Alaska Climate Dispatch A state-wide seasonal summary & outlook Brought to you by the Alaska Center for Climate Assessment and Policy in partnership with the Alaska Climate Research Center, SEARCH Sea Ice Outlook, National Centers for Environmental Prediction, and the National Weather Service. Autumn 2012 Issue IN THIS ISSUE: Alaska-Canada Cliome Shift Project...page 1-2 Solar Radiation Measurements... 2-4 Summer Weather Summary... 4-7 Sea Ice Update... 7-8 Upcoming Events... 8 Alaska-Canada Climate-Biome Shift Project Overview By Nancy Fresco, Scenarios Network for Alaska and Arctic Planning Figure 1. From the new SNAP Alaska-Canada Climate-Biome Shift project report: Eighteen-cluster map for the entire study area. The project is a climate-linked cluster analysis approach to analyzing possible ecological refugia and areas of greatest change. The Alaska Climate-Biome Shift Project (AK Cliomes) and the Yukon and Northwest Territories (NWT) Climate- Biome Shift Project (Ca Cliomes) is a collaborative effort that uses clustering methodology, existing land cover designations, and historical and projected climate data to identify areas of Alaska, the Yukon, and NWT (Figure 1) that are likely to undergo the greatest or least ecological pressure, given climate change. Project results and data are presented in the final project report, link below. Results are intended to serve as a framework for research and planning by land managers and other stakeholders with an interest in ecological and socioeconomic sustainability. Cliomes are broadly defined regions of temperature and precipitation patterns that reflect assemblages of species and vegetation communities (biomes) that occur or might be expected to occur based on linkages with climate conditions. They are not the same as actual biomes, since actual species shift incorporates significant and variable lag times, as well as factors not directly linked to climate. However, results serve as indicators of potential change and/or stress to ecosystems, and can help guide stakeholders in the management of areas of greatest and lowest resilience to changing climate. The AK Cliomes and Ca Cliomes projects modeled projected shifts in climate-biomes based on current and historical climatic conditions and projected climate change. The eighteen cliomes ACCAP is funded by the National Oceanic and Atmospheric Administration (NOAA) and is one of a group of Regional Integrated Sciences and Assessments (RISA) programs nation-wide. The RISA program supports research that addresses sensitive and complex climate issues of concern to decision-makers and policy planners at a regional level.
Alaska-Canada Cliomes Project Solar Radiation Measurements 2 used in this project were identified using the combined Random Forests and Partitioning Around Medoids (PAM) clustering algorithms, which are defined by monthly average temperature and precipitation, and used to create each cluster. They were also assessed via comparisons with four existing land-classification schemes for North America (NALCMS Land cover, AVHRR Land cover, GlobCover 2009, and a combination of the Unified Ecoregions of Alaska described by Nowacki et al. 2001 and Canadian Ecozones). We used Random Forests to model projected spatial shifts in climatebiomes, based on Scenarios Network for Alaska and Arctic Planning (SNAP) projections for monthly average temperature and precipitation for the decades 2001 2009, 2030 2039, 2060 2069, and 2090 2099. Alaska and the Yukon were modeled at 2km resolution. These fine-scale data are not available for Canada s Northwest Territories, so outputs for this territory are at 18.4km resolution. For all areas, we addressed the inevitable uncertainty of climate projections by analyzing outputs for five different downscaled General Circulation Models (GCMs) as well as for a composite (average) of all five, and for three different greenhouse-gas emissions scenarios (B2, A1B, and A2). The results of this modeling effort show that profound changes can be expected across the study area, with most regions experiencing at least one cliome shift by the end of the century, and some areas shifting three times. Although results differed according to which GCM was used and which emissions scenario was selected, the general patterns of change were relatively robust. These patterns involved a northward movement of cliomes, with arctic clusters shrinking or disappearing, interior boreal and taiga clusters shifting, and clusters currently found only outside of the study area appearing in Alaska, the Yukon, and the Northwest Territories. Cliomes that are currently typical of the central and southern British Columbia, Alberta, and Saskatchewan are likely to become prevalent in a large percentage of the study area. Interpretation suggests a high likelihood for changing precipitation and temperature conditions which may be beneficial to some existing plant and animal species while placing others under high stress. We analyzed all outputs for resilience (defined as lack of projected cliome shift) and vulnerability (defined as multiple cliome shifts over time). The most resilient regions are projected to be the coastal rainforest of southcentral and southeast Alaska, and the most vulnerable areas are projected to be interior and arctic regions, with the exception of the islands of the NWT. However, these conclusions may be affected by the relative dissimilarity of the coastal rainforest to any other cluster in North America; species change may be less there simply because surrounding cliomes differ so greatly. The ramifications of these projected changes for land managers and local residents are varied, and depend on the mandates and goals of the organizations and agencies involved. By linking species-specific data and local details of landscape ecology to these projections, land managers can make informed decisions about how to adapt to a changing landscape in an active manner. The Alaska project was funded and led by the U.S. Fish and Wildlife Service (USFWS), and the Canadian project was funded by The Nature Conservancy s Canada Project, Ducks Unlimited, and the Governments of YT and NWT. Data and analysis were provided by the University of Alaska Fairbanks (UAF) Scenarios Network for Alaska and Arctic Planning (SNAP) program and Ecological Wildlife Habitat Data Analysis for the Land and Seascape Laboratory (EWHALE) lab. Further input was provided by stakeholders from other interested organizations. Download the final report: http://bit.ly/q2enyw. Contact Nancy Fresco for questions: nlfresco@alaska.edu. Solar Radiation Measurements in Fairbanks By G. Wendler, K. Galloway, and B. Moore Alaska Climate Research Center In spring 2012, the Alaska Climate Research Center started making solar radiation measurements on the roof of the Geophysical Institute, UAF, Fairbanks. These observations were of the sum of direct beam and sky radiation, known as global radiation to climate scientists. In this article, we will refer to this as total radiation. Measurements were made on: (a) a horizontal surface (b) a south slope inclined to 65 (c) a south wall (90 )
Solar Radiation Measurements 3 Figure 2. Epply PSP (Precision Spectral Pyranometer), covered with a double glass dome with a transparency between 285-2800 um measuring the global radiation. Picture provided by the Alaska Climate Research Center (http://akclimate.org). Table 1. Average Monthly radiative fluxes (average, highest, and lowest daily value) for the time period April - August 2012. Table provided by the Alaska Climate Research Center (http://akclimate.org). These are most often the preferred inclinations for photovoltaic arrays. We will discuss the advantages and disadvantages of the different installations for a high latitude location in this article. (a) The horizontal installation (Figure 2) is the amount the Earth surface receives, therefore it is important for biological processes. Also, on a clear day in midsummer, the sun is above the horizon in Fairbanks for more than 19 hours, and the maximum solar radiation is received. The disadvantage is experienced in winter, when the solar elevation is very low, in midwinter, less than 5. Therefore at that time very little energy is received on a horizontal surface. In addition, snow may accumulate and the array may have to be frequently cleaned to receive solar radiation. (b) Over the year, the photovoltaic array inclined to latitude receives the greatest amount of radiation for a static installation. On a cloudy day it receives less radiation than the horizontal surface, but on clear days greater amounts are measured. Snow accumulation is less of a problem when compared to a horizontal exposure. During the spring and autumn equinoxes, the solar rays are perpendicular to the array at solar noon. (c) The south wall receives more radiation in winter than the other exposures, at a time of year when solar radiation is weak, however the annual sum is less than the two other installations because it has only southern exposure. This array is preferred when electricity is required year-round. In addition, it is the easiest to maintain, as snowfall does not normally affect it. Figure 3. Average monthly values of total radiation on a horizontal surface, south slope inclined to latitude, south wall, and the IR flux, April to August 2012. Figure provided by the Alaska Climate Research Center (http://akclimate.org).
Solar Radiation Measurements Summer Weather Summary 4 Figure 5. Average daily variation of the total radiation, June 2012. Figure provided by the Alaska Climate Research Center (http:// akclimate.org). Figure 4. Daily values of the total radiation on the horizontal, June 2012. Figure provided by the Alaska Climate Research Center (http:// akclimate.org). In addition to these sensors, we also measured the infrared radiative (IR) flux, which is nearly always negative. The total radiation (GL) on the horizontal reduced by the reflected amount minus the IR represents the surface radiation budget (RB), which is normally negative in winter and positive in summer, or expressed mathematically as: GL x (1- α) IR = RB, with α = surface reflectivity There is a strong daily variation in the output with average maxima at solar noon, for Fairbanks somewhat later than 12 pm, and no radiation around midnight. The average monthly daily variation for June is presented in Figure 4. The average monthly maximum for June is 291m 2. It might be useful to mention the so-called solar constant, this is the radiation perpendicular to the sun s rays and outside the Earth s atmosphere. The value is 1365W m 2, however, as the atmosphere absorbs some of the radiation, such a value can never be reached at the Earth s surface: it is the limit of available energy for satellites circling the Earth. We received a full month of data in April 2012. In Table 1, the average monthly values as well as the day with the highest and lowest value of the month are given. One would expect that June has the highest values, but May had very similar ones. This is caused by cloudiness, which increases fairly steadily from low values in spring to higher values in late summer. D. Dissing, who wrote her thesis on the solar radiation in Alaska, observed this trend for Interior Alaska. The average monthly total radiation values are presented in Figure 3. The average daily flux is just over 200W m 2 (1 m 2 = 10.72 ft), or over a 24-hour period, some 5 KWH are received per m 2. The observed values varied widely, with the maximum of 7.4 and a minimum of 2.1 KWH between a clear and overcast day, respectively. The actual output of such an array will be slightly less, as the efficiency of an array is not 100%. Summer Weather Conditions in Alaska By G. Wendler, B. Moore and K. Galloway Alaska Climate Research Center This article presents a summary of summer 2012 (June, July, August) temperatures and precipitation from the first order meteorological stations (operated by the National Weather Service meteorologists) in Alaska. The deviations from the long-term average are based on the new normal of 1981-2010. Temperature Figure 6 shows the summer temperature departure from the 30-year average (1981-2010). Alaska had temperatures noticeably colder than the normal (i.e. negative deviation). This is especially remarkable as the contiguous United States
Summer Weather Summary 5 Figure 6. Summer 2012 Isotherm map of the deviation in temperature ( F) from the 30-year normal (1981-2010) based on all first order meteorological stations in Alaska. Figure provided by the Alaska Climate Research Center (http://akclimate.org). reported record high summer temperatures. From the twenty first order stations, only Barrow (+3.7 F) and to a much lesser extent Bettles (+0.1 F) were above the seasonal expected values. The highest negative deviations (>2.0 F) in decreasing order were observed for Homer (-3.1 F), Talkeetna (-2.3 F), Bethel (-2.2 F) and Gulkana, King Salmon and Juneau (all -2.1 F). An especially strong gradient (6.8 F) in the departures can be seen in the north-south direction from Barrow to Homer. The strong negative deviations, which are especially pronounced in the coastal areas of southern Alaska, are strongly influenced by the Pacific Decadal Oscillation (PDO). The PDO is related to the ocean temperature in the northern Pacific, and negative values (which were found for all months of this year) reflect cooler ocean temperatures. In total, eighteen of the twenty stations analyzed here were colder than normal, while two had average temperatures above normal. The average deviation of all stations comes to -1.2 F. While this would not be a substantial value for a monthly deviation for one station, it is much more impressive when representing a seasonal (three months) deviation for an area as large as Alaska. It is the 5th season in a row with a below normal temperature. More details for specific stations can be seen from Table 2. Looking at the temperatures for the 3 summer months Temperature ( F) 70 60 50 40 30 20 10 0 separately, all three summer months had temperatures below normal. June started the season with temperatures deviation of -0.9 F of normal. Positive deviations greater than +2 F was only observed for one station, namely Bettles (+2.1 F), situated in northwestern Alaska. Further, thirteen of the twenty stations analyzed reported negative deviations, with the maximum amount found for Juneau (-2.9 F). July was particularly cool. Temperatures were below the 30-year average for nineteen stations in Alaska, with an average value of the twenty stations of -2.1 F. Only a single station, Barrow, in northern Alaska, was seasonably warmer than the average (+3.1 F). Strong negative deviations in declining order were measured for Homer (-4.3 F), Bethel (-3.8 F), Talkeetna (-3.6 F), and McGrath and Anchorage (both -3.3 F). August continued the cool seasonal temperature trend, with sixteen of the twenty stations reporting below normal values. The average monthly value for all stations was 0.6 F. However, Barrow (+6.3 F) was again the only station significantly Barrow, Alaska 80 1-Jun 6-Jun 11-Jun 16-Jun 21-Jun Daily Range Alaska Climate Research Center 26-Jun * Record Set / Tied 1-Jul 6-Jul 11-Jul 16-Jul Record High Record Low 21-Jul 26-Jul 31-Jul 5-Aug Normal Range * 10-Aug Summer 2012 1 15-Aug * * 20-Aug 25-Aug Precipitation 30-Aug 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Precipitation (inches) Geophysical Institute, UAF Figure 7. Daily temperature ranges and precipitation for Barrow (the station with the largest positive temperature deviation) for summer 2012. Note the generally warmer than normal temperatures with two corresponding record warm events. Not shown are the six new daily high minimum temperature records that were set between the 14th and 22nd of August. Figure provided by the Alaska Climate Research Center (http://akclimate.org).
Summer Weather Summary 6 Figure 8. Summer 2012 precipitation departures (%) from the 30-year normal (1981-2010) based on all first order meteorological stations in Alaska. Figure provided by the Alaska Climate Research Center (http://akclimate.org). warmer than normal. This is related to the strong retreat of the sea ice in the Beaufort Sea and the Arctic Ocean in general, as open water in the coastal areas is able to warm above the freezing point of sea ice. By the end of August, the sea ice in the Arctic Ocean had a new absolute minimum in extent of about four million km 2 (see Sea Ice Update, page 7). Otherwise, the negative temperature deviations in Alaska were widespread and fairly uniform, with only one station, Homer (-2.2 F), reporting a value larger then 2 F. With the relatively cool temperatures this summer, we would expect that the number of new daily low temperature records would outnumber the new daily high records, and indeed, this was the case. Most surprising were the four new high records in St. Paul, in addition to the two new low records. Valdez, King Salmon and Barrow each set two new high records. The two record highs, as well as the six new daily high minimum temperature records that were set between the 14th and 22nd at Barrow (Figure 7) helped establish the significant temperature deviation of +3.7 F. Cold Bay set five new record cold events during the season; a remarkable number. Valdez set three new daily cold records. Annette, Kodiak, McGrath, Sitka and St. Paul each set two. On July 12th, record cold temperatures were measured in Juneau, Sitka and Annette as cold spell settled in across the Southeast. Precipitation As the variability in precipitation is very large in Alaska (a ratio greater than 100 can be found in the annual values between the driest and wettest locations) actual deviations from the long-term average are not very meaningful. Therefore, Figure 8 presents these deviations as percentages above (+) or below (-) normal, where normal is the 30 year average (1981-2010). As there can be also a strong gradient in precipitation from month to month in the long-term average, the deviations for the seasonal values are the sum of the precipitation for the three months, divided by the longterm average for the three months (Table 2), hence the average of the three monthly deviations might slightly depart from these values. In general the precipitation of the summer of 2012 was slightly (+6%) above normal (Figure 8), even though only 40% of the stations reported above normal rain. Five stations had a very wet summer, here expressed with values of at least 40% above normal. In declining order of the deviations these are: Kotzebue (+91%), Nome (+89%), McGrath (+51%), Juneau (+45%) and King Salmon (+43%). There was only one station with a very high negative deviation, namely Cold Bay with just above half of the expected value. For more details, see the Table 2, which presents the temperature and precipitation deviations for all three months and the season. Looking at the months separately, June and July were somewhat wetter than average, while August was slightly drier than average. Given the relative amounts of precipitation for each month, it is not surprising that there were slightly more precipitation records reported in July as for both June and August together. Juneau, King Salmon, Nome and Kotzebue each set three new daily records during the summer season. On July 9th, a number of records were set across the Southeast as a cyclonic system impacted the area. On July 18th Nome broke a 101 year record. The precipitation records in Nome and Kotzebue helped drive the stations to the highest percent deviations of all twenty stations. The combination of below normal temperatures
Summer Weather Summary Sea Ice Update 7 Table 2. The deviation in temperature ( F) and in precipitation (%) from the 30-year normal (1981-2010) is presented for all first order stations for each summer month and for the summer season. Table provided by the Alaska Climate Research Center (http://akclimate.org). and far above normal precipitation values in May and June made it a slower fire season in most area, with around 250,000 acres burned, about 1/4th of the long-term average value. Flood watches were issued for northwest Alaska as a once in 100-year rainfall event struck the region in August. Gauges in the region recorded four to six inches of total of precipitation over several days starting on August 13th; when an unusual low-pressure front stalled over the Chukchi Sea and poured rain into the region for a week. Kivalina bore the brunt of the storm as flooding knocked out the water supply, and then spread waste as the flooding hit the community landfill. The lack of water delayed the opening of school in September by about a month and has prompted the school and community to look at aggressive water conservation measures as winter approaches. The winter issue of the Alaska Climate Dispatch will provide a thorogh overview of fall 2012 flood events and the associated economic impacts to communities. Sea Ice Update By John Walsh, President s Professor of Climate Change & Chief Scientist, International Arctic Research Center, UAF At the time of the mid-september minimum, the main pack ice had receded to a position more than 500 miles north of Barrow, leaving some areas north of 75ºN ice-free for the first time since satellite records began in the 1970s. Despite the extreme retreat of the main pack ice, patches of ice drifted into the Chukchi sea during August and early September, interfering with exploratory oil drilling operations. Nevertheless, the summer minimum (reached on September 16, according to the National Snow and Ice Data Center) represented a dramatic ice loss from the moreextensive-than-normal coverage of the Bering Sea during the past winter. The extreme change from winter to summer points to the pervasiveness of seasonal thin ice, which is vulnerable to rapid melting during spring and summer. For the Arctic as a whole, the 2012 sea ice minimum broke the preceding record (set in 2007) by more than half
Sea Ice Update 8 Upcoming Events: ACCAP Alaska Climate Webinars October 30, 2012; Sea Ice Links to Weather in the Arctic and Beyond; with Jennifer Francis, Rutgers University. November 6, 2012; AOOS Data Portal and the Environmental Response Management Application for the Arctic Region; with Darcy Dugan, Alaska Ocean Observing System. December 11, 2012; Do Trophic Cascades Affect the Storage of Flux of Atmospheric Carbon? An Analysis of Sea Otters and Kelp Forests; with Chris Wilmers, University of California, Santa Cruz. To register for webinars or browse our multi-media webinar archives, please visit our website: www.accap.uaf.edu/ teleconference.htm. Figure 9. Sea ice concentration on September 22, 2012. Color-scale for concentrations is in upper left portion of figure. Figure courtesy of Cryosphere Today, http://arctic.atmos.uiuc.edu/cryosphere/. a million square kilometers. The minimum extent was below all the forecasts in the Sea Ice Outlook summarized in the June issue of the Climate Dispatch. Sea ice in the Arctic has decreased dramatically since the late 1970s, particularly in summer and autumn. As shown in Figure 10, the September minimum extent of 2012 was only about 50% of the average minimum extents of the 1980s and 1990s. Moreover, the six lowest summer minima have occurred in the past six years, 2007-2012. Ice loss increases Arctic warming by replacing white, reflective ice with dark water that absorbs more energy from the Sun during summer. More open water can also increase snowfall over northern land areas during the autumn. These types of atmospheric impacts of the diminished ice cover are beginning to appear in the observational data. For more information about the Alaska Center for Climate Assessment & Policy, please contact us: accap@uaf.edu www.accap.uaf.edu (907) 474-7812 UAF is an affirmative action/equal opportunity employer and educational institution. Figure 10. Seasonal cycles of Arctic sea ice extent in recent years (colored lines; 2012 in red). Averages for the decades of the 1980s, 1990s and 2000s are shown by gray dashed lines. Figure courtesy of IARC/JAXA, www.iarc.uaf.edu.