scholarly journals The impact of wintertime sea-ice anomalies on high surface heat flux events in the Iceland and Greenland Seas

2020 ◽  
Vol 54 (3-4) ◽  
pp. 1937-1952
Author(s):  
James O. Pope ◽  
Thomas J. Bracegirdle ◽  
Ian A. Renfrew ◽  
Andrew D. Elvidge
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Surface Heat Flux ◽  
High Surface ◽  
Surface Heat ◽  
The Impact

scholarly journals Thermodynamic feedback processes in a single-column sea-ice-ocean model

1997 ◽  
Vol 25 ◽  
pp. 327-332 ◽  
Author(s):  
Marika M. Holland ◽  
Julie L. Schramm ◽  
Judith A. Curry
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Surface Heat Flux ◽  
General Circulation ◽  
Accurate Determination ◽  
Circulation Model ◽  
Surface Heat ◽  
Physical Processes ◽  
Feedback Mechanisms ◽  
Albedo Feedback

Due to large uncertainties in many of the parameters used to model sea ice, it is possible that models with significantly different physical processes can be tuned to obtain realistic present-day simulations. However, in studies of climate change, it is the response of the model it various perturbations that is important, in studies response can be significantly different in sea-ice models that include or exclude various physical feedback mechanisms. Because simplifications in sea-ice physics are necessary for general circulation model experiments, it is important to assess which physical processes are essential for the accurate determination of the sensitivity of the ice pack to climate perturbations. We have attempted to address these issues using a new coupled ice-thickness distribution ocean mixed-layer model. The sensitivity of the model to surface heat-flux perturbations is examined and the importance of the ice ocean and ice-albedo feedback mechanisms in determining this sensitivity is analyzed. We find that the ice ocean and ice-albedo feedback processes are not mutually exclusive, and that they both significantly alter the model response to surface heat flux perturbations.

Crustal structure of the Valhalla complex, British Columbia, from Lithoprobe seismic-reflection and potential-field data

1990 ◽  
Vol 27 (8) ◽  
pp. 1048-1060 ◽  
Author(s):  
David W. S. Eaton ◽  
Frederick A. Cook
Keyword(s):  
Heat Flux ◽  
North American ◽  
Seismic Reflection ◽  
Surface Heat Flux ◽  
Field Data ◽  
High Surface ◽  
Surface Heat ◽  
Upper Crust ◽  
Potential Field Data ◽  
Lower Crustal

The Valhalla complex, situated in the Omineca crystalline belt in southeastern British Columbia, is a Cordilleran metamorphic core complex bordering the suture zone between Quesnellia and North American rocks. The region is tectonically interposed between a convergent plate margin along Canada's west coast and the stable North American craton, and is characterized by a crustal thickness of ~ 35 km, high surface heat flux, and elevated lower crustal electrical conductivity. In this study, Lithoprobe deep-crustal seismic-reflection data, potential-field data, and geological constraints have been used to gain a better understanding of crustal structure in the vicinity of the Valhalla complex. Analysis of Bouguer gravity and total-field aeromagnetic data indicates that mafic oceanic rocks and various syn- and post-accretionary granitoid plutonic rocks are not major constituents of the upper crust underlying the complex. The seismic data reveal a moderately reflective upper crust and image several fault zones, including a very high amplitude, west-dipping reflection that is interpreted as a significant Late Cretaceous or Paleocene thrust fault. The fault-zone reflectivity may be related to compositional heterogeneity and (or) seismic anisotropy associated with mylonites. The lower crust appears to be nonreflective, in contrast with other areas of high surface heat flux and elevated lower crustal conductivity. Taken together, the various data show that the Valhalla complex is likely cored by North American metasedimentary rocks and reveal features related to the Jurassic to Paleocene compressional fabric, which has been largely overprinted at the surface by subsequent Eocene extension.

Atmospheric and Oceanic Contributions to Irreducible Forecast Uncertainty of Arctic Surface Climate

2015 ◽  
Vol 29 (1) ◽  
pp. 331-346 ◽  
Author(s):  
Steffen Tietsche ◽  
Ed Hawkins ◽  
Jonathan J. Day
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Time Scales ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Initial State ◽  
Forecast Uncertainty ◽  
Surface Climate ◽  
Oceanic Heat Flux ◽  
Arctic Surface

Abstract Uncertainty of Arctic seasonal to interannual predictions arising from model errors and initial state uncertainty has been widely discussed in the literature, whereas the irreducible forecast uncertainty (IFU) arising from the chaoticity of the climate system has received less attention. However, IFU provides important insights into the mechanisms through which predictability is lost and hence can inform prioritization of model development and observations deployment. Here, the authors characterize how internal oceanic and surface atmospheric heat fluxes contribute to the IFU of Arctic sea ice and upper-ocean heat content in an Earth system model by analyzing a set of idealized ensemble prediction experiments. It is found that atmospheric and oceanic heat flux are often equally important for driving unpredictable Arctic-wide changes in sea ice and surface water temperatures and hence contribute equally to IFU. Atmospheric surface heat flux tends to dominate Arctic-wide changes for lead times of up to a year, whereas oceanic heat flux tends to dominate regionally and on interannual time scales. There is in general a strong negative covariance between surface heat flux and ocean vertical heat flux at depth, and anomalies of lateral ocean heat transport are wind driven, which suggests that the unpredictable oceanic heat flux variability is mainly forced by the atmosphere. These results are qualitatively robust across different initial states, but substantial variations in the amplitude of IFU exist. It is concluded that both atmospheric variability and the initial state of the upper ocean are key ingredients for predictions of Arctic surface climate on seasonal to interannual time scales.

scholarly journals Thermodynamic feedback processes in a single-column sea-ice–ocean model

1997 ◽  
Vol 25 ◽  
pp. 327-332
Author(s):  
Marika M. Holland ◽  
Julie L. Schramm ◽  
Judith A. Curry
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Surface Heat Flux ◽  
General Circulation ◽  
Accurate Determination ◽  
Circulation Model ◽  
Surface Heat ◽  
Physical Processes ◽  
Feedback Mechanisms ◽  
Albedo Feedback

Due to large uncertainties in many of the parameters used to model sea ice, it is possible that models with significantly different physical processes can be tuned to obtain realistic present-day simulations. However, in studies of climate change, it is the response of the model it various perturbations that is important, in studies response can be significantly different in sea-ice models that include or exclude various physical feedback mechanisms. Because simplifications in sea-ice physics are necessary for general circulation model experiments, it is important to assess which physical processes are essential for the accurate determination of the sensitivity of the ice pack to climate perturbations. We have attempted to address these issues using a new coupled ice-thickness distribution ocean mixed-layer model. The sensitivity of the model to surface heat-flux perturbations is examined and the importance of the ice ocean and ice-albedo feedback mechanisms in determining this sensitivity is analyzed. We find that the ice ocean and ice-albedo feedback processes are not mutually exclusive, and that they both significantly alter the model response to surface heat flux perturbations.

A Microscale Study of the Impact of Bubble Growth Dynamics on Surface Heat Flux in Microchannel Flow Boiling Process

2015 ◽  
Author(s):  
Sajjad Bigham ◽  
Saeed Moghaddam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Flow Boiling ◽  
Surface Heat ◽  
Bubble Wall ◽  
Average Surface ◽  
Boiling Process ◽  
The Impact

In this study, the physics of microscale heat transfer events at the wall-fluid interface during the growth of a moving bubble in a microchannel is analyzed. The study is enabled through development of a novel device that utilizes 53 microscale platinum resistance temperature detectors (RTDs) embedded in a composite substrate made of a high thermal conductivity material coated by a thin layer of a low thermal conductivity material. This sensors arrangement enables resolving the thermal field at the bubble-wall interface with unprecedented spatial and temporal resolutions of 40–65 μm and 50 μs, respectively. To prevent random bubble inception, a 300 nm in diameter cavity is fabricated using a focused ion beam (FIB) at the center of a pulsed function microheater. A detailed analysis of the surface heat transfer events and their relations to time scale of formation and dimensions of bubbles are conducted to decipher the underlying physics of the flow boiling process. Experimental results show that four mechanisms of heat transfer are active as a bubble grows and flows through the channel. These mechanisms of heat transfer are 1) microlayer evaporation, 2) interline evaporation, 3) transient conduction, and 4) micro-convection. The results suggest that the average surface heat flux enhances as the bubble grows in size resulting in expansion of the surface area over which the thin film evaporation mechanism is active. Above a certain bubble size, the average surface heat flux declines due to the formation of a dry region at the bubble-wall interface. Hence, the results indicate that there is an optimal bubble length at which the average surface heat flux is maximum.

scholarly journals Summer Cyclones and Their Association With Short-Term Sea Ice Variability in the Pacific Sector of the Arctic

2021 ◽  
Vol 9 ◽  
Author(s):  
Peter M. Finocchio ◽  
James D. Doyle
Keyword(s):  
Heat Flux ◽  
Surface Energy ◽  
Sea Ice ◽  
Surface Heat Flux ◽  
Radiative Forcing ◽  
Surface Heat ◽  
Wind Forcing ◽  
The Arctic ◽  
Large Sample ◽  
The Pacific

We investigate the effects of summer cyclones on sea ice within the Pacific sector of the Arctic by analyzing the surface energy flux and wind forcing from a large sample of cyclones. Consistent with recent studies, we find that cyclones earlier in the melt season tend to be associated with less 1–5 day sea ice loss than what occurs in the absence of cyclones. In contrast, cyclones later in the melt season slightly accelerate the 1-day sea ice loss. The reduced ice loss following cyclones in June is primarily due to increased cloud cover reducing the net shortwave flux at the surface. Clouds associated with cyclones in July and August also reduce the net shortwave flux at the surface, but only over high-concentration sea ice. Southerly winds associated with August cyclones increase both the negative local sea ice advection and the surface heat flux, particularly for the low concentration sea ice that is prevalent in August. Sea ice advection and surface heat flux are the only two factors we examined that can explain the enhanced ice loss on cyclone days in August. We also examined two cyclone cases that impacted sea ice in the East Siberian Sea in June 2012 and August 2016, and found for both cyclones that the sensible heat flux is the largest positive anomalous forcing and the shortwave radiative flux is the largest negative anomalous forcing. Similar to the large sample of cyclones, the shortwave flux has a stronger relationship to local changes in SIC in June than in August. Part of the reason for this is that the cloud shortwave radiative forcing during the August cyclone is 26% weaker than during the June cyclone. In an area averaged sense, the anomalous surface energy and wind forcing of both cyclone cases is similar in magnitude, yet the August cyclone is followed by a greater reduction in both sea ice area and mean sea ice concentration than the June cyclone. This result emphasizes how the underlying sea ice characteristics largely determine cyclone impacts on sea ice on short time scales.

Sign in / Sign up

Export Citation Format

Share Document