Oceanography and Atmospheric Sciences and Meteorology Commons^™

Correlated Variability Of Upwelling And Tracers Near The Tropical Tropopause, Marta Abalos

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Tropical upwelling should exert strong influence on temperatures and on tracers with large vertical gradients in the lower stratosphere. We test this behavior by comparing three upwelling estimates calculated from ERA‐Interim reanalysis data with observed temperatures in the tropical lower stratosphere, and with measurements of ozone and carbon monoxide (CO) from the Aura Microwave Limb Sounder (MLS) satellite instrument. Time series of temperature, ozone and CO are well correlated in the tropical lower stratosphere, and we quantify the influence of tropical upwelling on this joint variability. Strong coherent annual cycles observed in each quantity are found to reflect the seasonal …

Comparison Between Microphysical Model Simulation And Observed Cirrus Clouds Formation Within A Volcanic Aerosol Layer In The Tropical Tropopause Layer, Mayuko Sakurai

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

In order to know the formation process of cirrus clouds in tropical tropopause layer, we used a microphysical numerical model to calculate nucleation and growing process of cirrus cloud particles, and compared the results of the model simulations with observed results. The observations compared had been performed at Biak, Indonesia in January 2011. Formation of cirrus clouds was observed by lidar in an aerosol layer at the altitude from 17.5 to 19 km. The backscatter coefficient of cirrus clouds was 10^-8~10^-7/m/str and number concentration was estimated less than 10⁵/m³. Calculated results by …

Dehydration In The Ttl Estimated From The Water Vapor Match, Yoichi Inai

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

The match method is applied to the quantification of the dehydration process in the tropical tropopause layer (TTL) over the western Pacific. The match pairs are sought from the Soundings of Ozone and Water in the Equatorial Region (SOWER) campaign network observations with the use of isentropic trajectories. For those pairs identified, extensive screening procedures are performed to verify the representativeness of the air parcel and the validity of the isentropic treatment and to check possible water injection by deep convection, consistency between the sonde data and analysis field, and conservation of the ozone content. Among those pairs remaining, we …

Development Of A Balloon-Born Peltier-Based Chilled-Mirror Hygrometer For The Troposphere And The Lower Stratosphere, Takuji Sugidachi

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

We have developed a new balloon-borne hygrometer, which is based on a chilled-mirror principle and uses a two stage Peltier cooler. In January 2012, we have conducted flight tests at Biak, Indonesia (1.18⁰S, 136.11⁰E) to evaluate the performances of this sensor. The result showed that this hygrometer has the ability to measure atmospheric water vapor from the surface to the lower stratosphere. It is considered that our hygrometer is helpful for TTL observation campaigns because of its ease-in-handling.

Diurnal Variability Of Total Ozone, Nitrogen Dioxide And Sulfurdioxide Columns Over, Wiwiek Setyawati

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Atmospheric ozone plays important role in preserving living things on Earth from harmful solar ultraviolet radiation. Atmospheric nitrogen dioxide (NO2) and sulfur dioxide (SO2) act as very important substances as precursor and destructor of atmospheric ozone. Knowing the importance of these substances therefore LAPAN has conducted observations of total ozone, NO2 and SO2 columns in Bandung since 2007 using brewer spectrophotometer. Bandung is an urban area and a capital city of West Java province where rapid development of trading, tourism and industrial activities has declined its air quality. Diurnal variability of total ozone column showed its minimum around 11:00 AM …

Atmospheric Temperature Tides In The Tropical Upper Troposphere And Lower Stratosphere, Takatoshi Sakazaki

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Atmospheric thermal tides are global-scale waves with periods that are harmonics of a solar day, mainly excited by diurnally varying diabatic heating in the troposphere and the stratosphere. Some recent studies suggested that the tidal temperature variations in the TTL might affect the appearance of cirrus clouds and, thus, the dehydration process. It should be noted, however, that the global pattern of diurnal temperature variations in the TTL still remains unclear. In this study, we aim at revealing the 3D structure of diurnal temperature variations around the TTL, including its seasonal variations, by using data from global reanalyses for the …

Intraseasonal To Interannual Variations Of The Temperature Structure Around The Tropical Tropopause And Their Relationships With Convective Activities, Eriko Nishimoto

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Space-time variability in the tropical tropopause temperatures and its relationship with convective activities are examined by using the ERA40/ERA-interim re-analysis and NOAA/OLR data sets. Low temperatures around the tropical tropopause generally occur over the equator and extend northwestward and southwestward in the subtropics to form the horseshoe-shaped structure. This structure resembles a stationary wave response known as the Matsuno-Gill pattern, which is a superposition of the Rossby and Kelvin responses. Because of this, the two preliminary indices are first defined to represent the two responses. The horseshoe-shaped structure index is then calculated from the two indices. The seasonal and interannual …

The Dehydration Process In The Tropical Tropopause Layer, Moe Yamaki

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Water vapor contributes to the radiation budget of earth and the photochemistry of ozone. Therefore, it is important to understand the variation of water vapor in the research of global warming and ozone depletion. Noting that the saturation water vapor mixing ratio in the Cold-Point Tropopause (CPT) is not always a good estimate of water amount entering the stratosphere, Selkirk et al. (2010) defined the Tropopause Saturation Layer (TSL) using the cryogenic frostpoint hygrometer data taken in the tropical eastern Pacific during Northern Hemisphere summer. In the present study, the effectiveness of TSL is examined by using the SOWER data …

Testing The Role Of Radiation In Determining Tropical Cloud Top Temperature, Bryce Harrop

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Tropical anvil clouds that detrain near the mixing barrier near 13km in the tropics have a strong effect on the longwave and shortwave energy budgets of Earth. A cloud-resolving model is used to test the Fixed Anvil Temperature (FAT) Hypothesis proposed by Hartmann and Larson (2002). Results show that the radiative cooling, primarily due to water vapor, is the strongest control of the anvil cloud detrainment temperature. Water vapor concentrations are largely controlled by temperature, so, following the FAT hypothesis, the cloud detrainment should follow a fixed temperature. The results also show, however, that ozone contributes a significant heating rate …

Cirrus And Water Vapor Transport In The Tropical Tropopause Layer: A Modeling Study, Tra Dinh

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

In simulations of tropical-tropopause-layer (TTL) cirrus forced by a large-scale equatorial Kelvin wave, we show that the radiatively induced mesoscale dynamics in these clouds actively contributes to vertical transport of water vapor. In a typical TTL cirrus, the heating that results from absorption of radiation by ice crystals induces a mesoscale circulation. Advection of water vapor by the radiatively induced circulation leads to upward advection of the cloudy air. Upward advection of the cloudy air is equivalent to upward transport of water vapor when the air above the cloud is drier than the cloudy air. On the other hand, ice …

Analysis Of The Tropical Tropopause Layer Using The Global Nonhydrostatic Atmospheric Model, Hiroyasu Kubokawa

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Analysis Of The Ttl Cirrus And Their Convective Origin - A Water Perspective, Tao Wang, Andrew Dessler

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Two mechanisms are thought to be primarily responsible for the formation of cirrus in the Tropical Tropopause Layer (TTL): detrainment from deep convective anvils and in situ initiation. By analyzing water vapor measurements from the Aura Microwave Limb Sounder (MLS) and ice water content measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we identify TTL cirrus that contain too much ice to have been formed in situ—and therefore must be of convective origin. Analyzing 3 years of CALIPSO measurements (2008–2010), we found three maxima in the occurrence of convective cirrus: equatorial Africa, the tropical western Pacific, and …

The Representation Of The Ttl In A Tropical Channel Version Of Wrf Model, Stephanie Evan

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

In this study, the Weather Research Forecast (WRF) model is used to investigate key physical processes controlling the Tropical Tropopause Layer (TTL) temperature and water vapor distributions in December-January-February (DJF) 2006. The model domain is configured as a tropical channel with a horizontal grid-spacing of 37 km, a vertical grid-spacing of 500 m and a top at 0.1 hPa. Initial and boundary conditions are set using European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Interim data. An ozone distribution computed from satellite and ozonesonde measurements is used for radiative forcing calculations.

The modelʼs ability to replicate observed TTL temperature variability …

Water Vapor And Cloud Formation In The Ttl: Simulation Results Vs. Satellite Observations, Tao Wang, Andrew Dessler, Mark Schoeberl

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

Driven by analyzed winds and temperature, domain-filling forward trajectory calculations are used to reproduce water vapor and cloud formations in the tropical tropopause layer (TTL). As with most Lagrangian models of this type, excess water vapor is instantaneously removed from the parcel to keep the relative humidity with respect to ice from exceeding a specified (super) saturation level. The dehydration occurrences serve as an indication of where and when cloud forms. Convective moistening through ice lofting and gravity waves are also included in our simulations as mechanisms that could affect water vapor abundances and cloud formations in the TTL. Our …

Constraining Middle Atmospheric Mositure In Geos-5 Using Eos-Mls Observations, Jianjun Jin

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

On The Turbulent Mixing And Ozone Variations Around The Tropical Tropopause Associated With Kelvin Waves, Kazunari Koishi

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

The observed variations of ozone around the tropical tropopause layer in relation to large-scale waves both in the altitude and isentropic coordinates were examined by analyzing ozonesondes provided by SHADOZ (Southern Hemisphere Additional Ozonesondes). Because ozone near this level can be used for the tracer of atmospheric motion, we regarded an ozone enhancement as the signal of a turbulent mixing. Focusing on the vertical fine structure of ozone and temperature, this study presents observed variations of 10 stations near the equator. Based on the signals of Kelvin waves (an eastward-traveling component of equatorial waves) which is filtered in the spectral-frequency …

Data Assimilation, Kazuyuki Miyazaki

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Simulations (Idealized To Global), Eric Jensen

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Satellite Observations, Masato Shiotani

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Ground Based Observations, Fumio Hasebe, Takashi Shibata

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

In-Situ Aircraft Observations, Karen Rosenlof

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Stratospheric Dynamics (Including Waves), Joan Alexander

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Trace Species And Chemistry (Besides Water), Anne Thompson

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Ttl Transport & Wave Processes, Masatomo Fujiwara

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Water Vapor, William Randel

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Cirrus Clouds And Convection In The Ttl, Leonard Pfister

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Ttl Overview And Radiative Transfer, Andrew Gettelman

U.S. - Japan Bilateral Workshop on the Tropical Tropopause Layer: State of the Current Science and Future Observational Needs

No abstract provided.

Shallow Water Flow Modeling Using Space-Time Least-Squares Finite-Element Method, Shin-Jye Liang, Chiung-Yang Lan, Ying-Chih Chen

Journal of Marine Science and Technology–Taiwan

Various aglogrithms of least-squares finite-element methods (LSFEM) for convection-diffusion equation (CDE) and shallow-water equations (SWE) are formulated. The associated condition number of the resulting system of equations is systematically compared. It is found that condition number of the resulting system of equations depends on the choice of variables, interpolations, and size of element (∆x). In general, a better conditioned system is obtained by introducing auxiliary variable with low-order interpolation. The developed better conditioned shallow-water model is used to simulate wave propagation over a submerged bar and wave propagation past an elliptical hump. Computed results are compared with experiment data and …

Design And Implementation Of An Simulation Of Water Wave Transformation Using Higher Order Mild-Slope Equation, Yuan-Jyh Lan, Tai-Wen Hsu, Ta-Yuan Lin, Shin-Jye Liang

Journal of Marine Science and Technology–Taiwan

A higher-order mild-slope equation (HOMSE) is derived based on theory of Hsu et al. [14]. Depth function is approximated up to third-order accurate in terms of both wave nonlinearity and bottom slope. Classical Galerkin method is used to solve HOMSE. Developed model is verified with a series of benchmark tests, including propagation of a sinusoidal wave past a submerged bar, wave propagating on a sloping bed, wave propagating over an elliptic shoal on a uniform slope, and wave propagating through a semicircular slope bottom, respectively. Computed results are compared with experiment data and prediction of low-order mild-slope equation model as …

Inverting Sediment Sound Speed Profile Using A Parameterized Geoacoustic Model: Numerical And Statistical Analysis, Chen-Fen Huang, Shih-Feng Yang, Jin-Yuan Liu

Journal of Marine Science and Technology–Taiwan

The objective of this paper is to develop and evaluate an inversion algorithm for estimating the parameters in a geoacoustic model for a marine sediment layer. The geoacoustic model employs a generalized-exponential function for sound speed profile, and an inverse-square function for density distribution. Based upon plane-wave reflection from a nonuniform sediment layer overlying an elastic seafloor, an inversion procedure is established and numerically implemented for estimating the parameters using synthetic noisecontaminated data. The sensitivity of each model parameter is first studied, and then three highly sensitive parameters in the geoacoustic model and one statistical parameter are chosen for inversion …