The TKE budget in the convective Martian planetary boundary layer

Abstract

AbstractThe turbulent kinetic energy (TKE) budget has been obtained for the first time from ground‐based data on Mars, both for the unstable surface layer (SL) and for the convectively driven mixed layer (CML). Values for storage, buoyancy, shear, vertical turbulent transport, dissipation, and an imbalance term accounting for the rest of the TKE budget have been determined and weighted for significance.These results have been derived from ground‐based measurements made by Viking Lander 1 (VL1) on Sol 28, Viking Lander 2 (VL2) on Sol 20, and Pathfinder (PF) on Sol 25, and through an adaptation to Mars of terrestrial similarity theory, which constitutes a new approach to the study of the TKE budget on Mars.Shear is the main TKE generator in the unstable SL for VL1 Sol 28 and PF Sol 25. It is narrowly exceeded by dissipation, the main mechanism removing TKE. Both terms present values ∼10−1m2s−3. Buoyancy generates TKE, though it plays a minor role (∼10−2m2s−3). Vertical turbulent transport balances buoyancy, removing TKE from the SL by sending it upwards. The imbalance term represents 30% of the main mechanisms, while storage plays an insignificant role (∼10−5m2s−3). The SL TKE budget for VL2 Sol 20 presents a different behaviour instead, with the imbalance term becoming the main TKE generator, likely due to the anomalous atmospheric conditions existing during this Sol.Buoyancy and dissipation play the major roles generating and removing TKE in the CML for the three Sols under study, respectively, both showing values around 5×10−3m2s−3. Vertical turbulent transport plays a minor role (∼10−4m2s−3), and so does the imbalance term, with values about 25% of buoyancy or dissipation. Finally, shear and storage terms are negligible, presenting values ∼10−6 and ∼10−5m2s−3, respectively. Copyright © 2011 Royal Meteorological Society