Nutrient enrichment and precipitation changes do not enhance resiliency of salt marshes to sea level rise in the Northeastern U.S.

In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and marsh drowning, while development of adjacent uplands limits upslope migration. Measures of marsh vegetation loss for eight sites in Rhode Island and New York between ca.1970 and 2011 indicate that substantial loss has occurred over past decades, with higher loss rates found for lower elevation salt marshes. Using inundation experiments, field surveys, and LiDAR datasets, we developed an elevation-productivity relationship for Spartina alterniflora specific to the U.S. Northeast, and located current salt marsh orthometric heights on this curve. We estimate that 87 % of Northeastern salt marshes are located at elevations where growth is limited by inundation. By manipulating water column nutrients, precipitation, and elevation, we further found that altered precipitation regime was associated with significant reductions in biomass, and that nutrient enrichment adversely impacts organic matter accumulation and peat formation. These results provide evidence that Northeastern U.S. marshes are vulnerable to the effects of accelerated sea level rise, and that neither precipitation changes, nor cultural eutrophication, will contribute positively to long-term salt marsh survival.     

High resolution numerical simulation of Tropical Cyclone Drena undergoing extra-tropical transition

Summary Tropical Cyclone Drena, a relatively long lived cyclone lasting from January 2, 1997 to January 10, 1997, crossed over three well separated island groups and affected a fourth in the south western Pacific Ocean during different stages of its life cycle. Midway through its transition into an extra-tropical low, it passed over the eastern edge of Norfolk Island, an isolated island located in the western Pacific Ocean midway between New Zealand and New Caledonia, at 0615 UTC (1745 local) on January 9, 1997. The tropical cyclone exhibited markedly different characteristics during each phase of its life cycle, with thick fog being reported during the eye passage at Norfolk Island. Although routine global and Australian region numerical models were able to provide the operational forecasters with broad scale guidance as to the movement of the tropical cyclone, the level of detail available at these resolutions is insufficient to identify the characteristics important to communities in the tropical cyclone's path. The high resolution numerical model (HIRES) developed by the University of New South Wales, was run at a resolution of 25 kilometres to investigate the evolution of the tropical cyclone from a warm cored, quasi-symmetrical vortex into a highly asymmetrical mid latitude low pressure system. The model captures the observed wind and precipitation structure of the cyclone very well during this crucial transition phase. The comparison extends into the vertical with a model derived vertical cross section depicting the key features observed in a sequence of ten specially requested radiosonde flights, released at six hourly intervals, from Norfolk Island which transect the passage of the tropical cyclone over this remote island.With 10 Figures     

台湾岛地形对“麦德姆”台风的影响

采用WRF模式,以2014年10号台风"麦德姆"为例,针对台湾岛中央山脉的局部地形,设计精细化地形试验,数值模拟了"麦德姆"台风登陆台湾岛前后地形对其路径、强度及风雨分布的影响。研究结果表明:真实的地形能更好的模拟和再现"麦德姆"台风发生发展的过程;台湾岛中央山脉地形对登岛"麦德姆"台风的路径有实质性的影响,降低台湾地形高度试验导致台风路径向西南偏转,而提高台湾岛地形高度则导致台风路径向东北偏转,地形高度改变的程度与路径偏转程度成正相关,地形高度改变所导致阻挡效应及台风环流与大尺度环流的相互作用是导致路径偏转的主要原因;台湾岛地形高度的改变对台风强度有明显的影响,增加或减少台湾岛地形高度,都会使台风强度有所减弱,这与地形变化引起的动力狭管效应、云水物质分布及外围云带的对流运动有关;台湾岛地形影响"麦德姆"台风降水的机制更为复杂,其不仅与地形引发的台风强度及结构变化有关,更与地形引起的眼区对流活动和螺旋云带及外围云系的时空分布有关。     

A wind tunnel boundary-layer simulation of wind flow over complex terrain: Effect of terrain and model construction

The report presents the results of a wind-tunnel study of the flow of the natural wind over complex terrain. A 1:4000 undistorted scale model of Gebbies Pass in the South Island of New Zealand was prepared and tested in the boundary-layer wind tunnel in the Department of Mechanical Engineering at the University of Canterbury.Three forms of construction, viz., terraced, contoured and roughness-added, were compared. Velocity and turbulence profiles, Reynolds stresses and spectra were measured, and correlation of results between different types of construction was calculated. The terraced form was much simpler to construct but was found to be unsatisfactory. The correlation between the contoured and roughness-added models was as high as 0.94, although the roughness-added model made a significant difference to the results in the lower 20%; of the boundary layer. The results of these tests will be compared with results from the field in a future report.     

Wet deposition of excess sulfate at Macquarie Island, 54° S

Annual wet deposition of excess sulfate at Macquarie Island has been estimated from 5 months of rainwater composition data covering the Austral summer of 1985/86. The resulting figure of 2.1±0.6 mmol/m²/yr is at the low end of previous estimates of maritime excess sulfate deposition by precipitation. Within estimated uncertainty limits this figure is consistent with the DMS emission flux which would be predicted for latitude 50°–60° S, based solely on available Northern Hemispheric DMS measurements.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden.     

台湾岛地形对台风“海棠”(0505)移动路径影响的数值试验研究

利用非静力模式MM5模拟台风“海棠”（0505）穿过台湾岛再次登陆的移动路径，分析了“海棠”登陆台湾岛前后结构特征变化。结果表明：台风自身的非对称结构与台风异常移动路径密切相关。另外，就台湾岛地形对台风“海棠”登陆台湾前打转和在台湾海峡出现“V”型移动异常路径影响进行数值试验表明：台湾岛地形不但可以直接影响台风移动路径，而且通过影响台风非对称结构来改变台风移动路径，因此，登陆台湾前逆时针打转异常路径是在弱引导气流中台风自身非对称结构和台湾岛地形共同作用的结果；台湾岛地形有使台风东北-西南向非对称增大趋势，而在台风进入台湾海峡前后对东南。西北向非对称有明显不同影响。     

Concentrations of metallic elements in long-range-transported aerosols measured simultaneously at three coastal sites in China and Japan

To determine the effects of long-range transport of aerosols from an upwind area in East Asia to a downwind area in Japan, we chemically analyzed aerosols collected simultaneously on Tuoji Island (Shandong Province, China), Fukue Island (Nagasaki Prefecture, Japan), and Cape Hedo (Okinawa Prefecture, Japan). We focused on changes in the metallic composition of PM_2.5 aerosols during long-range transport. The average mass concentrations of PM_2.5 at the three sites decreased in the order Tuoji Island > Fukue Island ≈ Cape Hedo (48.3 ± 4.5, 13.9 ± 1.5, and 13.2 ± 0.9 μg/m³, respectively). The fraction of coarse particles in total suspended particles estimated by (1–PM_2.5/TSP) was highest on Cape Hedo, indicating that the contribution of sea salts was increased by long-range transport of the aerosols over the ocean. Enrichment factor analysis revealed that at all three sites, Al, K, Ca, Mn, Fe, Co, Sr, and Ba originated from soil; whereas Cr, Ni, Cu, Zn, As, Mo, Ag, Cd, Sn, Sb, Tl, and P appeared to be of anthropogenic origin. Na was the most abundant element on Cape Hedo, indicating the addition of sea salts during aerosol transport. The V concentration was highest at Fukue Island, which was ascribed to V emission from ships. Sixty-one percent of the V on Fukue Island and 62% of the V on Cape Hedo were determined to have originated from ships, implicating of data obtained on dates during which backward trajectory analysis indicated that the same air mass passed over Tuoji Island, Fukue Island, and Cape Hedo in that order.     

海南岛蒸发量的变化特征及其影响因子分析

利用海南岛18个气象观测站1966—2001年逐日20cm口径小型蒸发皿蒸发量及气象要素资料,通过数理统计方法分析了海南岛年和四季的蒸发量变化特征及气象因子对蒸发量的影响。结果表明:从时间上看,海南岛年蒸发量变化呈波动式下降,蒸发量的减少主要出现在春季,冬季和夏季次之。从空间上看,年蒸发量呈东北少、西南多的分布,其大值区主要集中在西南部,小值区主要集中在东北部和中部地区。M-K检验说明年与春冬两季蒸发量的变化呈下降趋势且在1994年前后发生突变。影响蒸发量变化的因子中,日照时数和风速是造成蒸发量减小的主要因子,降水量的影响仅次于风速和日照时数,而气温不是造成海南岛蒸发量减小的主要因子,相对湿度可能是海南岛的蒸发量减小的影响因子。     

The measurement of natural sulfur emissions from soils and vegetation: Three sites in the Eastern United States revisited

Sulfur fluxes from bare soils, naturally vegetated surfaces and from several agricultural crops were measured at two mid-continent sites (Ames, Iowa and Celeryville, Ohio) and from one salt water marsh site (Cedar Island, North Carolina) during a field program conducted jointly by the NOAA Aeronomy Laboratory, Washington State University Laboratory for Atmospheric Research and University of Idaho Department of Chemistry during July and August 1985. The sites were chosen specifically because they had been characterized by previous studies (Anejaet al., 1979; Adamset al., 1980, 1981). The NOAA gas chromatographic/dynamic-enclosure measurements yielded bare soil surfaces fluxes from the mid-continent sites composed predominantly of COS, H₂S, CH₃–S–CH₃ (DMS) and CS₂, all of which were strongly correlated with air temperature. Net fluxes of approximately 5 and 15 ng S/m² min were observed in Iowa and Ohio, respectively, at appropriate weighted mean July temperatures. These fluxes are roughly a factor of 10 smaller than the earlier measurements, the greatest difference being in the measurement of the H₂S flux. The presence of growing vegetation was observed to measurably increase the flux of H₂S, significantly increase that of DMS and to decrease that of COS. Sulfur fluxes in the Cedar Island environs were observed to be both spatially and temporally much more variable and to include CH₃SH as a measurable contributor. Net fluxes, composed predominantly of DMS and H₂S, were estimated to be about 300 ngS/m²min during August; again about a factor of 10 lower than previous estimates. All measurements were corroborated to within about a factor of 2 by those of the other participating laboratories.     

1961—2008年台湾地区降水的变化

利用EOF、REOF、M-K突变检验等方法,分析了台湾地区1961—2008年降水量的变化情况,结果表明:台湾本岛年降水量丰沛,澎湖列岛的年降水较少。台湾岛年降水的空间分布既有一致性,也存在东-西部、南-北部的差异。台湾岛的年降水可分为3个气候区,即北部、中西部和东南部。除台湾岛东南部外,整个台湾地区的年降水量均有增加趋势和突变现象。     

海南岛台风灾害危险性评价研究

应用G IS技术,以县市行政区为单位,选用多年平均台风灾害过程中的综合灾度、风速和降水因子,利用台风灾害危险性指数法对海南岛台风灾害危险性进行评估。结果表明:危险性最大值分布在海南岛的沿海市县。台风灾害危险性评估可为海南岛的可持续发展和防灾减灾决策提供科学依据。     

海南岛农业气候生产力的估算

发挥气候资源的生产潜力,是农作物增产的有效途径。本文用Lieth法估算海南岛的农业气候生产力。光、热、水资源丰富的海南岛,植物的气候产量高,农作物的增产潜力至少为现在生产水平的一倍以上。水分是海南岛(尤其是西南部)农业产量的主要限制性因子。通过灌溉来补充所欠缺的水分(全岛平均每公顷需灌溉1778吨水),可期望达到最大气候产量。      

Spatially explicit modelling of the impact of climate changes on pasture production in the North Island,New Zealand

To assess the potential impact of climate changes on pasture production in the North Island, New Zealand, eight climate scenarios of increased temperature and increased (or decreased) rainfall were investigated by integrating a polynomial regression model for pasture production with a Geographic Information System (GIS). The results indicated that the climate change scenarios assuming an increase in temperature by 1–2°C and a rainfall change by −20 to +20% would have a very significant impact on pasture production with a predicted pasture production variation from −46.2 to +51.9% compared with the normal climate from 1961–1990. Increased temperature would generally have a positive effect on pasture production in the south and southeast of the North Island, and increased rainfall would have a positive effect in the central, south and southeast of the North Island and a negative effect in the north of the North Island. The interaction of decreased rainfall and increased temperature would have a negative impact for the whole North Island except some central areas with high rainfall. Relevant management practices for coping with potential climate change are discussed.     

南澳岛风能资源的评估

利用南澳站30年气候资料对南澳岛风能资源进行评估,为南澳风能资源合理的开发和利用提供一定依据。     

2016—2017年冬春季海南3市气溶胶质量浓度特征对比分析

利用2016年12月至2017年5月海南省3个地级市（三沙市永兴岛、三亚、海口）监测的PM_2.5、PM₁₀数据,对比分析其污染特征。结果表明：相较于海口、三亚,永兴岛空气质量最好,细粒子污染程度最轻且PM_2.5、PM₁₀质量浓度日变化最平稳,其主要原因是人类生产活动对空气质量的影响不大。进一步通过分析3个站点的PM_2.5质量浓度与近地面气象要素（相对湿度、月总降水量、能见度）发现,永兴岛PM_2.5质量浓度与能见度整体呈负相关,永兴岛在不同风速、风向上的PM_2.5质量浓度最小,三亚次之,海口最大。永兴岛PM_2.5的大值区主要出现在东北风向上,其他方向上的气流则相对比较清洁,且在静风或者微风条件下,永兴岛的初始PM_2.5质量浓度比较低。通过每天逐6 h的72 h后向轨迹分析发现,冬季、夏季风影响期间,永兴岛分别受来源于西太平洋、南海的海洋性气流影响,这与永兴岛的空气质量有直接关系。     

Laboratory simulation of the ocean currents in the Barents sea

A rotating laboratory model of the Barents Sea was forced by computed inflows of Atlantic Water and Arctic Surface Water for the period 1979–1984. Ad hoc tidal excursions over the shoals north of Bear Island and deep water production as a result of winter cooling and salt rejection in the eastern part of the basin were calibrated in the model. The high spatial resolution in the basin, which was 5 m in diameter, provided the basis for simulating several physical scales simultaneously. The simulated current features of interest include (1) the spreading of the Norwegian Coastal Current over Tromsøflaket, (2) a warm-core jet along the southeastern slope of the Svalbardbanken, which pushes the ice front far to the NE of Hopen Island, (3) the anticyclonic circulation around Sentralbanken, which drives Arctic Surface Water and ice far south in the eastern basin, (4) Norwegian Coastal Water flowing north across the Bear Island Channel, (5) deep water outflows north through the Franz-Victoria Trough and west through the Bear Island Channel, (6) the dependence of dense water accumulation and flushing on the variable Atlantic inflow, and (7) a robust, tidally driven circulation on the Svalbardbanken and around Bear Island. The Polar Front along the Svalbardbanken is fairly stationary, although its location is highly variable in the Sentralbanken area as a result of underflows (and winds—which were not simulated). The residence time for the Arctic Surface Water on Sentralbanken is about 8 months. Comparisons with available field measurements show a validation that is better than existing numerical model simulations.Entrainment of Arctic Surface Water on Svalbardbanken to the Atlantic inflow holds the Polar Front sharp and modifies the Atlantic Water as it flows to the Arctic Ocean. The simulated warm-core jet along this slope had a core speed up to 85 cm s⁻¹, whereas the best available current measurements near the core show surges up to about 30 cm s⁻¹. The simulated vorticity of the current is −0.33f, where f is the planetary vorticity. This can be provided from the conservation of potential vorticity. Both field data and laboratory simulations show that particles trapped in the Bear Island Current take 5–8 days to circle the island, which is 20 km in diameter. Except for surface confetti, agreement between model and field data was good for the southern flow east of Sentralbanken, but poor for the Murman Current. A model ‘wind’ caused a significant departure in this region and may be responsible for an exaggerated warm-core jet past Svalbardbanken.     

A NUMERICAL STUDY OF THE EFFECT OF TAIWAN ISLAND TERRAIN ON TYPHOON HAITANG （0505） TRACK

The track of Typhoon Haitang (0505), which passed through the Taiwan Island and landed again,has been successfully simulated by using the non-hydrostatic mesoscale atmospheric model MM5. Itsstructure is analyzed on the landing stage, and it is found that there exist good relationships between thetyphoon abnormal moving track and its asymmetry structure. The effect of terrain of Taiwan Island on thetyphoon Haitang, which made it rotate before landing and present a "V" type abnormal moving track inTaiwan straits, has also been simulated. Further analysis shows that the terrain of Taiwan Island not onlydirectly affects the typhoon moving track, but also changes the typhoon track by affecting its asymmetricstructure. Therefore, the typhoon asymmetric structure and the effect of terrain of Taiwan Island togetherresults in the abnormal rotating track. The terrain of Taiwan Island tends to increase the SW-NEasymmetric structure of the typhoon and has different effect on SE-NW asymmetric structure during thelandfall process of typhoon Haitang before entering and moving out of the Taiwan straits.     

基于格点实况的海南岛网格晴雨预报检验

采用高分辨率的格点降水实况资料,对2019年5月1日—9月30日中国气象局广东快速更新同化数值预报系统(CMA-GD)、中国气象局上海数值预报模式系统(CMA-SH9)和欧洲中期天气预报中心全球模式(ECMWF)的降水预报产品作海南岛晴雨预报的检验评估,结果表明:(1) CMA-SH9具有较高的晴雨准确率及较小的雨区面积偏差。CMA-GD(ECMWF)评分偏低与较高漏(空)报比例有关,漏(空)报易出现在五指山以南和东部沿海一带。三个模式在海南岛东部沿海一带的晴雨准确率随预报时效减小而提高;(2) CMA-GD多漏报,CMA-SH9和ECMWF多空报。CMA-GD和CMA-SH9比ECMWF具有较快速的调整能力,预报时效缩短,雨区面积偏差减小,晴雨评分提高;(3) 降水面积百分比为0~20%、20%~40%、40%~60% 的局地降水事件中,CMAGD和CMA-SH9预报雨区面积偏大,预报时效增加,面积偏差由偏多转偏少;降水面积百分比为60%~80%、80%~100%的降水事件中,雨区面积随时效增加呈增加趋势。(4) CMA-GD对海南岛北部高频降水中心具有较强的预报能力,但易漏报南部高频降水中心。CMA-SH9在海南岛北部易出现高频降水面积偏大,质心偏东的误差,但对南部的高频降水预报能力优于CMA-GD。通过最优面积阈值择优方案迭代集成CMA-GD、CMASH9和ECMWF的降水预报,可有效提高海南岛高分辨率网格晴雨预报准确率。      

南海海岛自动气象站防护应用技术探索

立足海南及南海的自然条件,结合海岛自动气象站在南海高温、高湿、高盐雾、强辐射、强风等恶劣气候环境下使用情况,通过对历年来海岛自动气象站故障及失效模式的统计和分析,总结分析故障原因。根据设备维护人员多年气象设备保障工作积累总结的经验,从海岛自动气象站结构和防护要求出发,集成应用市场上优质材料、先进工艺和多种成熟、关键设备防护技术,形成一些气象设备防护的有效方法措施,以提高海岛自动气象站对海洋环境的适应性和性能,延长设备使用寿命。     

The multiscale factors favorable for a persistent heavy rain event over Hainan Island in October 2010

A case study is presented of the multiscale characteristics that produced the record-breaking persistent heavy rainfall event(PHRE) over Hainan Island,northern South China Sea(SCS),in autumn 2010.The study documents several key weather systems,from planetary scale to mesoscale,that contributed to the extreme rainfall during this event.The main findings of this study are as follows.First,the convectively active phase of the MJO was favorable for the establishment of a cyclonic circulation and the northward expansion of the Intertropical Convergence Zone(ITCZ).The active disturbances in the northward ITCZ helped direct abundant moisture from adjacent oceans towards Hainan Island continuously throughout the event,where it interacted with cold air from the midlatitudes and caused heavy rain.Second,the 8-daylong PHRE can be divided into three processes according to different synoptic systems:peripheral cloud clusters of a tropical depression-type disturbance over the central SCS in process 1;interactions between the abnormally far north ITCZ and the invading cold air in process 2;and the newly formed tropical depression near Hainan Island in process 3.In the relatively stable synoptic background of each process,meso-α and meso-β-scale cloud clusters repeatedly traveled along the same path to Hainan Island.Finally,based on these analyses,a conceptual model is proposed for this type of PHRE in autumn over the northern SCS,which demonstrates the influences of multiscale systems.