Abstract: We show useful seasonal deterministic and probabilistic prediction skill of streamflow and nutrient loading over watersheds in the Southeastern United States (SEUS) for the winter and spring seasons. The study accounts for forecast uncertainties stemming from the meteorological forcing and hydrological model uncertainty. Multi-model estimation from three hydrological models, each forced with an ensemble of forcing derived by matching observed analogues of forecasted quartile rainfall anomalies from a seasonal climate forecast is used. The attained useful hydrological prediction skill is despite the climate model overestimating rainfall by over 23% over these SEUS watersheds in December–May period. The prediction skill in the month of April and May is deteriorated as compared to the period from December–March (zero lead forecast). A nutrient streamflow rating curve is developed using a log linear tool for this purpose. The skill in the prediction of seasonal nutrient loading is identical to the skill of seasonal streamflow forecast.

Abstract: From the 1930s through the 1950s-the decades bracketing the second and third international polar years research in the physical and biological environmental sciences of the Arctic increased dramatically. The heroic, expedition-based style of Arctic science, dominant in the first decades of the twentieth century, gave way to a systematic, long-term, strategic and largely statefunded model of research which increased both Arctic presence and the volume of research output. Factors that made this change possible were distinct for each of the five circumpolar nation-states considered here. For Soviet leaders, the Arctic was an untamed land containing vast economic resources, all within reach if its long-sought Northern Sea Route became reality; Soviet officials sought environmental knowledge of this region with a range of motivations from economic and strategic concerns to enhancing the prestige of socialism. In contrast, United States officials largely ignored the Arctic until the outbreak of World War II, when military commanders quickly grasped the strategic importance of this region. Anxious that the Arctic might become a literal battleground between East and West by 1947, as the Cold War began, Pentagon leaders funded vast northern research programs, including in strategically located Greenland. Canadian leaders while appreciating the national security concerns of its powerful southern neighbor were even more concerned with maintaining sovereignty over its northern territories and gaining knowledge to assist its northern economic ambitions. Norway and Sweden, as smaller states, faced distinct challenges. With strong claims to Arctic heritage but limited resources, leaders of these states sought to create independent research strategies while, especially in the case of Norway, protecting their geopolitical interests in relation to the Soviet Union and the U.S. This article provides the first internationally comparative study of the multiple economic, military, political, and strategic factors that motivated scientific activities and programs in the far north, from the interwar period through World War II and the Cold War, when carefully coordinated, station-based research programs were introduced. The production of knowledge about Arctic's physical environment including its changing climate had little resemblance either to ideas of science-based 'progress,' or responses to perceived environmental concerns. Instead, it demonstrates that strategic military, economic, geopolitical, and national security concerns influenced and shaped most science undertakings, including those of the International Polar Year of 1932-1933 and the following polar year, the International Geophysical Year of 1957-1958.

Abstract: Tall fescue (Festuca arundinacea Schreb.) is the predominant perennial cool-season grass grown in the USA. Typically, tall fescue is infected with the endophyte, Neotyphodium coenophialum Morgan-Jones & Gams, which produces alkaloids that are toxic to grazing animals. Nontoxic endophyte-infected cultivars of tall fescue have been developed, but to maximize their utility for profitable livestock production a better understanding of conditions affecting seed and tiller transmission is needed to maintain endophytes in seed. Our understanding of mechanisms of endophyte transmission in planta is limited. Seasonal variations of endophyte in established tall fescue pastures in Watkinsville, GA, and seed fields near Salem, OR, were examined. Growth chamber experiments were conducted to examine temperature effects on plant and endophyte growth and to determine the cardinal minimum temperatures for each. Endophyte frequency varied over months in both Georgia and Oregon. Frequency averaged 93.4% when sampled April through December, but was 80.5% when sampled January through March in Georgia. Frequency averaged 64.5% when sampled February through April, but was 88.6% during other months in Oregon. Cardinal minimum temperature for plant growth was 5.2C (0.5), but for endophyte was 10.3C (0.7). Temperature appears to be a major variable affecting fluctuation of endophyte frequency in plant tissue.

Abstract: Agricultural productivity is strongly dependent on local climate conditions determined by meteorological parameters thus assessing the potential impact of the climate change and variability on regional agricultural systems has become crucial. To ensure food security, it is required to find under performing regions to investments and assess yields change in high-performing regions in coming decades under climate change and variability. In this study, we investigate the response of maize yield potential (Yp) on climate change scenario using Agricultural Production Systems sIMulator (APSIM) crop model over the Southwestern U.S. (SWUS) region. APSIM's modules are essentially point-based models representing the system at a single point in space. We develop automated modeling framework (ApsimRegions, 2013), which allows the APSIM to be run over a large domain with about a thousand points over the study area. Using 21-year period (1991-2011) of North American Regional Reanalysis (NARR) data, we perform sensitivity test of the maize Yp to assess the relative contribution of climate variables, by adding standard deviation of the climatological values. The results show that maximum and minimum temperature greatly contribute to the variation of maize yields over the SWUS on the interannual time scale, depending on geographical locations with varied local climates. In order to access data of present and future climate, we have completed high-resolution regional climate simulation by dynamically downscaling general circulation model results (GFDL-ESM2M) using regional climate models (WRF and OLAM). In this study, 20 years of integration period is selected in both historical period (1981-2000) and future period (2031-2050). The potential maize yields in the future period under the RCP8.5 greenhouse gas concentrations pathways show that the yields are significantly changed comparing to the historical period. In the generally rising temperature regime, the projected Yp shows strong geospatial variations according to the regional climate characteristics. (C) 2015 The Authors. Published by Elsevier B.V.

Abstract: The impacts of irrigation on southeast United States diurnal climate are investigated using simulations from a regional climate model. An extreme case is assumed, wherein irrigation is set to 100 % of field capacity over the growing season of May through October. Irrigation is applied to the root zone layers of 10�40 and 40�100 cm soil layers only. It is found that in this regime there is a pronounced decrease in monthly averaged temperatures in irrigated regions across all months. In non-irrigated areas a slight warming is simulated. Diurnal maximum temperatures in irrigated areas warm, while diurnal minimum temperatures cool. The daytime warming is attributed to an increase in shortwave flux at the surface owing to diminished low cloud cover. Nighttime and daily mean cooling result as a consequence repartitioning of energy into latent heat flux over sensible heat flux, and of a higher net downward ground heat flux. Excess heat is transported into the deep soil layer, preventing a rapidly intensifying positive feedback loop. Both diurnal and monthly average precipitations are reduced over irrigated areas at a magnitude and spatial pattern similar to one another. Due to the excess moisture availability, evaporation is seen to increase, but this is nearly balanced by a corresponding reduction in sensible heat flux. Concomitant with additional moisture availability is an increase in both transient and stationary moisture flux convergences. However, despite the increase, there is a large-scale stabilization of the atmosphere stemming from a cooled surface.

Abstract: Along the Atlantic coast of the United States, interannual sea-level variations of up to 20 mm are superimposed regionally upon the global average sea-level rise (~3 mm/year) from human-caused global warming. These variations affect the degree of coastal flooding and related damage during the highest annual tides. Interannual sea-level variations have been attributed to several atmospheric and oceanographic processes. In the present analysis, detrended tide gauge data isolate >5-year interannual variations. These variations can be reliably reconstructed (>77% of the variance explained) with Fourier coefficients that have frequencies related to lunar orbit (nodal and apsidal precessions) combined with solar activity. Although a causal relationship between astronomical forcing and extreme sea levels remains elusive, the reconstructions may provide an effective method for projections of extreme sea levels. Two reconstructions project that anomalously high sea levels may occur in the late 2020s, mid-2050s, early 2060s, early 2070s, and late 2090s.