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An introduction of TIPEX-III

09-07-2014Source:China Meteorological News Press

Motivation

Conventional meteorological observation stations are scarce over the Tibetan Plateau (TP) due to the harsh environment, thereby the in-site observations are urgently needed; and there is large uncertainty in remote-sensing data. These hinder progress of the Tibetan meteorology. Moreover, numerical models have become vital tools for weather and climate forecasts. Because of the unique boundary layer structures and the complicated cloud/rainfall physical processes, almost all of the current numerical models have lower capabilities in simulating East Asian climate, especially in simulating the Tibetan cloud and precipitation. This restricts the performance of numerical models.

 

Under the support of both the Ministry of Science and Technology of China and the State Planning Commission of China (currently National Development and Reform Commission), the Chinese Academy of Sciences and the Central Meteorological Bureau carried out the First TP Atmospheric Scientific Experiment from May to August in 1979. Under the support of the Ministry of Science and Technology of China, the China Meteorological Administration and the Chinese Academy of Sciences conducted the Second TP Atmospheric Scientific Experiment from May to August in 1998. These experiments made significant progress in land-air interactions and boundary-layer physical processes over the TP, which provide valuable experience for the Tibetan atmospheric scientific experiment.

 

Plan of the TIPEX—III

In 2013, the TIPEX-III was jointly  launched  by China Meteorological Administration (CMA), National Natural Science Foundation of China (NNSFC), and Chinese Academy of Sciences (CAS). It focuses on the unique land surface-boundary layer-troposphere–stratosphere interactions in the TP and their effects on regional climate to answer the key scientific and technical issues. They are: (1) merging and analysis techniques of different observational data, (2) multi-scale topographic effects and physical processes between land surface and boundary layer in the TP, (3) cloud-precipitation physical processes and atmospheric water cycle in the TP, (4) physical and chemical processes of stratosphere-troposphere exchanges over the TP, (5) integrated diagnosis and prediction methods on the TP weather systems and the resulted disasters, and (6) mechanisms for the TP climate anomalies, their effects on floods/droughts in China, and the predictability. The TIPEX-III lasting 8-10 years will carry out the 3-D integrated field experiments from land surface to the stratosphere and the researches of scientific theories and techniques.

 

Unique land-atmosphere physical processes in the TP

 

Overall Goals

Focusing on the key techniques of weather and climate forecasts, the TIPEX-III will construct a 3-D system integrating sky-based, space-based and ground-based observations for land surface, boundary layer and troposphere over the TP and its surrounding areas and will gradually promote to long-term observations. The conventional observational and remote-sensing data of the present operational observational systems and those being built in the 12th Five-Year Plan of CMA and in TIPEX-III will be fully used to enhance the quality of satellite retrieval  products over the TP, to develop the merging and analysis techniques for multi-source data, to develop techniques to parameterize the physical processes of Tibetan land surface and  boundary layer, to improve the cloud and precipitation descriptions in numerical prediction models, to obtain new knowledge about Tibetan impacts on severe weather and extreme climate events, to develop the methods and techniques for prediction of the severe weather and the extreme climatic events, and to raise the capability of forecasting rainstorms and droughts/floods in China.

 

 

Field Observation Task

The TIPEX-III will rely on the existing and ongoing meteorological observation system and combine satellite remote sensing with surface observation and 3-D atmospheric integrated observations. During the period of TIPEX-III, the land-atmosphere interactions, boundary-layer, cloud and precipitation micro-physical processes, and stratosphere-troposphere exchange processes will be intensively observed to obtain data for these processes over the TP. In summer, the observations over the TP sensitive area and its downstream regions will carried simultaneously to obtain the comprehensive information for the disastrous weather processes over the downstream areas.

 

Automatic sounding equipment

 

In the period of TIPEX-III, three conventional automatic sounding stations will be installed over western Tibet and used in continuous observations of atmospheric temperature, pressure, humidity, and wind for at least two years. Eighteen AWS stations with multi-level soil temperature/moisture detectors and surface radiation detectors will also be installed over western Tibet and used in continuous observations for land surface processes.

 

About ten wind/temperature gradient towers and associated detectors will be used in continuous observations for boundary-layer observations over the TP.  In summer, aircrafts with airborne detectors and ground-based dual polarization radar, laser radar, cloud radar, millimeter-wave radar, microwave radiometers, disdrometer, and ceilometers will be used to observe cloud and precipitation processes in some areas of the TP.  Aerosols, cirrus and some atmospheric compositions (such as CO, NO2, O3, Be-7, Be-10 and Pb-210) will be observed at nine stations of the TP. Moreover, GPS mobile sounding equipment, wind profiler radars, and GPS/MET will also be used in TIPEX-III.

 

Schedule for Field Observation
Phase 1: 2014--2017
·Observation for water and energy balance of land surface processes in the TP
·Observation for atmospheric boundary layer processes (Tibetan autonomous region, Sichuan Province, and Yunnan Province)
·Observation for cloud and rain physical processes (Tibetan autonomous region, Sichuan Province, and Yunnan Province)
· Comprehensive observation for atmospheric water cycle over the TP
·Comprehensive observation over the TP and its downstream areas for disastrous weather processes
· Integrated observation for satellite remote-sensing product calibration over the TP

Phase 2: 2018--2021
· Observation for atmospheric boundary layer (Qinghai, Gansu, and Shaanxi Provinces)
·Observation for cloud and rain physical processes (Qinghai, Gansu, and Shaanxi Provinces)
·Observation for stratosphere- troposphere exchanges over the TP