Kaj Williams, Ph.D.
I'm an applied mathematician working as a Research Physical Scientist at USGS. My expertise is in developing mathematical and computational methods to understand physical processes on planetary surfaces and atmospheres.
Science and Products
Imagery, soil temperature and humidity profiles, and meteorological data from December 2020 to April 2021, Grand Falls Dune Field, Arizona
Grand Falls dune field (GFDF) is located on the Navajo Nation, ~70 km NE of Flagstaff, AZ. This active dune field displays a range of morphologies, including barchans, smaller dunes, and ripples, and is bimodal in composition. The felsic component is likely derived from the Little Colorado River, and the mafic component (basaltic grains) is locally sourced from nearby cinder cones [1]...
Locations and Properties of Ice-Exposing Scarps and New Impact Craters in the Mid-Latitudes of Mars
Although ice in the Martian mid-latitudes is typically covered by a layer of dust or regolith, it is exposed in some locations by fresh impact craters or in erosional scarps. In both cases, the exposed ice is massive or excess ice with a low lithic content. We find that erosional scarps occur between 50-61 north and south latitude, and that they are concentrated in and near Milankovi...
Filter Total Items: 17
Mass balance of two perennial snowfields: Niwot Ridge, Colorado and the Ulaan Taiga, Mongolia.
Perennial snowfields are generally receding worldwide, though the precise mechanisms causing recessions are not always well understood. Here we apply a numerical snowpack model to identify the leading factors controlling the mass balance of two perennial snowfields that have significant human interest: Arapaho glacier, located at Niwot Ridge in the Colorado Rocky Mountains (United States...
Authors
Kaj E. Williams, Christopher P. McKay, Owen B. Toon, Keith S. Jennings
A numerical model for the cooling of a lava sill with heat pipe effects
Understanding the cooling process of volcanic intrusions into wet sediments is a difficult but important problem, given the presence of extremely large temperature gradients and potentially complex water-magma interactions. This report presents a numerical model to study such interactions, including the effect of heat pipes on the cooling of volcanic intrusions. Udell (1985) has shown...
Authors
Kaj E. Williams, Colin M. Dundas, Laszlo Kestay
A roadmap for planetary caves science and exploration
While researchers have pondered the possibility of extraterrestrial caves for more than 50 years, we have now entered the incipient phase of planetary caves exploration. Our knowledge of planetary caves varies from body to body. Earth represents the most advanced level of exploration, but many unanswered questions remain. Beyond Earth, identification of possible caves is most advanced...
Authors
Timothy N. Titus, J. Judson Wynne, Michael J. Malaska, Ali-akbar Agha-Mohammadi, Peter B. Buhler, E. Calvin Alexander, James W. Ashley, Armando Azua-Bustos, Penelope J. Boston, Debra L. Buczkowski, Leroy Chiao, Glen E. Cushing, John DeDecker, Pablo de León, Cansu Demirel-Floyd, Jo de Waele, Alberto G. Fairen, Amos Frumkin, Gary L. Harris, Heather Jones, Laura H. Kerber, Erin J. Leonard, Richard J. Léveillé, Kavya Manyapu, Matteo Massironi, Ana Z. Miller, John E. Mylroie, Bogdan P. Onac, Scott E. Parazynski, Cynthia B. Phillips, Charity M. Phillips-Lander, Thomas H. Prettyman, Haley M. Sapers, Francesco Sauro, Norbert Schorghofer, Dirk Schulze-Makuch, Jennifer E. C. Scully, Kyle Uckert, Robert V. Wagner, William L. Whittaker, Kaj E. Williams, Uland Y. Wong
Aeolian processes and landforms across the Solar System: Science and technology requirements for the next decade
Discussions of planetary atmospheric-surface interactions (including aeolian processes and phenomena and the resulting landforms) are often tied to a specific planetary body. Considering this, a series of workshops were initiated in 2008 to facilitate an interdisciplinary and interplanetary body approach to further our understanding of aeolian processes, phenomena, and landforms (Titus...
Authors
Timothy N. Titus, Serina Diniega, L.K. Fenton, Lynn D.V. Neakrase, Jaap H. Nienhuis, Jani Radebaugh, Kaj E. Williams, James R. Zimbelman
Science and technology requirements to explore caves in our Solar System
We are in the incipient phase of exploring the subterranean realm of our Solar System. Planetary caves research offers interdisciplinary, cross-planetary body investigations spanning geology, climatology, astrobiology, robotics, and human use. Caves are of great importance in advancing our understanding of planetary processes and the search for life beyond Earth. Given these advances, a...
Authors
Timothy N. Titus, Janna Wynne, P. J. Boston, P. de Leon, Cansu Demirel-Floyd, H Jones, Francesco Sauro, Kyle Uckert, Ali-akbar Agha-Mohammadi, E. Calvin Alexander, James W. Ashley, Armando Azua-Bustos, Leroy Chiao, Glen E. Cushing, John DeDecker, Alberto G. Fairen, Amos Frumkin, Jo de Waele, Gary L. Harris, Laura H. Kerber, Richard J. Léveillé, Michael J. Malaska, Kavya Manyapu, Matteo Massironi, Ana Z. Miller, John E. Mylroie, Bogdan P. Onac, Scott E. Parazynski, Charity M. Phillips-Lander, Thomas H. Prettyman, Haley M. Sapers, Norbert Schorghofer, Dirk Schulze-Makuch, Red Whittaker, Kaj E. Williams, Uland Y. Wong
A critical gap: In situ measurements of surface-atmosphere interactions from outside earth
This white paper demonstrates five points: (1) The lack of robust measurements of the vertical gradients of natural boundary layers and transport fluxes on other planetary bodies precludes adequate estimation of aeolian and other meteorological processes throughout our Solar System (§1). (2) Thus, there exist critical knowledge gaps within high-priority planetary science questions that...
Authors
Serina Diniega, Devon M. Burr, Colin M. Dundas, Brian P. Jackson, Michael A. Mischna, Scot C.R. Rafkin, Isaac B. Smith, Robert M. Sullivan, Timothy N. Titus, Nathalie Vriend, Ian J. Walker, Kaj E. Williams
Non-USGS Publications**
Williams, Kaj, Christopher P. McKay and J.L Heldmann. (2015) Modeling the effects of Martian surface frost on ice table depth. Icarus, 261, 58-65.
Williams, Kaj and Chris McKay. (2015). Comparing flow-through and static ice cave models for Shoshone Ice Cave. International Journal of Speleology, 44: 1.
Heldmann, J. L., W. Pollard, C. P. Mckay, M. M. Marinova, A. Davila, K. E. Williams, D. Lacelle, and D. T. Andersen (2013), The high elevation Dry Valleys in Antarctica as analog sites for subsurface ice on Mars, Planetary and Space Science, 85(C), doi:10.1016/j.pss.2013.05.019.
J.L. Heldmann, M. Marinova, K.E. Williams, D. Lacelle, C.P. McKay, A. Davila, W. Pollard and D.T. Andersen (2012). Formation and evolution of buried snowpack deposits in Pearse Valley, Antarctica, and implications for Mars. Antarctic Science, 24, doi:10.1017/S0954102011000903
Williams, K. E., McKay, C. P. and Persson, F. (2012) The surface energy balance at the Huygens Landing site and the moist surface conditions on Titan. Planetary and Space Science. Vol 60, nr. 1.
Williams, K. E., Pappalardo, R. T. (2011) Variability in the Small Crater Population of Callisto. Icarus 215,1.
Williams, K.E., McKay, C. P., Toon, O.B., Head, J. W. (2010) Do Ice Caves Exist on Mars? Icarus 209,2.
Williams, K.E., Toon, O. B., Heldmann, J. L., Mellon, M. (2009) Ancient melting of mid-latitude snowpacks on Mars as a water source for gullies, Icarus, 200.
Williams, K.E., Toon, O.B., Heldmann, J.L. , McKay C.P. and Mellon, M. (2008) Stability of Mid-Latitude Snowpacks on Mars, Icarus, 196.
Williams, K. E., O. B. Toon, and J. Heldmann (2007), Modeling water ice lifetimes at recent Martian gully locations, Geophys. Res. Lett., 34, L09204, doi:10.1029/2007GL029507.
Lai, Y.C., Lerner, D, Williams, K and Crebogi, C. (Nov. 1999) Unstable dimension variability in coupled chaotic systems. Physical Review E 60 (5): 5445-5454 : A.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Imagery, soil temperature and humidity profiles, and meteorological data from December 2020 to April 2021, Grand Falls Dune Field, Arizona
Grand Falls dune field (GFDF) is located on the Navajo Nation, ~70 km NE of Flagstaff, AZ. This active dune field displays a range of morphologies, including barchans, smaller dunes, and ripples, and is bimodal in composition. The felsic component is likely derived from the Little Colorado River, and the mafic component (basaltic grains) is locally sourced from nearby cinder cones [1]...
Locations and Properties of Ice-Exposing Scarps and New Impact Craters in the Mid-Latitudes of Mars
Although ice in the Martian mid-latitudes is typically covered by a layer of dust or regolith, it is exposed in some locations by fresh impact craters or in erosional scarps. In both cases, the exposed ice is massive or excess ice with a low lithic content. We find that erosional scarps occur between 50-61 north and south latitude, and that they are concentrated in and near Milankovi...
Filter Total Items: 17
Mass balance of two perennial snowfields: Niwot Ridge, Colorado and the Ulaan Taiga, Mongolia.
Perennial snowfields are generally receding worldwide, though the precise mechanisms causing recessions are not always well understood. Here we apply a numerical snowpack model to identify the leading factors controlling the mass balance of two perennial snowfields that have significant human interest: Arapaho glacier, located at Niwot Ridge in the Colorado Rocky Mountains (United States...
Authors
Kaj E. Williams, Christopher P. McKay, Owen B. Toon, Keith S. Jennings
A numerical model for the cooling of a lava sill with heat pipe effects
Understanding the cooling process of volcanic intrusions into wet sediments is a difficult but important problem, given the presence of extremely large temperature gradients and potentially complex water-magma interactions. This report presents a numerical model to study such interactions, including the effect of heat pipes on the cooling of volcanic intrusions. Udell (1985) has shown...
Authors
Kaj E. Williams, Colin M. Dundas, Laszlo Kestay
A roadmap for planetary caves science and exploration
While researchers have pondered the possibility of extraterrestrial caves for more than 50 years, we have now entered the incipient phase of planetary caves exploration. Our knowledge of planetary caves varies from body to body. Earth represents the most advanced level of exploration, but many unanswered questions remain. Beyond Earth, identification of possible caves is most advanced...
Authors
Timothy N. Titus, J. Judson Wynne, Michael J. Malaska, Ali-akbar Agha-Mohammadi, Peter B. Buhler, E. Calvin Alexander, James W. Ashley, Armando Azua-Bustos, Penelope J. Boston, Debra L. Buczkowski, Leroy Chiao, Glen E. Cushing, John DeDecker, Pablo de León, Cansu Demirel-Floyd, Jo de Waele, Alberto G. Fairen, Amos Frumkin, Gary L. Harris, Heather Jones, Laura H. Kerber, Erin J. Leonard, Richard J. Léveillé, Kavya Manyapu, Matteo Massironi, Ana Z. Miller, John E. Mylroie, Bogdan P. Onac, Scott E. Parazynski, Cynthia B. Phillips, Charity M. Phillips-Lander, Thomas H. Prettyman, Haley M. Sapers, Francesco Sauro, Norbert Schorghofer, Dirk Schulze-Makuch, Jennifer E. C. Scully, Kyle Uckert, Robert V. Wagner, William L. Whittaker, Kaj E. Williams, Uland Y. Wong
Aeolian processes and landforms across the Solar System: Science and technology requirements for the next decade
Discussions of planetary atmospheric-surface interactions (including aeolian processes and phenomena and the resulting landforms) are often tied to a specific planetary body. Considering this, a series of workshops were initiated in 2008 to facilitate an interdisciplinary and interplanetary body approach to further our understanding of aeolian processes, phenomena, and landforms (Titus...
Authors
Timothy N. Titus, Serina Diniega, L.K. Fenton, Lynn D.V. Neakrase, Jaap H. Nienhuis, Jani Radebaugh, Kaj E. Williams, James R. Zimbelman
Science and technology requirements to explore caves in our Solar System
We are in the incipient phase of exploring the subterranean realm of our Solar System. Planetary caves research offers interdisciplinary, cross-planetary body investigations spanning geology, climatology, astrobiology, robotics, and human use. Caves are of great importance in advancing our understanding of planetary processes and the search for life beyond Earth. Given these advances, a...
Authors
Timothy N. Titus, Janna Wynne, P. J. Boston, P. de Leon, Cansu Demirel-Floyd, H Jones, Francesco Sauro, Kyle Uckert, Ali-akbar Agha-Mohammadi, E. Calvin Alexander, James W. Ashley, Armando Azua-Bustos, Leroy Chiao, Glen E. Cushing, John DeDecker, Alberto G. Fairen, Amos Frumkin, Jo de Waele, Gary L. Harris, Laura H. Kerber, Richard J. Léveillé, Michael J. Malaska, Kavya Manyapu, Matteo Massironi, Ana Z. Miller, John E. Mylroie, Bogdan P. Onac, Scott E. Parazynski, Charity M. Phillips-Lander, Thomas H. Prettyman, Haley M. Sapers, Norbert Schorghofer, Dirk Schulze-Makuch, Red Whittaker, Kaj E. Williams, Uland Y. Wong
A critical gap: In situ measurements of surface-atmosphere interactions from outside earth
This white paper demonstrates five points: (1) The lack of robust measurements of the vertical gradients of natural boundary layers and transport fluxes on other planetary bodies precludes adequate estimation of aeolian and other meteorological processes throughout our Solar System (§1). (2) Thus, there exist critical knowledge gaps within high-priority planetary science questions that...
Authors
Serina Diniega, Devon M. Burr, Colin M. Dundas, Brian P. Jackson, Michael A. Mischna, Scot C.R. Rafkin, Isaac B. Smith, Robert M. Sullivan, Timothy N. Titus, Nathalie Vriend, Ian J. Walker, Kaj E. Williams
Non-USGS Publications**
Williams, Kaj, Christopher P. McKay and J.L Heldmann. (2015) Modeling the effects of Martian surface frost on ice table depth. Icarus, 261, 58-65.
Williams, Kaj and Chris McKay. (2015). Comparing flow-through and static ice cave models for Shoshone Ice Cave. International Journal of Speleology, 44: 1.
Heldmann, J. L., W. Pollard, C. P. Mckay, M. M. Marinova, A. Davila, K. E. Williams, D. Lacelle, and D. T. Andersen (2013), The high elevation Dry Valleys in Antarctica as analog sites for subsurface ice on Mars, Planetary and Space Science, 85(C), doi:10.1016/j.pss.2013.05.019.
J.L. Heldmann, M. Marinova, K.E. Williams, D. Lacelle, C.P. McKay, A. Davila, W. Pollard and D.T. Andersen (2012). Formation and evolution of buried snowpack deposits in Pearse Valley, Antarctica, and implications for Mars. Antarctic Science, 24, doi:10.1017/S0954102011000903
Williams, K. E., McKay, C. P. and Persson, F. (2012) The surface energy balance at the Huygens Landing site and the moist surface conditions on Titan. Planetary and Space Science. Vol 60, nr. 1.
Williams, K. E., Pappalardo, R. T. (2011) Variability in the Small Crater Population of Callisto. Icarus 215,1.
Williams, K.E., McKay, C. P., Toon, O.B., Head, J. W. (2010) Do Ice Caves Exist on Mars? Icarus 209,2.
Williams, K.E., Toon, O. B., Heldmann, J. L., Mellon, M. (2009) Ancient melting of mid-latitude snowpacks on Mars as a water source for gullies, Icarus, 200.
Williams, K.E., Toon, O.B., Heldmann, J.L. , McKay C.P. and Mellon, M. (2008) Stability of Mid-Latitude Snowpacks on Mars, Icarus, 196.
Williams, K. E., O. B. Toon, and J. Heldmann (2007), Modeling water ice lifetimes at recent Martian gully locations, Geophys. Res. Lett., 34, L09204, doi:10.1029/2007GL029507.
Lai, Y.C., Lerner, D, Williams, K and Crebogi, C. (Nov. 1999) Unstable dimension variability in coupled chaotic systems. Physical Review E 60 (5): 5445-5454 : A.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.