Brian Vant-Hull

Variability of CONUS Lightning in 2003–12 and Associated Impacts

AbstractChanges in lightning characteristics over the conterminous United States (CONUS) are examined to support the National Climate Assessment (NCA) program. Details of the variability of cloud-to-ground (CG) lightning characteristics over the decade 2003–12 are provided using data from the National Lightning Detection Network (NLDN). Changes in total (CG + cloud flash) lightning across part of the CONUS during the decade are provided using satellite Lightning Imaging Sensor (LIS) data. The variations in NLDN-derived CG lightning are compared with available statistics on lightning-caused impacts to various U.S. economic sectors. Overall, a downward trend in total CG lightning count is found for the decadal period; the 5-yr mean NLDN CG count decreased by 12.8% from 25 204 345.8 (2003–07) to 21 986 578.8 (2008–12). There is a slow upward trend in the fraction and number of positive-polarity CG lightning, however. Associated lightning-caused fatalities and injuries, and the number of lightning-caused wild...

Urban surface energy budget study using flux tower observations and remote sensing measurements

Urban heat islands cause that built up areas experience warmer temperature than their surrounding rural regions. This issue can adversely affect the energy consumption and public health especially in highly populated cities. The aim of this research study is to characterize the effect and the response of each surface type in the cities to increase our understanding of climate, anthropogenic heat, and urban heat islands. Flux tower observations as well as satellite-based remote sensing measurements are two source of valuable information. Flux towers are rarely deployed in the cities or built up environment and mostly take measurements in natural surfaces. Here we deploy several flux towers on different surface in New York City to enhance our understanding about the reaction of each surface to the energy balance. Complete energy balance stations are installed over distinct materials such as concrete, asphalt, and rooftops. This study can help to provide a novel approach to use ground observations and map the maxima and minima air temperature in New York City using satellite measurements. Satellites also provide many measurements from the earth surface at various spatial resolutions. MODIS data sets particularly deliver skin temperature. Moreover, satellite observations from Landsat 8 are utilized to classify the city surfaces to distinct defined surfaces where ground observations were obtained. The mapped temperatures will be linked to MODIS surface temperatures to develop a model that can downscale MODIS skin temperatures to fine resolution air temperature over urban regions. The evaluation of results against independent ground observations reveals that the proposed method is promising for studying surface energy balance in urban regions.