Margulis, S.A.2
  • 31
    • 18144441533 scopus 로고    scopus 로고
    • Incorporating remotely-sensed snow albedo in a spatially-distributed snowmelt model
    • Molotch, N. P., T. H. Painter, R. C. Bales, and J. Dozier, 2004: Incorporating remotely-sensed snow albedo in a spatially-distributed snowmelt model. Geophys. Res. Lett., 31, L03501, doi:10.1029/2003GL019063.
    • (2004) Geophys. Res. Lett. , vol.31 , pp. L03501
    • Molotch, N.P.1    Painter, T.H.2    Bales, R.C.3    Dozier, J.4
  • 32
    • 20844449766 scopus 로고    scopus 로고
    • Uncertainty assessment of hydrologic model states and parameters: Sequential data assimilation using the particle filter
    • Moradkhani, H., K.-L. Hsu, H. Gupta, and S. Sorooshian, 2005: Uncertainty assessment of hydrologic model states and parameters: Sequential data assimilation using the particle filter. Water Resour. Res., 41, W05012, doi:10.1029/2004WR003604.
    • (2005) Water Resour. Res. , vol.41 , pp. W05012
    • Moradkhani, H.1    Hsu, K.-L.2    Gupta, H.3    Sorooshian, S.4
  • 34
    • 26444536141 scopus 로고    scopus 로고
    • Snow process modeling in the North American Land Data Assimilation System (NLDAS): 2. Evaluation of model simulated snow water equivalent
    • Pan, M., and Coauthors, 2003: Snow process modeling in the North American Land Data Assimilation System (NLDAS): 2. Evaluation of model simulated snow water equivalent. J. Geophys. Res., 108, 8850, doi:10.1029/2003JD003994.
    • (2003) J. Geophys. Res. , vol.108 , pp. 8850
    • Pan, M.1
  • 35
    • 0030425245 scopus 로고    scopus 로고
    • A new long-wave formula for estimating downward clear-sky radiation at the surface
    • Prata, A. J., 1996: A new long-wave formula for estimating downward clear-sky radiation at the surface. Quart. J. Roy. Meteor. Soc., 122, 1127-1151, doi:10.1002/qj.49712253306.
    • (1996) Quart. J. Roy. Meteor. Soc. , vol.122 , pp. 1127-1151
    • Prata, A.J.1
  • 36
    • 80052066133 scopus 로고    scopus 로고
    • Snow water equivalent along elevation gradients in the Merced and Tuolumne River basins of the Sierra Nevada
    • Rice, R., R. C. Bales, T. H. Painter, and J. Dozier, 2011: Snow water equivalent along elevation gradients in the Merced and Tuolumne River basins of the Sierra Nevada. Water Resour. Res., 47, W08515, doi:10.1029/2010WR009278.
    • (2011) Water Resour. Res. , vol.47 , pp. W08515
    • Rice, R.1    Bales, R.C.2    Painter, T.H.3    Dozier, J.4
  • 37
    • 84880153209 scopus 로고    scopus 로고
    • Spatial estimates of snow water equivalent in the Sierra Nevada
    • Ph.D. thesis, University of California, Santa Barbara
    • Rittger, K. E., 2012: Spatial estimates of snow water equivalent in the Sierra Nevada. Ph.D. thesis, University of California, Santa Barbara, 245 pp.
    • (2012) , pp. 245
    • Rittger, K.E.1
  • 38
    • 0029667341 scopus 로고    scopus 로고
    • Automated mapping of montane snow cover at subpixel resolution from the Landsat Thematic Mapper
    • Rosenthal, W., and J. Dozier, 1996: Automated mapping of montane snow cover at subpixel resolution from the Landsat Thematic Mapper. Water Resour. Res., 32, 115-130, doi:10.1029/95WR02718.
    • (1996) Water Resour. Res. , vol.32 , pp. 115-130
    • Rosenthal, W.1    Dozier, J.2
  • 39
    • 21244467259 scopus 로고    scopus 로고
    • Bayesian estimation, optimal interpolation, statistical linear estimation
    • R. Swinbank, V. Shutyaev, and W. A. Lahoz, Eds., NATO Science Series: IV, Kluwer Academic
    • Talagrand, O., 2003: Bayesian estimation, optimal interpolation, statistical linear estimation. Data Assimilation for the Earth System, R. Swinbank, V. Shutyaev, and W. A. Lahoz, Eds., NATO Science Series: IV, Vol. 26, Kluwer Academic, 21-35.
    • (2003) Data Assimilation for the Earth System , vol.26 , pp. 21-35
    • Talagrand, O.1
  • 40
    • 78649247335 scopus 로고    scopus 로고
    • Dynamic approaches for snow depth retrieval from spaceborne microwave brightness temperature
    • Tedesco, M., R. H. Reichle, A. Loew, T. Markus, and J. L. Foster, 2010: Dynamic approaches for snow depth retrieval from spaceborne microwave brightness temperature. IEEE Trans. Geosci. Remote Sens., 48, 1955-1967, doi:10.1109/TGRS.2009.2036910.
    • (2010) IEEE Trans. Geosci. Remote Sens. , vol.48 , pp. 1955-1967
    • Tedesco, M.1    Reichle, R.H.2    Loew, A.3    Markus, T.4    Foster, J.L.5
  • 41
    • 84866987729 scopus 로고    scopus 로고
    • Elevation-dependent influence of snow accumulation on forest greening
    • Trujillo,E., N. P. Molotch, M. L. Goulden,A. E. Kelly, andR.C.Bales, 2012: Elevation-dependent influence of snow accumulation on forest greening. Nat. Geosci., 5, 705-709, doi:10.1038/ngeo1571.
    • (2012) Nat. Geosci. , vol.5 , pp. 705-709
    • Trujillo, E.1    Molotch, N.P.2    Goulden, M.L.3    Kelly, A.E.4    Bales, R.C.5
  • 42
    • 84878487816 scopus 로고    scopus 로고
    • The effect of spatial variability on the sensitivity of passive microwave measurements to snow water equivalent
    • Vander Jagt, B. J., M. T. Durand, S. A. Margulis, E. J. Kim, and N. P. Molotch, 2013: The effect of spatial variability on the sensitivity of passive microwave measurements to snow water equivalent. Remote Sens. Environ., 136, 163-179, doi:10.1016/j.rse.2013.05.002.
    • (2013) Remote Sens. Environ. , vol.136 , pp. 163-179
    • Vander Jagt, B.J.1    Durand, M.T.2    Margulis, S.A.3    Kim, E.J.4    Molotch, N.P.5
  • 43
    • 36749095779 scopus 로고    scopus 로고
    • Mountains of the world, water towers for humanity: Typology, mapping, and global significance
    • Viviroli, D., H. H. Dürr, B. Messerli, M. Meybeck, and R. Weingartner, 2007: Mountains of the world, water towers for humanity: Typology, mapping, and global significance. Water Resour. Res., 43, W07447, doi:10.1029/2006WR005653.
    • (2007) Water Resour. Res. , vol.43 , pp. W07447
    • Viviroli, D.1    Dürr, H.H.2    Messerli, B.3    Meybeck, M.4    Weingartner, R.5
  • 44
    • 84856976659 scopus 로고    scopus 로고
    • Continental-scale water and energy flux analysis and validation for the North American Land Data Assimilation System project phase 2 (NLDAS-2): 1. Intercomparison and application of model products
    • Xia, Y., and Coauthors, 2012: Continental-scale water and energy flux analysis and validation for the North American Land Data Assimilation System project phase 2 (NLDAS-2): 1. Intercomparison and application of model products. J. Geophys. Res., 117, D03109, doi:10.1029/2011JD016048.
    • (2012) J. Geophys. Res. , vol.117 , pp. D03109
    • Xia, Y.1
  • 45
    • 1442263642 scopus 로고    scopus 로고
    • Impact of parameterizations in snow physics and interface processes on the simulation of snow cover and runoff at several cold region sites
    • Xue, Y., S. Sun, D. S. Kahan, and Y. Jiao, 2003: Impact of parameterizations in snow physics and interface processes on the simulation of snow cover and runoff at several cold region sites. J. Geophys. Res., 108, 8859, doi:10.1029/2002JD003174.
    • (2003) J. Geophys. Res. , vol.108 , pp. 8859
    • Xue, Y.1    Sun, S.2    Kahan, D.S.3    Jiao, Y.4
  • 46
    • 33747775838 scopus 로고    scopus 로고
    • Assessing the performance of the ensemble Kalman filter for land surface data assimilation
    • Zhou, Y., D. McLaughlin, and D. Entekhabi, 2006: Assessing the performance of the ensemble Kalman filter for land surface data assimilation. Mon. Wea. Rev., 134, 2128-2142, doi:10.1175/MWR3153.1.
    • (2006) Mon. Wea. Rev. , vol.134 , pp. 2128-2142
    • Zhou, Y.1    McLaughlin, D.2    Entekhabi, D.3


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