A5050388008- Arctic and Antarctic ice dynamics
- Climate variability and models
- Cryospheric studies and observations
- Oceanographic and Atmospheric Processes
- Geology and Paleoclimatology Research
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Polar Research and Ecology
- Methane Hydrates and Related Phenomena
- Climate change and permafrost
- Atmospheric Ozone and Climate
- Tropical and Extratropical Cyclones Research
- Historical Geography and Geographical Thought
- Ocean Acidification Effects and Responses
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Climate Change, Adaptation, Migration
- Atmospheric chemistry and aerosols
- Science and Climate Studies
- History of Science and Natural History
- Conservation Techniques and Studies
- Geophysics and Gravity Measurements
- Sustainable Development and Environmental Policy
- Climate Change Communication and Perception
- Diverse Historical and Scientific Studies
University of California, Los Angeles
2015-2024
ORCID
2021
UCLA Health
2014
American Geophysical Union
2013
The Ohio State University
1990
Abstract The Amundsen Sea low (ASL) is a climatological pressure center that exerts considerable influence on the climate of West Antarctica. Its potential to explain important recent changes in Antarctic climate, for example, temperature and sea ice extent, means it has become focus an increasing number studies. Here, authors summarize current understanding ASL, using reanalysis datasets analyze variability trends, as well ice-core chemistry model projections, examine past future...
Abstract Fully coupled climate models have long shown a wide range of Antarctic sea ice states and evolution over the satellite era. Here, we present high‐level evaluation in 40 from most recent phase Coupled Model Intercomparison Project (CMIP6). Many capture key characteristics mean seasonal cycle area (SIA), but some simulate implausible historical compared to observations, leading large intermodel spread. Summer SIA is consistently biased low across ensemble. Compared previous model...
In this study 500 hPa geopotential heights from the NCAR‐NCEP Reanalysis are used to calculate an index describing spatial and temporal characteristics of zonal wave three (ZW3) in high latitude Southern Hemisphere atmosphere. The spans period 1958–2001. Wavelet analysis shows strong interannual variation which is characteristic ZW3 also reveals significant, amplitude decadal‐scale variation. This takes form marked fluctuation sign magnitude index. It appears occur when there rapid changes...
Abstract. In contrast to the Arctic, where total sea ice extent (SIE) has been decreasing for last three decades, Antarctic SIE shown a small, but significant, increase during same time period. However, in 2016, an unusually early onset of melt season was observed; maximum already reached as August rather than end September, and followed by rapid decrease. The decay particularly strong November, when exhibited negative anomaly (compared 1979–2015 average) approximately 2 million km2. ECMWF...
The manuscript assesses the current and expected future global drivers of Southern Ocean (SO) ecosystems. Atmospheric ozone depletion over Antarctic since 1970s, has been a key driver, resulting in springtime cooling stratosphere intensification polar vortex, increasing frequency positive phases Annular Mode (SAM). This increases warm air-flow East Pacific sector (Western Peninsula) cold air flow West sector. SAM as well El Niño Oscillation events also affect Amundsen Sea Low leading to...
The view from the south is, more than ever, dominated by ominous signs of change. Antarctica and Southern Ocean are intrinsic to Earth system, their evolution is intertwined with influences course Anthropocene. In turn, changes in Antarctic affect presage humanity's future. Growing understanding countering popular beliefs that pristine, stable, isolated, reliably frozen. An aspirational roadmap for science has facilitated research since 2014. A renewed commitment gathering further knowledge...
A 33-yr, numerical dataset of the occurrence Santa Ana winds for period 1968–2000 has been created and validated. Daily Weather Maps were examined to identify days when a surface high pressure system existed over Great Basin simultaneously with low offshore southern California, prevailing wind California was from northeast quadrant. The dates these occurrences, as well speed, temperature, dewpoint temperature among other variables, extracted tabulated. frequency events derived weather maps...
The study examines the relationship between atmospheric zonal wave three and Antarctic sea ice variability using an index of concentration. net sensible heat flux surface air temperature are used to explain apparent atmosphere‐sea interaction. results show that forces alternating pattern equatorward (colder) poleward (warmer) flow which influences difference atmosphere ocean. is positive, ocean loss greater, growth expansion greater in regions colder air. reverse true warmer This influence...
Abstract Antarctic sea ice, a key component of the Southern Hemisphere climate system, is influenced by several large‐scale modes atmospheric circulation. ice variability spatially heterogeneous, and links between circulation are unclear. Using observed concentration data, this research isolates distinct regions around Antarctica determines advance retreat periods for each them. The latter then statistically linked with geopotential height data to determine pattern associated in period...
Abstract Recent attention has focused on accelerated glacial losses along the Amundsen Sea coast that result from changes in atmosphere and ocean circulation, with sea ice playing a mediating but not well-understood role. Here, we investigated how changed over period of 1979 to 2014, focusing spatio-temporal edge advance/retreat percent cover relation winds. In contrast widespread decreases east increases west Sea, were confined three areas: (i) offshore shelf break, (ii) southern Pine...
Abstract. Landfast sea ice (fast ice) is an important though poorly understood component of the cryosphere on Antarctic continental shelf, where it plays a key role in atmosphere–ocean–ice-sheet interaction and coupled ecological biogeochemical processes. Here, we present first in-depth baseline analysis variability change circum-Antarctic fast-ice distribution (including its relationship to bathymetry), based new high-resolution satellite-derived time series for period 2000 2018. This...
Abstract Climate observations inform about the past and present state of climate system. They underpin science, feed into policies for adaptation mitigation, increase awareness impacts change. The Global Observing System (GCOS), a body World Meteorological Organization (WMO), assesses maturity required observing system gives guidance its development. Essential Variables (ECVs) are central to GCOS, global community must monitor them with highest standards in form Data Records (CDR). Today,...
Abstract Using optimal fingerprinting techniques, a detection analysis is performed to determine whether observed trends in Southern Ocean sea ice extent since 1979 are outside the expected range of natural variability. Consistent with previous studies, it found that for seasons maximum cover (i.e., winter and early spring), not variability some West Antarctic sectors they may be partially due tropical However, when information about spatial pattern included analysis, summer autumn fall...
Quantitative estimates of future Antarctic climate change are derived from numerical global models. Evaluation the reliability model projections involves many lines evidence on past performance combined with knowledge processes that need to be represented. Routine evaluation is mainly based modern observational period, which started establishment a network weather stations in 1957/58. This period too short evaluate fundamental aspects and Southern Ocean system, such as decadal-to-century...
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...
© 2023 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses). Corresponding author: Kyle R. Clem / kyle.clem@vuw.ac.nz
Abstract. At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements were initiated in 2006 and are being continued until today. The amounts stable isotope ratios of samples as well crystal types determined. Within measuring period, two years 2009 2010 showed striking contrasting temperature anomalies, particularly winter seasons. reasons for these anomalies analysed using data from mesoscale atmospheric model WRF (Weather Research Forecasting Model) run under...
Abstract. The total Antarctic sea ice extent (SIE) experiences a distinct annual cycle, peaking in September and reaching its minimum February. In this paper we propose mathematical statistical decomposition of temporal variation SIE. Each component is interpretable and, when combined, gives complete picture the ice. We consider timescales varying from instantaneous not previously defined to multi-decadal curvilinear trend, longest. Because our representation daily, these variability give...
Following efforts from leading centres for climate forecasting, sustained routine operational near-term predictions (NTCP) are now produced that bridge the gap between seasonal forecasts and change projections offering prospect of seamless services. Though NTCP is a new area science active research taking place to increase understanding processes mechanisms required produce skillful predictions, this significant technical achievement combines advances in initialisation with ensemble...