Sensitivity of June near‐surface temperatures and precipitation in the eastern United States to historical land cover changes since European settlement

Abstract

[1] Land cover changes alter the near surface weather and climate. Changes in land surface properties such as albedo, roughness length, stomatal resistance, and leaf area index alter the surface energy balance, leading to differences in near surface temperatures. This study utilized a newly developed land cover data set for the eastern United States to examine the influence of historical land cover change on June temperatures and precipitation. The new data set contains representations of the land cover and associated biophysical parameters for 1650, 1850, 1920, and 1992, capturing the clearing of the forest and the expansion of agriculture over the eastern United States from 1650 to the early twentieth century and the subsequent forest regrowth. The data set also includes the inferred distribution of potentially water-saturated soils at each time slice for use in the sensitivity tests. The Regional Atmospheric Modeling System, equipped with the Land Ecosystem-Atmosphere Feedback (LEAF-2) land surface parameterization, was used to simulate the weather of June 1996 using the 1992, 1920, 1850, and 1650 land cover representations. The results suggest that changes in surface roughness and stomatal resistance have caused present-day maximum and minimum temperatures in the eastern United States to warm by about 0.3°C and 0.4°C, respectively, when compared to values in 1650. In contrast, the maximum temperatures have remained about the same, while the minimums have cooled by about 0.1°C when compared to 1920. Little change in precipitation was found.Citation: Strack, J. E., R. A. Pielke Sr., L. T. Steyaert, and R. G. Knox (2008), Sensitivity of June near-surface temperatures and precipitation in the eastern United States to historical land cover changes since European settlement, Water Resour. Res.,

Ecosystem Feedbacks to Climate Change in California: Development, Testing, and Analysis Using a Coupled Regional Atmosphere and Land Surface Model (WRF3–CLM3.5)

“…(For the purposes of this discussion, a study examining a decrease in forest cover from a baseline is interpreted analogously to the opposite of an increase in forest cover from the baseline.) However, our results are consistent with other studies that have found net cooling due to increased ET and cloudiness as a result of increased temperate forest cover (Jackson et al 2005;Juang et al 2007;Ramankutty et al 2006;Roy et al 2003;Strack et al 2008). Even some of the studies that found a net warming predicted some contrasting seasonal and regional effects, in which shortwave warming from afforestation dominated in winter months in snowy regions and evaporative cooling dominated in summer months (Diffenbaugh 2005;Snyder et al 2004a).…”

“…Other modeling studies and one observational study have found that decreased Bowen ratios and increased cloudiness dominate, causing a net cooling (Jackson et al 2005;Juang et al 2007;Ramankutty et al 2006;Roy et al 2003;Strack et al 2008). Many studies find seasonal and regional contrasts, with the albedo decrease being most significant in the winter over snow, and the evapotranspiration effect being more important in the summer during the daytime (Diffenbaugh 2005;Lamptey et al 2005;Roy et al 2003).…”

Impacts of Land Use/Land Cover Change on Climate and Future Research Priorities

“…Rather, they use fundamental physical parameters such as heat capacity (McNider et al 2005), roughness lengths, and canopy resistance. Fundamental work is required to develop robust relationships between the land use class and these fundamental variables, such as has been applied in the studies of Steyaert and Knox (2008) and Strack et al (2008). Additional focus on the statistical distribution of these parameters that characterizes LULCC is needed.…”

Reduced wind strengthens top‐down control of an insect herbivore

“…This gradient is responsible for atmospheric circulation, and as the gradient decreases wind speeds are expected to decrease as well (McVicar et al 2012). Second, reforestation, agricultural abandonment, and manmade structures have increased the number of physical obstacles on the landscape (Strack et al 2008, Vautard et al 2010. These obstacles slow wind speeds by physically impeding air flow (Sud et al 1988, Strack et al 2008 and can have reciprocating effects on temperature and precipitation patterns (Sud et al 1988, Nair et al 2011.…”