Anderson, E. A.: National Weather Service river forecast system-snow accumulation
and ablation model. National Oceanographic and Atmospheric Administration (NOAA), Tech.
Mem., NWS
HYDRO-17, US Dept. of Commerce, Silver Spring, MD, 217 pp.,
https://repository.library.noaa.gov/view/noaa/13507 (last access: 3 January 2023), 1973.
Anderson, E. A.: Snow Accumulation and Ablation Model – SNOW-17, NOAA's
National Weather Service, Office of Hydrologic Development, Silver Spring,
https://www.weather.gov/media/owp/oh/hrl/docs/22snow17.pdf (last access: 3 January 2023),
2006.
Annandale, J., Jovanovic, N., Benadé, N., and Allen, R.: Software for
missing data error analysis of Penman-Monteith reference evapotranspiration,
Irrigation Sci., 21, 57–67, https://doi.org/10.1007/s002710100047, 2002.
Arendt, A. A. and Sharp, M. J.: Energy balance measurements on a Canadian
high Arctic glacier and their implications for mass balance modelling,
IAHS-AISH publication, 256, 165–172, 1999.
Asaoka, Y. and Kominami, Y.: Incorporation of satellite-derived snow-cover
area in spatial snowmelt modeling for a large area: determination of a
gridded degree-day factor, Ann. Glaciol., 54, 205–213,
https://doi.org/10.3189/2013AoG62A218, 2013.
Badescu, V. (Ed.): Modeling solar radiation at the earth's surface: recent
advances, Springer, Berlin, 517 pp., https://doi.org/10.1007/978-3-540-77455-6, 2008.
Badescu, V. and Paulescu, M.: Statistical properties of the sunshine number
illustrated with measurements from Timisoara (Romania), Atmos.
Res., 101, 194–204, https://doi.org/10.1016/j.atmosres.2011.02.009,
2011.
Bagchi, A. K.: Areal value of degree-day factor/Valeur spatiale du facteur
degré-jour, Hydrolog. Sci. J., 28, 499–511,
https://doi.org/10.1080/02626668309491991, 1983.
Bergström, S.: Development and application conceptual runoff model for
scandinavian catchments, SMHI, Research Department, Hydrology, 162 pp.,
http://urn.kb.se/resolve?urn=urn:nbn:se:smhi:diva-5738 (last access: 3 January 2023),
1976.
Bogacki, W. and Ismail, M. F.: Seasonal forecast of Kharif flows from Upper Jhelum catchment, Proc. IAHS, 374, 137–142, https://doi.org/10.5194/piahs-374-137-2016, 2016.
Bolibar, J., Rabatel, A., Gouttevin, I., Zekollari, H., and Galiez, C.:
Nonlinear sensitivity of glacier mass balance to future climate change
unveiled by deep learning, Nat. Commun., 13, 409,
https://doi.org/10.1038/s41467-022-28033-0, 2022.
Bormann, K. J., Evans, J. P., and McCabe, M. F.: Constraining snowmelt in a
temperature-index model using simulated snow densities, J.
Hydrol., 517, 652–667, https://doi.org/10.1016/j.jhydrol.2014.05.073,
2014.
Braithwaite, R. J.: Positive degree-day factors for ablation on the
Greenland ice sheet studied by energy-balance modelling, J. Glaciol., 41,
153–160, https://doi.org/10.3189/S0022143000017846, 1995.
Braithwaite, R. J.: Temperature and precipitation climate at the
equilibrium-line altitude of glaciers expressed by the degree-day factor for
melting snow, J. Glaciol., 54, 437–444,
https://doi.org/10.3189/002214308785836968, 2008.
Braithwaite, R. J. and Hughes, P. D.: Positive degree-day sums in the Alps:
a direct link between glacier melt and international climate policy, J.
Glaciol., 68, 901–911, https://doi.org/10.1017/jog.2021.140, 2022.
Braithwaite, R. J., Konzelmann, T., Marty, C., and Olesen, O. B.:
Reconnaissance Study of glacier energy balance in North Greenland, 1993–94,
J. Glaciol., 44, 239–247, https://doi.org/10.3189/S0022143000002586, 1998.
Braun, L., Grabs, W., and Rana, B.: Application of a Conceptual
Precipitation Runoff Model in the Langtang Kfaola Basin, Nepal Himalaya,
Snow and Glacier Hydrology, 1993.
Braun, L. N.: Simulation of snowmelt-runoff in lowland and lower alpine
regions of Switzerland, PhD Thesis, ETH Zurich,
https://doi.org/10.3929/ETHZ-A-000334295, 1984.
Bristow, K. L. and Campbell, G. S.: On the relationship between incoming
solar radiation and daily maximum and minimum temperature, Agri.
Forest Meteorol., 31, 159–166,
https://doi.org/10.1016/0168-1923(84)90017-0, 1984.
Brutsaert, W.: On a derivable formula for long-wave radiation from clear
skies, Water Resour. Res., 11, 742–744,
https://doi.org/10.1029/WR011i005p00742, 1975.
Brutsaert, W.: Evaporation into the Atmosphere, Springer Netherlands,
Dordrecht, https://doi.org/10.1007/978-94-017-1497-6, 1982.
Campbell, G. S. and Norman, J. M.: Introduction to environmental biophysics,
2nd Edn., Springer, New York, 286 pp.,
https://www.umfcv.ro/files/!/x/4/_/4_ Intro_Env_MED_.pdf (last access: 3 January 2023), 1998.
Carenzo, M., Pellicciotti, F., Rimkus, S., and Burlando, P.: Assessing the
transferability and robustness of an enhanced temperature-index glacier-melt
model, J. Glaciol., 55, 258–274,
https://doi.org/10.3189/002214309788608804, 2009.
DeWalle, D. R. and Rango, A.: Principles of Snow Hydrology, Cambridge
University Press, Cambridge, https://doi.org/10.1017/CBO9780511535673, 2008.
Doorenbos, J. and Pruitt, W. O.: Guidelines for predicting crop water
requirements, Rev., Food and Agriculture Organization of the United Nations,
Rome, 144 pp., https://www.posmet.ufv.br/wp-content/uploads/2015/08/LIVRO-385-Doorenbos-e-Pruitt-Guidelines-for-predicting-crop-water-requirements.pdf (last access: 3 January 2023) 1977.
Ekici, C.: Total Global Solar Radiation Estimation Models and Applications:
A review, International Journal of Innovative Technology and Interdisciplinary Sciences, 2, 212–228,
https://doi.org/10.15157/IJITIS.2019.2.2.212-228, 2019.
Evrendilek, F. and Ertekin, C.: Assessing solar radiation models using
multiple variables over Turkey, Clim. Dynam., 31, 131–149,
https://doi.org/10.1007/s00382-007-0338-6, 2008.
Gafurov, A.: Water balance modeling using remote sensing information: focus
on Central Asia, PhD Thesis, Inst. für Wasserbau, Stuttgart, 116 pp., 2010.
Harpold, A. A. and Brooks, P. D.: Humidity determines snowpack ablation
under a warming climate, P. Natl. Acad. Sci. USA, 115, 1215–1220,
https://doi.org/10.1073/pnas.1716789115, 2018.
Hasson, S., Saeed, F., Böhner, J., and Schleussner, C.-F.: Water
availability in Pakistan from Hindukush–Karakoram–Himalayan watersheds at
1.5
∘C and 2
∘C Paris Agreement targets, Adv.
Water Resour., 131, 103365,
https://doi.org/10.1016/j.advwatres.2019.06.010, 2019.
He, Z. H., Parajka, J., Tian, F. Q., and Blöschl, G.: Estimating degree-day factors from MODIS for snowmelt runoff modeling, Hydrol. Earth Syst. Sci., 18, 4773–4789, https://doi.org/10.5194/hess-18-4773-2014, 2014.
Hempel, S., Frieler, K., Warszawski, L., Schewe, J., and Piontek, F.: A trend-preserving bias correction – the ISI-MIP approach, Earth Syst. Dynam., 4, 219–236, https://doi.org/10.5194/esd-4-219-2013, 2013.
Hinzman, L. D. and Kane, D. L.: Snow hydrology of a headwater Arctic basin:
2. Conceptual analysis and computer modeling, Water Resour. Res., 27,
1111–1121, https://doi.org/10.1029/91WR00261, 1991.
Hock, R.: A distributed temperature-index ice- and snowmelt model including
potential direct solar radiation, J. Glaciol., 45, 101–111,
https://doi.org/10.3189/S0022143000003087, 1999.
Hock, R.: Temperature index melt modelling in mountain areas, J.
Hydrol., 282, 104–115, https://doi.org/10.1016/S0022-1694(03)00257-9,
2003.
Hock, R.: Glacier melt: a review of processes and their modelling, Prog.
Phys. Geog., 29, 362–391,
https://doi.org/10.1191/0309133305pp453ra, 2005.
Hock, R. and Noetzli, C.: Areal melt and discharge modelling of
Storglaciären, Sweden, Ann. Glaciol., 24, 211–216,
https://doi.org/10.3189/S0260305500012192, 1997.
Huss, M. and Hock, R.: Global-scale hydrological response to future glacier
mass loss, Nat. Clim. Change, 8, 135–140,
https://doi.org/10.1038/s41558-017-0049-x, 2018.
Immerzeel, W. W., Droogers, P., de Jong, S. M., and Bierkens, M. F. P.:
Large-scale monitoring of snow cover and runoff simulation in Himalayan
river basins using remote sensing, Remote Sens. Environ., 113,
40–49, https://doi.org/10.1016/j.rse.2008.08.010, 2009.
Ismail, M. F. and Bogacki, W.: Scenario approach for the seasonal forecast of Kharif flows from the Upper Indus Basin, Hydrol. Earth Syst. Sci., 22, 1391–1409, https://doi.org/10.5194/hess-22-1391-2018, 2018.
Ismail, M. F., Naz, B. S., Wortmann, M., Disse, M., Bowling, L. C., and
Bogacki, W.: Comparison of two model calibration approaches and their
influence on future projections under climate change in the Upper Indus
Basin, Climatic Change, 163, 1227–1246,
https://doi.org/10.1007/s10584-020-02902-3, 2020.
Jansson, P., Hock, R., and Schneider, T.: The concept of glacier storage: a
review, J. Hydrol., 282, 116–129,
https://doi.org/10.1016/S0022-1694(03)00258-0, 2003.
Jennings, K. S., Kittel, T. G. F., and Molotch, N. P.: Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget, The Cryosphere, 12, 1595–1614, https://doi.org/10.5194/tc-12-1595-2018, 2018.
Jin, Z., Yezheng, W., and Gang, Y.: General formula for estimation of
monthly average daily global solar radiation in China, Energ. Convers.
Managem., 46, 257–268, https://doi.org/10.1016/j.enconman.2004.02.020,
2005.
Kane, D. L., Gieck, R. E., and Hinzman, L. D.: Snowmelt Modeling at Small
Alaskan Arctic Watershed, J. Hydrol. Eng., 2, 204–210,
https://doi.org/10.1061/(ASCE)1084-0699(1997)2:4(204), 1997.
Kayastha, R. B. and Kayastha, R.: Glacio-Hydrological Degree-Day Model (GDM)
Useful for the Himalayan River Basins, in: Himalayan Weather and Climate and
their Impact on the Environment, edited by: Dimri, A. P., Bookhagen, B.,
Stoffel, M., and Yasunari, T., Springer International Publishing, Cham,
379–398, https://doi.org/10.1007/978-3-030-29684-1_19, 2020.
Kayastha, R. B., Ageta, Y., and Nakawo, M.: Positive degree-day factors for
ablation on glaciers in the Nepalese Himalayas: case study on Glacier AX010
in Shorong Himal, Nepal, Bulletin of Glaciological Research, 17, 1–10, 2000.
Kayastha, R. B., Yutaka, A., Masayoshi, N., Koji, F., Akiko, S., and
Yoshihiro, M.: Positive degree-day factors for ice ablation on four glaciers
in the Nepalese Himalayas and Qinghai-Tibetan Plateau, Bulletin of
Glaciological Research, 20, 7–14, 2003.
Klok, E. J., Jasper, K., Roelofsma, K. P., Gurtz, J., and Badoux, A.:
Distributed hydrological modelling of a heavily glaciated Alpine river
basin, Hydrolog. Sci. J., 46, 553–570,
https://doi.org/10.1080/02626660109492850, 2001.
Kopp, G. and Lean, J. L.: A new, lower value of total solar irradiance:
Evidence and climate significance: FRONTIER, Geophys. Res. Lett., 38, L01706,
https://doi.org/10.1029/2010GL045777, 2011.
Kopp, M., Tuo, Y., and Disse, M.: Fully automated snow depth measurements
from time-lapse images applying a convolutional neural network, Sci.
Total Environ., 697, 134213,
https://doi.org/10.1016/j.scitotenv.2019.134213, 2019.
Kustas, W. P., Rango, A., and Uijlenhoet, R.: A simple energy budget
algorithm for the snowmelt runoff model, Water Resour. Res., 30, 1515–1527,
https://doi.org/10.1029/94WR00152, 1994.
Lang, H.: Forecasting Meltwater Runoff from Snow-Covered Areas and from
Glacier Basins, in: River Flow Modelling and Forecasting, edited by:
Kraijenhoff, D. A. and Moll, J. R., Springer Netherlands, Dordrecht, vol. 3,
99–127, https://doi.org/10.1007/978-94-009-4536-4_5, 1986.
Lang, H. and Braun, L.: On the information content of air temperature in the
context of snow melt estimation, IAHS-AISH P., 190, 347–354, 1990.
Lawrence, M. G.: The Relationship between Relative Humidity and the Dewpoint
Temperature in Moist Air: A Simple Conversion and Applications, B. Am.
Meteorol. Soc., 86, 225–234, https://doi.org/10.1175/BAMS-86-2-225, 2005.
Lehning, M., Bartelt, P., Brown, B., and Fierz, C.: A physical SNOWPACK
model for the Swiss avalanche warning, Cold Reg. Sci. Technol.,
35, 169–184, https://doi.org/10.1016/S0165-232X(02)00072-1, 2002.
Liu, Y., Tan, Q., and Pan, T.: Determining the Parameters of the
Ångström-Prescott Model for Estimating Solar Radiation in Different
Regions of China: Calibration and Modeling, Earth Space Sci., 6,
1976–1986, https://doi.org/10.1029/2019EA000635, 2019.
Luo, Y., Arnold, J., Liu, S., Wang, X., and Chen, X.: Inclusion of glacier
processes for distributed hydrological modeling at basin scale with
application to a watershed in Tianshan Mountains, northwest China, J.
Hydrol., 477, 72–85, https://doi.org/10.1016/j.jhydrol.2012.11.005,
2013.
Lutz, A. F., Immerzeel, W. W., Kraaijenbrink, P. D. A., Shrestha, A. B., and
Bierkens, M. F. P.: Climate Change Impacts on the Upper Indus Hydrology:
Sources, Shifts and Extremes, PLoS ONE, 11, e0165630,
https://doi.org/10.1371/journal.pone.0165630, 2016.
MacDougall, A. H., Wheler, B. A., and Flowers, G. E.: A preliminary assessment of glacier melt-model parameter sensitivity and transferability in a dry subarctic environment, The Cryosphere, 5, 1011–1028, https://doi.org/10.5194/tc-5-1011-2011, 2011.
Marks, D., Domingo, J., Susong, D., Link, T., and Garen, D.: A spatially
distributed energy balance snowmelt model for application in mountain
basins, Hydrol. Process., 13, 1935–1959,
https://doi.org/10.1002/(SICI)1099-1085(199909)13:12/13<1935::AID-HYP868>3.0.CO;2-C, 1999.
Marsh, C. B., Pomeroy, J. W., and Spiteri, R. J.: Implications of mountain
shading on calculating energy for snowmelt using unstructured triangular
meshes: Implication of Mountains shading for snowmelt, Hydrol. Process., 26,
1767–1778, https://doi.org/10.1002/hyp.9329, 2012.
Martinec, J.: The degree-day factor for snowmelt-runoff forecasting, IAHS
Commission of Surface Waters, 51, 468–477, 1960.
Martinec, J.: Snowmelt – runoff model for stream flow forecasts, Nord.
Hydrol., 6, 145–154, 1975.
Masters, G. M.: Renewable and efficient electric power systems, John Wiley
& Sons, Hoboken, NJ, 654 pp.,
http://www.a-ghadimi.com/files/Courses/Renewable Energy/REN_Book.pdf (last access: 3 January 2023), 2004.
Matthews, T. and Hodgkins, R.: Interdecadal variability of degree-day
factors on Vestari Hagafellsjökull (Langjökull, Iceland) and the
importance of threshold air temperatures, J. Glaciol., 62, 310–322,
https://doi.org/10.1017/jog.2016.21, 2016.
McGinn, R. A.: Degree-day snowmelt runoff experiments; Clear Lake Watershed,
Riding Mountain National Park, Geographical Essays, 15, ISSN 1911-5814,
https://pcag.uwinnipeg.ca/Prairie-Perspectives/PP-Vol15/McGinn.pdf (last access: 3 January 2023), 2012.
Meeus, J.: Astronomical algorithms, 1st English Edn., Willmann-Bell,
Richmond, Va, 429 pp.,
https://www.agopax.it/Libri_astronomia/pdf/Astronomical Algorithms.pdf (last access: 3 January 2023), 1991.
Monteith, J. L. and Unsworth, M. H.: Principles of environmental physics:
plants, animals, and the atmosphere, 4th Edn., Elsevier/Academic Press,
Amsterdam, Boston, 401 pp.,
https://denning.atmos.colostate.edu/readings/Monteith.and.Unsworth.4thEd.pdf (last access: 3 January 2023), 2013.
Muhammad, S., Tian, L., Ali, S., Latif, Y., Wazir, M. A., Goheer, M. A.,
Saifullah, M., Hussain, I., and Shiyin, L.: Thin debris layers do not
enhance melting of the Karakoram glaciers, Sci. Total Environ.,
746, 141119, https://doi.org/10.1016/j.scitotenv.2020.141119, 2020.
Murray, F. W.: On the Computation of Saturation Vapor Pressure, J. Appl.
Meteorol., 6, 203–204, https://doi.org/10.1175/1520-0450(1967)006<0203:OTCOSV>2.0.CO;2, 1967.
Musselman, K. N., Clark, M. P., Liu, C., Ikeda, K., and Rasmussen, R.:
Slower snowmelt in a warmer world, Nat. Clim. Change, 7, 214–219,
https://doi.org/10.1038/nclimate3225, 2017.
Oerlemans, J.: Glaciers and climate change, A.A. Balkema Publishers, Lisse,
Exton (PA), 148 pp., 2001.
Pelkowski, J.: A physical rationale for generalized
Ångström–Prescott regression, Sol. Energy, 83, 955–963,
https://doi.org/10.1016/j.solener.2008.12.011, 2009.
Pellicciotti, F., Brock, B., Strasser, U., Burlando, P., Funk, M., and
Corripio, J.: An enhanced temperature-index glacier melt model including the
shortwave radiation balance: development and testing for Haut Glacier
d'Arolla, Switzerland, J. Glaciol., 51, 573–587,
https://doi.org/10.3189/172756505781829124, 2005.
Prasad, V. H. and Roy, P. S.: Estimation of Snowmelt Runoff in Beas Basin,
India, Geocarto Int., 20, 41–47,
https://doi.org/10.1080/10106040508542344, 2005.
Quick, M. C. and Pipes, A.: U.B.C. Watershed model/Le modèle du bassin
versant U.C.B, Hydrolog. Sci. Bull. 22, 153–161,
https://doi.org/10.1080/02626667709491701, 1977.
Rango, A. and Martinec, J.: Application of a Snowmelt-Runoff Model Using
Landsat Data, Hydrol. Res., 10, 225–238,
https://doi.org/10.2166/nh.1979.0006, 1979.
Rango, A. and Martinec, J.: Revisiting the degree-day method for snowmelt
computations, J. Am. Water Resour. Assoc., 31, 657–669,
https://doi.org/10.1111/j.1752-1688.1995.tb03392.x, 1995.
Reda, I. and Andreas, A.: Solar position algorithm for solar radiation
applications, Sol. Energy, 76, 577–589,
https://doi.org/10.1016/j.solener.2003.12.003, 2004.
Rensheng, C., Shihua, L., Ersi, K., Jianping, Y., and Xibin, J.: Estimating
daily global radiation using two types of revised models in China, Energ.
Convers. Manage., 47, 865–878,
https://doi.org/10.1016/j.enconman.2005.06.015, 2006.
Schaefli, B. and Huss, M.: Integrating point glacier mass balance observations into hydrologic model identification, Hydrol. Earth Syst. Sci., 15, 1227–1241, https://doi.org/10.5194/hess-15-1227-2011, 2011.
Schmid, M.-O., Gubler, S., Fiddes, J., and Gruber, S.: Inferring snowpack ripening and melt-out from distributed measurements of near-surface ground temperatures, The Cryosphere, 6, 1127–1139, https://doi.org/10.5194/tc-6-1127-2012, 2012.
Schreider, S. Yu., Whetton, P. H., Jakeman, A. J., and Pittock, A. B.:
Runoff modelling for snow-affected catchments in the Australian alpine
region, eastern Victoria, J. Hydrol., 200, 1–23,
https://doi.org/10.1016/S0022-1694(97)00006-1, 1997.
Shea, J. M., Dan Moore, R., and Stahl, K.: Derivation of melt factors from
glacier mass-balance records in western Canada, J. Glaciol., 55, 123–130,
https://doi.org/10.3189/002214309788608886, 2009.
Swinbank, W. C.: Long-wave radiation from clear skies, Q. J. Roy. Meteor. Soc.,
89, 339–348, https://doi.org/10.1002/qj.49708938105, 1963.
Tahir, A. A., Chevallier, P., Arnaud, Y., and Ahmad, B.: Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan, Hydrol. Earth Syst. Sci., 15, 2275–2290, https://doi.org/10.5194/hess-15-2275-2011, 2011.
US Army Corps of Engineers (USACE): Snow hydrology: Summary report of the snow investigations, US Army Corps of Engineers, North Pacific Division, Portlandm
https://usace.contentdm.oclc.org/digital/collection/p266001coll1/id/4172/ (last access: 3 January 2023), 1956.
US Army Corps of Engineers (USACE): Runoff from Snowmelt, Engineer Manual reference no. 1110-2-1406, 142 pp.,
https://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-1406.pdf (last access: 3 January 2023),
1998.
Vincent, C. and Thibert, E.: Brief communication: Nonlinear sensitivity of glacier-mass balance attested by temperature-index models, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2022-210, in review, 2022.
Walter, M. T., Brooks, E. S., McCool, D. K., King, L. G., Molnau, M., and
Boll, J.: Process-based snowmelt modeling: does it require more input data
than temperature-index modeling, J. Hydrol., 300, 65–75, 2005.
Warren, S. G.: Optical properties of snow, Rev. Geophys., 20, 67–89,
https://doi.org/10.1029/RG020i001p00067, 1982.
Warren, S. G. and Wiscombe, W. J.: A Model for the Spectral Albedo of Snow.
II: Snow Containing Atmospheric Aerosols, J. Atmos. Sci., 37, 2734–2745,
https://doi.org/10.1175/1520-0469(1980)037<2734:AMFTSA>2.0.CO;2, 1980.
Wheler, B. A.: Glacier melt modelling in the Donjek Range, St. Elias
Mountains, Yukon Territory, MS thesis, Dept. of Earth Sciences, Simon
Fraser University, 283 pp., 2009.
Wiscombe, W. J. and Warren, S. G.: A Model for the Spectral Albedo of Snow.
I: Pure Snow, J. Atmos. Sci., 37, 2712–2733,
https://doi.org/10.1175/1520-0469(1980)037<2712:AMFTSA>2.0.CO;2, 1980.
Yang, K. and Koike, T.: A general model to estimate hourly and daily solar
radiation for hydrological studies: GENERAL SOLAR RADIATION, Water Resour.
Res., 41, W10403, https://doi.org/10.1029/2005WR003976, 2005.
Zhang, Y., Liu, S., Xie, C., and Ding, Y.: Application of a degree-day model
for the determination of contributions to glacier meltwater and runoff near
Keqicar Baqi glacier, southwestern Tien Shan, Ann. Glaciol., 43, 280–284,
https://doi.org/10.3189/172756406781812320, 2006.
Zingg, T.: Beziehung zwischen Temperature und Schmelzwasser und ihre
Bedeutung für Niederschlags- und Abflussfragen, Publication of
Association of Hydrological Sciences, 32, 266–269, 1951.
