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Project Leader	Yihui DING Director, National Climate Center China Meteorological Administration 46 Baishiqiao Road, Beijing 100081 CHINA Tel: +86-10- 6840-6246 Fax: +86-6840-6488 Email: yhding@public.bta.net.cn
Funding	US $30,000 for 2000/01
Participating countries	Australia, China, Indonesia, Japan, Malaysia, the Philippines, South Korea, Vietnam

Introduction /Background
Since the 1990s, scientists from China, Japan, and South Korea have paid more and more attention to the relationships between climate variability and anomaly, and ENSO event and warm pool over the Western Pacific Ocean and Asian Monsoon. It is now recognised that there are some definite correlative relationships between the onset, mature and decay behaviors of ENSO and the intensity of winter and summer monsoon over Asia. Therefore it is extremely important to develop a network system for monitoring and predicting ENSO event and SSTA over the warm pool in the Western Pacific Ocean. Such a project (APN 99012) was first approved in 1999-2000, with funding amounting to US $85,000. However, the establishment of this network has an enormous work amount and one-year time period is rather short, hence it is difficult to fully complete the achieved goal. So it is necessary to continue to support this project. A renewal proposal was put forward in 1999, and was approved in March 2000, but with the fund for the second year (2001) pending due to the delayed opening of the network after official approval.

Outline of activities conducted

• Undertaking scientific research work;
• Improving monitoring system and updating this network on a monthly basis;
• Improving El Nino /La Nina prediction system;
• Assessing effect of the El Nino event and warm pool on weather and climate;
• Maintaining an updated network and issuing related information and products; and
• Organizing related Interim Examination Meeting of project 2000-12 on 27-28 September, 2000 in Beijing.

We have made significant progress on building-up an APN project network and scientific research. For example, the establishment and updating of the network, the improvement of the existing model prediction system, the verification of model predictions, and the issue of recent forecasts of the Tropical Pacific Sea Surface Temperature (SST) anomalies. The contributions of each participating country have been included in the updated network. Besides the existing contents in the aspects of monitoring, historical perspectives, predictions and outlook of tropical SSTA and El Nino/La Nina events as well as the released digital data related with the system, many other data sets and information associated with ENSO and the warm pool, such as TOGA-TAO and SCSMEX (South China Sea Monsoon Experiment)-A，B，C mooring buoy data, oceanic data of the warm pool and the South China Sea, the oceanic observations of Japan along 137°E, and satellite data such as OLR and TBB, have been widely collected and most of them have been put on to the network. In addition, the quality and scope of the network has improved and extended continuously. This can be shown in the following examples:

• Adding more information of historical background;
• Inclusion of more contributions from participating countries, such as Japan, South Korea, CPC (Climate Prediction Center) of USA, Malaysia, Hong Kong City University, the Philippines et al.;
• Adding new information and data sets accessible to users in APN countries;
• Establishing a full and updated network, with internal memory capacity of our expanding workstation, thus providing a more complete set of monitoring information data sets and prediction products as well as graphic outputs; and
• Issuing the predictions of the Tropical Pacific Sea Surface Temperature anomalies and typhoons on the network.

Highlight of research achievements

Scientists from the NCC of China have studied the meteorological and oceanographic conditions over warm pool and the South China Sea and the effect of ENSO events and SSTA over warm pool onset of summer monsoon and tropical cyclones. The useful relationships between ENSO and SSTA of warm pool, and anomalous weather-climate condition in Southern Asia and East Asia have been established and used in operational seasonal and interannual prediction, especially for extreme events such as monsoon anomalous variability and droughts/floods. For instance, by using the subsurface currents and temperature dataset from TOGA-TAO, observational evidence is presented to reveal the formation mechanism and eastward propagation features of subsurface current anomalies driven by the strong westerly wind anomalies over warm pool in western Pacific Ocean. The dominant factor leading to the equatorial sea temperature anomaly within the mixed layer of Pacific is the anomalous up welling caused by the convergence of subsurface currents rather than the horizontal thermal advections of surface currents. On the basis of the diagnostic study for 1998-2000 cold episode, the main features of this ENSO cycle such as rapid onset, great intensity, quick return to near-normal condition of SST, and slow response of the atmospheric condition were revealed. Results have also indicated that the enhancement and eastward development of the subsurface temperatures are the basis of the onset of cold episodes. Change in sea surface winds played a crucial role in the onset and development of cold episodes. In addition the effects of temporal variation of SSTA in the eastern and central equatorial Pacific Ocean on formation and seasonal predictability of heavy rainfalls over the Yangtze River valley in the summer of 1998 as simulated by NCAR CCM3 was examined. It was found that the effect might result from not only the intensity, but also the declining rate of positive SSTA in the eastern and central equatorial Pacific Ocean. Moreover, the El Nino/La Nina prediction system initialization schemes, boundary condition and predictive techniques of ENSO prediction models have been further refined. Any user and scientific community may visit and look at the network to obtain the necessary prediction.

In November the web page was redesigned: www.ncc.gov.cn/apn.

Future directions/Follow-up work
1) Improve the design of the main web page of the network with a newer layout and clearer catalogue and more easily accessible mode so that users can pick up the information effectively.
2) Improve the content of the network with the prediction of ENSO, enhancing the research and prediction outputs of the warm pool, adding the information of winter monsoon and expanding the data and information contributed by each participating country of this APN project.
3) Asking the related countries and experts that participated in this project through Email to update and supplement information and data, promote time efficiency in updating the web, and validate contact and accessible method.
4) Continue to enhance research work, increase the amount of papers, and add
related research papers on the web.