Impacts of Land Use Land Cover on Temperature Trends Over the Continental United States: Assessment Using the North American Regional Analysis

conterminous United States (CONUS) using the observation minus reanalysis (OMR) approach. We estimated the OMR

trends for the 1979–2003 period from the US Historical Climate Network (USHCN), and the NCEP-NCAR North American

Regional Reanalysis (NARR). We used a new mean square differences (MSDs)-based assessment for the comparisons

between temperature anomalies from observations and interpolated reanalysis data. Trends of monthly mean temperature

anomalies show a strong agreement, especially between adjusted USHCN and NARR (

that NARR captures the climate variability at different time scales. OMR trend results suggest that, unlike findings from

studies based on the global reanalysis (NCEP/NCAR reanalysis), NARR often has a larger warming trend than adjusted

observations (on average, 0.28 and 0.27

OMR trends were found to be sensitive to land cover types. We analysed decadal OMR trends as a function of land

types using the Advanced Very High Resolution Radiometer (AVHRR) and new National Land Cover Database (NLCD)

1992–2001 Retrofit Land Cover Change. The magnitude of OMR trends obtained from the NLDC is larger than the one

derived from the ‘static’ AVHRR. Moreover, land use conversion often results in more warming than cooling.

Overall, our results confirm the robustness of the OMR method for detecting non-climatic changes at the station level,

evaluating the impacts of adjustments performed on raw observations, and most importantly, providing a quantitative

estimate of additional warming trends associated with LULC changes at local and regional scales. As most of the warming

trends that we identify can be explained on the basis of LULC changes, we suggest that in addition to considering the

greenhouse gases–driven radiative forcings, multi-decadal and longer climate models simulations must further include

LULC changes.