Le Kuai

Intraseasonal variations of the tropical total ozone and their connection to the Madden‐Julian Oscillation

We investigate the intraseasonal (30–90 day) variations in satellite-observed tropical total ozone (O_3) and their connection to the Madden-Julian Oscillation (MJO). Tropical total O_3 intraseasonal variations are large (∼±10 DU) and comparable to those in annual and interannual time scales. These O_3 anomalies are mainly evident in the subtropics over the Pacific and eastern; hemisphere and propagate slowly eastward (∼5 m s^(−1)). The subtropical negative (positive) O_3 anomalies are typically collocated with the subtropical upper troposphere anticyclones (cyclones) generated by equatorial MJO convection and flank or lie to the west of the equatorial enhanced (suppressed) MJO convection. The subtropical O_3 are anti-correlated with geopotential height anomalies near the tropopause and thus mainly associated with the O_3 variability in the stratosphere rather the troposphere. Over the equatorial regions, total O_3 anomalies are small.

Estimate of carbonyl sulfide tropical oceanic surface fluxes using Aura Tropospheric Emission Spectrometer observations

Author(s): Kuai, L; Worden, JR; Campbell, JE; Kulawik, SS; Li, KF; Lee, M; Weidner, RJ; Montzka, SA; Moore, FL; Berry, JA; Baker, I; Denning, AS; Bian, H; Bowman, KW; Liu, J; Yung, YL | Abstract:

Modulation of the Period of the Quasi-Biennial Oscillation by the Solar Cycle

The authors examine the mechanism of solar cycle modulation of the Quasi-Biennial Oscillation (QBO) period using the Two-and-a-Half-Dimensional Interactive Isentropic Research (THINAIR) model. Previous model results (using 2D and 3D models of varying complexity) have not convincingly established the proposed link of longer QBO periods during solar minima. Observational evidence for such a modulation is also controversial because it is only found during the period from the 1960s to the early 1990s, which is contaminated by volcanic aerosols. In the model, 200- and 400-yr runs without volcano influence can be obtained, long enough to establish some statistical robustness. Both in model and observed data, there is a strong synchronization of the QBO period with integer multiples of the semiannual oscillation (SAO) in the upper stratosphere. Under the current level of wave forcing, the period of the QBO jumps from one multiple of SAO to another and back so that it averages to 28 months, never settling down to a constant period. The “decadal” variability in the QBO period takes the form of “quantum” jumps; these, however, do not appear to follow the level of the solar flux in either the observation or the model using realistic quasi-periodic solar cycle (SC) forcing. To understand the solar modulation of the QBO period, the authors perform model runs with a range of perpetual solar forcing, either lower or higher than the current level. At the current level of solar forcing, the model QBO period consists of a distribution of four and five SAO periods, similar to the observed distribution. This distribution changes as solar forcing changes. For lower (higher) solar forcing, the distribution shifts to more (less) four SAO periods than five SAO periods. The record-averaged QBO period increases with the solar forcing. However, because this effect is rather weak and is detectable only with exaggerated forcing, the authors suggest that the previous result of the anticorrelation of the QBO period with the SC seen in short observational records reflects only a chance behavior of the QBO period, which naturally jumps in a nonstationary manner even if the solar forcing is held constant, and the correlation can change as the record gets longer.

Assessing a New Clue to How Much Carbon Plants Take Up

Current climate models disagree on how much carbon dioxide land ecosystems take up for photosynthesis. Tracking the stronger carbonyl sulfide signal could help.