Water Vapor and Ozone Variations in the Tropical Tropopause Layer during the Central Equatorial Pacific Experiment Campaign

Abstract

Water vapor and ozone profiles in the tropical tropopause layer (TTL) are investigated using measurements from balloon-borne frost-point hygrometers and ozone sensors during the Central Equatorial Pacific Experiment campaign. Variations in water vapor, ozone, and temperature are described during soundings taken over a period of two weeks and over a distance of approximately 2,700 km along the equator. These observations indicate that the first and latter halves of the campaign period are characterized as cold and warm phases near the cold point tropopause, respectively. Stationary and eastward-traveling components equally contributed to these temperature anomalies. During the transition between the two phases, the ozone increased around 350-400 K, with the maxima around the 360 K isentrope. The water vapor simultaneously increased and decreased around the 360-400 K and 350-360 K isentropes, respectively. Simultaneous increases in ozone and water vapor around 360-400 K with a reduction in the vertical gradients suggest the possibility of turbulent mixing associated with a large-scale wave structure. The enhancement of vertical shear of zonal wind during the transition between the two phases also supports this idea. The decrease in water vapor around the 350-360 K isentropes could be understood as a result of saturation on the isentropic surface. This study shows the importance of observing variations in isentropic coordinates, rather than altitude coordinates, around the TTL in order to make a quantitative argument concerning mixing and dehydration when a large-amplitude disturbance exists.

Comparisons between high-resolution profiles of squared refractive index gradient <i>M</i><sup>2</sup> measured by the Middle and Upper Atmosphere Radar and unmanned aerial vehicles (UAVs) during the Shigaraki UAV-Radar Experiment 2015 campaign

“…The importance of hypothesis (2) is extremely difficult to evaluate, making hypothesis (3) impossible to ascertain since it all depends on the horizontal extent of the gradients that may be vertical-scale dependent. In addition, tilts of the isentropic surfaces due to baroclinic conditions or internal wave motions can produce apparent discrepancies that would not appear if altitude coordinates were replaced by the potential temperature θ coordinates (e.g., Koishi and Shiotani, 2012). However, hypothesis (3) could be suggested for the important case of saturated conditions (Vaughan and Worthington, 2000).…”

Variasi Trace Gases Selama 10 Tahun Dan Pencampuran Di Sekitar Lapisan Tropopause Di Indonesia Berbasis Satelit (Trace Gases Variation for 10 Years and Mixing Around the Tropopause Layers in Indonesia Based on Satellite)

“…Penurunan jumlah H2O di TTL disebabkan oleh mekanisme dehidrasi fisik. Saat udara troposfer yang membawa uap air mencapai TTL, terjadi proses dehidrasi akibat penurunan temperatur yang ekstrim di TTL (CPT) (Marcy et al, 2007;Koishi and Shiotani, 2012).…”

“…Hal ini diperkirakan karena temperatur yang dingin pada lapisan TTL sehingga jumlah uap air yang dapat mencapai TTL menurun atau disebut juga dengan istilah dehidrasi di TTL seperti yang telah dijelaskan sebelumnya (Koishi and Shiotani, 2012).…”