Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

Munneke, Peter Kuipers; Broeke, M. R. van den; King, John C.; Gray, T. I.; Reijmer, C. H.

doi:10.5194/tcd-5-2665-2011

Cited by 36 publications

(77 citation statements)

References 26 publications

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“…), which is similar to the daily melt from the WRF simulations presented here for the same latitude (9.8 mm). The melting rates from Kuipers Munneke et al (2012) were, however, quite variable from day to day with the low melt days generally corresponding to low net SW input. Also, the melt due to SH and LH were generally quite large compared to the WRF simulation values, with mean values of 4.3 and −3.4 mm, respectively.…”

Section: Discussion Of the Melting Results In Light Of The Previous Lmentioning

confidence: 99%

“…A comparison of the non-föhn and föhn periods identified in Kuipers Munneke et al (2012) showed that net surface SW input was higher in the föhn period (equivalent mean melt values of 16.3 vs. 9.8 mm), as were net longwave losses (−12.8 vs. −6.5 mm). This is consistent with the idea of a lack of cloud during föhn events.…”

Section: Discussion Of the Melting Results In Light Of The Previous Lmentioning

confidence: 99%

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Downslope föhn winds over the Antarctic Peninsula and their effect on the Larsen ice shelves

2014

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Abstract.Mesoscale model simulations are presented of a westerly föhn event over the Antarctic Peninsula mountain ridge and onto the Larsen C ice shelf, just south of the recently collapsed Larsen B ice shelf. Aircraft observations showed the presence of föhn jets descending near the ice shelf surface with maximum wind speeds at 250-350 m in height. Surface flux measurements suggested that melting was occurring. Simulated profiles of wind speed, temperature and wind direction were very similar to the observations. However, the good match only occurred at a model time corresponding to ∼ 9 h before the aircraft observations were made since the model föhn jets died down after this. This was despite the fact that the model was nudged towards analysis for heights greater than ∼1.15 km above the surface.Timing issues aside, the otherwise good comparison between the model and observations gave confidence that the model flow structure was similar to that in reality. Details of the model jet structure are explored and discussed and are found to have ramifications for the placement of automatic weather station (AWS) stations on the ice shelf in order to detect föhn flow. Cross sections of the flow are also examined and were found to compare well to the aircraft measurements. Gravity wave breaking above the mountain crest likely created a situation similar to hydraulic flow and allowed föhn flow and ice shelf surface warming to occur despite strong upwind blocking, which in previous studies of this region has generally not been considered. Our results therefore suggest that reduced upwind blocking, due to wind speed increases or stability decreases, might not result in an increased likelihood of föhn events over the Antarctic Peninsula, as previously suggested.The surface energy budget of the model during the melting periods showed that the net downwelling short-wave surface flux was the largest contributor to the melting energy, indicating that the cloud clearing effect of föhn events is likely to be the most important factor for increased melting relative to non-föhn days. The results also indicate that the warmth of the föhn jets through sensible heat flux ("SH") may not be critical in causing melting beyond boundary layer stabilisation effects (which may help to prevent cloud cover and suppress loss of heat by convection) and are actually cancelled by latent heat flux ("LH") effects (snow ablation). It was found that ground heat flux ("GRD") was likely to be an important factor when considering the changing surface energy budget for the southern regions of the ice shelf as the climate warms.

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Section: Discussion Of the Melting Results In Light Of The Previous Lmentioning

confidence: 99%

Section: Discussion Of the Melting Results In Light Of The Previous Lmentioning

confidence: 99%

Downslope föhn winds over the Antarctic Peninsula and their effect on the Larsen ice shelves

2014

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“…RACMO2.3 has been adapted for use over the large ice sheets of Greenland and Antarctica ; it includes a multilayer snow model to calculate melt, percolation, refreezing, and runoff of liquid water (Ettema et al 2010); a prognostic scheme for snow grain size to calculate surface albedo (Kuipers Munneke et al 2011); and a routine that simulates the interaction of drifting snow with the surface and the lower atmosphere (Lenaerts et al 2012a). ERA-Interim data with 6-hourly resolution from January 1979 to December 2013 (Dee et al 2011) are used to force the model at the lateral atmospheric boundaries as well as at the lower ocean boundaries by prescribing sea ice fraction and sea surface temperatures.…”

Section: A Regional Atmospheric Climate Modelmentioning

confidence: 99%

“…We use the upper-air monthly climatology (2002-13) of these stations from the SCAR-READER database to assess the quality of simulated RACMO2.3 upper-air conditions. In addition, at AWS 14 on the Larsen Ice Shelf (LIS), during a short experimental campaign in January 2011 and at irregular intervals, additional balloon soundings were performed (Kuipers Munneke et al 2012). Two of these profiles are used together with simultaneous Rothera soundings to evaluate RACMO2.3-modeled gradients across the AP mountain range.…”

Section: ) Balloon Soundingsmentioning

confidence: 99%

Temperature and Wind Climate of the Antarctic Peninsula as Simulated by a High-Resolution Regional Atmospheric Climate Model

et al. 2015

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTThe latest polar version of the Regional Atmospheric Climate Model (RACMO2.3) has been applied to the Antarctic Peninsula (AP). In this study, the authors present results of a climate run at 5.5 km for the period 1979-2013, in which RACMO2.3 is forced by ERA-Interim atmospheric and ocean surface fields, using an updated AP surface topography. The model results are evaluated with near-surface temperature and wind measurements from 12 manned and automatic weather stations and vertical profiles from balloon soundings made at three stations. The seasonal cycle of near-surface temperature and wind is simulated well, with most biases still related to the limited model resolution. High-resolution climate maps of temperature and wind showing that the AP climate exhibits large spatial variability are discussed. Over the steep and high mountains of the northern AP, large west-to-east climate gradients exist, while over the gentle southern AP mountains the near-surface climate is dominated by katabatic winds. Over the flat ice shelves, where katabatic wind forcing is weak, interannual variability in temperature is largest. Finally, decadal trends of temperature and wind are presented, and it is shown that recently there has been distinct warming over the northwestern AP and cooling over the rest of the AP, related to changes in sea ice cover.

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“…In recent years, studies have been conducted on surface energy balance and near-surface processes in Greenland (e.g., Miller et al, 2013Miller et al, , 2015Miller et al, , 2017Berkelhammer et al, 2016) and Antarctica (e.g., van As et al, 2005;van den Broeke et al, 2006;Kuipers Munneke et al, 2012). At our study site at Summit, Greenland, Miller et al (2013) studied the inversions over 2 years but considered the 2 m air temperature to be the base of these inversions, and they did not investigate Miller et al (2017).…”

Section: Introductionmentioning

confidence: 99%

Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures

2018

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Abstract. As rapid warming of the Arctic occurs, it is imperative that climate indicators such as temperature be monitored over large areas to understand and predict the effects of climate changes. Temperatures are traditionally tracked using in situ 2 m air temperatures and can also be assessed using remote sensing techniques. Remote sensing is especially valuable over the Greenland Ice Sheet, where few ground-based air temperature measurements exist. Because of the presence of surface-based temperature inversions in ice-covered areas, differences between 2 m air temperature and the temperature of the actual snow surface (referred to as "skin" temperature) can be significant and are particularly relevant when considering validation and application of remote sensing temperature data. We present results from a field campaign extending from 8 June to 18 July 2015, near Summit Station in Greenland, to study surface temperature using the following measurements: skin temperature measured by an infrared (IR) sensor, 2 m air temperature measured by a National Oceanic and Atmospheric Administration (NOAA) meteorological station, and a Moderate Resolution Imaging Spectroradiometer (MODIS) surface temperature product. Our data indicate that 2 m air temperature is often significantly higher than snow skin temperature measured in situ, and this finding may account for apparent biases in previous studies of MODIS products that used 2 m air temperature for validation. This inversion is present during our study period when incoming solar radiation and wind speed are both low. As compared to our in situ IR skin temperature measurements, after additional cloud masking, the MOD/MYD11 Collection 6 surface temperature standard product has an RMSE of 1.0 • C and a mean bias of −0.4 • C, spanning a range of temperatures from −35 to −5 • C (RMSE = 1.6 • C and mean bias = −0.7 • C prior to cloud masking). For our study area and time series, MODIS surface temperature products agree with skin surface temperatures better than previous studies indicated, especially at temperatures below −20 • C, where other studies found a significant cold bias. We show that the apparent cold bias present in other comparisons of 2 m air temperature and MODIS surface temperature may be a result of the near-surface temperature inversion. Further investigation of how in situ IR skin temperatures compare to MODIS surface temperature at lower temperatures (below −35 • C) is warranted to determine whether a cold bias exists for those temperatures.

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Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

Cited by 36 publications

References 26 publications

Downslope föhn winds over the Antarctic Peninsula and their effect on the Larsen ice shelves

Downslope föhn winds over the Antarctic Peninsula and their effect on the Larsen ice shelves

Temperature and Wind Climate of the Antarctic Peninsula as Simulated by a High-Resolution Regional Atmospheric Climate Model

Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures

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