10 research outputs found
The Ross Sea Dipole-temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually dated ice core record from the eastern Ross Sea, named the Roosevelt Island Climate Evolution (RICE) ice core. Comparison of this record with climate reanalysis data for the 1979-2012 interval shows that RICE reliably captures temperature and snow precipitation variability in the region. Trends over the past 2700 years in RICE are shown to be distinct from those in West Antarctica and the western Ross Sea captured by other ice cores. For most of this interval, the eastern Ross Sea was warming (or showing isotopic enrichment for other reasons), with increased snow accumulation and perhaps decreased sea ice concentration. However, West Antarctica cooled and the western Ross Sea showed no significant isotope temperature trend. This pattern here is referred to as the Ross Sea Dipole. Notably, during the Little Ice Age, West Antarctica and the western Ross Sea experienced colder than average temperatures, while the eastern Ross Sea underwent a period of warming or increased isotopic enrichment. From the 17th century onwards, this dipole relationship changed. All three regions show current warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea but increasing in the western Ross Sea. We interpret this pattern as reflecting an increase in sea ice in the eastern Ross Sea with perhaps the establishment of a modern Roosevelt Island polynya as a local moisture source for RICE
The Ross Sea Dipole - temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
Wind redistribution of snow impacts the Ka- and Ku-band radar signatures of Arctic sea ice
Wind-driven redistribution of snow on sea ice alters its
topography and microstructure, yet the impact of these processes on radar
signatures is poorly understood. Here, we examine the effects of snow
redistribution over Arctic sea ice on radar waveforms and backscatter
signatures obtained from a surface-based, fully polarimetric Ka- and Ku-band
radar at incidence angles between 0∘ (nadir) and 50∘.
Two wind events in November 2019 during the Multidisciplinary drifting Observatory for
the Study of Arctic Climate (MOSAiC) expedition are evaluated. During both events, changes in Ka- and
Ku-band radar waveforms and backscatter coefficients at nadir are observed,
coincident with surface topography changes measured by a terrestrial laser
scanner. At both frequencies, redistribution caused snow densification at
the surface and the uppermost layers, increasing the scattering at the
air–snow interface at nadir and its prevalence as the dominant radar scattering surface. The waveform data also detected the presence of previous
air–snow interfaces, buried beneath newly deposited snow. The additional
scattering from previous air–snow interfaces could therefore affect the
range retrieved from Ka- and Ku-band satellite altimeters. With increasing
incidence angles, the relative scattering contribution of the air–snow
interface decreases, and the snow–sea ice interface scattering increases.
Relative to pre-wind event conditions, azimuthally averaged backscatter at
nadir during the wind events increases by up to 8 dB (Ka-band) and 5 dB (Ku-band). Results show substantial backscatter variability within the scan
area at all incidence angles and polarizations, in response to increasing
wind speed and changes in wind direction. Our results show that snow
redistribution and wind compaction need to be accounted for to interpret
airborne and satellite radar measurements of snow-covered sea ice.</p
Exploring Ultrafast Electronic Processes of Quasi-Type II Nanocrystals by Two-Dimensional Electronic Spectroscopy
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The Ross Sea Dipole - temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
Abstract. High-resolution, well-dated climate archives provide an
opportunity to investigate the dynamic interactions of climate patterns
relevant for future projections. Here, we present data from a new, annually
dated ice core record from the eastern Ross Sea, named the Roosevelt Island
Climate Evolution (RICE) ice core. Comparison of this record with climate
reanalysis data for the 1979–2012 interval shows that RICE reliably captures
temperature and snow precipitation variability in the region. Trends over the
past 2700 years in RICE are shown to be distinct from those in West
Antarctica and the western Ross Sea captured by other ice cores. For most of
this interval, the eastern Ross Sea was warming (or showing isotopic
enrichment for other reasons), with increased snow accumulation and perhaps
decreased sea ice concentration. However, West Antarctica cooled and the
western Ross Sea showed no significant isotope temperature trend. This
pattern here is referred to as the Ross Sea Dipole. Notably, during the
Little Ice Age, West Antarctica and the western Ross Sea experienced colder
than average temperatures, while the eastern Ross Sea underwent a period of
warming or increased isotopic enrichment. From the 17th century onwards, this
dipole relationship changed. All three regions show current warming, with
snow accumulation declining in West Antarctica and the eastern Ross Sea but
increasing in the western Ross Sea. We interpret this pattern as reflecting
an increase in sea ice in the eastern Ross Sea with perhaps the establishment
of a modern Roosevelt Island polynya as a local moisture source for RICE
Roosevelt Island Climate Evolution (RICE) ice core isotope record
High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually-dated ice core record from the eastern Ross Sea. Comparison of the Roosevelt Island Climate Evolution (RICE) ice core records with climate reanalysis data for the 1979-2012 calibration period shows that RICE records reliably capture temperature and snow precipitation variability of the region. RICE is compared with data from West Antarctica (West Antarctic Ice Sheet Divide Ice Core) and the western (Talos Dome) and eastern (Siple Dome) Ross Sea. For most of the past 2,700 years, the eastern Ross Sea was warming with perhaps increased snow accumulation and decreased sea ice extent. However, West Antarctica cooled whereas the western Ross Sea showed no significant temperature trend. From the 17th Century onwards, this relationship changes. All three regions now show signs of warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea, but increasing in the western Ross Sea. Analysis of decadal to centennial-scale climate variability superimposed on the longer term trend reveal that periods characterised by opposing temperature trends between the Eastern and Western Ross Sea have occurred since the 3rd Century but are masked by longer-term trends. This pattern here is referred to as the Ross Sea Dipole, caused by a sensitive response of the region to dynamic interactions of the Southern Annual Mode and tropical forcings
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The Ross Sea Dipole – Temperature, Snow Accumulation and Sea Ice Variability in the Ross Sea Region, Antarctica, over the Past 2,700 Years
Abstract. High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually-dated ice core record from the eastern Ross Sea. Comparison of the Roosevelt Island Climate Evolution (RICE) ice core records with climate reanalysis data for the 1979–2012 calibration period shows that RICE records reliably capture temperature and snow precipitation variability of the region. RICE is compared with data from West Antarctica (West Antarctic Ice Sheet Divide Ice Core) and the western (Talos Dome) and eastern (Siple Dome) Ross Sea. For most of the past 2,700 years, the eastern Ross Sea was warming with perhaps increased snow accumulation and decreased sea ice extent. However, West Antarctica cooled whereas the western Ross Sea showed no significant temperature trend. From the 17th Century onwards, this relationship changes. All three regions now show signs of warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea, but increasing in the western Ross Sea. Analysis of decadal to centennial-scale climate variability superimposed on the longer term trend reveal that periods characterised by opposing temperature trends between the Eastern and Western Ross Sea have occurred since the 3rd Century but are masked by longer-term trends. This pattern here is referred to as the Ross Sea Dipole, caused by a sensitive response of the region to dynamic interactions of the Southern Annual Mode and tropical forcings
Overview of the MOSAiC expedition: Snow and sea ice
Year-round observations of the physical snow and ice properties and processes that govern the ice pack
evolution and its interaction with the atmosphere and the ocean were conducted during the
Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition of the
research vessel Polarstern in the Arctic Ocean from October 2019 to September 2020. This work was
embedded into the interdisciplinary design of the 5 MOSAiC teams, studying the atmosphere, the sea ice,
the ocean, the ecosystem, and biogeochemical processes.The overall aim of the snow and sea ice observations
during MOSAiC was to characterize the physical properties of the snow and ice cover comprehensively in the
central Arctic over an entire annual cycle. This objective was achieved by detailed observations of physical
properties and of energy and mass balance of snow and ice. By studying snow and sea ice dynamics over nested
spatial scales from centimeters to tens of kilometers, the variability across scales can be considered. On-ice
observations of in situ and remote sensing properties of the different surface types over all seasons will help
to improve numerical process and climate models and to establish and validate novel satellite remote sensing
methods; the linkages to accompanying airborne measurements, satellite observations, and results of
numerical models are discussed. We found large spatial variabilities of snow metamorphism and thermal
regimes impacting sea ice growth. We conclude that the highly variable snow cover needs to be considered
in more detail (in observations, remote sensing, and models) to better understand snow-related feedback
processes.The ice pack revealed rapid transformations and motions along the drift in all seasons. The number
of coupled ice–ocean interface processes observed in detail are expected to guide upcoming research with
respect to the changing Arctic sea ice