长春机场春季大风特点及个例分析

通过对长春龙嘉机场从2006-2019年14年的气象观测资料进行统计,总结出主要影响长春机场飞行的春季大风的特征,并以南高北低型,冷锋型,地面低压发展型这三种典型的大风天气为例,分析大风出现时的天气形势产生机制等,为春季大风的预报提供预报思路,从而更好地保障飞行安全和航班正点。

Mountain Effect and Differences in Storm Floods between Northern and Southern Sources of the Songhua River Basin

In this study, the differences in annual rainstorm changes in the Second Songhua River Basin and the Nenjiang River basin and their causes were compared from the perspective of mountain effects. The following results were drawn: (1) Altitude effect is the primary factor leading to increased rainstorms in the southern source; (2) Slope effect primarily leads to differences of the weather systems in the two sources, and thus cause the difference of the rainstorms; (3) Slope effect is responsible for the greater fluctuation in the observed floods in the southern source. These landform differences eventually lead to the differences in the characteristics of floods in the southern and northern sources. Commensurability method was used to identify the period of rainstorms in the southern and northern sources. The results showed that although rainstorms do not appear at the same time in the two sources they are characteristic of a 10 years' period in both areas. These results can serve as hydrological references for flood control and long-term flood disaster predictions.

Vorticity Budget Study on the Seasonal Upper Circulation in the Northern South China Sea from Altimetry Data and a Numerical Model

Based on the EOF analyses of Absolute Dynamic Topography satellite data, it is found that, in summer, the northern South China Sea （SCS） is dominated by an anticyclonic gyre whilst by a cyclonic one in winter. A connected single-layer and two-layer model is employed here to investigate the dynamic mechanism of the circulation in the northern SCS. Numerical experi- ments show that the nonlinear term, the pressure torque and the planetary vorticity adveetion play important roles in the circulation of the northern SCS, whilst the contribution by seasonal wind stress curl is local and limited. Only a small part of the Kuroshio water intrudes into the SCS, it then induces a positive vorticity band extending southwestward from the west of the Luzon Strait （LS） and a negative vorticity band along the 200 m isobath of the northern basin. The positive vorticity field induced by the local summer wind stress curl is weaker than that induced in winter in the northern SCS. Besides the Kuroshio intrusion and monsoon, the water trans- ports via the Sunda Shelf and the Sibutu Passage are also important to the circulation in the northern SCS, and the induced vorticity field in summer is almost contrary to that in winter. The strength variations of these three key factors （Kuroshio, monsoon and the water transports via the Sunda Shelf and the Sibutu Passage） determine the seasonal variations of the vorticity and eddy fields in the northern SCS. As for the water exchange via the LS, the Kuroshio intrusion brings about a net inflow into the SCS, and the monsoon has a less effect, whilst the water transports via the Sunda Shelf and the Sibutu Passage are the most important influencing factors, thus, the water exchange of the SCS with the Pacific via the LS changes dramatically from an outflow of the SCS in summer to an inflow into the SCS in winter.

Research on the Distribution Features of the Benioff Strain Ratio in the North-South Seismic Belt after the Two Yutian M_S7.3 Earthquakes

In view of the correlation between tectonic activity and seismicity,the strong earthquake risk in the North-South Seismic Belt aroused wide concern after the 2014 Yutian M_S7.3 earthquake. Using the seismic catalog of the China Earthquake Networks Center,the Benioff strain ratio in the North-South Seismic Belt is calculated in 30 days before and after the March 21,2008 and February 12,2014 Yutian M_S7.3 earthquakes. Results show that in a year after the 2008 Yutian M_S7.3 earthquake,M > 5. 0 earthquakes all occurred near the high strain ratio area or the junction between the low and high strain ratio areas,the activity of strong earthquakes obviously coincides with the high strain ratio area,which indicates that these areas have a higher stress level. The Yutian earthquakes promoted the release of small earthquakes in the high stress areas. This research is of certain indicating significance to the study of subsequent strong earthquakes of this region.

Sea surface height oscillation with quasi-four-month period along the continental slope in the northern South China Sea

The sea surface height oscillation with a quasi-four-month period （SSHO4） along continental slope in the northern South China Sea （NSCS） is detected using satellite altimeter data and an ocean model simulation. The SSHO4 is at southwest of Dongsha Island, and is characterized by a wavelength of-600 km and a southwestward phase speed of-0.1 m/s. Crossing the climatological background SST front, geostrophic currents corresponding to the SSHO4 generally induce sea surface temperature （SST） ＂tongues＂ during January-March. The cold and warm SST tongues appear southwest of cyclonic and anticyclonic eddies, respectively. The distance between the warm and cold SST tongues is about half the wavelength of the SSHO4. The geostrophic currents play an important role in lateral mixing, as manifested by the SST tongue phenomena in the NSCS.

Comparison of nonlinear and linear PCA on surface wind,surface height,and SST in the South China Sea

We compared nonlinear principal component analysis(NLPCA) with linear principal component analysis(LPCA) with the data of sea surface wind anomalies(SWA),surface height anomalies(SSHA),and sea surface temperature anomalies(SSTA),taken in the South China Sea(SCS) between 1993 and 2003.The SCS monthly data for SWA,SSHA and SSTA(i.e.,the anomalies with climatological seasonal cycle removed) were pre-filtered by LPCA,with only three leading modes retained.The first three modes of SWA,SSHA,and SSTA of LPCA explained 86%,71%,and 94% of the total variance in the original data,respectively.Thus,the three associated time coefficient functions(TCFs) were used as the input data for NLPCA network.The NLPCA was made based on feed-forward neural network models.Compared with classical linear PCA,the first NLPCA mode could explain more variance than linear PCA for the above data.The nonlinearity of SWA and SSHA were stronger in most areas of the SCS.The first mode of the NLPCA on the SWA and SSHA accounted for 67.26% of the variance versus 54.7%,and 60.24% versus 50.43%,respectively for the first LPCA mode.Conversely,the nonlinear SSTA,localized in the northern SCS and southern continental shelf region,resulted in little improvement in the explanation of the variance for the first NLPCA.

淄博市房家遗址发掘报告

一、自然环境与工作概况房家遗址位于山东省淄博市张店区傅家镇房家村北,新建房家小区之西,靠近淄博市城区,处于西外环路和西八路之间。遗址地处泰沂山系北麓的冲积平原地带,地势南高北低,西距孝妇河2公里。遗址地表为农田,保存状况较好,北部被原济青铁路穿过。地理坐标为北纬36°47′37.9″,东经118°00′03.6″(图一)。

Effect of opening the Drake Passage on the oceanic general circulation:A box model study

The impacts of opening the Drake Passage(DP) on the oceanic general circulation are examined.When the DP is open,wind stress at mid-and high latitudes gives rise to a wind-driven gyre,which induces a meridional heat exchange between mid-and high latitudes in the Southern Ocean.After the opening of the DP,the Antarctic Circumpolar Current(ACC) forms and its associated strong temperature front blocks the heat transport from mid-latitudes to high latitudes.A simple box model is formulated,in which the effects of the wind stress(for the case of DP closed) and the thermal front(for the case of DP open) on the variability of Antarctic Bottom Water(AABW) and North Atlantic Deep Water(NADW) are explored.The sensitivity experiments demonstrate that:(1) When the DP is closed,the enhancement of the wind-driven gyre leads to the decline of AABW formation in the Southern Ocean and the increase of NADW formation in the North Atlantic.As a result,water in high latitudes of the Southern Ocean becomes warmer,so does the bottom water of global ocean.(2) When the DP is open,there is no formation of AABW until the intensity of thermal front along ACC exceeds a threshold value(it is 4.03℃ in our model).Before the formation of AABW,temperature in most of the oceans is higher than that after the formation of AABW,which usually leads to the cooling of high latitudes of the Southern Hemisphere and the bottom water in global ocean.When the strength of the thermal front is lower than the critical value,there is no AABW formation,and temperature in most of the oceans is slightly higher.These results demonstrate that during the opening of the DP,changes in wind stress and the formation of the thermal front in the Southern Ocean can substantially affect the formation of AABW and NADW,thus changing the state of meridional overturning circulation in the global ocean.