Past Accumulation rates derived from observed annual layers in the GRIP ice core from Summit, Central Greenland

Dahl‐Jensen, Dorthe; Johnsen, S. J.; Hammer, C. U.; Clausen, Henrik; Jouzel, Jean

doi:10.1007/978-3-642-85016-5_29

Cited by 104 publications

(74 citation statements)

References 10 publications

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“…yr −1 to 0.11 m w.e. yr −1 , in agreement with accumulation rates derived from the GRIP ice core (Dahl-Jensen et al, 1993). On the other hand, margin SMB increases from −2 m w.e.…”

Section: Evolution Of Surface Forcing Conditionssupporting

confidence: 87%

A technique for generating consistent ice sheet initial conditions for coupled ice sheet/climate models

2014

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Abstract.A transient technique for generating ice sheet preindustrial initial conditions for long-term coupled ice sheet/climate model simulations is developed and demonstrated over the Greenland ice sheet using the Community Earth System Model (CESM). End-member paleoclimate simulations of the last glacial maximum, mid-Holocene optimum and the preindustrial are combined using weighting provided by ice core data time series to derive continuous energy-balance-model-derived surface mass balance and surface temperature fields, which are subsequently used to force a long transient ice sheet model simulation of the last glacial cycle, ending at the preindustrial. The procedure accounts for the evolution of climate through the last glacial period and converges to a simulated preindustrial ice sheet that is geometrically and thermodynamically consistent with the preindustrial CESM state, yet contains a transient memory of past climate. The preindustrial state generated using this technique notably improves upon the standard equilibrium spinup technique, relative to observations and other model studies, although in the demonstration we present here, large biases remain due primarily to climate model forcing biases. Ultimately, the method we describe provides a clear template for generating initial conditions for ice sheets within a fully coupled climate model framework that allows for the effects of past climate history to be self-consistently included in long-term simulations of the fully coupled ice sheet/climate system.

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“…yr −1 to 0.11 m w.e. yr −1 , in agreement with accumulation rates derived from the GRIP ice core (Dahl-Jensen et al, 1993). On the other hand, margin SMB increases from −2 m w.e.…”

Section: Evolution Of Surface Forcing Conditionssupporting

confidence: 87%

A technique for generating consistent ice sheet initial conditions for coupled ice sheet/climate models

2014

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“…18 O values found in the Greenland records for the last glacial period [29] (though not for the Holocene [30]) and inferred for most other Antarctic ice cores. It is expected that at near-coastal sites like Taylor Dome and Law Dome, snowfall may be dependent on non-temperature linked effects like the moist -air cyclonic activity or sea ice conditions [12].…”

Section: Ice Timescale and Accumulation Rate Calculationsmentioning

confidence: 63%

Evidence for substantial accumulation rate variability in Antarctica during the Holocene, through synchronization of CO 2 in the Taylor Dome, Dome C and DML ice cores

Monnin

Steig

Siegenthaler

et al. 2004

Earth and Planetary Science Letters

358

260

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High resolution records of atmospheric CO 2 concentration during the Holocene are obtained from the Dome Concordia and Dronning Maud Land (Antarctica) ice cores. These records confirm that the CO 2 concentration varied between 260 and 280 ppmv in the Holocene as measured in the Taylor Dome ice core. However, there are differences in the CO 2 records most likely caused by mismatches in timescales. Matching the Taylor Dome timescale to the Dome C timescale by synchronization of CO 2 indicates that the accumulation rate at Taylor Dome increased through the Holocene by a factor two and bears little resemblance to the stable isotope record used as a proxy for temperature. This result shows that different locations experienced substantially different accumulation changes, and casts doubt on the often-used assumption that accumulation rate scales with the saturation vapor pressure as a function of temperature, at least for coastal locations. D

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“…Recent glaciological evidence [28,29] suggests that the LGM surface topography used in the PMIP simulations [30] is much too high over Central Greenland, the real LGM surface altitude having probably been close to the present-day value, both at Summit and at Vostok. Thus, the simulated LGM surface air temperature has been interpolated from the LGM model surface altitude to present-day altitude, using y = DT s /Dh = 10 ‡C/1000 m. This value, typical for the interior of Greenland and Antarctica [31], is not an atmospheric lapse rate, but the dependency of surface air temperature T s on surface altitude h. The simulated (altitude-corrected) climate change v c T s = vT s +yvh from the LGM to present (Table 3) is generally not as strong as ice core data indicate [32,33].…”

Section: Simulated Lgm Climatementioning

confidence: 98%

Impact of precipitation seasonality changes on isotopic signals in polar ice cores: a multi-model analysis

Krinner

Werner

2003

Earth and Planetary Science Letters

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For Central Greenland, water isotope analysis indicates a temperature difference of about 10 ‡C since the Last Glacial Maximum (LGM). However, borehole thermometry and gas diffusion thermometry indicate that LGM surface temperatures were about 20 ‡C colder than today. Two general circulation model studies have shown that changes in the seasonal precipitation timing in Central Greenland might have caused a warm bias in the LGM water isotope proxy temperatures, and that this bias could explain the difference in the estimated paleotemperatures. Here we present an analysis of a number of atmospheric general circulation model simulations mostly done within the framework of the Paleoclimate Modeling Intercomparison Project. The models suggest that the seasonal cycle of precipitation and surface mass balance over Central Greenland at the LGM might have been very different from today. This supports the idea that the accuracy of the water isotope thermometry at the LGM in Greenland might be compromised as a result of a modified surface mass balance seasonality. However, the models disagree on the amplitude and sign of the bias. For Central East Antarctica, a strong seasonality effect on the LGM isotopic signal is not simulated by any of the analyzed models. For the mid-Holocene (6 kyr BP) the models suggest relatively weak isotope paleothermometry biases linked to changes in the surface mass balance seasonality over both ice sheets. ß

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Past Accumulation rates derived from observed annual layers in the GRIP ice core from Summit, Central Greenland

Cited by 104 publications

References 10 publications

A technique for generating consistent ice sheet initial conditions for coupled ice sheet/climate models

A technique for generating consistent ice sheet initial conditions for coupled ice sheet/climate models

Evidence for substantial accumulation rate variability in Antarctica during the Holocene, through synchronization of CO 2 in the Taylor Dome, Dome C and DML ice cores

Impact of precipitation seasonality changes on isotopic signals in polar ice cores: a multi-model analysis

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