Abstract
The planetary boundary layer height (PBLH) is a diagnostic field related to the effective heat capacity of the lower atmosphere, both stable and convective, and it constrains motion in this layer as well as impacts surface warming. Here, we used radiosonde data from five icebreaker cruises to the Chukchi and Beaufort Seas during both spring and fall to derive PBLH using the bulk Ri method, which were then compared with results from ERA5 reanalysis. The ERA5 PBLH was similar to but slightly lower than the ship observations. Clear and consistent seasonal changes were found in both the observations and the reanalysis: PBLH decreased from mid-May to mid-June and subsequently increased after August. The comparison with ERA5 shows that, besides surface temperature, biases in PBLH are also a function of wind direction, suggesting that the availability of upwind observations is also important in representing processes active in the boundary layer over the Arctic Ocean.
Highlights
The Arctic has experienced a rapid warming since the 1980s in a so-called Arctic Amplification [1,2,3,4,5], and the rate of surface warming is more than twice that of the entire globe [6,7,8,9]
We analyzed the planetary boundary layer (PBL) height (PBLH) of five cruises observed in 2013~2015 from late spring to autumn in the Chukchi–Beaufort Sea and compared them with ERA5 results
It turns out that the seasonal variations observed in ERA5 PBLH are evident and parallel
Summary
The Arctic has experienced a rapid warming since the 1980s in a so-called Arctic Amplification [1,2,3,4,5], and the rate of surface warming is more than twice that of the entire globe [6,7,8,9]. The root-mean-square error (RMSE) between ERA5 and observed PBLH is 201 m averaged over all the cruises and varied from 143 m for cruise Mirai 2014 to 345 m for cruise Louis 2014 (Table 1), indicating some large differences at individual locations.
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