Chilly Trade Winds

Traders brave the ill effects of the global economic crisis in one of China’s largest export centers Hongye Cartons Packing Salesroom in Yiwu sells carton packages just across the street from Yiwu International Trade City,a mam-

Shifting Trade Winds

China aims to optimize its processing trade structure in an attempt to strike an international trade

Lift Force at Equatorial Sea Level Due to Compressed Air Dynamics of the Trade Wind’s Boundary Layer

Starting with a recent unconventional explanation of the lift force on a wing, featuring compressibility of the air, an application of the same concept is made to the lift force on the equatorial sea surface due to the Trade Winds, by greatly increasing the spatial scales. If the equatorial sea level does rise up, the northward slope to the sea level should facilitate the poleward flux of summer heat in both the North Pacific and North Atlantic Oceans, as two examples, in accordance with the heat budget requirements of these oceans. Compressed air dynamics consists of Bernoulli’s law applied to the streamlines of the Trade Winds, the force balance between the upward centrifugal force of the curved streamlines at the earth’s surface and a downward pressure force, and the perfect gas law for air.

Interannual Weakening of the Tropical Pacific Walker Circulation Due to Strong Tropical Volcanism

In order to examine the response of the tropical Pacific Walker circulation（PWC） to strong tropical volcanic eruptions（SVEs）, we analyzed a three-member long-term simulation performed with Had CM3, and carried out four additional CAM4 experiments. We found that the PWC shows a significant interannual weakening after SVEs. The cooling effect from SVEs is able to cool the entire tropics. However, cooling over the Maritime Continent is stronger than that over the central-eastern tropical Pacific. Thus, non-uniform zonal temperature anomalies can be seen following SVEs. As a result, the sea level pressure gradient between the tropical Pacific and the Maritime Continent is reduced, which weakens trade winds over the tropical Pacific. Therefore, the PWC is weakened during this period. At the same time, due to the cooling subtropical and midlatitude Pacific, the Intertropical Convergence Zone（ITCZ） and South Pacific convergence zone（SPCZ） are weakened and shift to the equator. These changes also contribute to the weakened PWC. Meanwhile, through the positive Bjerknes feedback, weakened trade winds cause El Nino-like SST anomalies over the tropical Pacific, which in turn further influence the PWC. Therefore, the PWC significantly weakens after SVEs. The CAM4 experiments further confirm the influences from surface cooling over the Maritime Continent and subtropical/midlatitude Pacific on the PWC. Moreover, they indicate that the stronger cooling over the Maritime Continent plays a dominant role in weakening the PWC after SVEs. In the observations,a weakened PWC and a related El Nino-like SST pattern can be found following SVEs.

Two climate factors in May that affect Korean rainfall in September

This study revealed a high positive correlation between rainfall in Korea during September and the trade wind （TW）/Arctic Oscillation （AO） index in May that combines two climate factors, low-level TWs and the AO. This correlation was identified on the basis of the difference in the 850 hPa streamline analysis between the positive and negative phases selected using the combined TW/AO index. In May, the spatial pattern of the anomalous pressure systems is similar to that in the positive AO phase. These anomalous pressure sys- tems continue in June to August （JJA） and September, but the overall spatial distribution shifts a little to the south. Particularly in September, a huge anomalous anticyclone centered over the southeast seas of Japan strengthens in most of the western north Pacific region and supplies a large volume of warm and humid air to the region near Korea. This characteristic is confirmed by the facts that during the positive TW/AO phase, the subtropical western north Pacific high （SWNPH） is more developed to the north and that the continu- ous positioning of the upper troposphere jet over Korea from May to September strengthens the anomalous upward flow, bringing warm and humid air to all layers. These factors contribute to increasing September rainfall in Korea during the positive TW/AO phase. Because the SWNPH develops more to the north in the positive phase, tropical cyclones tend to make landfall in Korea frequently, which also plays a positive role in increasing September rainfall in Korea.The above features are also reflected by the differences in average rainfall between the six years that had the highest May Nifio 3.4 indices （El Niflo phase） and the six years that had the lowest May Niflo 3.4 indices （La Nifia phase）.

TRMM-Observed Summer Warm Rain over the Tropical and Subtropical Pacific Ocean:Characteristics and Regional Differences

Based on the merged measurements from the TRMM Precipitation Radar and Visible and Infrared Scanner,refined characteristics（intensity,frequency,vertical structure,and diurnal variation） and regional differences of the warm rain over the tropical and subtropical Pacific Ocean（40°S-40°N,120°E-70°W）in boreal summer are investigated for the period 1998-2012.The results reveal that three warm rain types（phased,pure,and mixed） exist over these regions.The phased warm rain,which occurs during the developing or declining stage of precipitation weather systems,is located over the central to western Intertropical Convergence Zone,South Pacific Convergence Zone,and Northwest Pacific.Its occurrence frequency peaks at midnight and minimizes during daytime with a 5.5-km maximum echo top.The frequency of this warm rain type is about 2.2%,and it contributes to 40%of the regional total rainfall.The pure warm rain is characterized by typical stable precipitation with an echo top lower than 4 km,and mostly occurs in Southeast Pacific.Although its frequency is less than 1.3%,this type of warm rain accounts for 95%of the regional total rainfall.Its occurrence peaks before dawn and it usually disappears in the afternoon.For the mixed warm rain,some may develop into deep convective precipitation,while most are similar to those of the pure type.The mixed warm rain is mainly located over the ocean east of Hawaii.Its frequency is 1.2%,but this type of warm rain could contribute to 80%of the regional total rainfall.The results also uncover that the mixed and pure types occur over the regions where SST ranges from 295 to 299 K,accompanied by relatively strong downdrafts at 500 hPa.Both the mixed and pure warm rains happen in a more unstable atmosphere,compared with the phased warm rain.

Transmission Cost Allocation by Power Tracing Based Equivalent Bilateral Exchanges

The allocation of transmission cost provides important references and signals for system expansions and investments.This paper proposes a power tracing based equivalent bilateral exchange(PTEBX)method in which network users are responsible for not only their induced power flows,but also power flows induced by whom they have equivalent bilateral exchanges with.The equivalent bilateral exchanges are recognized based on the power tracing.To evaluate the performance of different methods of allocating transmission cost,seven criteria are put forward that take into consideration characteristics of power systems.Theoretical analysis is then conducted to certify whether the methods satisfy the criteria.The results indicate that only the PTEBX method is able to satisfy all the seven criteria.Numerical examples based on the IEEE-30 system are presented to further demonstrate the applicability of the proposed method.