A multi-data set comparison of the vertical structure of temperature variability and change over the Arctic during the past 100 years

Abstract

A multi-data set comparison of the vertical structure of temperature variability and change over the Arctic during the past 100 yearsBrönnimann, S; Grant, A N; Compo, G P; Ewen, T; Griesser, T; Fischer, A M; Schraner, M; Stickler, A Abstract: We compare the daily, interannual, and decadal variability and trends in the thermal structure of the Arctic troposphere using eight observation-based, vertically resolved data sets, four of which have data prior to 1948. Comparisons on the daily scale between historical reanalysis data and historical upper-air observations were performed for Svalbard for the cold winters 1911/1912 and 1988/1989, the warm winters 1944/1945, and the International Geophysical Year 1957/1958. Excellent agreement is found at mid-tropospheric levels. Near the ground and at the tropopause level, however, systematic differences are identified. On the interannual time scale, the correlations between all data sets are high, but there are systematic biases in terms of absolute values as well as discrepancies in the magnitude of the variability. The causes of these differences are discussed. While none of the data sets individually may be suitable for trend analysis, consistent features can be identified from analyzing all data sets together. To illustrate this, we examine trends and 20-year averages for those regions and seasons that exhibit large sea-ice changes and have enough data for comparison. In the summertime Pacific Arctic and the autumn eastern Canadian Arctic, the lower tropospheric temperature anomalies for the recent two decades are higher than in any previous 20-year period. AbstractWe compare the variability and trends in the thermal structure of the Arctic troposphere in eight observation-based, vertically resolved data sets, four of which have data prior to 1948.

Anomalous radioactivity level and high concentrations of heavy minerals in Lemme area, South-West Estonia

“…The largest uncertainties associated with this database identified in Polar Regions as well as in the stratospheric layers. In general 20CR data has lower level of accuracy for the period until 1940s (Brönnimann et al 2012;Paek, Huang 2012).…”

The coupled atmosphere–chemistry–ocean model SOCOL-MPIOM

“…In 20CR regions with temperature reductions are more pronounced than in the other two data sets -in particular, large differences are found in the NH and SH polar regions. For 20CR it is known that the Arctic temperature field suffers from a large, time-varying bias (Brönnimann et al, 2012) and an incorrect sea-ice distribution (Compo et al, 2011). However, HadCRUT4 and GIS-TEMP are also affected by a very low spatial and temporal coverage of instrument-based observations in these regions.…”

“…Both components, the atmosphere and the ocean, are coupled every 24 h using the OA-SIS3 coupler (Budich et al, 2010;Valcke, 2013). At the beginning of each model day the coupler exchanges momentum, heat, freshwater fluxes, as well as information on the SSTs, sea-ice extent, and snow cover on sea ice between the atmosphere and the ocean.…”

Manifestation of reanalyzed QBO and SSC signals

“…This is in agreement with the findings presented by Paek and Huang (2012) who showed the total absence of the QBO in the 20CR series over the tropical stratosphere. Brönnimann et al (2012) demonstrated inconsistencies in the variability of the 20CR series within the stratosphere too. Taking into account this lack of realistic representation of the major stratospheric phenomena, the 20CR dataset should be considered as unsuitable for stratospheric studies.…”