scholarly journals Effects of Diurnal Cycle on a Simulated Asian Summer Monsoon

2012 ◽  
Vol 25 (24) ◽  
pp. 8394-8408 ◽  
Author(s):  
Song-You Hong ◽  
Masao Kanamitsu ◽  
Jung-Eun Kim ◽  
Myung-Seo Koo

Abstract This study investigates the effects of the diurnal cycle on monsoonal circulations over Asia in summer with a focus on precipitation. To this end, two sets of experiments are designed in a regional climate modeling framework forced by reanalysis data. The control experiment is a normal integration in which radiation is computed hourly, whereas the no-diurnal experiment is an experimental integration in which the daily averaged solar flux is computed once a day. Analysis of the results from the two experiments reveals that the diurnal cycle enhances the daily averaged sensible heat flux over land and the latent flux over oceans, which means that daytime net solar heating exceeds nighttime cooling in terms of the effects in surface climate and monsoonal circulations. Seasonal precipitation increased by about 3% over land and 11% over oceans. The surface hydroclimate over land is strongly influenced by the interaction between land and the atmosphere, and results in cooler surface temperatures except over the Tibetan Plateau. Over oceans, a robust increase in precipitation results from enhanced planetary boundary layer mixing. The diurnal cycle over the Tibetan Plateau region is found to decrease surface albedo by melting snow during the daytime, which contributes to the formation of the thermal low near the surface and the Tibetan high in the upper troposphere. The resultant monsoonal precipitation is modulated by an increase (decrease) in precipitation over northern (southern) India. This modulation results in the summer monsoon over East Asia being shifted northward.

2009 ◽  
Vol 6 (6) ◽  
pp. 10849-10881
Author(s):  
J. Hong ◽  
J. Kim

Abstract. The Tibetan Plateau is a critical region in the research of biosphere-atmosphere interactions on both regional and global scales due to its relation to Asian summer monsoon and El Niño. The unique environment on the Plateau provides valuable information for the evaluation of the models' surface energy partitioning associated with the summer monsoon. In this study, we investigated the surface energy partitioning on this important area through comparative analysis of two biosphere models constrained by the in-situ observation data. Indeed, the characteristics of the Plateau provide a unique opportunity to clarify the structural deficiencies of biosphere models as well as new insight into the surface energy partitioning on the Plateau. Our analysis showed that the observed inconsistency between the two biosphere models was mainly related to: 1) the parameterization for soil evaporation; 2) the way to deal with roughness lengths of momentum and scalars; and 3) the parameterization of subgrid velocity scale for aerodynamic conductance. Our study demonstrates that one should carefully interpret the modeling results on the Plateau especially during the pre-monsoon period.


2020 ◽  
Vol 7 (3) ◽  
pp. 516-533 ◽  
Author(s):  
Jianchun Bian ◽  
Dan Li ◽  
Zhixuan Bai ◽  
Qian Li ◽  
Daren Lyu ◽  
...  

Abstract Due to its surrounding strong and deep Asian summer monsoon (ASM) circulation and active surface pollutant emissions, surface pollutants are transported to the stratosphere from the Tibetan Plateau region, which may have critical impacts on global climate through chemical, microphysical and radiative processes. This article reviews major recent advances in research regarding troposphere–stratosphere transport from the region of the Tibetan Plateau. Since the discovery of the total ozone valley over the Tibetan Plateau in summer from satellite observations in the early 1990s, new satellite-borne instruments have become operational and have provided significant new information on atmospheric composition. In addition, in situ measurements and model simulations are used to investigate deep convection and the ASM anticyclone, surface sources and pathways, atmospheric chemical transformations and the impact on global climate. Also challenges are discussed for further understanding critical questions on microphysics and microchemistry in clouds during the pathway to the global stratosphere over the Tibetan Plateau.


2020 ◽  
Vol 202 ◽  
pp. 103114 ◽  
Author(s):  
Jin-Feng Li ◽  
Gan Xie ◽  
Jian Yang ◽  
David K. Ferguson ◽  
Xiao-Dong Liu ◽  
...  

2020 ◽  
Vol 11 (9) ◽  
pp. 1543-1551
Author(s):  
Jinqiang Zhang ◽  
Xiangao Xia ◽  
Hongrong Shi ◽  
Xuemei Zong ◽  
Jun Li

2020 ◽  
Author(s):  
Janna Abalichin ◽  
Birte-Marie Ehlers ◽  
Frank Janssen

<p>The ‘German Strategy for Adaptation to Climate Change’ (DAS) provides the political framework to climate change mitigation and adaptation in Germany. The associated ‘Adaption Action Plan’ envisages the establishment of an operational forecasting and projection service for climate, extreme weather and coastal and inland waterbodies. This service is intended to make use of a regional climate modeling framework, with NEMO v4.0.(1) as the ocean component. The atmospheric component will be provided by the German Weather Service (either the current weather forecasting model ICON or COSMO will be used) and will be coupled to NEMO after testing and calibration of NEMO on the regional scale.</p><p>The area of interest includes besides the North Sea and the Baltic Sea the entire North-West-Shelf to take into account cross-shelf transport, the water exchange between North Sea and Baltic Sea and the impact of North Atlantic weather systems on the internal dynamics of the seas. One focus area will be German Bight, well known for its large tidal flats, which make wetting & drying a desirable model feature, which will be tested in future. The used/implemented bathymetry includes the up to date measurements of the sea floor from the EMODNET network.</p><p>To achieve a proper description of the dynamics in this region the model has to be calibrated with regard to the timing and amplitude of the water levels in the coastal waters, the water inflow through the Danish straits, the thermal stratification as well as the seasonality and thickness of the sea ice in the Northern Baltic Sea.</p><p>These efforts are carried out in the pilot project ‘Projection Service for Waterways and Shipping’ (ProWaS).</p>


2016 ◽  
Vol 48 (5-6) ◽  
pp. 1503-1516 ◽  
Author(s):  
Ibourahima Kebe ◽  
Mouhamadou Bamba Sylla ◽  
Jerome Adebayo Omotosho ◽  
Pinghouinde Michel Nikiema ◽  
Peter Gibba ◽  
...  

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