Calendar

Mar
31
Tue
PDS Atmospheres Node meeting
Mar 31 @ 2:00 pm – 3:00 pm
Apr
3
Fri
Colloquium Thesis Defense: Jeremy Emmett
Apr 3 @ 3:15 pm – 4:15 pm
Colloquium Thesis Defense: Jeremy Emmett @ BX102

Dependence upon Obliquity of the Formation of Martian PLD Vertical Structure

Jeremy Emmett, NMSU

Mars’ polar layered deposits (PLD) are comprised of layers of varying dust-to-water ice volume mixing ratios (VMR) that are thought to record astronomically-forced climatic variation over Mars’ recent orbital history. Retracing the formation history of these layers by quantifying the sensitivity of polar rates of deposition to astronomical forcing may be critical for the interpretation of this record. Using a Mars global climate model (GCM), we investigate the sensitivity of annual polar water ice and dust surface deposition to a variety of obliquity and surface water ice source configurations at zero eccentricity that may provide a reasonable characterization of the evolution of the PLD during recent low-eccentricity epochs. The GCM employs a fully interactive dust lifting/transport scheme and accounts for dust-and-water physics coupling effects on the transport and deposition of water ice and dust. GCM results suggest that snowfall in the form of water ice-nucleated dust particles generally provides the greatest contribution to both water ice and dust deposition on the polar surfaces, suggesting that dust-and-water physics coupling is an important consideration in the modelling of PLD layer formation processes. Under a range of tested obliquities (15° – 35°), predicted net annual accumulation rates range from -1 mm/yr to +14 mm/yr for water ice and from 0.005 – 0.57 mm/yr for dust. When these GCM-derived accumulation rates are ingested into an integration model that simulates polar accumulation of water ice and dust over five consecutive obliquity cycles (~700 thousand years) during a low eccentricity epoch, select integration model simulations predict combined north polar water and dust accumulation rates that correspond to the observationally-inferred average growth rate of the north PLD (0.5 mm/yr) over its ~5 million year formation history. These integration model simulation results are characterized by net water transfer from the south to the north polar region. In the north, a ~230 m-thick deposit is accumulated over ~700 thousand years. Three types of layers are produced per obliquity cycle: a ~30 m-thick dust-rich (20 – 30% dust volume mixing ratio) layer that forms at high obliquity when both water ice and dust deposition rates are large, a ~0.5 m-thick dust lag deposit (pure dust) that forms at low obliquity when net removal of water ice occurs, and two ~10 m-thick dust-poor (~3%) layers that separate the dust rich layers and form when obliquity is increasing or decreasing. The ~30 m-thick dust-rich layer is reminiscent of a ~30 m scale length feature derived from analysis of visible imagery of north PLD vertical structure. This work demonstrates the capability of obliquity variations to produce PLD stratigraphy reminiscent of observed PLD structure when water and dust deposition are interactively coupled.

Observatory Open House
Apr 3 @ 9:00 pm – 11:00 pm
Observatory Open House @ BX102, Tombaugh Observatory

Host: Wladimir Lyra. Assisted by Rachel Marra, Ali Hyder, Audrey Dijeau

Apr
10
Fri
No Colloquium – Spring Holiday
Apr 10 @ 3:15 pm – 4:15 pm
No Colloquium - Spring Holiday @ BX102

Colloquium Title

Colloquium Speaker Name, Affiliation

Abstract text

Apr
14
Tue
PDS Atmospheres Node meeting
Apr 14 @ 2:00 pm – 3:00 pm
Apr
17
Fri
Colloquium: Fuyan Bian (remote)
Apr 17 @ 3:15 pm – 4:15 pm
Colloquium: Fuyan Bian (remote) @ BX102

Colloquium Title

Fuyan Bian, European Southern Observatory

Abstract text

Apr
20
Mon
Cappuccino Talk: Valentina D’Orodico
Apr 20 @ 10:00 am – 11:00 am
Cappuccino Talk: Valentina D'Orodico @ AY 119

Title

Apr
24
Fri
Colloquium: Sebastiaan Krijt (Host: Wladimir Lyra)
Apr 24 @ 3:15 pm – 4:15 pm
Colloquium: Sebastiaan Krijt (Host: Wladimir Lyra) @ BX102

Colloquium Title

Sebastiaan Krijt (University of Arizona)

Abstract text

Apr
28
Tue
PDS Atmospheres Node meeting
Apr 28 @ 2:00 pm – 3:00 pm
May
1
Fri
Colloquium: Christina Richey (Host: Jodi Berdis)
May 1 @ 3:15 pm – 4:15 pm
Colloquium: Christina Richey (Host: Jodi Berdis) @ BX102

Colloquium Title

Colloquium Speaker Name, Affiliation

Abstract text