Vertically Resolved Trends and Imprints of Recent Record Years in the UTLS from GPS RO

Warming of Earth's surface continues and led to an unprecedentedrecord high in average global temperature in 2015, continuing in2016. According to the US National Oceanic and AtmosphericAdministration, 2015 had global temperatures of 0.9 °C above the 20thcentury average, which is a remarkable jump of 0.16 °C from the lastrecord year 2014. The strong El Niño conditions late in the yearcontributed to the record, but the main driver likely continues to beanthropogenic forcing.Information about the free atmosphere is sparse in comparison to thesurface, and uncertainties are much higher. In the UTLS, temperaturemeasurements with global coverage, high vertical resolution, and highquality are provided by the GPS Radio Occultation (RO) satellitedataset. RO now provides 15 years of observations, and while this isstill a short record from a climate perspective, its properties enablea long-term stable and consistent data record with global coverage.In this work, we take advantage of the properties of RO to investigatehow the record surface temperatures of 2015 and 2014 translate intothe vertical structure of the free atmosphere. We also use the wholeRO time series to investigate atmospheric trend signals with highvertical resolution. We carefully separate the different contributionsto the atmospheric variability, including vertically resolvedvariability indices for the Quasi-Biennial Oscillation and the ElNiño-Southern Oscillation based on the RO temperature. Based on theability of RO to vertically resolve the tropopause region, wefurthermore compute trends in the tropopause height and temperature.