Diurnal Circulation of the Bolivian Altiplano. Part I: Observations

Abstract

In July and August 2003 a field campaign was conducted to explore the diurnal circulation of the Bolivian Altiplano. Vertical soundings by remote-controlled aircraft yielded profiles of temperature, pressure, and humidity at six passes and in a valley. Pilot balloon observations provided wind profiles. Two permanent stations collected additional data. Typically, inflow toward the Altiplano commences a few hours after sunrise at about the time when the stable nocturnal layer near the ground is transformed by the solar heating into an almost neutrally stratified convective boundary layer. The depth of the inflow layer is comparable to but normally less than that of this boundary layer. There are indications of return flow aloft. The inflow continues at least until sunset. Moisture is imported at the passes leading to the Yungas in the east. Strong upvalley flows were found in the valley of the Rio de La Paz, which connects the wide canyon of La Paz with the tropical lowlands to the east. Inflow was absent at one of the passes despite favorable synoptic conditions. Cases of synoptically forced flows are presented as well where the diurnal signal is difficult to separate. A simple flow scheme is presented that fits the observations reasonably well.

Study on impact of the South Asian summer monsoon on the down‐valley wind on the northern slope of Mt. Everest

“…Furthermore, the down-valley wind dominates the diurnal cycle of along-valley wind in the Rongbuk Valley, with duration more than 15 hours. This diurnal cycle dominated by the long-lasting down-valley wind is distinguished from those in other mountain regions [Bosser et al, 1989;Whiteman, 2000;Egger et al, 2005].…”

MISR-based passive optical bathymetry from orbit with few-cm level of accuracy on the Salar de Uyuni, Bolivia

“…There are quite significant diurnal and semidiurnal winds on the Altiplano, both those associated with the South American low level jet (Bonner, 1968;Falvey & Garreaud, 2005;Garreaud & Wallace, 1997), and those driven locally (Egger et al, 2005). It is tempting to suppose that these ridges in the salt surface are somehow analogous to tidal sand bars in shallow marine environments (Hulsher, 1996;Hulsher et al, 1993;Roos et al, 2004), though the details of the formation process surely differ.…”

Convective Boundary Layer Heights Over Mountainous Terrain—A Review of Concepts

“…While some geographical regions are denoted as "plateau" they should probably be classified meteorologically as elevated broad valleys or basins. Studies such as those by Yang et al (2004) over the Tibetan Plateau in Asia or by Egger et al (2005) over the Altiplano of South America may therefore not necessarily be representative of "pure" plateau CBLs. On the other hand, the Mexico "basin" may be classified meteorologically as an elevated basin or even as a plateau (Bossert, 1997;Whiteman et al, 2000).…”