Surface mean temperature from the observational stations and multiple reanalyses over the Tibetan Plateau
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Surface mean temperature from the observational stations and multiple reanalyses over the Tibetan Plateau Yuping Yan1 · Qinglong You2 · Fangying Wu3 · Nick Pepin4 · Shichang Kang5,6 Received: 8 May 2020 / Accepted: 21 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The Tibetan Plateau (TP), also called the “Third pole”, is sensitive to climate change due to extensive areas at high elevation presently dominated by snow and ice. In this study, observed surface temperature trends at 150 stations over the TP during 1979–2018 are analyzed and compared with surface temperatures from multiple reanalyses (NCEP1, NCEP2, ERA-Interim, MERRA, JRA55). Observed warming at the stations has a mean annual rate of 0.46 °C/decade during 1979–2018. Although all reanalyses underestimate observed temperatures (cold bias), most reproduce much of the inter-decadal variations of surface temperature shown in the observations. Absolute errors of mean surface temperature (reanalysis minus observation) are closely correlated with elevation errors, suggesting that parts of the cold bias can be interpreted by elevation errors of reanalysis. After elevation-temperature correction, about half of the cold bias is typically eliminated, more for both ERAInterim and JRA55. Compared with the observations, corrected NCEP2 surface temperatures still have larger cold biases, and fail to capture the overall warming over the TP. Since the elevation-temperature correction fails to improve trend magnitudes even when a significant proportion of the bias has been removed, this suggests that a more sophisticated modeling of the lapse rate in each reanalysis is required to realistically model warming trends across complex topography. Keywords Tibetan Plateau · Elevation correction · Multiple reanalysis · Surface mean temperature
1 Introduction
* Qinglong You [email protected]; [email protected] 1
National Climate Center, China Meteorological Administration, Beijing 100081, China
2
Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Science, Fudan University, Room 5002‑1, Environmental Science Building, No. 2005 Songhu Road, Yangpu, Shanghai 200438, China
3
Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, China
4
Department of Geography, University of Portsmouth, Portsmouth PO1 2UP, UK
5
State key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China
6
CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China
The Tibetan Plateau (TP hereafter), with an average elevation of over 4000 m, is the highest and the largest highland in the world, which is thus called the “Third Pole”. It also contains the largest cryospheric region (snow cover, ice and glaciers, permafrost) outside the polar regions, and has been referred to as the “Asian water tower” (Duan and Xiao 2
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