Abstract
Abstract. The Arctic region is responding heavily to climate change, and yet, the air temperature of ice-covered areas in the Arctic is heavily under-sampled when it comes to in situ measurements, resulting in large uncertainties in existing weather and reanalysis products. This paper presents a method for estimating daily mean clear-sky 2 m air temperatures (T2m) in the Arctic from satellite observations of skin temperature, using the Arctic and Antarctic ice Surface Temperatures from thermal Infrared (AASTI) satellite dataset, providing spatially detailed observations of the Arctic. The method is based on a linear regression model, which has been tuned against in situ observations to estimate daily mean T2m based on clear-sky satellite ice surface skin temperatures. The daily satellite-derived T2m product includes estimated uncertainties and covers the Arctic sea ice and the Greenland Ice Sheet during clear skies for the period 2000–2009, provided on a 0.25∘ regular latitude–longitude grid. Comparisons with independent in situ measured T2m show average biases of 0.30 and 0.35∘C and average root-mean-square errors of 3.47 and 3.20 ∘C for land ice and sea ice, respectively. The associated uncertainties are verified to be very realistic for both land ice and sea ice, using in situ observations. The reconstruction provides a much better spatial coverage than the sparse in situ observations of T2m in the Arctic and is independent of numerical weather prediction model input. Therefore, it provides an important supplement to simulated air temperatures to be used for assimilation or global surface temperature reconstructions. A comparison of T2m derived from satellite and ERA-Interim/ERA5 estimates shows that the satellite-derived T2m validates similar to or better than ERA-Interim/ERA5 against in situ measurements in the Arctic.
Highlights
The Arctic climate is changing rapidly with surface temperatures rising faster than other regions of the world due to Arctic amplification (Graversen et al, 2008; IPCC, 2013; Pithan and Mauritsen, 2014; Richter-Menge et al, 2017), with the maximum warming occurring during late autumn and early winter (Box et al, 2019; Screen and Simmonds, 2010)
The Arctic surface air temperature is one of the key climate indicators used to assess regional and global climate changes (Hansen et al, 2010; Pielke et al, 2007), and both model simulations and observations indicate that warming in the global climate is amplified at the northern high latitudes (e.g. Collins et al, 2013; Holland and Bitz, 2003; Overland et al, 2018)
The land ice temperatures have been calculated for grid cells categorized as ice sheet by the ETOPO1 global relief model (Amante and Eakins, 2009), averaged to the 0.25◦ grid
Summary
The Arctic climate is changing rapidly with surface temperatures rising faster than other regions of the world due to Arctic amplification (Graversen et al, 2008; IPCC, 2013; Pithan and Mauritsen, 2014; Richter-Menge et al, 2017), with the maximum warming occurring during late autumn and early winter (Box et al, 2019; Screen and Simmonds, 2010). The Arctic surface air temperature is one of the key climate indicators used to assess regional and global climate changes (Hansen et al, 2010; Pielke et al, 2007), and both model simulations and observations indicate that warming in the global climate is amplified at the northern high latitudes Near-surface air temperatures have been measured at the height of 1–2 m using automatic weather stations (AWSs) or buoys (Hansen et al, 2010; Jones et al, 2012; Rayner, 2003; World Meteorological Organization, 2014). It is challenging to achieve climate-quality temperature records for this region
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