The First Decade of the New Century: A Cooling Trend for Most of Alaska

Wendler, Gerd; Chen, L.; Moore, Blake

doi:10.2174/1874282301206010111

Cited by 33 publications

(42 citation statements)

References 14 publications

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“…In the state of Alaska, accelerated warming has been observed between 1970 and 2000 [6]. In subsequent years, temperatures have continued to rise in northern Alaska, although a decrease in temperature has been observed in the south [7]. This disproportionate increase in temperatures, at high latitudes in general and in Alaska in particular, makes Alaskan wetlands especially vulnerable to climate change.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of ALOS PALSAR Data for High-Resolution Mapping of Vegetated Wetlands in Alaska

et al. 2015

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As the largest natural source of methane, wetlands play an important role in the carbon cycle. High-resolution maps of wetland type and extent are required to quantify wetland responses to climate change. Mapping northern wetlands is particularly important because of a disproportionate increase in temperatures at higher latitudes. Synthetic aperture radar data from a spaceborne platform can be used to map wetland types and dynamics over large areas. Following from earlier work by using Japanese Earth Resources Satellite (JERS-1) data, we applied the "random forests" classification algorithm to variables from L-band ALOS PALSAR data for 2007, topographic data (e.g., slope, elevation) and locational information (latitude, longitude) to derive a map of vegetated wetlands in Alaska, with a spatial resolution of 50 m. We used the National Wetlands Inventory and National Land Cover Database (for upland areas) to select training and validation data and further validated classification results with an independent dataset that we created. A number of improvements were made to the method of Whitcomb et al. (2009): (1) more consistent training data in upland areas; (2) better distribution of training data across Remote Sens. 2015, 7 7273 all classes by taking a stratified random sample of all available training pixels; and (3) a more efficient implementation, which allowed classification of the entire state as a single entity (rather than in separate tiles), which eliminated discontinuities at tile boundaries. The overall accuracy for discriminating wetland from upland was 95%, and the accuracy at the level of wetland classes was 85%. The total area of wetlands mapped was 0.59 million km 2 , or 36% of the total land area of the state of Alaska. The map will be made available to download from NASA's wetland monitoring website.

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Section: Introductionmentioning

confidence: 99%

Evaluation of ALOS PALSAR Data for High-Resolution Mapping of Vegetated Wetlands in Alaska

et al. 2015

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“…5) indicate a cooling of the North Pacific waters. Such cooling will weaken the semipermanent Aleutian Low (Overland et al 1999;Rodionov et al 2007;Wendler et al 2012). We wanted to test this hypothesis with surface observations.…”

Section: Resultsmentioning

confidence: 99%

“…We offered as explanation the shift in the PDO index, which went to more negative values, bringing colder temperatures to Alaska (Wendler et al 2012). This decrease in temperature was especially pronounced in Western Alaska (Overland et al 2012), which lead to a weakening of the semipermanent Aleutian Low.…”

Section: Resultsmentioning

confidence: 99%

Recent sea ice increase and temperature decrease in the Bering Sea area, Alaska

Wendler

Chen

Moore

2013

Theor Appl Climatol

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“…In contrast, exp-2012 shows a significantly stronger cooling over Alaska. The negative PDO phase results in less warm air being advected from the North Pacific into this region, a transport which is especially important if solar radiation is weakened (Wendler, 2012). In 30 later simulation years, the cooling effect is less pronounced in both experiments (Fig 3 b, d, and f).…”

Section: Air Temperaturementioning

confidence: 89%

Assessing the Impact of a Future Volcanic Eruption on Decadal Predictions

Illing¹,

Kadow²,

Pohlmann³

et al. 2018

Preprint

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Abstract. The likelihood of a large volcanic eruption in the future provides the largest uncertainty concerning the evolution of the climate system on the time scale of a few years; but also an excellent opportunity to learn about the behavior of the climate system, and our models thereof. So the question emerges how predictable is the response of the climate system to future eruptions? By this we mean, to what extent will the volcanic perturbation affect decadal climate predictions and how 10 does the pre-eruption climate state influence the impact of the volcanic signal on the predictions? To address these questions, we performed decadal forecasts with the MiKlip prediction system in the low-resolution configuration for the initialization years 2012 and 2014, which differ in the Pacific Decadal Oscillation (PDO) phase among other things. Each forecast contains an artificial Pinatubo-like eruption starting in June of the first prediction year. For the construction of the aerosol radiative forcing, we used the global aerosol model ECHAM5-HAM in a version adapted for volcanic eruptions. We 15 investigate the response of different climate variables, including near-surface air temperature, precipitation, frost days, and sea ice area fraction. Our results show that the average global cooling response over four years of about 0.2K and the precipitation decrease of about 0.025mm/day, is relatively robust throughout the different experiments and seemingly independent of the initialization state. However, on a regional scale, we find substantial differences between the initializations. The cooling effect in the North Atlantic and Europe lasts longer and the Arctic sea ice increase is stronger 20 than in the simulations initialized in 2014. In contrast, the forecast initialized with a negative PDO shows a prolonged cooling in the North Pacific basin.

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The First Decade of the New Century: A Cooling Trend for Most of Alaska

Cited by 33 publications

References 14 publications

Evaluation of ALOS PALSAR Data for High-Resolution Mapping of Vegetated Wetlands in Alaska

Evaluation of ALOS PALSAR Data for High-Resolution Mapping of Vegetated Wetlands in Alaska

Recent sea ice increase and temperature decrease in the Bering Sea area, Alaska

Assessing the Impact of a Future Volcanic Eruption on Decadal Predictions

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