A Data Gap Analysis and Efforts Towards Improving NOAA's Global Surface Temperature

Estimates of global surface temperature trends from some sources have indicated slowing in the rate of warming over the last decade compared to the long-term warming trend since the industrial revolution. It has been debated whether this recent slowdown is due to natural variability or a missed signal due to gaps in the global observation networks, particularly over the Arctic Region. To examine this more closely, we quantify the impact of data gaps on the global surface temperature trends in several regions of the world (e.g. Polar Regions and the Continents of African and South America), using major global datasets including NOAA's Merged Land-Ocean Temperature dataset (NOAATemp). We also study the impact of the greater observational coverage in a recently released global temperature data set as part of the International Surface Temperature Initiative (ISTI), and analyze the spatial-temporal variation patterns of the homogenization effect on NOAATemp. A summary of the progress and challenges in filling in grid boxes where observations are sparse over large areas are presented.