Browsing by Author "Boisvert, Linette N."
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Item Analysis of the warmest Arctic winter, 2015–2016(AGU, 2016-10-06) Cullather, Richard I.; Lim, Young-Kwon; Boisvert, Linette N.; Brucker, Ludovic; Lee, Jae N.; Nowicki, Sophie M. J.December through February 2015–2016 defines the warmest winter season over the Arctic in the observational record. Positive 2 m temperature anomalies were focused over regions of reduced sea ice cover in the Kara and Barents Seas and southwestern Alaska. A third region is found over the ice-covered central Arctic Ocean. The period is marked by a strong synoptic pattern which produced melting temperatures in close proximity to the North Pole in late December and anomalous high pressure near the Taymyr Peninsula. Atmospheric teleconnections from the Atlantic contributed to warming over Eurasian high-latitude land surfaces, and El Niño-related teleconnections explain warming over southwestern Alaska and British Columbia, while warm anomalies over the central Arctic are associated with physical processes including the presence of enhanced atmospheric water vapor and an increased downwelling longwave radiative flux. Preconditioning of sea ice conditions by warm temperatures affected the ensuing spring extent.Item Using remotely sensed data from AIRS to estimate the vapor flux on the Greenland ice sheet: Comparisons with observations and a regional climate model(AGU, 2016-12-22) Boisvert, Linette N.; Lee, Jae N.; Lenaerts, Jan T. M.; Noël, Brice; Broeke, Michiel R. van den; Nolin, Anne W.Mass loss from the Greenland ice sheet (GrIS) in recent years has been dominated by runoff from surface melt. It is currently being studied extensively, while little interest has been given to the smallest component of surface mass balance (SMB): the vapor flux. Although poorly understood, it is not negligible and could potentially play a larger role in SMB in a warming climate where temperature, relative humidity, and precipitation changes remain uncertain. Here we present an innovative approach to estimate the vapor flux using the Atmospheric Infrared Sounder (AIRS) version 6 data and a modified vapor flux model (BMF13) over the GrIS between 2003 and 2014. One modification to the BMF13 model includes a new Multiangle Imaging SpectroRadiometer surface aerodynamic roughness product, which likely produces more accurate estimates of the drag coefficient on the ice sheet. When comparing AIRS data with GC-Net and Programme for Monitoring of the Greenland Ice Sheet automatic weather station observations of skin temperature, near-surface air temperature, and humidity, they agree within 2 K, 2.68 K, and 0.34 g kg⁻¹. Largest differences occur in the ablation zone where there is significant subgrid heterogeneity. Overall, the average vapor flux from the GrIS between 2003 and 2014 was found to be 14.6 ± 3.6 Gt yr⁻¹. No statistically significant trends were found during the data record. This data set is compared to the Regional Atmospheric Climate Model (RACMO2.3) vapor flux, and BMF13 produced smaller vapor fluxes in the summer (~0.05 Gt d⁻¹) and slightly more deposition in the winter (~9.4 × 10⁻³ Gt d⁻¹). Annually, differences between BMF13 and RACMO2.3 were only 30 ± 15%.