A combined sea and sea-ice surface temperature climate dataset of the Arctic, 1982–2021

The surface temperature is one of the main parameters for assessing climate change. Temperature change is most pronounced in the Arctic, and therefore, it is crucial to accurately estimate sea and sea ice surface temperatures in this region. The availability of in situ observations is limited in the Arctic, thus, increasing the need for satellite observations to estimate surface temperatures.

We present the first Arctic (>58°N) gap-free climate dataset covering the surface temperatures of the ocean, sea ice and the marginal ice zone from 1 January 1982 to 31 May 2021 based on observations from infrared satellite sensors. The underlying algorithm combines the multi-satellite observations and performs a statistical optimal interpolation to obtain daily gap-free fields, with a spatial resolution of 0.05° in latitude and longitude.

In situ observations have been used to derive consistent validation statistics over the ocean and sea ice. Comparison of the derived sea surface temperatures against in situ measurements from drifting buoys, moored buoys and Argo floats shows mean differences of 0.01 °C, 0.04 °C and 0.04 °C and standard deviations of 0.54 °C, 0.56 °C and 0.51 °C, respectively.

Over sea ice, the derived ice surface temperatures have been compared with KT-19 measurements from IceBridge flights, showing a mean difference of 1.52 °C and standard deviation of 3.12 °C, and with air temperatures from the North Pole (NP) ice drifting stations as well as ECMWF distributed buoys and CRREL buoys, with mean differences of −2.35 °C, −3.21 °C and –2.87 °C and standard deviations of 3.12 °C, 3.34 °C and 3.36 °C, respectively.

The combination of sea and sea-ice surface temperature provides a consistent dataset for climate analysis, which is crucial for studying climate change and trends in the Arctic. The combined sea and sea-ice surface temperature of the Arctic has risen with about 4.5 °C over the period 1982–2021, with a peak warming of around 10 °C in the northeastern Barents Sea.