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Historically, Michigan's climate had mainly three challenges for grape production: growing season temperatures were too low, the growing season was too short and there was too much rain near harvest. However, climate change in the past decades has led to a vastly different landscape that is evolving to meet the new climate. Recently, there has been a significant move from Vitis labrusca (North American) grape plantings to Vitis vinifera (wine grapes) as a consequence of Michigan's shifting climate. The goal of this study was to analyze the historical shift in climate and its potential future impact on the grape industry. We obtained data climate model projection data from two greenhouse gas (GHG) emission scenarios. First, a multi-linear regression model was built to predict future grape yields (t/ac) using data from the climate model projections. Second, trends in the severity of the three challenges (temperature, season length, precipitation timing) were analyzed. In both GHG scenarios grape yields are seen to improve, but to different extents. The improvement is likely a response to warmer season temperatures canceling out losses to early season frost. Model projections recommend that Michigan's future climate will be more accommodating for all varieties of grapes. This suggests that grape production will continue to grow, but the landscape will continue to evolve with more emphasis on varieties that are more climatically sensitive to cold temperatures. Climate change has greatly affected Michigan's viticultural landscape, and will continue to do so in the coming decades. [ABSTRACT FROM AUTHOR]

Soil temperature can exhibit considerable memory from weather and climate signals and is among the most important initial conditions in numerical weather and climate models. Consequently, a more accurate long-term land surface soil temperature dataset is needed to improve weather and climate simulation and prediction, and is also important for the simulation of agricultural crop yield and ecological processes. The North American Land Data Assimilation phase 2 (NLDAS-2) has generated 31 years (1979-2009) of simulated hourly soil temperature data with a spatial resolution of ⅛°. This dataset has not been comprehensively evaluated to date. Thus, the purpose of this paper is to assess Noah-simulated soil temperature for different soil depths and time scales. The authors used long-term (1979-2001) observed monthly mean soil temperatures from 137 cooperative stations over the United States to evaluate simulated soil temperature for three soil layers (0-10, 10-40, and 40-100 cm) for annual and monthly time scales. Short-term (1997-99) observed soil temperatures from 72 Oklahoma Mesonet stations were used to validate simulated soil temperatures for three soil layers and for daily and hourly time scales. The results showed that the Noah land surface model generally matches observed soil temperature well for different soil layers and time scales. At greater depths, the simulation skill (anomaly correlation) decreased for all time scales. The monthly mean diurnal cycle difference between simulated and observed soil temperature revealed large midnight biases in the cold season that are due to small downward longwave radiation and issues related to model parameters. [ABSTRACT FROM AUTHOR]

To assess the influence of global climate change at the regional scale, we examine past and future changes in key climate, hydrological, and biophysical indicators across the US Northeast (NE). We first consider the extent to which simulations of twentieth century climate from nine atmosphere-ocean general circulation models (AOGCMs) are able to reproduce observed changes in these indicators. We then evaluate projected future trends in primary climate characteristics and indicators of change, including seasonal temperatures, rainfall and drought, snow cover, soil moisture, streamflow, and changes in biometeorological indicators that depend on threshold or accumulated temperatures such as growing season, frost days, and Spring Indices (SI). Changes in indicators for which temperature-related signals have already been observed (seasonal warming patterns, advances in high-spring streamflow, decreases in snow depth, extended growing seasons, earlier bloom dates) are generally reproduced by past model simulations and are projected to continue in the future. Other indicators for which trends have not yet been observed also show projected future changes consistent with a warmer climate (shrinking snow cover, more frequent droughts, and extended low-flow periods in summer). The magnitude of temperature-driven trends in the future are generally projected to be higher under the Special Report on Emission Scenarios (SRES) mid-high (A2) and higher (A1FI) emissions scenarios than under the lower (B1) scenario. These results provide confidence regarding the direction of many regional climate trends, and highlight the fundamental role of future emissions in determining the potential magnitude of changes we can expect over the coming century. [ABSTRACT FROM AUTHOR]

The climatology of shallow foehn, also known locally as elevated south-easterly gales (ESEGs), on the northern lee side of the central Tianshan Mountains is analysed using radiosonde data recorded over a period of 10 years at Urumqi, the capital of Xinjiang Uygur Autonomous Region in north-western China. ESEGs are a frequent weather phenomenon in the region, occurring on average 128.5 days/yr and most often in winter (47.0 days), particularly January (17.5 days), and least in summer (18 days). The vertical ESEG structures also undergo seasonal variations, with the height of the maximum ESEG wind and the base and top of the ESEG layer more elevated in the warm half (late spring through early fall) of the year than the cold half. However, the monthly mean maximum wind speeds, which vary around 10 m/s, appear to be independent of season. A typical synoptic pattern accompanying ESEGs is characterized by opposite air masses to the east (cold) and west (warm) of Xinjiang. A strong low-level west-east pressure gradient helps push cold air to enter Xinjiang from the east, which subsequently induces a north-south pressure gradient across the Tianshan Mountains. This regional pressure gradient combined with terrain channelling leads to the development of ESEGs. A comparison of boundary layer structure between days with/without ESEGs in winter shows that the ESEG days are accompanied by deeper (average of 900 m) and more intense (average 6 °C) inversion, but there is little difference in the cold air pool Froude Number between the two types of days. • A climatology of shallow foehn on the lee side of the central Tianshan Mountains in northwestern China is produced; • Regional pressure gradients combined with terrain channelling lead to the development of shallow foehn events • A deeper, more intense surface-based inversion usually accompanies a shallow foehn event [ABSTRACT FROM AUTHOR]