A5068460472- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Climate variability and models
- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Oceanographic and Atmospheric Processes
- Atmospheric and Environmental Gas Dynamics
- Geology and Paleoclimatology Research
- Marine and coastal ecosystems
- Avian ecology and behavior
- Polar Research and Ecology
- Tree-ring climate responses
- Atmospheric Ozone and Climate
- Marine and fisheries research
- Arctic and Russian Policy Studies
- Freezing and Crystallization Processes
- Scientific Research and Discoveries
- Ocean Acidification Effects and Responses
- Species Distribution and Climate Change
- Spacecraft and Cryogenic Technologies
- Peatlands and Wetlands Ecology
- Space Science and Extraterrestrial Life
- Food Industry and Aquatic Biology
- Hydrology and Watershed Management Studies
- Marine animal studies overview
NSF National Center for Atmospheric Research
2016-2025
Climate and Global Dynamics Laboratory
2015-2025
University Corporation for Atmospheric Research
2024
Woods Hole Oceanographic Institution
2023
University of Maryland, College Park
2023
Colorado State University
2005
Abstract The climate of the past millennium provides a baseline for understanding background natural variability upon which current anthropogenic changes are superimposed. As this period also contains high data density from proxy sources (e.g., ice cores, stalagmites, corals, tree rings, and sediments), it unique opportunity both global regional-scale responses to forcing. Toward that end, an ensemble simulations with Community Earth System Model (CESM) 850–2005 (the CESM Last Millennium...
Abstract An overview of a simulation referred to as the “Last Millennium” (LM) Community Climate System Model, version 4 (CCSM4), is presented. The CCSM4 LM reproduces many large-scale climate patterns suggested by historical and proxy-data records, with Northern Hemisphere (NH) Southern (SH) surface temperatures cooling early 1800s Common Era ~0.5°C ~0.3°C (SH), followed warming present. High latitudes both hemispheres show polar amplification from Medieval Anomaly (MCA) Little Ice Age...
Abstract Observations show that increased Arctic cloud cover in the spring is linked with sea ice decline. As atmosphere and can influence each other, which one plays leading role remains unclear. Here we demonstrate, through observational data diagnosis numerical modeling, there active coupling between early spring. Sea melting thus presence of more open water lead to stronger evaporation promote formation increases downward longwave flux, even melt. Spring clouds are a driving force...
Abstract The Paris Agreement is a multinational initiative to combat climate change by keeping global temperature increase in this century 2°C above preindustrial levels while pursuing efforts limit the 1.5°C. Until recently, ensembles of coupled simulations producing temporal dynamics en route stable mean at 1.5 and were not available. Hence, few studies that have assessed ecological impact used ad‐hoc approaches. development new specific mitigation now provides an unprecedented opportunity...
Abstract The effect of stratospheric ozone depletion on the Amundsen Sea Low (ASL), a climatological low‐pressure center important for climate West Antarctica, remains uncertain. Using state‐of‐the‐art models, we here show that can cause statistically significant deepening ASL in summer with an amplitude approximately 1 hPa per decade. We are able to attribute modeled changes by contrasting ensembles historical integrations and without realistic hole. In presence very large natural...
Abstract Colonially-breeding seabirds have long served as indicator species for the health of oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in hopes that changes abundance productivity may be useful adaptive management marine resources, but their suitability this purpose is often unknown. To address this, we fit a Bayesian population dynamics model includes process observation error to all known Adélie penguin (1982–2015) Antarctic,...
Abstract Autumn sea ice trends in the western Ross Sea dominate increases Antarctic and are outside range simulated by climate models. Here we use a number of independent data sets to show that variability autumn conditions is largely driven springtime zonal winds high latitude South Pacific, with lead-time 5 months. Enhanced dynamically thin ice, allowing an earlier melt out, enhanced solar absorption, reduced cover next autumn. This seasonal lag relationship has implications for...
Under rising atmospheric greenhouse gas concentrations, the Arctic exhibits amplified warming relative to globe. This amplification is a defining feature of global warming. However, also home large internal variability, which can make detection forced climate response difficult. Here we use results from seven model ensembles, have different rates and sea ice loss, assess time emergence anthropogenically-forced amplification. We find that this occurs at turn century in all models, ranging...
Abstract Population ecology and biogeography applications often necessitate the transfer of models across spatial and/or temporal dimensions to make predictions outside bounds data used for model fitting. However, ecological are spatiotemporally unbalanced such that or dimension tends contain more than other. This unbalance frequently leads transfers become substitutions, which a different predictive was built on. Despite prevalence substitutions in ecology, studies validating their...
Abstract Antarctic sea ice exhibits considerable regional variability that is influenced by ocean and atmospheric conditions. Previous studies have suggested this may be predictable on seasonal to interannual timescales. Here we use initial-value predictability experiments of the Community Earth System Model 2 (CESM2), paired with analysis CESM2 Large Ensemble, further assess inherent in As previous studies, find area high for several months after initialization. It then lost when retreats,...
Abstract The new Community Climate System Model, version 4 (CCSM4), provides a powerful tool to understand and predict the earth’s climate system. Several aspects of Southern Ocean in CCSM4 are explored, including surface climatology interannual variability, simulation key water masses (Antarctic Bottom Water, Subantarctic Mode Antarctic Intermediate Water), transport structure Circumpolar Current, interbasin exchange via Agulhas Tasman leakages at Brazil–Malvinas Confluence. It is found...
Abstract A preindustrial control run and an ensemble of twentieth-century integrations the Community Climate System Model, version 4 (CCSM4), are evaluated for Antarctic sea ice climatology, modes variability, trends, covariance with related physical variables such as surface temperature level pressure. Compared to observations, mean cover is too extensive in all months. This part excessively strong westerly winds over ~50°–60°S, which drive a large equatorward meridional transport enhanced...
We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation ice conditions. For increases absorption albedo reductions, relative influence sea properties areal coverage is assessed. Changes are an earlier melt season onset, longer snow-free enhanced ponding. Because many these occur during peak insolation, they have...
Abstract We assess Antarctic sea ice climatology and variability in version 2 of the Community Earth System Model (CESM2) compare it to that older CESM1 (where appropriate) real‐world observations. In CESM2, is thinner less extensive than CESM1, though area still approximately 1 million km greater CESM2 present‐day Though there annual cycle growth melt more vigorous CESM1. A new mushy layer thermodynamics formulation implemented latest Ice Code (CICE) accounts for both frazil formation...
Abstract. The diminishing Arctic sea ice pack has been widely studied, but previous research mostly focused on time-mean changes in rather than short-term variations that also have important physical and societal consequences. In this study we test the hypothesis future interannual area variability will increase by utilizing 40 independent simulations from Community Earth System Model's Large Ensemble (CESM-LE) for 1920–2100 period augment with 12 models participating Coupled Model...
Abstract. In the high-latitude Arctic, wintertime sea ice and snow insulate relatively warmer ocean from colder atmosphere. While climate warms, Arctic surface heat fluxes remain dominated by insulating effects of covering until thins enough or concentrations decrease to allow for direct ocean–atmosphere fluxes. The Community Earth System Model version 1 Large Ensemble (CESM1-LE) simulates increases in conductive ice-covered Ocean ∼ 7–11 W m−2 mid-21st century, thereby driving an increased...
Abstract The Amundsen Sea Low (ASL) is an important driver of Antarctic sea ice variations largely because wind‐driven and ocean transport anomalies. However, the nature relationship between ASL complicated by large seasonality in cover location depth. Here we explore these relationships as a function region, season, lag. We find that can have markedly different sometimes opposite sign influence on some regions, such western Ross Sea, depending season. This part due to differing influences...