Lin Yi-Hua

Seasonal Characteristics of Precipitation in 1998 over East Asia as Derived from TRMM PR

Precipitation radar data derived from the Tropical Rainfall Measuring Mission (TRMM) satellite are used to study precipitation characteristics in 1998 over East Asia (10°–38°N, 100°–145°E), especially over mid-latitude land (continental land) and ocean (East China Sea and South China Sea). Results are compared with precipitations in the tropics. Yearly statistics show dominant stratiform rain events over East Asia (about 83.7% by area fraction) contributing to 50% of the total precipitation. Deep convective rains contribute 48% to the total precipitation with a 13.7% area fraction. The statistics also show the unimportance of warm convective rain in East Asia, contributing 1.5% to the total precipitation with a 2.7% area fraction. On a seasonal scale, the results indicate that the rainfall ratio of stratiform rain to deep convective rain is proportional to their rainfall pixel ratio. Seasonal precipitation patterns compare well between Global Precipitation Climatology Project rainfall and TRMM PR measurements except in summer. Studies indicate a clear opposite shift of rainfall amount and events between deep convective and stratiform rains in the meridional in East Asia, which corresponds to the alternative activities of summer monsoon and winter monsoon in the region. The vertical structures of precipitation also exhibit strong seasonal variability in precipitation Contoured Rainrate by Altitude Diagrams (CRADs) and mean profiles in the mid-latitudes of East Asia. However, these structures in the South China Sea are of a tropical type except in winter. The analysis of CRADs reveals a wide range of surface rainfall rates for most deep convective rains, especially in the continental land, and light rain rate for most stratiform rains in East Asia, regardless of over land or ocean.

Variational iteration method for solving the mechanism of the Equatorial Eastern Pacific El Nino-Southern Oscillation

A class of coupled system for the El Nino–Southern Oscillation (ENSO) mechanism is studied. Using the method of variational iteration for perturbation theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behaviour of solution for corresponding problem is considered.

Modelling the global monsoon system by IAP 9L AGCM

The global monsoon system is simulated by IAP 9L AGCM. The result indicates that the model successfully simulates the monsoon system in the lower troposphere including the classic tropical monsoon, the subtropical monsoon and the temperate-frigid monsoon. Besides, the planetary monsoon in the upper troposphere is also realistically reproduced. On the other hand, the stratospheric monsoon is poorly simulated, a further analysis reveals that this is caused by the systematic overestimation of the westerly in the model.

The homotopic mapping method for sea?air oscillator model of interdecadal climate fluctuations

The El Nino/La Nina Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific ocean–atmosphere interactions. In this paper, a coupled system of sea–air oscillator model is studied. The aim is to create an asymptotic solving method of nonlinear equation for the ENSO model. And based on a class of oscillators of ENSO model, employing the method of homotopic mapping, the approximate solution of corresponding problem is studied. It is proven from the results that the homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere–ocean oscillation for ENSO model.

Asymptotic Solutions to a Nonlinear Climate Oscillation Model

Abstract A class of nonlinear global climate oscillation models is considered. Using perturbation theory and its methods, solutions to the asymptotic expansions of some related problems are constructed. These asymptotic ex-pansions of the solutions for the original problem possess a higher approximation. The perturbed asymptotic method is an analyt method.

A climatic dataset of ocean vertical turbulent mixing coefficient based on real energy sources

Using data on wind stress, significant height of combined wind waves and swell, potential temperature, salinity and seawater velocity, as well as objectively-analyzed in situ temperature and salinity, we established a global ocean dataset of calculated wind- and tide-induced vertical turbulent mixing coefficients. We then examined energy conservation of ocean vertical mixing from the point of view of ocean wind energy inputs, gravitational potential energy change due to mixing (with and without artificially limiting themixing coefficient), and K-theory vertical turbulent parameterization schemes regardless of energy inputs. Our research showed that calculating the mixing coefficient with average data and artificial limiting the mixing coefficient can cause a remarkable lack of energy conservation, with energy losses of up to 90% and changes in the energy oscillation period. The data also show that wind can introduce a huge amount of energy into the upper layers of the Southern Ocean, and that tidesdo so in regions around underwater mountains. We argue that it is necessary to take wind and tidal energy inputs into account forlong-term ocean climate numerical simulations. We believe that using this ocean vertical turbulent mixing coefficient climatic dataset is a fast and efficient method to maintain the ocean energy balance in ocean modeling research.

Homotopic mapping solving method of the reduces equation for Kelvin waves

A reduces equation of the Kelvin wave is considered. By using the homotopic mapping solving method, the approximate solution is obtained. The homptopic mapping method is an analytic method, the obtained solution can analyse operations sequentially.

Simulated Heat Sink in the Southern Ocean and Its Contribution to the Recent Hiatus Decade

Abstract A set of numerical experiments is designed and carried out to understand a heat sink in the Southern Ocean in the recent hiatus decade. By using an oceanic general circulation model, the authors focus on the contributions from two types of forcing: wind stress and thermohaline forcing. The simulated results show that the heat sink in the upper Southern Ocean comes mainly from thermohaline forcing; while in the deeper layers, wind stress forcing also plays an important role. These different contributions may be due to different physical processes for the heat budget. The combination of these two types of forcing shows a significant heat sink in the Southern Ocean in the recent hiatus decade, and this is consistent with the observations and conclusions of a similar recently published study.

A method of solving a class of disturbed Lorenz system

A solving problem for the Lorenz system in atmospheric physics is considered. First, a set of variational iterations is constructed by using the generalized variation principle. Then, the initial approximate solution is determined. Finally, using the variational iteration, each approximate solution for corresponding model is found. The generalized variational iteration method is an analytic method, and the obtained solution can be analytically operated further.