Antarctic station‐based seasonal pressure reconstructions since 1905: 1. Reconstruction evaluation

Abstract

Seasonal mean Antarctic pressures at 17 stations are reconstructed based on the method of principal component regression, employing midlatitude pressure data as predictors. Several reconstruction methods were performed in order to assess the stability and reliability of the reconstructions obtained, including performing the reconstructions over a shorter 30 year window and withholding the remaining data for an independent validation. Generally, there were small differences between the various approaches, but typically reconstructions conducted on data with the trends still present and over the full period of observations achieved the highest skill. Seasonally, reconstruction skill was high in austral summer across the entire Antarctic continent. Reconstructions that employed gridded pressure data over oceans as well as the observations (here termed “pseudoreconstructions”) also performed remarkably well in austral winter. Spatially, the reconstruction skill was highest near the Antarctic Peninsula in all seasons, and weakest in coastal East Antarctica and the Antarctic Interior during austral spring and autumn; the spatial variability of the skill in part reflects the distance to the nearest midlatitude predictor. Nonetheless, for nearly all seasons and locations the observed trends since 1957 were well captured by the reconstructions, as was the low‐frequency decadal‐scale variability. These results suggest Antarctic pressure observations can be extended throughout the twentieth century with high confidence, especially in summer, allowing for a more precise understanding of the role and magnitude of natural atmospheric circulation variability across Antarctica.

Can Temperature Extremes in East Antarctica be Replicated from ERA Interim Reanalysis?

“…This suggests that underestimation of daily temperature range increased with increasing altitude, latitude, and distance from the coast across the East Antarctic Ice Sheet. This is consistent with in situ surface meteorological observations that decrease with increasing latitude and altitude (Fogt et al, 2016).…”

“…Furthermore, the paucity of data toward the interior can also explicate the regional difference of performance of ERA Interim daily T min and T max and daily temperature range. The following two reasons are most significant: (1) The stations over the Antarctic continent are confined mainly to coastal margins, and huge interior areas are devoid of long-term, in situ tropospheric temperature observations (Fogt et al, 2016). (2) There are no observations poleward of 82.5° from the polar orbiting satellites (Johanson and Fu, 2007), hence ERA Interim reanalysis is devoid of one of the most important data sets that could be assimilated (Dee et al, 2011).…”

Artifacts in Century‐Length Atmospheric and Coupled Reanalyses Over Antarctica Due To Historical Data Availability

“…The reconstruction was developed in two stages. First, seasonal mean pressure was reconstructed at 18 Antarctic research stations using midlatitude pressure data as predictors (Fogt, Goergens, et al, ; Fogt, Jones, et al, ). In the second stage, the reconstructed stations were used as anchoring points for infilling the 60°S–90°S domain using a kriging scheme.…”

A twentieth century perspective on summer Antarctic pressure change and variability and contributions from tropical SSTs and ozone depletion

“…Monthly mean pressure records from staffed research stations and automatic weather stations are obtained from the Reference Antarctic Data for Environmental Research (READER; http://www.antarctica.ac.uk./met/READER) archive [ Turner et al ., ] (see Figure for locations). To extend the observations throughout the twentieth century at each station except Orcadas [ Zazulie et al ., ], the summer station‐based pressure reconstructions [ Fogt et al ., , ] were used. These reconstructions all have calibration correlations with observations greater than 0.75 and independent validation correlations with observations above 0.63; a full listing of the reconstruction performance at the 18 stations is given in supporting information Table S1.…”

“…After 1957, negative pressure trends are seen everywhere across Antarctica, and our reconstruction aligns well with the observations (circles in Figures c and d), although the reconstruction trends (and therefore, the individual Antarctic station reconstructions that are interpolated) tend to be a bit stronger than observations in the Antarctic interior [cf. Fogt et al ., , Figure 6a]. Spatially, the negative trends are the strongest from the southern Antarctic Peninsula eastward along the Antarctic coast to ~30°E, and also across the Ross Ice Shelf.…”