BEGIN:VCALENDAR VERSION:2.0 PRODID:-//18.83.4.138//NONSGML kigkonsult.se iCalcreator 2.20// CALSCALE:GREGORIAN METHOD:PUBLISH X-WR-CALNAME:Oceans at MIT X-WR-CALDESC:Striving to understand\, harness and sustain Earth'\;s def ining frontier. X-FROM-URL:http://oceans.mit.edu X-WR-TIMEZONE:America/New_York BEGIN:VTIMEZONE TZID:America/New_York X-LIC-LOCATION:America/New_York BEGIN:STANDARD DTSTART:20171105T020000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 RDATE:20181104T020000 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:20180311T020000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE BEGIN:VEVENT UID:pk0iqfejbpehn1plfruqhpea5o@google.com DTSTAMP:20180503T094943Z CATEGORIES;LANGUAGE=en-US:MIT Seminar | PAOC Oceanography and Climate Sack Lunch CONTACT: DESCRIPTION:Stability and Internal Flow Variability of Ice Sheets\n\nIce st reams are regions of fast-flowing ice embedded within ice sheets that acco unt for the majority of mass transport from ice sheet interiors to the oce an. Variability of ice stream flow on centennial to millennial time scales plays an important role in the present mass balance of the West Antarctic Ice Sheet. In this talk\, I show how a simple model of subglacial meltwat er production coupled to ice flow explains the underlying physical mechani sm for millennial-scale\, unforced ice stream variability and predicts the transition to steady ice stream flow. The model equally well reproduces m odern ice stream variability in the Siple Coast region of West Antarctica and Heinrich events\, periods of increased ice discharge from the Laurenti de Ice Sheet during the last glacial period. In a more realistic\, purpose -built model\, the same mechanism produces variability and rapid migration s of the ice stream grounding line. These migrations are always associated with mass imbalance near the grounding line\, but not necessarily in the ice stream at large\, which is important to consider when interpreting mod ern observations of grounding line variability. Under certain conditions\, this ice stream variability may cause the grounding line to slow down for hundreds to thousands of years even as it retreats onto a reverse bed slo pe\, before readvancing. Such behavior runs counter to the conventional th eories predicting the instability of ice sheets on reverse bed slopes. Det ermining if such behavior occurs in real ice sheets is important when eval uating the likelihood of irreversible ice sheet collapse and rapid sea lev el rise in the future. DTSTART;TZID=America/New_York:20161130T120000 DTEND;TZID=America/New_York:20161130T130000 LOCATION:54-915 SEQUENCE:0 SUMMARY:SLS – Alexander Robel (California Institute of Technology & Univers ity of Chicago) URL:http://oceans.mit.edu/event/sls-alexander-robel X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\n\\n\\nStability and In ternal Flow Variability of Ice Sheets\n\nIce streams are regions of fast-f lowing ice embedded within ice sheets that account for the majority of mas s transport from ice sheet interiors to the ocean. Variability of ice stre am flow on centennial to millennial time scales plays an important role in the present mass balance of the West Antarctic Ice Sheet. In this talk\, I show how a simple model of subglacial meltwater production coupled to ic e flow explains the underlying physical mechanism for millennial-scale\, u nforced ice stream variability and predicts the transition to steady ice s tream flow. The model equally well reproduces modern ice stream variabilit y in the Siple Coast region of West Antarctica and Heinrich events\, perio ds of increased ice discharge from the Laurentide Ice Sheet during the las t glacial period. In a more realistic\, purpose-built model\, the same mec hanism produces variability and rapid migrations of the ice stream groundi ng line. These migrations are always associated with mass imbalance near t he grounding line\, but not necessarily in the ice stream at large\, which is important to consider when interpreting modern observations of groundi ng line variability. Under certain conditions\, this ice stream variabilit y may cause the grounding line to slow down for hundreds to thousands of y ears even as it retreats onto a reverse bed slope\, before readvancing. Su ch behavior runs counter to the conventional theories predicting the insta bility of ice sheets on reverse bed slopes. Determining if such behavior o ccurs in real ice sheets is important when evaluating the likelihood of ir reversible ice sheet collapse and rapid sea level rise in the future.\n END:VEVENT END:VCALENDAR