It is not yet known how these fires started. Fires on carbon-rich soils can be initiated by an external source, e. The fires burned relatively close to the town of Sisimiut, so it is quite possible that humans started the fires. Self-heating is another possibility as porous solid fuels can undergo spontaneous exothermic reactions in oxidative atmospheres at low temperatures Drysdale, ; Restuccia et al. This process starts by slow exothermic oxidation at ambient temperature, causing a temperature increase, which is determined by the imbalance between the rate of heat generation and the rate of heat losses Drysdale, Fire initiated by self-heating ignition is a well-known hazard for many natural materials Fernandez Anez et al.
It might be possible that this long period of almost continuous insolation at these latitudes in July heated the soil enough to self-ignite. In any case, the continuous sunshine had dried the soil, making it susceptible to fire. The fact that these fires were burning for about 3 weeks but spread relatively slowly compared to above-ground vegetation fires indicates that the main fuel was probably peat.
In addition, the observed smoke was nearly white, indicating damp fuel, such as freshly thawed permafrost, which produces smoke rich in OC aerosol Stockwell et al. Literally no fires should be expected in Greenland, since there is little available fuel as it has been suggested by global models and validated by observations Daanen et al. However, it has been suggested that significant permafrost loss in Greenland may occur only by the end of the 21st century Daanen et al. The fires in might indicate that significant permafrost degradation has occurred sooner than expected.
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Due to the low injection altitude of the releases within the boundary layer, transport was relatively slow, and thus the emitted substances initially remained quite close to their source. Slow transport was also favored by mostly anticyclonic influence during the first half of August. It seems that even though katabatic winds from the Greenland ice sheet occasionally transported the plume westwards, most of the time the large-scale circulation pushed the plume back towards Greenland see animations in the Supplement.
Consequently, a large fraction of the emitted substances were deposited in southwestern Greenland. The colored rectangle depicts the nested high-resolution domain. This indicates the high relative potential of Greenland fires to pollute the cryosphere on a per unit emission basis , likely also giving them a particularly high radiative forcing efficiency. Considering that the projected rise of Greenland temperatures is expected to result in further degradation of the permafrost Daanen et al. We also calculated the concentration of the deposited carbon aerosols in Greenland snow Fig.
As expected, snow concentrations show the same general patterns as the simulated deposition with the highest concentrations obtained close to the source western side of Greenland. High snow concentrations were also computed in some regions of the ice sheet due to relatively intense precipitation events. By contrast, dry deposition example for BC over the ice sheets was low Fig. Dry deposition was only responsible for a major fraction of the deposition in regions where the plume was transported during dry weather, and in most of these regions total deposition was low.
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A notable exception is the region close to the fires, where dry deposition was relatively important due to the generally dry weather when the fires were burning. It can be also ascribed to the fact that dry deposition occurs in the quasi-laminar sublayer close to the surface. A fraction of the aerosols can be quickly deposited close to the sources before they are transported to higher altitudes and away from the sources Bellouin and Haywood, Snow BrC was estimated to be even less; though, to the best of our knowledge, no available measurements exist in the relevant literature so far.
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It has been reported that the size of rapidly coagulated aerosol particles produced by different types of fires ranges between 0. Therefore, we simulated the Greenland fires with an aerodynamic mean diameter of 0. To examine the sensitivity of deposition in the Greenland ice sheet from the Greenland fires of to the particle size distribution used in the model, we simulated the same event for particles with aerodynamic mean diameters of 0.
The results are shown in Fig. S5 for BC. In summertime , intense wildfires were reported in British Columbia, Western Canada NASA, c , and fires also burned at midlatitudes in Eurasia, as is typical during spring and summer Hao et al. Previous studies of wildfires have shown that the produced energy can be sufficient to loft smoke above the boundary layer by supercell convection Fromm et al. As a result, emitted aerosols can become subject to long-range transport over long distances Forster et al. As can be seen in Fig. In contrast, emissions from fires in Eurasia seem to have affected Greenland less.
Using gridded emissions for BC and OC, the contribution of both biomass burning and anthropogenic sources to surface concentrations in the four different regions over Greenland northwestern, northeastern, southwestern and southeastern Greenland; Fig. S7 was calculated see Sect. About one-third of BC and OC originated from wildfires in Eurasia and the rest from North America, where the year appears to have been a particularly high fire year. S7 , similar to what has been suggested previously for the Arctic in summer Winiger et al.
The anthropogenic contribution is larger in southern Greenland than in northern Greenland, due to the shorter distance from the main emission areas of North America and western Europe, but it remains much lower than the biomass burning contribution. For instance, von Schneidemesser et al. We attribute this difference in the calculated concentrations to more active fires during in Greenland than in previous years see Fig.
As an example of the importance of northern hemispheric biomass burning emissions for the air over Greenland, we present time series of surface BC concentrations in northwestern, northeastern, southwestern and southeastern Greenland from the fires in Greenland and from all the other wildfire emission sources occurring outside Greenland Northern Hemisphere for the same period of time Fig.
The calculated dosages concentrations summed over a specific time period for the same time period were also computed.
The fires in Greenland affected mainly its western part with concentrations that reached up to 4. The numbers represent the respective dosages time-integrated concentrations for the time period shown. The color codes are reported in the legend. There are few observations available that can be used to evaluate our model results. The simulated contribution of the Greenland fires to simulated BC burdens was negligible by comparison, except at Kangerlussuaq in the beginning of August when the Greenland fire emissions were the highest.
Column-integrated BC from anthropogenic sources was extremely small and it is not plotted here. High aerosol backscatter was only found in the close vicinity of the fires. The vertical distribution of simulated BC as a function of longitude is illustrated in Fig. In particular, the smoke resides at altitudes below 1.
This day is shown because almost all the aerosols emitted by the fires had been deposited, thus giving a high IRF via albedo reduction due to snow contamination. Note that the maximum albedo change due to deposited smoke is 0. The IRF depends on the optical properties of the smoke from the fire, which are not known. To estimate the uncertainty due to the choice of BC optical properties, additional calculations were made by scaling the SSA red solid lines in Fig.
Pokhrel et al. As such, our adopted SSA may be considered low compare black solid line and red line with upward-pointing triangles. The daily averaged IRF is seen to increase as the plume from the fires spreads out and starts to decline after the fires were extinguished at the end of the month. The fact that the reduction towards the end of August is relatively slow is caused by the effect of the albedo reduction, which persists until clean snow covers the polluted snow.
This indicates that BrC is most important for the IRF when it is airborne, even in the extreme scenario.
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According to Hansen et al. Skeie et al. For Greenland, Skeie et al. This number may be compared to our area averaged IRF estimate due to the Greenland fire. The maximum albedo change was about 0. Adding BrC from the most extreme scenario, the maximum albedo change was calculated to be 0. This albedo change has an impact on IRF, but it is too small to be measured by satellites. Also, Polashenski et al. Our conclusions can be summarized below. The fires burned on peatlands that became vulnerable by permafrost thawing.
The region where the fires burned was identified previously as being susceptible to permafrost melting; however, large-scale melting was expected to occur only towards the end of the 21st century. The fires show that at least in some locations substantial permafrost thawing is already occurring now.
We estimate that the maximum albedo change due to the BC deposition from the Greenland fires to be about 0. The average value when only BC was considered is up to an order of magnitude smaller than the radiative forcing due to BC from other sources. We conclude that the fires burning in Greenland in the summer of had a small impact on the Greenland ice sheet, causing almost negligible extra radiative forcing.
Thus, while the fires in were still relatively small on a global scale, if the expected future warming of the Arctic IPCC, produces more and larger fires in Greenland Keegan et al. All data used for the present publication can be obtained from the corresponding author upon request. NE performed the simulations and analyses, wrote the paper and coordinated the paper. AK performed the radiation calculations and wrote parts of the paper.
RP made all the runs for the injection height calculations using the PRMv2 model. SE and AS coordinated and commented on the manuscript. All authors contributed to the final version of the paper. Edited by: Alma Hodzic Reviewed by: three anonymous referees. Abdalati, W. Akagi, S. Anderson, C. Andreae, M. The nature of light-absorbing carbonaceous aerosols, Atmos.
Antony, R. Aurell, J. Bellouin, N. Results A total of patients were included in the validity analysis and 58 in the reliability analysis.
Download statistics No data available. University of Groningen staff: edit these data print. Follow the UG facebook twitter linkedin rss instagram youtube. Lynden Wash. Looks for our Saturday edition later today with all the results from today. Unbeknownst to the Irish, however, the coolant had leaked into the storage bay under the bus. By the time we arrived, we had about a 30 minute warm-up. We kept our poise and went in down a point at halftime. More than that, the Irish had built a lead before the Lions finished the game on a run of 38 unanswered points. Basil Schincariol, on runs of 12 and 25 yards, put the Irish on top in the first quarter before Connor Louis booted a yard field goal in the second.
He had our D prepared for their 2-QB system, which has threats in the air and on the ground. This was an opponent that will help us grow and play faster and more physically in future games. Schincariol rushed 13 times for yards and two scores and Louis caught five passes for 64 yards. Jason Soriano returned an interception 11 yards.
Vancouver College plays host to Handsworth this coming Saturday in its final home regular season game. Quarterback Dario Ciccone rallied the Knights , from a deficit in the second half, manufacturing a pair of fourth-quarter touchdown drives as STM beat the visiting Terry Fox Ravens , It was the kind of game in which the Knights took a figurative hit in the mouth before they knew what hit them.
Ciccone wound up taking it in from two-yards out to tie the game, before hitting Ricky Parsons with a yard touchdown pass that gave the hosts a halftime lead. The Ravens came back in the third quarter with back-to-back majors in the third quarter for a lead. But Ciccone led the Knights on a fourth-quarter rally, first hitting Parsons with an eight-yard swing pass for the score, then later calling his own number from two yards out for the winning major.
Ciccone had perhaps his best game of the season, rushing for 90 yards and two scores, while passing for yards and two scores. Simon had nine catches for yards, while Parsons finished with seven catches for 70 yards and two majors. Cade Cote and Liam Cumarasamy were a difficult one-two punch to stop. Thomas More is at Kelowna next week and at home to Mission to finish the regular season.
Tweedsmuir plays at Mission next week and closes at Abbotsford. Terry Fox closes out with two home games, first against Abbotsford and then against Centennial.
Quarterback Jalen Edwards rushed for 65 yards and his first major score of the season. Additionally, Calum Rowsell rushed for his first TD of the season in the fourth quarter, this one from 40 yards out. Jeff Vanderwerff controlled the middle of the line with three tackles and three batted balls, one of which was intercepted. As they have gotten healthier at the skill positions, the Notre Dame Jugglers have grown into an imposing football team. Notre Dame took the opening kickoff and drove the ball 70 yards, capping things with a five-yard Alexander-Amour score.
Handsworth then hit the score sheet for the only time as their defensive end scooped up a Clarke fumble and scored from midfield. In the second quarter, the Jugglers added two more touchdowns, a yard Alexander-Amour scamper and then another from 15 yards out for a lead at the break. In the second half the Notre Dame attack was slowed by penalties but they still had another Alexander-Amour touchdown in them, this one from 35 yards out.
All seven of the Notre Dame touchdowns were converted by Tristan Torresan.