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Peter A. Bieniek
International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775, USA

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Journal article
Published: 17 January 2021 in Land
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The late-season extreme fire activity in Southcentral Alaska during 2019 was highly unusual and consequential. Firefighting operations had to be extended by a month in 2019 due to the extreme conditions of hot summer temperature and prolonged drought. The ongoing fires created poor air quality in the region containing most of Alaska’s population, leading to substantial impacts to public health. Suppression costs totaled over $70 million for Southcentral Alaska. This study’s main goals are to place the 2019 season into historical context, provide an attribution analysis, and assess future changes in wildfire risk in the region. The primary tools are meteorological observations and climate model simulations from the NCAR CESM Large Ensemble (LENS). The 2019 fire season in Southcentral Alaska included the hottest and driest June–August season over the 1979–2019 period. The LENS simulation analysis suggests that the anthropogenic signal of increased fire risk had not yet emerged in 2019 because of the CESM’s internal variability, but that the anthropogenic signal will emerge by the 2040–80 period. The effect of warming temperatures dominates the effect of enhanced precipitation in the trend towards increased fire risk.

ACS Style

Uma S. Bhatt; Rick T. Lader; John E. Walsh; Peter A. Bieniek; Richard Thoman; Matthew Berman; Cecilia Borries-Strigle; Kristi Bulock; Jonathan Chriest; Micah Hahn; Amy S. Hendricks; Randi Jandt; Joseph Little; Daniel McEvoy; Chris Moore; T. Scott Rupp; Jennifer Schmidt; Eric Stevens; Heidi Strader; Christine Waigl; James White; Alison York; Robert Ziel. Emerging Anthropogenic Influences on the Southcentral Alaska Temperature and Precipitation Extremes and Related Fires in 2019. Land 2021, 10, 82 .

AMA Style

Uma S. Bhatt, Rick T. Lader, John E. Walsh, Peter A. Bieniek, Richard Thoman, Matthew Berman, Cecilia Borries-Strigle, Kristi Bulock, Jonathan Chriest, Micah Hahn, Amy S. Hendricks, Randi Jandt, Joseph Little, Daniel McEvoy, Chris Moore, T. Scott Rupp, Jennifer Schmidt, Eric Stevens, Heidi Strader, Christine Waigl, James White, Alison York, Robert Ziel. Emerging Anthropogenic Influences on the Southcentral Alaska Temperature and Precipitation Extremes and Related Fires in 2019. Land. 2021; 10 (1):82.

Chicago/Turabian Style

Uma S. Bhatt; Rick T. Lader; John E. Walsh; Peter A. Bieniek; Richard Thoman; Matthew Berman; Cecilia Borries-Strigle; Kristi Bulock; Jonathan Chriest; Micah Hahn; Amy S. Hendricks; Randi Jandt; Joseph Little; Daniel McEvoy; Chris Moore; T. Scott Rupp; Jennifer Schmidt; Eric Stevens; Heidi Strader; Christine Waigl; James White; Alison York; Robert Ziel. 2021. "Emerging Anthropogenic Influences on the Southcentral Alaska Temperature and Precipitation Extremes and Related Fires in 2019." Land 10, no. 1: 82.

Journal article
Published: 01 June 2020 in Journal of Applied Meteorology and Climatology
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Lightning is a key driver of wildfire activity in Alaska. Quantifying its historical variability and trends has been challenging because of changes in the observational network, but understanding historical and possible future changes in lightning activity is important for fire management planning. Dynamically downscaled reanalysis and global climate model (GCM) data were used to statistically assess lightning data in geographic zones used operationally by fire managers across Alaska. Convective precipitation was found to be a key predictor of weekly lightning activity through multiple regression analysis, along with additional atmospheric stability, moisture, and temperature predictor variables. Model-derived estimates of historical June–July lightning since 1979 showed increasing but lower-magnitude trends than the observed record, derived from the highly heterogeneous lightning sensor network, over the same period throughout interior Alaska. Two downscaled GCM projections estimate a doubling of lightning activity over the same June–July season and geographic region by the end of the twenty-first century. Such a substantial increase in lightning activity may have significant impacts on future wildfire activity in Alaska because of increased opportunities for ignitions, although the final outcome also depends on fire weather conditions and fuels.

ACS Style

Peter A. Bieniek; Uma S. Bhatt; Alison York; John Walsh; Rick Lader; Heidi Strader; Robert Ziel; Randi R. Jandt; Richard L. Thoman. Lightning Variability in Dynamically Downscaled Simulations of Alaska’s Present and Future Summer Climate. Journal of Applied Meteorology and Climatology 2020, 59, 1139 -1152.

AMA Style

Peter A. Bieniek, Uma S. Bhatt, Alison York, John Walsh, Rick Lader, Heidi Strader, Robert Ziel, Randi R. Jandt, Richard L. Thoman. Lightning Variability in Dynamically Downscaled Simulations of Alaska’s Present and Future Summer Climate. Journal of Applied Meteorology and Climatology. 2020; 59 (6):1139-1152.

Chicago/Turabian Style

Peter A. Bieniek; Uma S. Bhatt; Alison York; John Walsh; Rick Lader; Heidi Strader; Robert Ziel; Randi R. Jandt; Richard L. Thoman. 2020. "Lightning Variability in Dynamically Downscaled Simulations of Alaska’s Present and Future Summer Climate." Journal of Applied Meteorology and Climatology 59, no. 6: 1139-1152.

Journal article
Published: 03 May 2020 in Forests
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Research Highlights: Flammability of wildland fuels is a key factor influencing risk-based decisions related to preparedness, response, and safety in Alaska. However, without effective measures of current and expected flammability, the expected likelihood of active and problematic wildfires in the future is difficult to assess and prepare for. This study evaluates the effectiveness of diverse indices to capture high-risk fires. Indicators of drought and atmospheric drivers are assessed along with the operational Canadian Forest Fire Danger Rating System (CFFDRS). Background and Objectives: In this study, 13 different indicators of atmospheric conditions, fuel moisture, and flammability are compared to determine how effective each is at identifying thresholds and trends for significant wildfire activity. Materials and Methods: Flammability indices are compared with remote sensing characterizations that identify where and when fire activity has occurred. Results: Among these flammability indicators, conventional tools calibrated to wildfire thresholds (Duff Moisture Code (DMC) and Buildup Index (BUI)), as well as measures of atmospheric forcing (Vapor Pressure Deficit (VPD)), performed best at representing the conditions favoring initiation and size of significant wildfire events. Conventional assessments of seasonal severity and overall landscape flammability using DMC and BUI can be continued with confidence. Fire models that incorporate BUI in overall fire potential and fire behavior assessments are likely to produce effective results throughout boreal landscapes in Alaska. One novel result is the effectiveness of VPD throughout the state, making it a potential alternative to FFMC among the short-lag/1-day indices. Conclusions: This study demonstrates the societal value of research that joins new academic research results with operational needs. Developing the framework to do this more effectively will bring science to action with a shorter lag time, which is critical as we face growing challenges from a changing climate.

ACS Style

Robert H. Ziel; Peter A. Bieniek; Uma S. Bhatt; Heidi Strader; T. Scott Rupp; Alison York. A Comparison of Fire Weather Indices with MODIS Fire Days for the Natural Regions of Alaska. Forests 2020, 11, 516 .

AMA Style

Robert H. Ziel, Peter A. Bieniek, Uma S. Bhatt, Heidi Strader, T. Scott Rupp, Alison York. A Comparison of Fire Weather Indices with MODIS Fire Days for the Natural Regions of Alaska. Forests. 2020; 11 (5):516.

Chicago/Turabian Style

Robert H. Ziel; Peter A. Bieniek; Uma S. Bhatt; Heidi Strader; T. Scott Rupp; Alison York. 2020. "A Comparison of Fire Weather Indices with MODIS Fire Days for the Natural Regions of Alaska." Forests 11, no. 5: 516.

Journal article
Published: 01 October 2018 in Earth Interactions
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Climate warming is expected to disproportionately affect crop yields in the southern United States due to excessive heat stress, while presenting new farming opportunities through a longer growing season farther north. Few studies have investigated the impact of this warming on agro-climate indices that link meteorological data with important field dates in northern regions. This study employs regional dynamical downscaling using the Weather Research and Forecasting (WRF) Model to assess changes in growing season length (GSL), spring planting dates, and occurrences of plant heat stress (PHS) for five regions in Alaska. Differences between future representative concentration pathway 8.5 (RCP8.5; 2011–40, 2041–70, 2071–2100) and historical (1981–2010) periods are obtained using boundary forcing from the Geophysical Fluid Dynamics Laboratory Climate Model, version 3, and the NCAR Community Climate System Model, version 4. The model output is bias corrected using ERA-Interim. Median GSL shows increases of 48–87 days by 2071–2100, with the largest changes in northern Alaska. Similarly, by 2071–2100, planting dates advance 2–4 weeks, and PHS days increase from near 0 to 5–10 instances per summer in the hottest areas. The largest GSL changes occur in the mid- (2041–70) and late century (2071–2100), when a warming signal emerges from the historical interannual variability. These periods coincide with the greatest divergence of the RCPs, suggesting that near-term decision-making may affect substantial future changes. Early-century (2011–40) projections show median GSL increases of 8–27 days, which is close to the historical standard deviation of GSL. Thus, internal variability will remain an important source of uncertainty into the midcentury, despite a trend for longer growing seasons.

ACS Style

Rick Lader; John E. Walsh; Uma S. Bhatt; Peter A. Bieniek. Agro-Climate Projections for a Warming Alaska. Earth Interactions 2018, 22, 1 -24.

AMA Style

Rick Lader, John E. Walsh, Uma S. Bhatt, Peter A. Bieniek. Agro-Climate Projections for a Warming Alaska. Earth Interactions. 2018; 22 (18):1-24.

Chicago/Turabian Style

Rick Lader; John E. Walsh; Uma S. Bhatt; Peter A. Bieniek. 2018. "Agro-Climate Projections for a Warming Alaska." Earth Interactions 22, no. 18: 1-24.

Journal article
Published: 01 August 2018 in Journal of Applied Meteorology and Climatology
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The ice formed by cold-season rainfall or rain on snow (ROS) has striking impacts on the economy and ecology of Alaska. An understanding of the atmospheric drivers of ROS events is required to better predict them and plan for environmental change. The spatially/temporally sparse network of stations in Alaska makes studying such events challenging, and gridded reanalysis or remote sensing products are necessary to fill the gaps. Recently developed dynamically downscaled climate data provide a new suite of high-resolution variables for investigating historical and projected ROS events across all of Alaska from 1979 to 2100. The dynamically downscaled reanalysis data of ERA-Interim replicated the seasonal patterns of ROS events but tended to produce more rain events than in station observations. However, dynamical downscaling reduced the bias toward more rain events in the coarse reanalysis. ROS occurred most frequently over southwestern and southern coastal regions. Extreme events with the heaviest rainfall generally coincided with anomalous high pressure centered to the south/southeast of the locations receiving the event and warm-air advection from the resulting southwesterly wind flow. ROS events were projected to increase in frequency overall and for extremes across most of the region but were expected to decline over southwestern/southern Alaska. Increases in frequency were projected as a result of more frequent winter rainfall, but the number of ROS events may ultimately decline in some areas as a result of temperatures rising above the freezing threshold. These projected changes in ROS can significantly affect wildlife, vegetation, and human activities across the Alaska landscape.

ACS Style

Peter A. Bieniek; Uma S. Bhatt; John E. Walsh; Rick Lader; Brad Griffith; Jennifer K. Roach; Richard L. Thoman. Assessment of Alaska Rain-on-Snow Events Using Dynamical Downscaling. Journal of Applied Meteorology and Climatology 2018, 57, 1847 -1863.

AMA Style

Peter A. Bieniek, Uma S. Bhatt, John E. Walsh, Rick Lader, Brad Griffith, Jennifer K. Roach, Richard L. Thoman. Assessment of Alaska Rain-on-Snow Events Using Dynamical Downscaling. Journal of Applied Meteorology and Climatology. 2018; 57 (8):1847-1863.

Chicago/Turabian Style

Peter A. Bieniek; Uma S. Bhatt; John E. Walsh; Rick Lader; Brad Griffith; Jennifer K. Roach; Richard L. Thoman. 2018. "Assessment of Alaska Rain-on-Snow Events Using Dynamical Downscaling." Journal of Applied Meteorology and Climatology 57, no. 8: 1847-1863.

Journal article
Published: 01 January 2018 in Atmospheric and Climate Sciences
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The wetness of high-latitude land surfaces is strongly dependent on the difference between precipitation (P) and evapotranspiration (ET). If climate models are to capture the trajectory of surface wetness in high latitudes, they must be able to simulate the seasonality and variations of the surface moisture fluxes, as well as the sensitivities to the variations to the drivers. In this study, a combination of regional climate model output and eddy covariance measurements from flux tower locations in Alaska is used to evaluate model simulations of the surface moisture fluxes and their variations. In particular, we use the model output and the field measurements to test the hypothesis that temperature (T) is the key driver of variations of ET in tundra regions underlain by permafrost, while precipitation plays a greater role in boreal forest areas. Although the model’s hydrologic cycle is stronger (larger P, larger ET) relative to the in situ measurements at all the sites, the prominent seasonal cycles of P, T, and ET are captured by the model. The tower measurements from all sites show a short period (one or two months) of negative P-ET during summer, indicative of surface drying, although the model does not show this period of drying at the inland tundra site. At all the tundra sites, both the flux tower data and the model simulations show that daily and warm-season totals of ET are largely temperature-driven. Daily ET shows a weak negative correlation with precipitation in the measurements and in the model results for all the sites. Precipitation is the main driver of year-to-year variations of the seasonally integrated net moisture flux at all the sites, implying that precipitation will be at least as important as temperature in the future trajectory of surface wetness.

ACS Style

Ross Fischer; John E. Walsh; Eugénie S. Euskirchen; Peter A. Bieniek. Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions. Atmospheric and Climate Sciences 2018, 08, 29 -54.

AMA Style

Ross Fischer, John E. Walsh, Eugénie S. Euskirchen, Peter A. Bieniek. Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions. Atmospheric and Climate Sciences. 2018; 08 (01):29-54.

Chicago/Turabian Style

Ross Fischer; John E. Walsh; Eugénie S. Euskirchen; Peter A. Bieniek. 2018. "Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions." Atmospheric and Climate Sciences 08, no. 01: 29-54.

Journal article
Published: 01 January 2018 in Bulletin of the American Meteorological Society
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ACS Style

John E. Walsh; Richard L. Thoman; Uma S. Bhatt; Peter A. Bieniek; Brian Brettschneider; Michael Brubaker; Seth Danielson; Rick Lader; Florence Fetterer; Kris Holderied; Katrin Iken; Andy Mahoney; Molly McCammon; James Partain. The High Latitude Marine Heat Wave of 2016 and Its Impacts on Alaska. Bulletin of the American Meteorological Society 2018, 99, S39 -S43.

AMA Style

John E. Walsh, Richard L. Thoman, Uma S. Bhatt, Peter A. Bieniek, Brian Brettschneider, Michael Brubaker, Seth Danielson, Rick Lader, Florence Fetterer, Kris Holderied, Katrin Iken, Andy Mahoney, Molly McCammon, James Partain. The High Latitude Marine Heat Wave of 2016 and Its Impacts on Alaska. Bulletin of the American Meteorological Society. 2018; 99 (1):S39-S43.

Chicago/Turabian Style

John E. Walsh; Richard L. Thoman; Uma S. Bhatt; Peter A. Bieniek; Brian Brettschneider; Michael Brubaker; Seth Danielson; Rick Lader; Florence Fetterer; Kris Holderied; Katrin Iken; Andy Mahoney; Molly McCammon; James Partain. 2018. "The High Latitude Marine Heat Wave of 2016 and Its Impacts on Alaska." Bulletin of the American Meteorological Society 99, no. 1: S39-S43.

Article
Published: 25 January 2017 in International Journal of Climatology
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This study presents (1) the temporal variations and trends of monthly and daily temperature and precipitation extremes in Alaska, and (2) the synoptic-scale circulation patterns associated with these extremes. The analysis is based on daily station observations of maximum temperature, minimum temperature and precipitation from 1948–2012 as well as monthly average temperatures and precipitation from 1920–2012 from 13 Alaska climate divisions. The frequencies of daily and monthly temperature extremes show variability and trends over the past 50–90 years consistent with a warming climate in Alaska. This warming is superimposed on low-frequency variability attributed to the Pacific Decadal Oscillation. Unlike the temperature extremes, occurrences of heavy-precipitation extremes do not display a coherent signal through time. The changes do not appear to be linked with an overall increase in the variance of temperature or precipitation. Composite analysis of sea level pressure (SLP) anomalies associated with a representative sample of different daily and monthly temperature extremes across Alaska shows that temperature and moisture advection, subject to topographic and coastal influences, is a key driver of these events. Composite SLP fields for daily and monthly extremes are similar, especially in winter, indicating that monthly extremes represent the recurrence of daily extreme patterns during those extreme months. The SLP anomalies were also often reduced in magnitude in the summer events compared with winter, consistent with the lower variance of temperature and SLP during summer.

ACS Style

Peter A. Bieniek; John E. Walsh. Atmospheric circulation patterns associated with monthly and daily temperature and precipitation extremes in Alaska. International Journal of Climatology 2017, 37, 208 -217.

AMA Style

Peter A. Bieniek, John E. Walsh. Atmospheric circulation patterns associated with monthly and daily temperature and precipitation extremes in Alaska. International Journal of Climatology. 2017; 37 ():208-217.

Chicago/Turabian Style

Peter A. Bieniek; John E. Walsh. 2017. "Atmospheric circulation patterns associated with monthly and daily temperature and precipitation extremes in Alaska." International Journal of Climatology 37, no. : 208-217.

Journal article
Published: 01 December 2016 in Bulletin of the American Meteorological Society
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ACS Style

James L. Partain; Sharon Alden; Heidi Strader; Uma Bhatt; Peter A. Bieniek; Brian R. Brettschneider; John E. Walsh; Rick T. Lader; Peter Q. Olsson; T. Scott Rupp; Richard L. Thoman; Alison D. York; Robert H. Ziel. An Assessment of the Role of Anthropogenic Climate Change in the Alaska Fire Season of 2015. Bulletin of the American Meteorological Society 2016, 97, S14 -S18.

AMA Style

James L. Partain, Sharon Alden, Heidi Strader, Uma Bhatt, Peter A. Bieniek, Brian R. Brettschneider, John E. Walsh, Rick T. Lader, Peter Q. Olsson, T. Scott Rupp, Richard L. Thoman, Alison D. York, Robert H. Ziel. An Assessment of the Role of Anthropogenic Climate Change in the Alaska Fire Season of 2015. Bulletin of the American Meteorological Society. 2016; 97 (12):S14-S18.

Chicago/Turabian Style

James L. Partain; Sharon Alden; Heidi Strader; Uma Bhatt; Peter A. Bieniek; Brian R. Brettschneider; John E. Walsh; Rick T. Lader; Peter Q. Olsson; T. Scott Rupp; Richard L. Thoman; Alison D. York; Robert H. Ziel. 2016. "An Assessment of the Role of Anthropogenic Climate Change in the Alaska Fire Season of 2015." Bulletin of the American Meteorological Society 97, no. 12: S14-S18.

Journal article
Published: 01 March 2016 in Journal of Applied Meteorology and Climatology
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The European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim) has been downscaled using a regional model covering Alaska at 20-km spatial and hourly temporal resolution for 1979–2013. Stakeholders can utilize these enhanced-resolution data to investigate climate- and weather-related phenomena in Alaska. Temperature and precipitation are analyzed and compared among ERA-Interim, WRF Model downscaling, and in situ observations. Relative to ERA-Interim, the downscaling is shown to improve the spatial representation of temperature and precipitation around Alaska’s complex terrain. Improvements include increased winter and decreased summer higher-elevation downscaled seasonal average temperatures. Precipitation is also enhanced over higher elevations in all seasons relative to the reanalysis. These spatial distributions of temperature and precipitation are consistent with the few available gridded observational datasets that account for topography. The downscaled precipitation generally exceeds observationally derived estimates in all seasons over mainland Alaska, and it is less than observations in the southeast. Temperature biases tended to be more mixed, and the downscaling reduces absolute bias at higher elevations, especially in winter. Careful selection of data for local site analysis from the downscaling can help to reduce these biases, especially those due to inconsistencies in elevation. Improved meteorological station coverage at higher elevations will be necessary to better evaluate gridded downscaled products in Alaska because biases vary and may even change sign with elevation.

ACS Style

Peter A. Bieniek; Uma S. Bhatt; John Walsh; T. Scott Rupp; Jing Zhang; Jeremy R. Krieger; Rick Lader. Dynamical Downscaling of ERA-Interim Temperature and Precipitation for Alaska. Journal of Applied Meteorology and Climatology 2016, 55, 635 -654.

AMA Style

Peter A. Bieniek, Uma S. Bhatt, John Walsh, T. Scott Rupp, Jing Zhang, Jeremy R. Krieger, Rick Lader. Dynamical Downscaling of ERA-Interim Temperature and Precipitation for Alaska. Journal of Applied Meteorology and Climatology. 2016; 55 (3):635-654.

Chicago/Turabian Style

Peter A. Bieniek; Uma S. Bhatt; John Walsh; T. Scott Rupp; Jing Zhang; Jeremy R. Krieger; Rick Lader. 2016. "Dynamical Downscaling of ERA-Interim Temperature and Precipitation for Alaska." Journal of Applied Meteorology and Climatology 55, no. 3: 635-654.

Journal article
Published: 01 December 2015 in Earth Interactions
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The mechanisms driving trends and variability of the normalized difference vegetation index (NDVI) for tundra in Alaska along the Beaufort, east Chukchi, and east Bering Seas for 1982–2013 are evaluated in the context of remote sensing, reanalysis, and meteorological station data as well as regional modeling. Over the entire season the tundra vegetation continues to green; however, biweekly NDVI has declined during the early part of the growing season in all of the Alaskan tundra domains. These springtime declines coincide with increased snow depth in spring documented in northern Alaska. The tundra region generally has warmed over the summer but intraseasonal analysis shows a decline in midsummer land surface temperatures. The midsummer cooling is consistent with recent large-scale circulation changes characterized by lower sea level pressures, which favor increased cloud cover. In northern Alaska, the sea-breeze circulation is strengthened with an increase in atmospheric moisture/cloudiness inland when the land surface is warmed in a regional model, suggesting the potential for increased vegetation to feedback onto the atmospheric circulation that could reduce midsummer temperatures. This study shows that both large- and local-scale climate drivers likely play a role in the observed seasonality of NDVI trends.

ACS Style

Peter A. Bieniek; Uma Bhatt; Donald A. Walker; Martha K. Raynolds; Josefino C. Comiso; Howard E. Epstein; Jorge E. Pinzon; Compton J. Tucker; Richard L. Thoman; Huy Tran; Nicole Mölders; Michael Steele; Jinlun Zhang; Wendy Ermold. Climate Drivers Linked to Changing Seasonality of Alaska Coastal Tundra Vegetation Productivity. Earth Interactions 2015, 19, 1 -29.

AMA Style

Peter A. Bieniek, Uma Bhatt, Donald A. Walker, Martha K. Raynolds, Josefino C. Comiso, Howard E. Epstein, Jorge E. Pinzon, Compton J. Tucker, Richard L. Thoman, Huy Tran, Nicole Mölders, Michael Steele, Jinlun Zhang, Wendy Ermold. Climate Drivers Linked to Changing Seasonality of Alaska Coastal Tundra Vegetation Productivity. Earth Interactions. 2015; 19 (19):1-29.

Chicago/Turabian Style

Peter A. Bieniek; Uma Bhatt; Donald A. Walker; Martha K. Raynolds; Josefino C. Comiso; Howard E. Epstein; Jorge E. Pinzon; Compton J. Tucker; Richard L. Thoman; Huy Tran; Nicole Mölders; Michael Steele; Jinlun Zhang; Wendy Ermold. 2015. "Climate Drivers Linked to Changing Seasonality of Alaska Coastal Tundra Vegetation Productivity." Earth Interactions 19, no. 19: 1-29.

Journal article
Published: 29 August 2013 in Remote Sensing
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Vegetation productivity trends for the Arctic tundra are updated for the 1982–2011 period and examined in the context of land surface temperatures and coastal sea ice. Understanding mechanistic links between vegetation and climate parameters contributes to model advancements that are necessary for improving climate projections. This study employs remote sensing data: Global Inventory Modeling and Mapping Studies (GIMMS) Maximum Normalized Difference Vegetation Index (MaxNDVI), Special Sensor Microwave Imager (SSM/I) sea-ice concentrations, and Advanced Very High Resolution Radiometer (AVHRR) radiometric surface temperatures. Spring sea ice is declining everywhere except in the Bering Sea, while summer open water area is increasing throughout the Arctic. Summer Warmth Index (SWI—sum of degree months above freezing) trends from 1982 to 2011 are positive around Beringia but are negative over Eurasia from the Barents to the Laptev Seas and in parts of northern Canada. Eastern North America continues to show increased summer warmth and a corresponding steady increase in MaxNDVI. Positive MaxNDVI trends from 1982 to 2011 are generally weaker compared to trends from 1982–2008. So to better understand the changing trends, break points in the time series were quantified using the Breakfit algorithm. The most notable break points identify declines in SWI since 2003 in Eurasia and 1998 in Western North America. The Time Integrated NDVI (TI-NDVI, sum of the biweekly growing season values of MaxNDVI) has declined since 2005 in Eurasia, consistent with SWI declines. Summer (June–August) sea level pressure (slp) averages from 1999–2011 were compared to those from 1982–1998 to reveal higher slp over Greenland and the western Arctic and generally lower pressure over the continental Arctic in the recent period. This suggests that the large-scale circulation is likely a key contributor to the cooler temperatures over Eurasia through increased summer cloud cover and warming in Eastern North America from more cloud-free skies.

ACS Style

Uma S. Bhatt; Donald A. Walker; Martha K. Raynolds; Peter A. Bieniek; Howard E. Epstein; Josefino C. Comiso; Jorge E. Pinzon; Compton J. Tucker; Igor V. Polyakov. Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra. Remote Sensing 2013, 5, 4229 -4254.

AMA Style

Uma S. Bhatt, Donald A. Walker, Martha K. Raynolds, Peter A. Bieniek, Howard E. Epstein, Josefino C. Comiso, Jorge E. Pinzon, Compton J. Tucker, Igor V. Polyakov. Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra. Remote Sensing. 2013; 5 (9):4229-4254.

Chicago/Turabian Style

Uma S. Bhatt; Donald A. Walker; Martha K. Raynolds; Peter A. Bieniek; Howard E. Epstein; Josefino C. Comiso; Jorge E. Pinzon; Compton J. Tucker; Igor V. Polyakov. 2013. "Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra." Remote Sensing 5, no. 9: 4229-4254.

Journal article
Published: 01 July 2012 in Journal of Applied Meteorology and Climatology
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Alaska encompasses several climate types because of its vast size, high-latitude location, proximity to oceans, and complex topography. There is a great need to understand how climate varies regionally for climatic research and forecasting applications. Although climate-type zones have been established for Alaska on the basis of seasonal climatological mean behavior, there has been little attempt to construct climate divisions that identify regions with consistently homogeneous climatic variability. In this study, cluster analysis was applied to monthly-average temperature data from 1977 to 2010 at a robust set of weather stations to develop climate divisions for the state. Mean-adjusted Advanced Very High Resolution Radiometer surface temperature estimates were employed to fill in missing temperature data when possible. Thirteen climate divisions were identified on the basis of the cluster analysis and were subsequently refined using local expert knowledge. Divisional boundary lines were drawn that encompass the grouped stations by following major surrounding topographic boundaries. Correlation analysis between station and gridded downscaled temperature and precipitation data supported the division placement and boundaries. The new divisions north of the Alaska Range were the North Slope, West Coast, Central Interior, Northeast Interior, and Northwest Interior. Divisions south of the Alaska Range were Cook Inlet, Bristol Bay, Aleutians, Northeast Gulf, Northwest Gulf, North Panhandle, Central Panhandle, and South Panhandle. Correlations with various Pacific Ocean and Arctic climatic teleconnection indices showed numerous significant relationships between seasonal division average temperature and the Arctic Oscillation, Pacific–North American pattern, North Pacific index, and Pacific decadal oscillation.

ACS Style

Peter A. Bieniek; Uma Bhatt; Richard L. Thoman; Heather Angeloff; James Partain; John Papineau; Frederick Fritsch; Eric Holloway; John Walsh; Christopher Daly; Martha Elizabeth Durr Shulski; Gary L Hufford; David F. Hill; Stavros Calos; Rudiger Gens. Climate Divisions for Alaska Based on Objective Methods. Journal of Applied Meteorology and Climatology 2012, 51, 1276 -1289.

AMA Style

Peter A. Bieniek, Uma Bhatt, Richard L. Thoman, Heather Angeloff, James Partain, John Papineau, Frederick Fritsch, Eric Holloway, John Walsh, Christopher Daly, Martha Elizabeth Durr Shulski, Gary L Hufford, David F. Hill, Stavros Calos, Rudiger Gens. Climate Divisions for Alaska Based on Objective Methods. Journal of Applied Meteorology and Climatology. 2012; 51 (7):1276-1289.

Chicago/Turabian Style

Peter A. Bieniek; Uma Bhatt; Richard L. Thoman; Heather Angeloff; James Partain; John Papineau; Frederick Fritsch; Eric Holloway; John Walsh; Christopher Daly; Martha Elizabeth Durr Shulski; Gary L Hufford; David F. Hill; Stavros Calos; Rudiger Gens. 2012. "Climate Divisions for Alaska Based on Objective Methods." Journal of Applied Meteorology and Climatology 51, no. 7: 1276-1289.