70 results on '"Nicholas G. Heavens"'
Search Results
2. Detecting upland glaciation in Earth’s pre-Pleistocene record
- Author
-
Gerilyn S. Soreghan, Lily S. Pfeifer, Dustin E. Sweet, and Nicholas G. Heavens
- Subjects
mountain glaciation ,alpine glaciation ,proglacial ,periglacial ,ice-contact ,loess ,Science - Abstract
Earth has sustained continental glaciation several times in its past. Because continental glaciers ground to low elevations, sedimentary records of ice contact can be preserved from regions that were below base level, or subject to subsidence. In such regions, glaciated pavements, ice-contact deposits such as glacial till with striated clasts, and glaciolacustrine or glaciomarine strata with dropstones reveal clear signs of former glaciation. But assessing upland (mountain) glaciation poses particular challenges because elevated regions typically erode, and thus have extraordinarily poor preservation potential. Here we propose approaches for detecting the former presence of glaciation in the absence or near-absence of ice-contact indicators; we apply this specifically to the problem of detecting upland glaciation, and consider the implications for Earth’s climate system. Where even piedmont regions are eroded, pro- and periglacial phenomena will constitute the primary record of upland glaciation. Striations on large (pebble and larger) clasts survive only a few km of fluvial transport, but microtextures developed on quartz sand survive longer distances of transport, and record high-stress fractures consistent with glaciation. Proglacial fluvial systems can be difficult to distinguish from non-glacial systems, but a preponderance of facies signaling abundant water and sediment, such as hyperconcentrated flood flows, non-cohesive fine-grained debris flows, and/or large-scale and coarse-grained cross-stratification are consistent with proglacial conditions, especially in combination with evidence for cold temperatures, such as rip-up clasts composed of noncohesive sediment, indicating frozen conditions, and/or evidence for a predominance of physical over chemical weathering. Other indicators of freezing (periglacial) conditions include frozen-ground phenomena such as fossil ice wedges and ice crystals. Voluminous loess deposits and eolian-marine silt/mudstone characterized by silt modes, a significant proportion of primary silicate minerals, and a provenance from non-silt precursors can indicate the operation of glacial grinding, even though such deposits may be far removed from the site(s) of glaciation. Ultimately, in the absence of unambiguous ice-contact indicators, inferences of glaciation must be grounded on an array of observations that together record abundant meltwater, temperatures capable of sustaining glaciation, and glacial weathering (e.g., glacial grinding). If such arguments are viable, they can bolster the accuracy of past climate models, and guide climate modelers in assessing the types of forcings that could enable glaciation at elevation, as well as the extent to which (extensive) upland glaciation might have influenced global climate.
- Published
- 2022
- Full Text
- View/download PDF
3. A Multiannual Record of Convective Instability in Mars’s Middle Atmosphere from the Mars Climate Sounder
- Author
-
Nicholas G. Heavens, Alexey Pankine, J. Michael Battalio, Corwin Wright, David M. Kass, and Armin Kleinböhl
- Subjects
Mars ,Planetary atmospheres ,Atmospheric variability ,Astronomy ,QB1-991 - Abstract
Gravity waves (GW) transfer energy and momentum from the lower to the middle and upper atmospheres of Earth and Mars. Momentum transfer can occur through the wave dissipative process of saturation associated with convective or shear instability. GW saturation both impacts the atmospheric circulation where saturation occurs and also mediates the GW flux above the level of saturation. It was previously demonstrated that convective instabilities are observable in Mars’s middle atmosphere. Here we characterize the seasonal, interannual, and dust event-driven variability in convective instability in Mars’s atmosphere using retrieved temperature profiles from more than 7 Martian yr of observations by the Mars Climate Sounder on board the Mars Reconnaissance Orbiter. The mean probability of convective instability in the middle atmosphere is
- Published
- 2023
- Full Text
- View/download PDF
4. Mars Climate Sounder Observations of Gravity Wave Activity throughout Mars’s Lower Atmosphere
- Author
-
Nicholas G Heavens, Alexey Pankine, J Michael Battalio, Corwin Wright, David M Kass, Armin Kleinboehl, Sylvain Piqueux, and John T Schofield
- Subjects
Lunar And Planetary Science And Exploration - Abstract
Gravity waves are one way Mars’s lower atmospheric weather can affect the circulation and even composition of Mars’s middle and upper atmosphere. A recent study showed how on-planet observations near the center of the 15 micron CO2band by the A3 channel(635–665 cm−1)of the Mars Climate Sounder on board Mars Reconnaissance Orbiter (MRO-MCS) could sense horizontally short, vertically broad gravity waves at≈25 km above the surface by looking at small-scale radiance variability in temperature-sensitive channels. This approach is extended here to two additional channels closer to the wings of the 15 micron CO2band,A1 (595–615 cm−1) and A2 (615–645 cm−1), to sense gravity waves throughout the lower atmosphere. Using information from all three channels demonstrates that gravity wave activity in Mars’s lowermost atmosphere is dominated by orographic sources, particularly over the extremely rough terrain of Valles Marineris. Much of this orographic population is either trapped or filtered in the lowest two scale heights, such that variations in filtering and non-orographic sources shape the gravity wave population observed at 25 km above the surface. During global dust storms, however, gravity wave activity in the first scale height decreases by approximately a factor of two, yet trapping/filtering of what activity remains in the tropics substantially weakens. Exceptionally high radiance variability at night in the tropics during the less dusty part of the year is the result of observing mesospheric clouds rather than gravity waves.
- Published
- 2022
- Full Text
- View/download PDF
5. Dusty Deep Convection in the Mars Year 34 Planet‐Encircling Dust Event
- Author
-
Nicholas G. Heavens, David M. Kass, and James H. Shirley
- Published
- 2019
- Full Text
- View/download PDF
6. An Observational Overview of Dusty Deep Convection in Martian Dust Storms
- Author
-
Nicholas G. Heavens, David M. Kass, James H. Shirley, Sylvain Piqueux, and Bruce A. Cantor
- Published
- 2019
- Full Text
- View/download PDF
7. The Horizontal Wavelength Spectrum of Gravity Wave Activity in Mars’s Lower Atmosphere: The Perspective from MGS–TES Nadir Observations
- Author
-
Nicholas G. Heavens, Alexey Pankine, J. Michael Battalio, and Corwin Wright
- Published
- 2022
- Full Text
- View/download PDF
8. Dust and loess as archives and agents of climate and climate change in the late Paleozoic Earth system
- Author
-
Gerilyn S. Soreghan, Nicholas G. Heavens, Lily S. Pfeifer, and Michael J. Soreghan
- Subjects
Geology ,Ocean Engineering ,Water Science and Technology - Abstract
Palaeo-loess and silty aeolian-marine strata are well recognized across the Carboniferous–Permian of equatorial Pangaea. Aeolian-transported dust and loess appear in the Late Devonian in the west, are common by the Late Carboniferous, and predominate across equatorial Pangaea by the Permian. The thickest loess deposits in Earth history – in excess of 1000 m – date from this time, and archive unusually dusty equatorial conditions, especially compared to the dearth of equatorial dust in the Cenozoic. Loess archives a confluence of silt generation, aeolian emission and transport, and ultimate accumulation in dust traps that included ephemerally wet surfaces and epeiric seas. Orogenic belts sourced the silt, and mountain glaciation may have exacerbated voluminous silt production, but remains controversial. In western Pangaea, large rivers transported silt westward, and floodplain deflation supplied silt for loess and dust. Expansion of dust deposition in Late Pennsylvanian time records aridification that progressed across Pangaea, from west to east. Contemporaneous volcanism may have created acidic atmospheric conditions to enhance nutrient reactivity of dusts, affecting Earth's carbon cycle. The late Paleozoic was Earth's largest and most long-lived dust bowl, and this dust represents both an archive and agent of climate and climate change.
- Published
- 2023
9. Report on ICDP Deep Dust workshops: probing continental climate of the late Paleozoic icehouse–greenhouse transition and beyond
- Author
-
Cindy V. Looy, Lily S. Pfeifer, Linda A. Hinnov, Kathleen C. Benison, Nicholas G. Heavens, Stéphane Pochat, Gerilyn S. Soreghan, Mehrdad Sardar Abadi, James J. Zambito, Georg Feulner, Sylvie Bourquin, Adam K. Huttenlocker, Natsuko Hamamura, Michael A. Hamilton, Laurent Beccaletto, University of Oklahoma (OU), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), West Virginia University [Morgantown], Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Potsdam Institute for Climate Impact Research (PIK), Kyushu University [Fukuoka], University of Toronto, Space Science Institute [Boulder] (SSI), George Mason University [Fairfax], University of Southern California (USC), University of California [Berkeley], University of California, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Beloit College, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Kyushu University, University of California [Berkeley] (UC Berkeley), and University of California (UC)
- Subjects
Pangaea ,010504 meteorology & atmospheric sciences ,Paleozoic ,Permian ,Mechanical Engineering ,Earth science ,lcsh:QE1-996.5 ,Energy Engineering and Power Technology ,Biosphere ,15. Life on land ,010502 geochemistry & geophysics ,01 natural sciences ,lcsh:Geology ,Earth system science ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,13. Climate action ,[SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy ,Paleoclimatology ,Period (geology) ,Paleoecology ,Geology ,0105 earth and related environmental sciences - Abstract
Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian – the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies – boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed “Deep Dust,” held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea.
- Published
- 2020
10. Dusty Deep Convection in the Mars Year 34 Planet‐Encircling Dust Event
- Author
-
D. M. Kass, Nicholas G. Heavens, and J. H. Shirley
- Subjects
Convection ,Martian ,010504 meteorology & atmospheric sciences ,Mesoscale meteorology ,Context (language use) ,Storm ,Mars Exploration Program ,Atmospheric sciences ,01 natural sciences ,Article ,Atmosphere ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Dust storm ,Earth and Planetary Sciences (miscellaneous) ,Geology ,0105 earth and related environmental sciences - Abstract
Dusty convection, convective activity powered by radiative heating of dust, is a ubiquitous phenomenon in Mars’s atmosphere but is especially deep (that is, impactful on the middle atmosphere) and widespread during planet-encircling dust events (PEDE) that occur every few Mars Years (MY). Yet the relative roles of dusty deep convection and global dynamics, such as the principal meridional overturning cell (PMOC) and the radiative tides, in dust storm development and the vertical transport of dust and water are still unclear. Here, observations from the Mars Climate Sounder on board Mars Reconnaissance Orbiter (MRO-MCS) are used to study dusty deep convection and its impact on middle atmospheric water content during the MY 34 PEDE (commenced June 2018). Additional context is provided by MRO-MCS observations of the MY 28 PEDE (commenced June 2007). This investigation establishes that a few, localized centers of dusty deep convection in the tropics formed in the initial phases of both PEDE simultaneously with a substantial increase in middle atmospheric water content. The growth phase of the MY 34 PEDE was defined by episodic outbreaks of deep convection along the Acidalia and Utopia storm tracks as opposed to less episodic, more longitudinally distributed convective activity during the MY 28 PEDE. The most intense convection during both PEDE was observed in southern/eastern Tharsis, where MRO-MCS observed multiple instances of deep convective clouds transporting dust to altitudes of 70–90 km. These results suggest that Martian PEDE typically contain multiple convectively active mesoscale weather systems.
- Published
- 2019
11. An Observational Overview of Dusty Deep Convection in Martian Dust Storms
- Author
-
Bruce A. Cantor, James H. Shirley, David M. Kass, Sylvain Piqueux, and Nicholas G. Heavens
- Subjects
Martian ,Convection ,Atmospheric Science ,Buoyancy ,010504 meteorology & atmospheric sciences ,Storm ,engineering.material ,Atmospheric sciences ,01 natural sciences ,Article ,Troposphere ,Deep convection ,Phase change ,0103 physical sciences ,engineering ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Physics::Atmospheric and Oceanic Physics ,Geology ,0105 earth and related environmental sciences - Abstract
Deep convection, as used in meteorology, refers to the rapid ascent of air parcels in Earth’s troposphere driven by the buoyancy generated by phase change in water. Deep convection undergirds some of Earth’s most important and violent weather phenomena and is responsible for many aspects of the observed distribution of energy, momentum, and constituents (particularly water) in Earth’s atmosphere. Deep convection driven by buoyancy generated by the radiative heating of atmospheric dust may be similarly important in the atmosphere of Mars but lacks a systematic description. Here we propose a comprehensive framework for this phenomenon of dusty deep convection (DDC) that is supported by energetic calculations and observations of the vertical dust distribution and exemplary dusty deep convective structures within local, regional, and global dust storm activity. In this framework, DDC is distinct from a spectrum of weaker dusty convective activity because DDC originates from preexisting or concurrently forming mesoscale circulations that generate high surface dust fluxes, oppose large-scale horizontal advective–diffusive processes, and are thus able to maintain higher dust concentrations than typically simulated. DDC takes two distinctive forms. Mesoscale circulations that form near Mars’s highest volcanoes in dust storms of all scales can transport dust to the base of the upper atmosphere in as little as 2 h. In the second distinctive form, mesoscale circulations at low elevations within regional and global dust storm activity generate freely convecting streamers of dust that are sheared into the middle atmosphere over the diurnal cycle.
- Published
- 2019
12. Downscaling CESM2 in CLM5 to Hindcast Preindustrial Equilibrium Line Altitudes for Tropical Mountain Glaciers
- Author
-
Nicholas G. Heavens
- Subjects
geography ,Geophysics ,geography.geographical_feature_category ,Climatology ,Tropical climate ,General Earth and Planetary Sciences ,Hindcast ,GCM transcription factors ,Glacier ,Geology ,Equilibrium line ,Downscaling - Published
- 2021
13. Large Eddy Simulations of the Dusty Martian Convective Boundary Layer With MarsWRF
- Author
-
Alejandro Soto, Jun Cui, Claire E. Newman, Nicholas G. Heavens, Anthony D. Toigo, Christopher Lee, Yuan Lian, Orkun Temel, Xi Zhang, Mark I. Richardson, Marcin Witek, Zhaopeng Wu, and Tao Li
- Subjects
Geochemistry & Geophysics ,DYNAMICS ,SURFACE ,IMPACT ,CIRCULATION ,Atmospheric sciences ,Convective Boundary Layer ,STORMS ,Physics::Fluid Dynamics ,dust inhomogeneity ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Astrophysics::Solar and Stellar Astrophysics ,PATHFINDER ,Physics::Atmospheric and Oceanic Physics ,DISSIPATION ,Martian ,Science & Technology ,radiative-dynamical feedback ,large eddy simulation ,Atmosphere of Mars ,ATMOSPHERE ,Aerosol ,Martian atmosphere ,MODEL ,convective boundary layer ,Geophysics ,RESOLUTION ,Space and Planetary Science ,Weather Research and Forecasting Model ,Physics::Space Physics ,Physical Sciences ,Environmental science ,Astrophysics::Earth and Planetary Astrophysics ,Large eddy simulation - Abstract
Large eddy simulation (LES) of the Martian convective boundary layer (CBL) with a Mars-adapted version of the Weather Research and Forecasting model (MarsWRF) is used to examine aerosol dust radiat...
- Published
- 2021
14. Measuring Mars Atmospheric Winds from Orbit
- Author
-
Leslie K. Tamppari, Roland M. B. Young, Luca Montabone, R. J. Wilson, X. Sun, Anthony Colaprete, L. L. Gordley, G. L. Villaneuva, James H. Shirley, A.Sj. Khayat, Jeffery L. Hollingsworth, Meredith Elrod, Alexey A. Pankine, B. T. Marshall, Claire E. Newman, Melinda A. Kahre, Nicholas G. Heavens, M. M. Baker, Devanshu Jha, M. D. Smith, James B. Abshire, Mackenzie Day, J. M. Battalio, Aymeric Spiga, Tanguy Bertrand, Haris Riris, Daniel Viúdez-Moreiras, Scott D. Guzewich, A. M. Cook, Alexandre Kling, Paul O. Hayne, Michael A. Mischna, German Martinez, V. Jha, Daniel R. Cremons, Adrian J. Brown, A.I. Dave, Matteo Crismani, M.-C. Desjean, Stephen R. Lewis, M. J. Wolff, Lori K. Fenton, and Jenny A. Fisher
- Subjects
Climate system ,Environmental science ,Mars Exploration Program ,Orbit (control theory) ,Astrobiology - Abstract
Wind is the process that connects Mars’ climate system. Measurements of Mars atmospheric winds from orbit would dramatically advance our understanding of Mars and help prepare for human exploration. Multiple instruments in development will be ready for flight in the next decade. We urge the Decadal Survey to make these measurements a priority.
- Published
- 2021
15. High-altitude water ice cloud formation on Mars controlled by interplanetary dust particles
- Author
-
V. L Hartwick, Owen B. Toon, and Nicholas G. Heavens
- Subjects
Martian ,Meteor (satellite) ,010504 meteorology & atmospheric sciences ,Mars Exploration Program ,Atmosphere of Mars ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Atmosphere ,Interplanetary dust cloud ,Thermal ,General Earth and Planetary Sciences ,Environmental science ,Hadley cell ,0105 earth and related environmental sciences - Abstract
Submicrometre-size meteoric smoke aggregates form when interplanetary dust particles ablate and re-coagulate in the Martian atmosphere. The MAVEN (Mars Atmosphere and Volatile Evolution) satellite has detected pervasive ionized metallic layers due to meteor ablation at an 80–90 km altitude, which suggests a continuous supply of meteoric smoke particles that settle to lower altitudes. Until now, meteoric smoke has been neglected in general circulation model studies of the formation of Martian water ice clouds. Here we show that when meteoric smoke is included in simulations of the atmospheric circulation on Mars, mesospheric water ice clouds form at low pressures and in discrete layers, polar hood clouds extend to higher altitudes and the seasonal Hadley cell is weakened. Furthermore, we find that the middle atmosphere water ice clouds respond to and influence the diurnal and semidiurnal migrating thermal tides. We conclude that Mars atmospheric simulations that neglect meteoric smoke do not reproduce the observed spatial distribution of water ice clouds and miss crucial radiative impacts on the overall atmospheric dynamics. Particles from interplanetary dust ablating in Mars’ atmosphere control high-altitude water ice cloud formation, according to numerical simulations of the Martian atmosphere.
- Published
- 2019
16. Explosive volcanism as a key driver of the late Paleozoic ice age
- Author
-
Michael J. Soreghan, Gerilyn S. Soreghan, and Nicholas G. Heavens
- Subjects
Paleontology ,Paleozoic ,Explosive material ,Ice age ,Key (lock) ,Geology ,Volcanism - Published
- 2019
17. Earth-like thermal and dynamical coupling processes in the Martian climate system
- Author
-
Zhaopeng Wu, Tao Li, Nicholas G. Heavens, Claire E. Newman, Mark I. Richardson, Chengyun Yang, Jing Li, and Jun Cui
- Subjects
General Earth and Planetary Sciences - Published
- 2022
18. An Urgently Needed Repository for Planetary Atmospheric Model Output
- Author
-
Michael Mischna, Shawn Domagal-Goldman, Scott D. Guzewich, Vladimir Airapetian, Claire E. Newman, Adrian J. Brown, Anthony D. Toigo, Lynn D. V. Neakrase, Anezina Solomonidou, Alexey A. Pankine, Siteng Fan, Mark I. Richardson, Daniel Viúdez-Moreiras, Melinda A. Kahre, Alejandro Soto, Tim McConnochie, Stephen W. Bougher, Jorge Pla-Garcia, Isaac B. Smith, Nicholas G. Heavens, Derek Jackson, and Michael Battalio
- Subjects
Meteorology ,Environmental science ,Atmospheric model - Published
- 2021
19. The case for a multi-channel polarization sensitive LIDAR for investigation of insolation-driven ices and atmospheres
- Author
-
K. E. Herkenhoff, Robert Lillis, Anthony Colaprete, Paul O. Hayne, Timothy I. Michaels, P. B. Buhler, R. W. Obbard, Margaret E. Landis, Aymeric Spiga, Tim McConnochie, Shane Byrne, Yongxiang Hu, Claire E. Newman, Bryana L. Henderson, J. W. Holt, Minsup Jeong, Chae Kyung Sim, Nicole Schlegel, Michael Veto, Scott D. Guzewich, John E. Moores, Patricio Becerra, Michael J. Wolff, Gorden Videen, Michael I. Mishchenko, Nicholas G. Heavens, Michael A. Mischna, M. R. Perry, Sylvain Piqueux, Evgenij Zubko, Colin R. Meyer, Isaac B. Smith, Alain S. J. Khayat, Lori K. Fenton, Timothy J. Stubbs, Christine S. Hvidberg, Timothy N. Titus, Wendy M. Calvin, Tanya N. Harrison, Adrian J. Brown, Leslie K. Tamppari, Bonnie Meineke, Young-Jun Choi, Ali M. Bramson, Sung-Soo Kim, Nathaniel E. Putzig, Jonathan A. R. Rall, Jennifer Hanley, Serina Diniega, Devanshu Jha, and Susan J. Conway
- Subjects
Insolation ,Polarization sensitive ,Lidar ,Environmental science ,Multi channel ,Remote sensing - Published
- 2021
20. Advancing Space Science Requires NASA Support for Coordination Between the Science Mission Directorate Communities
- Author
-
Michael Meyer, Britney E. Schmidt, Shawn Domagal-Goldman, Krista Soderland, Ian J. Cohen, Alejandro Soto, Kevin B. Stevenson, Yasuhiro Hasegawa, Lynnae C. Quick, Arif Solmaz, William C. Danchi, Dennis Bodewits, Paul K. Byrne, Amanda R. Hendrix, Rory Barnes, Thomas G. Beatty, Margaret Turnbull, Alice Cocoros, Diana Dragomir, Kathleen Mandt, Kelly E. Miller, Paul A. Dalba, Shannon Curry, Jeremy J. Drake, Nicholas G. Heavens, Flora Paganelli, Richard Cartwright, Kylie Lovato, Brian Jackson, Ronald J. Vervack, Mark S. Marley, Stefanie N. Milam, Aki Roberge, Dana M. Hurley, Kirby Runyon, Jonathan J. Fortney, Edwin A. Bergin, Monica Vidaurri, Carl Melis, Alberto Accomazzi, Carey M. Lisse, Peter Plavchan, Darby Dyar, Jason T. Wright, Tracy M. Becker, Anthony D. Del Genio, L. C. Mayorga, Neal J. Turner, Elena Provornikova, Paul R. Mahaffy, K. Garcia-Sage, Jon M. Jenkins, Amanda J. Bayless, Noemi Pinella-Alonso, Edgard G. Rivera-Valentin, Kurt D. Retherford, Giada Arney, Elisa V. Quintana, Seth Redfield, R. Nikoukar, Joshua Pepper, Karl R. Stapelfeldt, Jason S. Kalirai, Daniel Angerhausen, Stephen R. Kane, Abigail Rymer, Erin C. Smith, Amy Simon, S. Diniega, Robert Allen, Christina Richey, Miguel de Val-Borro, Pontus Brandt, Chuanfei Dong, Marilia Samara, Victoria S. Meadows, and Dawn M. Gelino
- Subjects
Engineering ,Engineering management ,business.industry ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Space Science ,business - Abstract
We outline specific steps that NASA and the space science community can take to advance collaboration and coordination between the communities represented by the four NASA Science Mission Directorate Divisions. It is important to note that the only way that this effort can succeed is if NASA initiates and supports it through directed resources.
- Published
- 2021
21. Mars Perihelion Cloud Trails as revealed by MARCI: Mesoscale Topographically Focussed Updrafts and Gravity Wave Forcing of High Altitude Clouds
- Author
-
Nicholas G. Heavens, Bruce A. Cantor, R. Todd Clancy, Steven W. Lee, Michael C. Malin, Daniel Tyler, Michael J. Wolff, Aymeric Spiga, P. B. James, and Brad J. Sandor
- Subjects
010504 meteorology & atmospheric sciences ,Mesoscale meteorology ,Astronomy and Astrophysics ,Mars Exploration Program ,Albedo ,Atmospheric sciences ,01 natural sciences ,Article ,Latitude ,Atmosphere ,Space and Planetary Science ,Dust storm ,0103 physical sciences ,Gravity wave ,010303 astronomy & astrophysics ,Water vapor ,Geology ,0105 earth and related environmental sciences - Abstract
Daily, global wide angle imaging of Mars clouds in MARCI (MARs Color Imager, (Malin et al., 2008)) ultraviolet and visible bands reveals the spatial/seasonal distributions and physical characteristics of perihelion cloud trails (PCT); a class of high altitude (40–50 km), horizontally extended (200–1000 km, trending W to WSW) water ice clouds formed over specific southern low-to-mid latitude (5S-40S), mesoscale ( ∼ 50 km) locations during the Mars perihelion, southern summer season. PCT were first reported in association with rim regions of Valles Marineris (Clancy et al., 2009). The current study employs MARCI 2007–2011 imaging to sample the broader distributions and properties of PCT; and indicates several distinct locations of peak occurrences, including SW Arsia Mons, elevated regions of Syria, Solis, and Thaumasia Planitia, along Valles Marineris margins, and the NE rim of Hellas Basin. PCT are present over Mars solar longitudes ( L S ) of 210–310 ° , in late morning to mid afternoon hours (10 am–3 pm), and are among the brightest and most distinctive clouds exhibited during the perihelion portion of the Mars orbit. Their locations ( i.e. , eastern margin origins) correspond to strong local elevation gradients, and their timing to peak solar heating conditions (perihelion, subsolar latitudes and midday local times). They occur approximately on a daily basis among all locations identified ( i.e. , not daily at a single location). Based on cloud surface shadow analyses, PCT form at 40–50 km aeroid altitudes, where water vapor is generally at near-saturation conditions in this perihelion period (e.g. Millour et al., 2014). They exhibited notable absences during periods of planet encircling and regional dust storm activity in 2007 and 2009, respectively, presumably due to reduced water saturation conditions above 35–40 km altitudes associated with increased dust heating over the vertically extended atmosphere (e.g. Neary et al., 2019). PCT exhibit smaller particle sizes (R e f f =0.2-0.5 μ m ) than typically exhibited in the lower atmosphere, and incorporate significant fractions of available water vapor at these altitudes. PCT ice particles are inferred to form continuously (over ∼ 4 h) at their PCT eastern origins, associated with localized updrafts, and are entrained in upper level zonal/meridional winds (towards W or WSW with ∼ 50 m/s speeds at 40–50 km altitudes) to create long, linear cloud trails. PCT cloud formation is apparently forced in the lower atmosphere ( ≤ 10–15 km) by strong updrafts associated with distinctive topographic gradients, such as simulated in mesoscale studies (e.g., Tyler and Barnes, 2015) and indicated by the surface-specific PCT locations. These lower scale height updrafts are proposed to generate vertically propagating gravity waves (GW), leading to PCT formation above ∼ 40 km altitudes where water vapor saturation conditions promote vigorous cloud ice formation. Recent mapping of GW amplitudes at ∼ 25 km altitudes, from Mars Climate Sounder 15 μ m radiance variations (Heavens et al., 2020) in fact demonstrates close correspondences to the detailed spatial distributions of observed PCT, relative to other potential factors such as surface albedo and surface elevation (or related boundary layer depths).
- Published
- 2021
22. Mars Climate Sounder Observation of Mars' 2018 Global Dust Storm
- Author
-
Nicholas G. Heavens, John T. Schofield, L. J. Steele, James H. Shirley, Armin Kleinböhl, David M. Kass, and Daniel J. McCleese
- Subjects
Geophysics ,Dust storm ,General Earth and Planetary Sciences ,Environmental science ,Atmosphere of Mars ,Mars Exploration Program ,Astrobiology - Published
- 2020
23. Atmospheric Escape Processes and Planetary Atmospheric Evolution: from misconceptions to challenges
- Author
-
Jared Bell, Guillaume Gronoff, Romain Maggiolo, Christopher D. Parkinson, Gaël Cessateur, Cecilia Garraffo, Ofer Cohen, Daniel R. Weimer, Nicholas G. Heavens, K. Lovato, Meredith Elrod, Phil Arras, Suleiman M Baraka, William B. Moore, Justin Erwin, Shannon Curry, Jeremy J. Drake, Katherine Garcia-Sage, and Cyril Simon Wedlund
- Subjects
Atmospheric escape ,Environmental science ,Astrobiology - Abstract
The recent discoveries of telluric exoplanets in the habitable zone of different stars have led to questioning the nature of their atmosphere, which is required to determine their habitability. Atmospheric escape is one of the challenging problems to be solved: simply adapting what is currently observed in the solar system is doomed to fail due to the large variations in the conditions encountered around other stars. A better strategy is to review the different processes that shaped planetary atmospheres and to evaluate their importance depending upon the stellar conditions. This approach allowed us to show that processes like ion-pickup were a more important way to lose atmosphere at Mars in the past. We reviewed the different escape mechanisms and their magnitude in function of the different conditions. This led us to discover discrepancies in the current literature concerning problems such as the Xenon paradox or the importance of a magnetic field in protecting an atmosphere.This shows that one should be very careful before claiming the presence of an atmosphere on planets in the habitable zone of their M-dwarfs: new criteria such as the Alfven surface location with respect to the planet should be taken into account a-priori.Overall, the habitability of a planet should not be claimed only on by its location in the habitable zone but also after careful analysis of the interaction between its atmosphere and its parent star [Gronoff et al. 2020]. Gronoff, G., Arras, P., Baraka, S., Bell, J. M., Cessateur, G., Cohen, O., et al. ( 2020). Atmospheric Escape Processes and Planetary Atmospheric Evolution. Journal of Geophysical Research: Space Physics, 125, e2019JA027639. https://doi.org/10.1029/2019JA027639
- Published
- 2020
24. Atmospheric dust flux in northeastern Gondwana during the peak of the late Paleozoic ice age
- Author
-
Gerilyn S. Soreghan, Linda A. Hinnov, James D. Gleason, Nicholas G. Heavens, and Mehrdad Sardar Abadi
- Subjects
Model reconstruction ,Gondwana ,Paleozoic ,Ice age ,Flux ,Geology ,Physical geography ,Atmospheric dust - Abstract
The silicate mineral fraction of shallow marine carbonates archives dust contributions to the Central Persian Terranes along the northeastern margin of Gondwana (∼30ºS paleolatitude), enabling reconstruction of atmospheric dust loading and circulation for intervals of the late Paleozoic ice age. The Central Persian Terranes hosted cyclic deposition of warm water carbonates from middle Pennsylvanian to earliest Permian time, and our data set includes two ∼28 m sections from the Moscovian and Asselian sampled at 20 cm intervals. Bounding surfaces between successive cycles (high-frequency sequences) are recognized by either abrupt basinward shifts in facies or subtle exposure features; these high-frequency sequences range from 1 m to 5 m thick and are interpreted to record glacioeustatic variations. Time series analysis of the dust fraction through the studied interval supports the hypothesis of orbital forcing for the dust signal. The stratigraphic pattern of the dust flux indicates minimal flux during interglacial highstands (0.19−0.27 g/cm2/kyr) and peak flux during glacial lowstands (3.77−4.57 g/cm2/kyr) after accounting for hiatal time at sequence boundaries. Grain size analysis of the dust for all samples (n = 230) reveals modal sizes (volume-based) of 1−15 µm through the Moscovian interval and 10−75 µm through the Asselian interval. Dust deposition increased during glacial times relative to interglacial times by a factor of 16 to 19. Additionally, the Asselian interval exhibits higher dust flux overall relative to the Moscovian interval, which is interpreted to reflect the more extreme icehouse conditions of the Asselian. Variation in the dust content through the studied sections provides an indicator of temporal changes in atmospheric loading that varied at both glacial−interglacial and higher-frequency (
- Published
- 2020
25. Atmospheric Escape Processes and Planetary Atmospheric Evolution
- Author
-
Alex Glocer, K. Garcia-Sage, William B. Moore, J. J. Drake, Ofer Cohen, Justin Erwin, Christopher D. Parkinson, K. Lovato, Suleiman M Baraka, Gaël Cessateur, Cecilia Garraffo, Daniel R. Weimer, Jared Bell, Phil Arras, Nicholas G. Heavens, Shannon Curry, Guillaume Gronoff, Romain Maggiolo, Meredith Elrod, C. Simon Wedlund, Chemistry and Dynamics Branch, NASA Langley Research Center, Hampton, VA, USA, Science Systems and Application, Inc., Hampton, VA, USA, National Institute of Aerospace, Hampton, VA, USA, Heliophysics Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), and Lowell Center for Space Science and Technology, University of Massachusetts Lowell, Lowell, MA, USA
- Subjects
Solar System ,010504 meteorology & atmospheric sciences ,[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,FOS: Physical sciences ,01 natural sciences ,Astrobiology ,Atmosphere ,Physics - Space Physics ,Planet ,Astrophysics::Solar and Stellar Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Atmospheric escape ,Habitability ,Space Physics (physics.space-ph) ,Exoplanet ,Stars ,Geophysics ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Environmental science ,Astrophysics::Earth and Planetary Astrophysics ,Thermosphere ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical and physical alteration of planetary atmospheres, including escape. Many known extrasolar planets experience vastly different stellar environments than those in our Solar system: it is crucial to understand the broad range of processes that lead to atmospheric escape and evolution under a wide range of conditions if we are to assess the habitability of worlds around other stars. One problem encountered between the planetary and the astrophysics communities is a lack of common language for describing escape processes. Each community has customary approximations that may be questioned by the other, such as the hypothesis of H-dominated thermosphere for astrophysicists, or the Sun-like nature of the stars for planetary scientists. Since exoplanets are becoming one of the main targets for the detection of life, a common set of definitions and hypotheses are required. We review the different escape mechanisms proposed for the evolution of planetary and exoplanetary atmospheres. We propose a common definition for the different escape mechanisms, and we show the important parameters to take into account when evaluating the escape at a planet in time. We show that the paradigm of the magnetic field as an atmospheric shield should be changed and that recent work on the history of Xenon in Earth's atmosphere gives an elegant explanation to its enrichment in heavier isotopes: the so-called Xenon paradox.
- Published
- 2020
26. Asymmetries in Snowfall, Emissivity, and Albedo of Mars' Seasonal Polar Caps: Mars Climate Sounder Observations
- Author
-
James H. Shirley, T. Horvath, John T. Schofield, C. E. Gary-Bicas, Armin Kleinböhl, Nicholas G. Heavens, Paul O. Hayne, David M. Kass, Sylvain Piqueux, and Daniel J. McCleese
- Subjects
Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Infrared ,Earth and Planetary Sciences (miscellaneous) ,Emissivity ,Environmental science ,Polar ,Mars Exploration Program ,Albedo ,Snow ,Atmospheric sciences - Published
- 2020
27. Rapid Expansion and Evolution of a Regional Dust Storm in the Acidalia Corridor During the Initial Growth Phase of the Martian Global Dust Storm of 2018
- Author
-
Sylvain Piqueux, James H. Shirley, David M. Kass, Armin Kleinböhl, Nicholas G. Heavens, John T. Schofield, L. J. Steele, Daniel J. McCleese, and S. Suzuki
- Subjects
Martian ,Geophysics ,Dust storm ,Rapid expansion ,Growth phase ,General Earth and Planetary Sciences ,Environmental science ,Atmosphere of Mars ,Mars Exploration Program ,Atmospheric sciences - Published
- 2020
28. A Multiannual Record of Gravity Wave Activity in Mars’s Lower Atmosphere from On-Planet Observations by the Mars Climate Sounder
- Author
-
Armin Kleinböhl, John T. Schofield, Nicholas G. Heavens, and David M. Kass
- Subjects
Martian ,010504 meteorology & atmospheric sciences ,Astronomy and Astrophysics ,Storm ,Mars Exploration Program ,Atmospheric sciences ,01 natural sciences ,Article ,Atmosphere ,Wavelength ,Altitude ,Space and Planetary Science ,0103 physical sciences ,Nadir ,Gravity wave ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Geology ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences - Abstract
Gravity waves in Mars’s atmosphere strongly affect the general circulation as well as middle atmospheric cloud formation, but the climatology and sources of gravity waves in the lower atmosphere remain poorly understood. At Earth, the statistical variance in satellite observations of thermal emission above the instrumental noise floor has been used to enable measurement of gravity wave activity at a global scale. Here is presented an analysis of variance in calibrated radiance at 15 . 4 μ m (635–665 cm−1) from off-nadir and nadir observations by the Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO); a major expansion in the observational data available for validating models of Martian gravity wave activity. These observations are sensitive to gravity waves at 20–30 km altitude with wavelength properties ( λ h =10–100 km, λ z > 5 km) that make them likely to affect the dynamics of the middle and upper atmosphere. We find that: (1) strong, moderately intermittent gravity wave activity is scattered over the tropical volcanoes and throughout the middle to high latitudes of both hemispheres during fall and winter, (2) gravity wave activity noticeably departs from climatology during regional and global dust storms; and (3) strong, intermittent variance is observed at night in parts of the southern tropics during its fall/winter, but frequent CO 2 ice clouds prevents unambiguous attribution to GW activity. The spatial distribution of wave activity is consistent with topographic sources being dominant, but contributions from boundary layer convection and other convective processes are possible.
- Published
- 2020
29. Atmospheric dust stimulated marine primary productivity during Earth’s penultimate icehouse
- Author
-
Xiao-Lei Liu, Nicholas G. Heavens, Mehrdad Sardar Abadi, Xingqian Cui, Theodore R. Them, Gerilyn S. Soreghan, and Jeremy D. Owens
- Subjects
010504 meteorology & atmospheric sciences ,Earth science ,Geology ,Earth (chemistry) ,Atmospheric dust ,010502 geochemistry & geophysics ,01 natural sciences ,Primary productivity ,0105 earth and related environmental sciences - Abstract
The importance of dust as a source of iron (Fe) for primary production in modern oceans is well studied but remains poorly explored for deep time. Vast dust deposits are well recognized from the late Paleozoic and provisionally implicated in primary production through Fe fertilization. Here, we document dust impacts on marine primary productivity in Moscovian (Pennsylvanian, ca. 307 Ma) and Asselian (Permian, ca. 295 Ma) carbonate strata from peri-Gondwanan terranes of Iran. Autotrophic contents of samples, detected by both point-count and lipid-biomarker analyses, track concentrations of highly reactive Fe, consistent with the hypothesis that dust stimulated primary productivity, also promoting carbonate precipitation. Additionally, highly reactive Fe tracks the fine-dust fraction. Dust-borne Fe fertilization increased organic and inorganic carbon cycling in low- and mid-latitude regions of Pangaea, maintaining low pCO2.
- Published
- 2019
30. Hydrogen escape from Mars enhanced by deep convection in dust storms
- Author
-
James H. Shirley, Nicholas G. Heavens, Armin Kleinböhl, Michael Chaffin, Sylvain Piqueux, Paul O. Hayne, Jasper Halekas, John T. Schofield, Daniel J. McCleese, and David M. Kass
- Subjects
Martian ,Water transport ,010504 meteorology & atmospheric sciences ,Astronomy and Astrophysics ,Storm ,Atmosphere of Mars ,Mars Exploration Program ,Atmospheric sciences ,01 natural sciences ,Atmosphere ,Atmospheric chemistry ,0103 physical sciences ,Environmental science ,010303 astronomy & astrophysics ,Water vapor ,0105 earth and related environmental sciences - Abstract
Present-day water loss from Mars provides insight into Mars’s past habitability1–3. Its main mechanism is thought to be Jeans escape of a steady hydrogen reservoir sourced from odd-oxygen reactions with near-surface water vapour2, 4,5. The observed escape rate, however, is strongly variable and correlates poorly with solar extreme-ultraviolet radiation flux6–8, which was predicted to modulate escape 9 . This variability has recently been attributed to hydrogen sourced from photolysed middle atmospheric water vapour 10 , whose vertical and seasonal distribution is only partly characterized and understood11–13. Here, we report multi-annual observational estimates of water content and dust and water transport to the middle atmosphere from Mars Climate Sounder data. We provide strong evidence that the transport of water vapour and ice to the middle atmosphere by deep convection in Martian dust storms can enhance hydrogen escape. Planet-encircling dust storms can raise the effective hygropause (where water content rapidly decreases to effectively zero) from 50 to 80 km above the areoid (the reference equipotential surface). Smaller dust storms contribute to an annual mode in water content at 40−50 km that may explain seasonal variability in escape. Our results imply that Martian atmospheric chemistry and evolution can be strongly affected by the meteorology of the lower and middle atmosphere of Mars. Mars Climate Sounder’s multi-annual observations of the vertical distribution of water and dust in the Martian atmosphere show that deep convection from dust storms transports water from the lower to the middle atmosphere, enhancing water loss to space.
- Published
- 2018
31. InSight searches high to see below
- Author
-
Nicholas G. Heavens
- Subjects
Atmosphere ,Seismometer ,010504 meteorology & atmospheric sciences ,General Earth and Planetary Sciences ,Environmental science ,Mars Exploration Program ,Churning ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences ,Astrobiology - Abstract
Mars’s newest seismometer needed to separate marsquakes from meteorology. Continuous weather observations to keep it honest are revealing new facets of Mars’s churning atmosphere.
- Published
- 2020
32. Discovery of a widespread low-latitude diurnal CO2 frost cycle on Mars
- Author
-
John T. Schofield, Armin Kleinböhl, David M. Kass, Paul O. Hayne, James H. Shirley, Daniel J. McCleese, Nicholas G. Heavens, and Sylvain Piqueux
- Subjects
Martian ,010504 meteorology & atmospheric sciences ,Water on Mars ,Ice crystals ,Martian soil ,Mars Exploration Program ,Atmosphere of Mars ,Atmospheric sciences ,01 natural sciences ,Astrobiology ,Geophysics ,Olympus Mons ,Space and Planetary Science ,Geochemistry and Petrology ,0103 physical sciences ,Earth and Planetary Sciences (miscellaneous) ,Martian polar ice caps ,010303 astronomy & astrophysics ,Geology ,0105 earth and related environmental sciences - Abstract
While the detection of CO2 ice has only been reported outside the Martian polar regions at very high elevation (i.e., Elysium, Olympus Mons, and the Tharsis Montes), nighttime surface observations by the Mars Climate Sounder on board the Mars Reconnaissance Orbiter document the widespread occurrence of atmospherically corrected ground temperatures consistent with the presence of extensive carbon dioxide frost deposits in the dusty low thermal inertia units at middle/low latitudes. Thermal infrared emissivities, interpreted in conjunction with mass balance modeling, suggest micrometer size CO2 ice crystals forming optically thin layers never exceeding a few hundreds of microns in thickness (i.e., 10−2 kg m−2) locally, which is insufficient to generate a measurable diurnal pressure cycle (<
- Published
- 2016
33. Coal-derived rates of atmospheric dust deposition during the Permian
- Author
-
Chris Marshall, David Large, and Nicholas G. Heavens
- Subjects
Biogeochemical cycle ,Peat ,010504 meteorology & atmospheric sciences ,Permian ,Atmospheric circulation ,Pangea ,Atmospheric deposition ,010502 geochemistry & geophysics ,Atmospheric sciences ,complex mixtures ,01 natural sciences ,Paleontology ,Coal ,Holocene ,0105 earth and related environmental sciences ,business.industry ,Dust ,Geology ,15. Life on land ,respiratory tract diseases ,Deposition (aerosol physics) ,13. Climate action ,Community Climate System Model ,business - Abstract
Despite widespread evidence for atmospheric dust deposition prior to the Quaternary, quantitative rate data remains sparse. As dust influences both climate and biological productivity, the absence of quantitative dust data limits the comprehensiveness of models of pre-Quaternary climate and biogeochemical cycles. Here, we propose that inorganic matter contained in coal primarily records atmospheric dust deposition. To test this, we use the average concentration of inorganic matter in Permian coal to map global patterns and deposition rates of atmospheric dust over Pangea. The dust accumulation rate is calculated assuming Permian peat carbon accumulation rates in temperate climates were similar to Holocene rates and accounting for the loss of carbon during coalification. Coal-derived rates vary from 0.02 to 25 g m− 2 year− 1, values that fall within the present-day global range. A well-constrained East–West pattern of dust deposition corresponding to expected palaeoclimate gradients extends across Gondwana with maximum dust deposition rates occurring close to arid regions. A similar pattern is partially defined over the northern hemisphere. Patterns are consistent with the presence of two large global dust plumes centred on the tropics. The spatial patterns of dust deposition were also compared to dust cycle simulations for the Permian made with the Community Climate System Model version 3 (CCSM3). Key differences between the simulations and the coal data are the lack of evidence for an Antarctic dust source, higher than expected dust deposition over N and S China and greater dust deposition rates over Western Gondwana. This new coal-based dust accumulation rate data expands the pre-Neogene quantitative record of atmospheric dust and can help to inform and validate models of global circulation and biogeochemical cycles over the past 350 Myr.
- Published
- 2016
34. Injecting Climate Modeling into Deep Time Studies: Ideas for Nearly Every Project
- Author
-
Nicholas G. Heavens
- Subjects
Climatology ,Environmental science ,Climate model ,Deep time - Published
- 2015
35. Reconstructing the Dust Cycle in Deep Time: the Case of the Late Paleozoic Icehouse
- Author
-
Gerilyn S. Soreghan, Linda A. Hinnov, Sarah M. Aciego, Carl Simpson, and Nicholas G. Heavens
- Subjects
Earth's energy budget ,Milankovitch cycles ,010504 meteorology & atmospheric sciences ,Earth science ,Climate change ,Radiative forcing ,010502 geochemistry & geophysics ,01 natural sciences ,Carbon cycle ,Loess ,Paleoclimatology ,Aeolian processes ,Geology ,0105 earth and related environmental sciences - Abstract
Atmospheric dust constitutes particles
- Published
- 2015
36. Warm-water carbonates in proximity to Gondwanan ice–sheets: A record from the Upper Paleozoic of Iran
- Author
-
Rimma M. Ivanova, Mehrdad Sardar Abadi, Nicholas G. Heavens, Dennis F. A. E. Voeten, and Gerilyn S. Soreghan
- Subjects
010506 paleontology ,geography ,geography.geographical_feature_category ,Permian ,Paleozoic ,Ocean current ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Sea surface temperature ,Gondwana ,Pennsylvanian ,Climate model ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Sedimentologic and paleontologic proxies recovered from the Alborz Basin, the Sanandaj – Sirjan Zone, and additional Iranian peri–Gondwanan continental blocks near the Arabian margin of northeastern Gondwana record the formation of warm-water, shallow-marine carbonates throughout the Late Pennsylvanian – earliest Permian. This reflects a prevailing favorable climatic and environmental regime that contrasts with the cold conditions of slightly more southerly Gondwanan regions that experienced profound glaciations. The sedimentologic and paleobiologic properties of these Iranian carbonates also differ greatly from coeval cool-water carbonates of Bolivia that developed at equivalent paleolatitudes along the northwestern margin of Gondwana. The complex climatic patterns reflected in the dispersal of marine taxa and their colonization of ecosystems relatively remote to their customary habitats and climate zones are interpreted to record the influence of ocean circulation. Based on these sedimentologic and paleobiologic data, we utilized a climate model (Community Climate System Model Version 3 (CCSM3)) to help resolve the mechanisms responsible for enabling transport of warm water to higher latitudes in northeastern Gondwana. These simulations reveal that spatial variations in sea surface temperatures exerted a strong forcing on Paleo-Tethyan oceanic circulation and thereby governed the distribution, diversity, and abundance of taxa in late Paleozoic marine ecosystems. Based on this outcome, we conclude that the climatic contrasts registered across Upper Pennsylvanian – Lower Permian carbonate platforms of the Paleo-Tethys and Panthalassic Ocean originated through oceanic circulation driven by geographic differences in sea surface temperature.
- Published
- 2019
37. THE CONTRIBUTION OF VOLCANIC AEROSOLS TO EARTH SYSTEM BEHAVIOR IN THE LATE PALEOZOIC
- Author
-
Nicholas G. Heavens, Michael J. Soreghan, and Gerilyn S. Soreghan
- Subjects
Earth system science ,geography ,geography.geographical_feature_category ,Volcano ,Paleozoic ,Geochemistry ,Geology - Published
- 2018
38. A solar escalator on Mars: Self‐lifting of dust layers by radiative heating
- Author
-
Frank Daerden, Mark T. Lemmon, Bruce A. Cantor, Eric Hébrard, Lori Neary, L. Komguem, James A. Whiteway, Nicholas G. Heavens, and M. D. Smith
- Subjects
Meteorology ,Planetary boundary layer ,Mars Exploration Program ,Atmosphere of Mars ,Atmospheric sciences ,Geophysics ,Lidar ,Dust storm ,Saltation (geology) ,Wind shear ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,General Earth and Planetary Sciences ,Environmental science ,Astrophysics::Earth and Planetary Astrophysics ,Stratosphere ,Physics::Atmospheric and Oceanic Physics - Abstract
Dust layers detected in the atmosphere of Mars by the light detection and ranging (LIDAR) instrument on the Phoenix Mars mission are explained using an atmospheric general circulation model. The layers were traced back to observed dust storm activity near the edge of the north polar ice cap where simulated surface winds exceeded the threshold for dust lifting by saltation. Heating of the atmospheric dust by solar radiation caused buoyant instability and mixing across the top of the planetary boundary layer (PBL). Differential advection by wind shear created detached dust layers above the PBL that ascended due to radiative heating and arrived at the Phoenix site at heights corresponding to the LIDAR observations. The self-lifting of the dust layers is similar to the “solar escalator” mechanism for aerosol layers in the Earth's stratosphere.
- Published
- 2015
39. Extreme detached dust layers near Martian volcanoes: Evidence for dust transport by mesoscale circulations forced by high topography
- Author
-
David M. Kass, John T. Schofield, Sylvain Piqueux, Daniel J. McCleese, Armin Kleinböhl, Paul O. Hayne, James H. Shirley, Nicholas G. Heavens, and Bruce A. Cantor
- Subjects
Martian ,Atmosphere ,Geophysics ,Olympus Mons ,Dust storm ,Tharsis Montes ,Mesoscale meteorology ,General Earth and Planetary Sciences ,Storm ,Mars Exploration Program ,Atmospheric sciences ,Geology - Abstract
Modeling suggests that thermal circulations over Mars's highest volcanoes transport water vapor and dust from the surface into the middle atmosphere, forming detached layers in these constituents. Intense vertical mixing also takes place in regional and global dust storms, which can generate detached layers that are extreme in both altitude and magnitude. Here we employ observations by the Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter, taking advantage of improved vertical coverage in MCS's aerosol retrievals, to discover a new class of extreme detached dust layers (EDDLs). Observed during minimal dust storm activity and furthermore distinguished by their potentially large and measurable horizontal extent (>1000 km), these EDDLs cluster near Olympus Mons and the Tharsis Montes, from which they likely originate. The existence of these EDDLs suggests that vertical mixing by topographic circulations can be much stronger than previously modeled and more frequent than previously observed.
- Published
- 2015
40. Temperatures and aerosol opacities of the Mars atmosphere at aphelion: Validation and inter-comparison of limb sounding profiles from MRO/MCS and MGS/TES
- Author
-
Daniel J. McCleese, Jennifer Benson, John T. Schofield, Joshua L. Bandfield, J. H. Shirley, Timothy H. McConnochie, D. M. Kass, Nicholas G. Heavens, David P. Hinson, and A. Kleinböhl
- Subjects
Thermal Emission Spectrometer ,Astronomy and Astrophysics ,Atmosphere of Mars ,Mars Exploration Program ,Atmospheric sciences ,Aerosol ,law.invention ,Atmosphere ,Orbiter ,Depth sounding ,Space and Planetary Science ,law ,Environmental science ,Radio occultation - Abstract
We exploit the relative stability and repeatability of the Mars atmosphere at aphelion for an inter-comparison of Mars Global Surveyor/Thermal Emission Spectrometer (MGS/TES) and Mars Reconnaissance Orbiter/Mars Climate Sounder (MRO/MCS) nighttime temperature profiles and aerosol opacity profiles in Mars years 25, 26, 29, 30, and 31. Cross-calibration of these datasets is important, as they together provide an extended climatology for this planetary atmosphere. As a standard of comparison we employ temperature profiles obtained by radio occultation methods during the MGS mission in Mars years 24, 25, and 26. We first compare both zonal mean TES limb sounding profiles and zonal mean MCS limb sounding profiles with zonal means of radio occultation temperature profiles for the same season (Ls = 70–80°) and latitudes (55–70°N). We employ a statistical z test for quantifying the degree of agreement of temperature profiles by pressure level. For pressures less than 610 Pa (altitudes > 3 km), the ensemble mean temperature difference between the radio occultation and TES limb sounding profiles found in these comparisons was 1.7 ± 0.7 K. The ensemble mean temperature difference between radio occultation and MCS profiles was 1.4 ± 1.0 K. These differences fall within the formal error estimates for both TES and MCS, validating the accuracy of the instruments and their respective retrieval algorithms. In the second phase of our investigation, we compare aphelion season zonal mean TES limb sounding temperature, water ice opacity, and dust opacity profiles with those obtained at the same latitudes in different years by MCS. The ensemble mean temperature difference found for three comparisons between TES and MCS zonal mean temperature profiles was 2.8 ± 2.1 K. MCS and TES temperatures between 610 Pa and 5 Pa from 55 to 70°N are largely in agreement (with differences
- Published
- 2015
41. A model-based evaluation of tropical climate in Pangaea during the late Palaeozoic icehouse
- Author
-
Michael J. Soreghan, Christine A. Shields, Natalie M. Mahowald, Gerilyn S. Soreghan, and Nicholas G. Heavens
- Subjects
geography ,geography.geographical_feature_category ,Orbital forcing ,Paleontology ,Oceanography ,Climatology ,Tropical climate ,Ice age ,Community Climate System Model ,Climate sensitivity ,Climate state ,Glacial period ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,Geology ,Earth-Surface Processes - Abstract
The late Palaeozoic ice age (LPIA) is the Earth's penultimate “icehouse climate.” Geological proxies for tropical Pangaean climate during the LPIA are significantly modulated on 100–400 kyr and sub-100 kyr scales. In addition, some geological proxies suggest that equatorial continental areas may have been colder and more arid during LPIA glacial intervals than during late Cenozoic glacial intervals. Furthermore, the relationship between polar and tropical climate variability remains controversial. The climate dynamics underlying these phenomena are only partly understood. Nevertheless, past modeling of LPIA climate has suggested that precipitation near the Equator was modulated by monsoonal circulation that itself was modulated by orbital variability. Here, the Earth's climate during Asselian–Sakmarian time (299–284 Ma) was simulated with the Community Climate System Model version 3 (CCSM3). These simulations address model climate sensitivity to direct and indirect effects of glaciation as well as variability in the Earth's orbit. The results of these simulations suggest that sea level and orbitally forced monsoon variability were the primary controls on tropical precipitation when ice sheets were confined to polar latitudes. Any impact of orbital forcing on glaciation therefore could have led to aliasing between glacial and monsoonal effects in particular regions, perhaps explaining contrasting geologically-based interpretations of how tropical climate responded to glaciation. Glaciation of the Central Pangaean Mountains would have led to widespread cold and aridity in equatorial Pangaea, but forming these glaciers would have required an unknown additional climate forcing with an unknown impact on tropical precipitation.
- Published
- 2015
42. Seasonal and diurnal variability of detached dust layers in the tropical Martian atmosphere
- Author
-
James H. Shirley, R. John Wilson, W. A. Abdou, David M. Kass, Nicholas G. Heavens, Armin Kleinböhl, Daniel J. McCleese, and Morgan S. Johnson
- Subjects
Tharsis Montes ,Mars Exploration Program ,Atmospheric model ,Atmosphere of Mars ,Atmospheric sciences ,Atmosphere ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Dust storm ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Upwelling ,Hadley cell - Abstract
Evidence for widespread nonuniform vertical mixing of dust in Mars's tropical atmosphere (in the form of features called “detached dust layers” or DDLs) is a challenge for atmospheric modeling. We characterize the seasonal, diurnal, and geographic variability of DDL activity in retrievals from observations by the Mars Climate Sounder onboard Mars Reconnaissance Orbiter. We find that dust injection above the boundary layer, which forms DDLs, is a spatially ubiquitous phenomenon in the tropics during the daytime, implying that it has a significant nontopographic component. DDL formation is more intense in northern spring and summer than in southern spring and summer but is still common when the zonal average dust distribution appears uniformly mixed. DDLs do not appear to follow the upwelling associated with Mars's Hadley circulation or the extant climatology of local dust storm activity in the tropics. Geographic variability in the nightside vertical dust distribution does not always correlate with the dayside vertical dust distribution, implying that there is spatial and seasonal variability in the efficiency of dust deposition/removal processes. Nighttime dust removal is especially efficient over the Tharsis Montes during northern spring and summer, which suggests some association between water ice clouds and removal. Intense injection combined with efficient removal results in a high amplitude of diurnal variability in the dust distribution at 15–30 km above the surface of the tropics during much of the Martian year.
- Published
- 2014
43. Convective instabilities during Mars Climate Sounder’s limb staring mode were overestimated
- Author
-
John T. Schofield, Robert M. Edmonds, Nicholas G. Heavens, and James R. Murphy
- Subjects
Convection ,Staring ,Meteorology ,Space and Planetary Science ,Mode (statistics) ,Astronomy and Astrophysics ,Lapse rate ,Atmosphere of Mars ,Mars Exploration Program ,Geodesy ,Geology - Abstract
We report that the onset, and temporary cessation, of instabilities in MCS temperature profiles during MY 28 coincided with the initiation and cessation of limb staring operation, suggesting instrument operation was a factor in the identification of instabilities by Heavens et al. (Heavens et al. [2010]. Icarus, 208, 574–589). We demonstrate that the limb staring instrument operation during northern autumn of MY 28 can produce erroneous unstable lapse rates.
- Published
- 2014
44. Upland Glaciation in Tropical Pangaea: Geologic Evidence and Implications for Late Paleozoic Climate Modeling
- Author
-
Nicholas G. Heavens, Gerilyn S. Soreghan, and Dustin E. Sweet
- Subjects
Diamictite ,Paleontology ,Pangaea ,Marinoan glaciation ,Paleozoic ,Fluvial ,Geology ,Siliciclastic ,Last Glacial Maximum ,Glacial period - Abstract
The late Paleozoic archives a prolonged icehouse, long recognized by means of Gondwanan continental glaciation. In contrast, the paleotropics have long been considered warm. Here we present the hypothesis of upland glaciation in the Ancestral Rocky Mountains (ARM) of western equatorial Pangaea, a region located within 11° of the paleoequator. The data to support this hypothesis include (a) a Permo-Pennsylvanian valley with glacial attributes and diamictite exhibiting rare striated clasts; (b) coarse-grained lacustrine strata onlapping the valley and preserving lonestones in Gilbert-type deltaic deposits proximally, along with (c) coarse-grained fluvial siliciclastic strata with microstriae and evidence for widespread flood deposition; (d) polygonally cracked paleosurfaces inferred to reflect frozen ground; and (e) voluminous paleoloess. Tropical glaciation occurs today at altitudes >4500 m and descended to 2100–3000 m at the last glacial maximum (LGM). However, ARM depositional systems terminating...
- Published
- 2014
45. The role of snowfall in forming the seasonal ice caps of Mars: Models and constraints from the Mars Climate Sounder
- Author
-
David A. Paige, Nicholas G. Heavens, and Paul O. Hayne
- Subjects
Martian ,Radiative cooling ,Advection ,Astronomy and Astrophysics ,Orography ,Mars Exploration Program ,Snow ,Atmospheric sciences ,Atmosphere ,Space and Planetary Science ,Environmental science ,Cloud condensation nuclei ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,Physics::Atmospheric and Oceanic Physics - Abstract
Wintertime observations of the martian polar regions by orbiting spacecraft have provided evidence for carbon dioxide clouds, which measurably alter the polar energy budget and the annual CO2 cycle. However, it has remained unclear whether snowfall contributes a substantial quantity to the accumulating seasonal ice caps. We develop models to constrain precipitation rates based on observations of south polar CO2 clouds by the Mars Climate Sounder (MCS), and show that snowfall contributes between 3% and 20% by mass to the seasonal deposits at latitudes 70–90°S. The lower bound on this estimate depends on a minimum effective cloud particle size of ∼50 μm, derived by comparing the short lifetimes (less than a few hours) of some clouds with calculated sedimentation velocities. Separate constraints from infrared spectra measured by MCS suggest CO2 cloud particles in the size range 10–100 μm. Snow particles are not likely to re-sublime before reaching the surface, because the lower atmosphere in this region remains near saturation with respect to CO2. Based on cooling rate calculations, snowfall originating below 4 km altitude likely contributes a comparable or greater amount to the seasonal deposits than the rest of the atmosphere. Due to the positive feedback between cloud particle number density and radiative cooling, CO2 snow clouds should propagate until they become limited by the availability of condensation nuclei or CO2 gas. Over the south polar residual cap, where cloud activity is greatest, atmospheric radiative cooling rates are high enough to offset heat advected into the polar regions and maintain consistent snowfall. At latitudes of 60–80°S the lower atmosphere tends to be slightly sub-saturated and rapid cooling by mechanical lift driven by orography or convergent flow may be required to initiate a snowstorm, consistent with the more sporadic clouds observed by MCS in this region, and their correlation with topographic features. Snowfall and accumulation at the surface are found to be inevitable consequences of the polar energy budget, unless advection redistributes heat from lower latitudes in much greater quantities than expected.
- Published
- 2014
46. Correction to 'Extensive MRO CRISM observations of 1.27 µm O2airglow in Mars polar night and their comparison to MRO MCS temperature profiles and LMD GCM simulations'
- Author
-
Scott L. Murchie, H. Nair, D. M. Kass, Michael J. Wolff, Nicholas G. Heavens, Frank P. Seelos, François Forget, Franck Lefèvre, David C. Humm, K. D. Seelos, R. Todd Clancy, Michael D. Smith, Jean-Baptiste Madeleine, Brad J. Sandor, A. Kleinböhl, and Anthony D. Toigo
- Subjects
010504 meteorology & atmospheric sciences ,Polar night ,GCM transcription factors ,Mars Exploration Program ,01 natural sciences ,CRISM ,Astrobiology ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,0103 physical sciences ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Remote sensing - Published
- 2013
47. MARS ON EARTH: THE PERMIAN DUST BOWL OF THE WESTERN PANGAEAN TROPICS
- Author
-
Gerilyn S. Soreghan, Linda A. Hinnov, Nicholas G. Heavens, and Michael J. Soreghan
- Subjects
Permian ,Earth science ,Dust bowl ,Tropics ,Earth (chemistry) ,Mars Exploration Program ,Geology ,Astrobiology - Published
- 2016
48. Of kangaroo rats and gypsum gravel: Probing the extremes of aeolian transport in the present and the past
- Author
-
Nicholas G. Heavens
- Subjects
Gypsum ,010504 meteorology & atmospheric sciences ,Meteorology ,Geology ,Mars Exploration Program ,engineering.material ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,engineering ,Aeolian processes ,Tornado ,Whirlwind ,0105 earth and related environmental sciences - Abstract
A whirlwind is “a small-scale, rotating column of air” ([American Meteorological Society, 2012a][1]): a terse definition for some of the most intriguing and terrifying phenomena in the atmospheres of Earth and Mars. Whirlwinds fall into two classes: those that hang from cumulus clouds (tornadoes
- Published
- 2017
49. Aerosol Impacts on Climate and Biogeochemistry
- Author
-
Peter Hess, Nicholas G. Heavens, Silvia Kloster, D. S. Ward, Patrick Y. Chuang, Natalie M. Mahowald, Jean-Francois Lamarque, Mark Flanner, and Colette L. Heald
- Subjects
Atmospheric chemistry ,Climatology ,Climate change ,Biogeochemistry ,Albedo ,Radiative forcing ,Sea salt aerosol ,Atmospheric sciences ,Snow ,General Environmental Science ,Aerosol - Abstract
Aerosols are suspensions of solid and/or liquid particles in the atmosphere and modify atmospheric radiative fluxes and chemistry. Aerosols move mass from one part of the earth system to other parts of the earth system, thereby modifying biogeochemistry and the snow surface albedo. This paper reviews our understanding of the impacts of aerosols on climate through direct radiative changes, aerosol-cloud interactions (indirect effects), atmospheric chemistry, snow albedo, and land and ocean biogeochemistry. Aerosols play an important role in the preindustrial (natural) climate system and have been perturbed substantially over the anthropocene, often directly by human activity. The most important impacts of aerosols, in terms of climate forcing, are from the direct and indirect effects, with large uncertainties. Similarly large impacts of aerosols on land and ocean biogeochemistry have been estimated, but these have larger uncertainties.
- Published
- 2011
50. Convective instability in the martian middle atmosphere
- Author
-
John T. Schofield, James H. Shirley, Nicholas G. Heavens, Mark I. Richardson, Christopher C. Lee, David M. Kass, W. G. Lawson, Armin Kleinböhl, Daniel J. McCleese, and W. A. Abdou
- Subjects
Martian ,Atmosphere ,Convective instability ,Space and Planetary Science ,Atmospheric instability ,Northern Hemisphere ,Astronomy and Astrophysics ,Atmosphere of Mars ,Gravity wave ,Atmospheric temperature ,Atmospheric sciences ,Geology - Abstract
Dry convective instabilities in Mars’s middle atmosphere are detected and mapped using temperature retrievals from Mars Climate Sounder observations spanning 1.5 martian years. The instabilities are moderately frequent in the winter extratropics. The frequency and strength of middle atmospheric convective instability in the northern extratropics is significantly higher in MY 28 than in MY 29. This may have coupled with changes to the northern hemisphere mid-latitude and tropical middle atmospheric temperatures and contributed to the development of the 2007 global dust storm. We interpret these instabilities to be the result of gravity waves saturating within regions of low stability created by the thermal tides. Gravity wave saturation in the winter extratropics has been proposed to provide the momentum lacking in general circulation models to produce the strong dynamically-maintained temperature maximum at 1–2 Pa over the winter pole, so these observations could be a partial control on modeling experiments.
- Published
- 2010
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.