Present-day and future Greenland Ice Sheet precipitation frequency from CloudSat observations and the  Community Earth System Model

Lenaerts, Jan T. M.; Camron, M. Drew; Wyburn-Powell, Christopher; Kay, J. E.

doi:10.5194/tc-14-2253-2020

Cited by 18 publications

(22 citation statements)

References 63 publications

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“…Despite the potential for SBIs to act as a barrier for turbulent mixing and hence reduce the rate that aerosol particles are transported down to the surface (Dibb et al, 1992;Li et al, 2019;Thomas et al, 2019), we found no consistent change in N 20 during the first 3 h of SBI events and no relationship between the change in N 20 and the mean intensity of the SBI, which ranges between 0.23 and 0.92 • C m −1 (not shown). SBIs may have a more important role on surface aerosol particle concentrations over longer timescales, especially because the loss of aerosol particles to the surface by dry deposition is slow (Garrett et al, 2010); however, because fog regularly forms during SBI events, it is difficult to isolate the influence of the SBI from the influence of fog scavenging on aerosol particle concentrations during longer events.…”

Section: Controls On Surface Aerosol Particle Concentrations At Summitcontrasting

confidence: 59%

Controls on surface aerosol particle number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet

et al. 2021

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Abstract. This study presents the first full annual cycle (2019–2020) of ambient surface aerosol particle number concentration measurements (condensation nuclei > 20 nm, N20) collected at Summit Station (Summit), in the centre of the Greenland Ice Sheet (72.58∘ N, −38.45∘ E; 3250 ma.s.l.). The mean surface concentration in 2019 was 129 cm−3, with the 6 h mean ranging between 1 and 1441 cm−3. The highest monthly mean concentrations occurred during the late spring and summer, with the minimum concentrations occurring in February (mean: 18 cm−3). High-N20 events are linked to anomalous anticyclonic circulation over Greenland and the descent of free-tropospheric aerosol down to the surface, whereas low-N20 events are linked to anomalous cyclonic circulation over south-east Greenland that drives upslope flow and enhances precipitation en route to Summit. Fog strongly affects particle number concentrations, on average reducing N20 by 20 % during the first 3 h of fog formation. Extremely-low-N20 events (< 10 cm−3) occur in all seasons, and we suggest that fog, and potentially cloud formation, can be limited by low aerosol particle concentrations over central Greenland.

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Section: Controls On Surface Aerosol Particle Concentrations At Summitcontrasting

confidence: 59%

Controls on surface aerosol particle number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet

et al. 2021

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“…Automated weather stations can indirectly measure snowfall using changes in surface height, providing high-temporalresolution data that can resolve accumulation from individual storms (Steffen and Box, 2001); however, the observations are limited to the particular location of the stations and their time period of operation. Both airborne and groundbased radars have been used to detect internal reflecting horizons below the surface to provide historical accumulations over the GrIS (Miège et al, 2013;Lewis et al, 2017), but those values are limited to specific transects, suffer complications from melt events, and only apply on annual or longer timescales. Estimating snowfall frequency and accumulation over the whole ice sheet is often achieved using regional climate models (e.g., Berdahl et al, 2018;Mouginot et al, 2019) or reanalyses (e.g., Schuenemann et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Satellite observations of snowfall regimes over the Greenland Ice Sheet

McIlhattan¹,

Pettersen

Wood

et al. 2020

The Cryosphere

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Abstract. The mass of the Greenland Ice Sheet (GrIS) is decreasing due to increasing surface melt and ice dynamics. Snowfall both adds mass to the GrIS and has the capacity to reduce surface melt by increasing surface brightness, reflecting additional solar radiation back to space. Modeling the GrIS’s current and future mass balance and potential contribution to future sea level rise requires reliable observational benchmarks for current snowfall accumulation as well as robust connections between individual snowfall events and the large-scale atmospheric circulation patterns that produce them. Previous work using ground-based observations showed that, for one research station on the GrIS, two distinct snowfall regimes exist: those associated with exclusively ice-phase cloud processes (IC) and those involving mixed-phase processes indicated by the presence of supercooled liquid water (CLW). The two regimes have markedly different accumulation characteristics and dynamical drivers. This study leverages the synergy between two satellite instruments, CloudSat's Cloud Profiling Radar (CPR) and CALIPSO's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), to identify snowfall cases over the full GrIS and partition them into the IC and CLW regimes. We find that, overall, most CPR observations of snowfall over the GrIS come from IC events (70 %); however, during the summer months, close to half of the snow observed is produced in CLW events (45 %). IC snowfall plays a dominant role in adding mass to the GrIS, producing ∼ 80 % of the total estimated 399 Gt yr−1 accumulation. Beyond the cloud phase that defines the snowfall regimes, the macrophysical cloud characteristics are distinct as well; the mean IC geometric cloud depth (∼ 4 km) is deeper than the CLW geometric cloud depth (∼ 2 km), consistent with previous studies based on surface observations. Two-dimensional histograms of the vertical distribution of CPR reflectivities show that IC events demonstrate consistently increasing reflectivity toward the surface while CLW events do not. Analysis of ERA5 reanalyses shows that IC events are associated with cyclone activity and CLW events generally occur under large-scale anomalously high geopotential heights over the GrIS. When combined with future climate predictions, this snapshot of GrIS snowfall characteristics may shed light on how this source of ice sheet mass might respond to changing synoptic patterns in a warming climate.

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“…Observed TIRS spectra and the AGHE estimates derived from them allow the contributions to OLR and DLR variability from changes in surface temperature, surface conditions, water vapor, and clouds to be isolated (Wielicki et al, 2013;Huang et al, 2014a (i.e., at a consistent spatial scale) comparisons against monthly gridded, monthly spectral fluxes, AGHE, and cloud impacts on AGHE derived from PREFIRE all-sky and clear-sky spectra. Recent work has highlighted the value of instrument simulators in polar regions for both precipitation (Lenaerts et al, 2020) and clouds/atmospheric opacity (Morrison et al, 2020).…”

Section: Benefit To Polar Modeling and Predictionmentioning

confidence: 99%

The Polar Radiant Energy in the Far Infrared Experiment: A New Perspective on Polar Longwave Energy Exchanges

L’Ecuyer

Drouin

Anheuser

et al. 2021

Bulletin of the American Meteorological Society

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The Earth’s climate is strongly influenced by energy deficits at the poles that emit more thermal energy than they receive from the sun. Energy exchanges between the surface and atmosphere influence the local environment while heat transport from lower latitudes drives midlatitude atmospheric and oceanic circulations. In the Arctic, in particular, local energy imbalances induce strong seasonality in surface-atmosphere heat exchanges and an acute sensitivity to forced climate variations. Despite these important local and global influences, the largest contributions to the polar atmospheric and surface energy budgets have not been fully characterized. The spectral variation of far-infrared radiation that makes up 60% of polar thermal emission has never been systematically measured impeding progress toward consensus in predicted rates of Arctic warming, sea ice decline, and ice sheet melt.Enabled by recent advances in sensor miniaturization and CubeSat technology, the Polar Radiant Energy in the Far InfraRed Experiment (PREFIRE) mission will document, for the first time, the spectral, spatial, and temporal variations of polar far-infrared emission. Selected under NASA’s Earth Ventures Instrument (EVI) program, PREFIRE will utilize new light weight, low-power, ambient temperature detectors capable of measuring at wavelengths up to 50 micrometers to quantify Earth’s far-infrared spectrum. Estimates of spectral surface emissivity, water vapor, cloud properties, and the atmospheric greenhouse effect derived from these measurements offer the potential to advance our understanding of the factors that modulate thermal fluxes in the cold, dry conditions characteristic of the polar regions.

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Present-day and future Greenland Ice Sheet precipitation frequency from CloudSat observations and the Community Earth System Model

Cited by 18 publications

References 63 publications

Controls on surface aerosol particle number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet

Controls on surface aerosol particle number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet

Satellite observations of snowfall regimes over the Greenland Ice Sheet

The Polar Radiant Energy in the Far Infrared Experiment: A New Perspective on Polar Longwave Energy Exchanges

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