Atmospheric Anomalies Related to Interdecadal Variability of SST in the North Pacific

Anomalous patterns of the atmospheric circulation and climate are studied corresponding to the two basic interdecadal variation modes of sea surface temperature (SST) in the North Pacific, namely, the 25-35-year mode and the 7-10-year mode. Results clearly indicate that corresponding to the positive and negative phases of the interdecadal modes of SST anomaly (SSTA) in the North Pacific, the anomalous patterns of the atmospheric circulation and climate are approximately out of phase, fully illustrating the important role of the interdecadal modes of SST. Since the two interdecadal modes of SSTA in the North Pacific have similar horizontal structures, their impacts on the atmospheric circulation and climate are also analogous. The impact of the interdecadal modes of the North Pacific SST on the atmospheric circulation is barotropic at middle latitudes and baroclinic in tropical regions.

STUDIES OF THE VERTICAL STRUCTURE MODEL AND THE MICROWAVE ATTENUATION OF CLOUDS AND PRECIPITATION OVER TROPICAL OCEAN AREA

Using radiosonde data and other related observations in the TOGA-COARE IOP(from November 1,1992 to February 28,1993),the microwave attenuation of non-precipitating clouds is investigated based on microwave radiative transfer model(MRTM)at the specific frequencies of 6.8,10.65,13.9,19.35,22.235,37.0,85.5 and 90.0 GHz.Besides,utilizing the data of the airborne radar and radiometer at 13.8 GHz in the IOP(Intensive Observation Period),vertical structure models for different types of precipitating clouds are obtained,and also the microwave attenuation of precipitating cloud is studied.Some statistical characteristics of 13.8 GHz microwave path integrated attenuation for stratiform and convective precipitating clouds are presented.The results given here are valuable for the spaceborne microwave remote sensing of precipitation,and the cloud and precipitation attenuation corrections in the spaceborne microwave remote sensing of earth surface over tropical ocean area.

STUDY ON THE AIR-SEA INTERACTION ON THE INTERANNUAL TIME SCALE IN THE SOUTH CHINA SEA

In this paper we document the correlationship between sea surface temperature (SST) and low level-winds such as sea level wind and 850 hPa wind in the South China Sea (SCS) based on COADS (1958—1987) and ECMWF objective analysis data (1973—1986).Further statistical analyses tell us that there is a fixed SCS basin mode for variations both of SST and low-level winds in the region on the interannual time scale due to air-sea interactions. A simplified,coupled model that is designed following the McCreary and Anderson's (1985) model and includes the feedback between the upper ocean and the circulation of East Asian monsoon demonstrates an interannual oscillation in the coupled air-sea system,which is similar to the observations in the SCS.

PHYSICAL DISSIPATIVE TECHNIQUE AND ITS APPLICATION TO THE MM4

Under the traditional framework of fluid dynamics,the problem of the numerical weather prediction is often expressed as the deterministic initial value problem of the classical Newtonian mechanics.The atmosphere is.however,a many-body system,the methodology by which the system with two bodies could be precisely solved would cause bigger errors and problems when handling the many-body system by it.A kind of technique to incorporate “the irreversible thermodynamic operators” into the numerical weather prediction models is.therefore,suggesting in this paper,to control the evolutionary direction of the many-body system according to the constraining way of the second law of thermodynamics,and thus the forecasting accuracy of the numerical weather prediction has been noticeably improved.For example,in the MM4 the averaged relative root mean square error of the fields of the temperature,humidity,height and whole wind velocity has decreased by about 13%,among which the averaged error of the 48 h forecasts has decreased by more than 20%.Since the technique to introduce the irreversable thermodynamic operator suggested in this paper is based on the physical law that describes the dissipativity and does not come from the computational consideration only.it is thus named as the physical dissipative technique.In view of the universality of the principle incorporating the irreversible thermodynamics operators suggested in this paper for the fluid dynamics and atmospheric numerical models,the applications and generalization of this incorporating technique would produce a great impact on the field of geophysical fluid dynamics.