2 Improve the Representation of Convection - PBL Interactions in Two Global

نویسنده

  • Tim Li
چکیده

Reducing systematic errors of state-of-the-art General Circulation Models (GCMs) will increase our confidence on the projection of future climate change and improve our forecast skills of present-day weather and climate variability. One systematic error of current GCMs is the failure to simulate a dominant tropical atmospheric variability: Madden-Julian Oscillation (MJO). Through downscale and upscale influences, MJO may modulate the occurrence of extreme hydo-meteorological events (e.g., hurricane, flood and drought etc.) and the onset and development of ENSO. This common model error not only hinders the achievement of seamless forecasts, but also undermines our confidence on the projection of future climate change. In this proposed study, we aim to improve the representation of MJO in CAM and ECHAM GCMs. Both models suffer a too red spectrum instead of an outstanding peak around 30-60-day owing to the overestimated persistence of daily precipitation. Through analyzing 3-D moisture profiles obtained from Aqua/AIRS, we discovered significant boundary-layer dryness underneath the MJO convection, which may play a critical role in disrupting the persistent rainfall. This new observational feature is missing in both CAM and ECHAM simulations and the ECMWF and NCEP reanalysis. This systematic bias is likely originated from the inappropriate representation of the convection-PBL interactions in the models. Another new observational feature is that MJO rainfall includes a large stratiform component. However, the effects of stratiform clouds, in particularly, mesoscale stratiform clouds, are not well represented in the current state-of-the-art GCMs. In this proposed study, we plan to systematically address the aforementioned issues/problems. First, high-resolution dynamically consistent regional datasets will be developed for two field campaign (TWP_ICE and THORPEX_PARC) periods using advanced data assimilation techniques. Then, these datasets will be used to diagnose convection-PBL interactions. Finally, improved parameterizations of convective and mesoscale stratiform clouds will be tested and implemented in CAM and ECHAM. The accomplishment of this project will provide improved regional datasets and reduce the systematic errors of CAM and ECHAM in simulating and predicting present-day weather and climate variability. We will also make a parameterization package available to global modeling community, which may lead toward the improved projection of future climate change, particularly those extreme events modulated by MJO.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

A New Vertical Diffusion Package with an Explicit Treatment of Entrainment Processes

This paper proposes a revised vertical diffusion package with a nonlocal turbulent mixing coefficient in the planetary boundary layer (PBL). Based on the study of Noh et al. and accumulated results of the behavior of the Hong and Pan algorithm, a revised vertical diffusion algorithm that is suitable for weather forecasting and climate prediction models is developed. The major ingredient of the ...

متن کامل

Double diffusive reaction-convection in viscous fluid layer

In the present study, the onset of double diffusive reaction-convection in a uid layer with viscous fluid, heated and salted from below subject to chemical equilibrium on the boundaries, has been investigated. Linear and nonlinear stability analysis have been performed. For linear analysis normal mode technique is used and for nonlinear analysis minimal representation of truncated Fourier serie...

متن کامل

A Comparative Study of the Effects of Two Educational Methods, PBL and E-PBL on the Learning of Cardiology Ward Interns

Introduction: There has been a growing trend in many countries to present medical courses electronically and in the form of learner-based learning. Hence, the present study aimed to compare the effects of two educational methods, Problem-based Learning (PBL) and Electronic Problem-based Learning (E-PBL), on the learning of cardiology ward interns in 2013. Methods: This pretest-posttest quasi-e...

متن کامل

Effect of Hybrid Problem-Based Learning versus the Conventional Teaching Method on Dental Students’ Knowledge and Performance in Endodontics

Background and Aim: With the advent of problem-based learning (PBL), pioneer universities across the world started using this method to improve learning quality. One of its modifications, hybrid-PBL, incorporates a combination of PBL and traditional teaching skills. This study compared the efficacy of hybrid PBL and the conventional instruction in terms of preclinical test scores and clinical p...

متن کامل

Global Stability for Thermal Convection in a Couple Stress Fluid Saturating a Porous Medium with Temperature-Pressure Dependent Viscosity: Galerkin Method

A global nonlinear stability analysis is performed for a couple-stress fluid layer heated from below saturating a porous medium with temperature-pressure dependent viscosity for different conducting boundary systems. Here, the global nonlinear stability threshold for convection is exactly the same as the linear instability boundary. This optimal result is important because it shows that lineari...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2016