Aircraft observations of the atmospheric boundary layer over a heterogeneous surface in eastern Siberia

Abstract

Abstract:This paper outlines specifications and gives preliminary results of aircraft observations made during the Intensive Observation Period in 2000 (IOP2000) over the Yakutsk area of eastern Siberia. The observations were part of the GAME-Siberia project. Spatial and seasonal variation in the fluxes of sensible heat, latent heat, and carbon dioxide were determined using a Russian aircraft equipped with turbulence sensors. Two flight paths covered 12 ð 32 km 2 grids over heterogeneous forest and grass surfaces on the left-and right-hand banks of the Lena River. The spatial flux distributions were consistent with the underlying vegetation cover. A video camera recorded aerial images of the land, while a spectrometer observed the spectral reflectance of the land surface. These data helped describe the relationship between the atmosphere and the land surface. The vertical structure of the atmospheric boundary layer (ABL) was also observed on long flight paths between the left and right banks of the Lena River. Thermally induced internal boundary layers (TIBLs) developed in the ABL under different thermal and dynamic conditions near the Lena River. The horizontal and vertical distributions of sensible and latent heats in the ABL were consistent with the generation of cumulus, which appeared over the forested area, but not over the Lena River lowland.

Applying wavelet transforms to analyse aircraft‐measured turbulence and turbulent fluxes in the atmospheric boundary layer over eastern Siberia

“…These data were obtained during aircraft observations on 19 June on a 60 km regional flight segment at 100 m height across the Lena River (Hiyama et al, 2003). Figure 4 compares the source data with restored data from the wavelet matrices using Equation (8).…”

“…Turbulence measurements included horizontal (longitudinal with respect to flight direction) wind speed fluctuations, vertical wind speed fluctuations, air temperature fluctuations, and absolute air humidity fluctuations. Hiyama et al (2003) described the detail of the aircraft observations.…”

“…The sampling area and flight paths are shown in Hiyama et al (2003: figure 1). Long flight paths (100 km) between the left-and the right-hand banks crossed the Lena River lowlands and were called regional flight paths.…”

“…An interesting and representative turbulence dataset was obtained during a joint Russian-Japanese aircraft mission to observe the atmospheric boundary layer (ABL) near Yakutsk, eastern Siberia (Hiyama et al, 2003). That dataset required analysis with spectral methods.…”

“…Turbulence data measured in the ABL with a Russian-built Ilyushin-18 (Hiyama et al, 2003) were analysed. Nine experimental flights were made, but we chose data only from 1 and 19 June 2000.…”