热带西太平洋海面的热量收支——中美西太平洋海-气合作考察观测事实之三

本文根据1986年2月8—14日中国“向阳红14号”考察船以及其它的船泊水文气象观测资料,计算了西太平洋热带海面(140—160°E、18°S—14°N)的能量收支各分量。计算结果表明,这个期间内该海面所获得的热量净收入的大小与赤道辐合带低值系统的增强或减弱有关;海面向大气输送的热量主要是以潜热通量输送方式进行的;考察海域内相当部分海面,供给大气能量大于它从大气接收的能量,其中最明显的地区出现在西太平洋热带地区(10°N附近),而不是在赤道地区。     

西太平洋热带地区能量和热量的总收支——中美西太平洋海-气合作考察观测事实之五

根据“向阳红14号”考察船在中美海-气考察第一次航程(1986年2月8—14日)所获取的水文气象和日射观测资料,以及特定区域内站点的海洋气象资料,探讨了热带西太平洋有限区域内下垫面和大气的冷、热源以及海气系统向周围大气的能量水平输送的源、汇问题。分析计算指出,在考察期间热带西太平洋地区是一个热量积贮区。     

热带西太平洋区域性大气能量收支的初步分析

本文探讨了中美西太平洋海-气相互作用合作考察期间，热带海洋不同海域上空大气能量的水平输送和局地变化。我们把热带西太平洋划分成三个多边形（东、中和西部区），分别计算了1986年1月9—15日、2月1—14日逐日三个海区上感热、潜热和位能的平均、扰动输送项、局地变化项以及各边界面上大气能量的输送。得出西太平洋西部海域上空大气柱内能量的平均输送是由外界向区内输送，而中、东部海域则相反。这表明西太平洋西部热带海洋上大气柱内增温明显，而中、东部则不然。另外，大气能量局地变化的区域性差异，其量值比输送项值要小些。     

1987年El Nino后期（9—11月）西太平洋大气静力能的收支

本文利用中科院1987年西太平洋考察资料和中央气象局出版的太平洋、大西洋资料反演出了一套利用温度和高度求算湿度的方法。通过该方法并利用美国国家气象中心的KWBC(5°N×5°S网格点资料)的温度和高度资料,计算了1987年厄尔尼诺期间9—11月西太平洋海域(0—30°N,120—170°E)大气静力能量的变化及其与周围的交换。结果表明,在这个时期,该区域上空大气是强的能源区,区域向周围输出能量。     

1986年冬季热带西太平洋区域性大气总能量收支

本文采用中美海-气合作考察第一次航程(1986.1.9—15,2.1—14)和若干站点的海洋气象资料,计算了热带西太平洋不同区域的大气湿静力能量的水平输送和局地变化、大气非绝热加热诸分量以及各区域海面与大气的热交换项。分析指出,在考察期间热带西太平洋上空,西部区是大气能量水平输送的能汇区,而东、中部区则反之。同时,热带西太平洋上空大气和海洋下垫面是个热源区,尤以西部区最为明显。由此可知,热带西太平洋大气能量收支具有明显的区域性差异,其西部区是较强的大气和海洋下垫面的热源区域,是热量、能量积存最多的地区。     

西太平洋热带海域动量、感热和潜热等湍流通量的观测研究

本文根据中国科学院“实验3号”科学考察船1986年10月至12月在菲律宾以东60多万平方公里辽阔的西太平洋热带海域6个连续测站上(146°E,0°;145°E,0°;150°E,0°;140°E,5°N;145°E,5°N;150°E,5°N),使用我国自行研制的小型系留气艇探测系统观测到的大气温度、湿度、气压和风等廓线资料,利用相似理论的通量-廓线关系,给出这一海域的动量通量(特别是曳力系数C_D)、感热通量和潜热通量。结果表明,这一海域上的曳力系数值C_D=(1.53±0.25)×10~(-3);该海域总是将其贮存的热量以感热形式特别是以潜热形式输送到大气中(其中感热输送仅占10％,其余主要为水汽潜热输送),使该海域成为地球上不可多见的热源。     

西太平洋赤道海域的热量平衡

本文利用1986年11月中国科学院实验3号考察船在西太平洋赤道海域(0°～5°N,130°～150°E)考察所获得的29天辐射资料和同期取得的温、压、湿、风和探空等资料,计算了这一海域11月份的热量平衡各量值和整层气柱的加热量。结果表明:该海域是一个强热源区,其上空大气也是一个强热源区。     

北太平洋中纬度地区海气热交换场的EOF分析

众所周知海洋与大气之间的热交换对大气环流的形成和变化有着童要的作用。本文根据Clark计算的资料对20°N以北北太平洋中纬度地区的蒸发潜热、净长波辐射和感热输送进行了EOF分析,以讨论其季节变化特征。资料范围在22.5—52.5°N,122.5°E—112.5°W,共128个网格点,格距5×5度,1950-1979年。     

盛夏我国东部地区热量平衡的个例计算

本文选取1959年7月23—26日4天正当高空副热带高压控制我国大陆时,对我国东部地区计算了能量方程中各项数值,以及各边界上的能量输送。计算表明,这个地区为能源区城,向外输送热量和水汽。至于在东、西、南、北四个边界上输送的情况有很大的差异,南界以输入为主;东界低层为输出,高层为输入。这种输送是由这个地区低空为大陆热低压,高空为副热带高压的环流特点所决定的。在热量输送中,扰动输送比平均输送为重要。在能量平衡中,支出项主要为平流输送和辐射冷却,而收入项主要是由下垫面向上输送感热和水汽潜热,大气本身的热量和水汽含量的变化在能量平衡中作用较小。湍流感热输送约为蒸发潜热输送的1.84倍。     

西太平洋黑潮、流冰和中国东部地区降水的关系

前言海-气作用是近年来人们感兴趣的课题,把大尺度海气相互作用与天气、气候相联系,开始取得某些有实际预报意义的结果。现试从海-气长期反馈效应来探讨我国东部地区降水气候趋势。海洋的巨大体积和热容量以及它的内部交换使得它的变化比大气缓慢得多,具有明显的滞后性,特别是下层海洋参数比较稳定,似可作为长期预报的一个指标。某些研究表明,强洋流区是海洋与大气之间相互作用最活跃的区域。黑潮是太平洋西部一股巨大的暖洋流,它经台湾向北至日本,约在35°N—40°N转向东去,挟带了大量热量向北输送,因而在海洋的反馈作用上占有重要位置,东亚及西太平洋大气环流及气候状况已经     

川西平原一次暖区暴雨的能量天气学分析

利用NCEP 1°×1°再分析资料,应用能量天气学方法对发生在2015年8月14日的川西平原暖区暴雨进行了分析。结果表明,总能量在8月14日经历了在上午积聚和午后释放的过程,并且随着时间由北向南增加,这和雨带从成都往眉山、乐山移动一致。总能量极大值14时出现在30°N附近,这和强降雨中心午间出现在眉山吻合。14日白天潜热能和总能量变化趋势一致,且不同时段变化值接近,潜热能的变化是导致总能量变化的主要因子,潜热能是此次川西平原暖区暴雨的主要贡献者。川西平原潜热能明显增大,有利于出现降水,潜在不稳定区和雨区有较好的对应关系。饱和能差较小,对流不稳定能量增加,有利于出现降水。14日14时对流不稳定能量和潜在不稳定能量显著增大,能量平衡高度达到200h Pa附近,导致成片暴雨区的出现。      

ENERGY BALANCE IN 40－50 DAY PERIODIC OSCILLATION OVER THE ASIAN SUMMER MONSOON REGION DURING THE 1979 SUMMER

Based on calculations of data from FGGE Level III b, a discussion is made of the energy balance in the 40－50 day periodic oscillation over the Asian monsoon region during the 1979 summer. It is found that the main source of 40－50 day periodic perturbation is the monsoon region extending from central South Asia to Southeast Asia. In the upper layer over the North Pacific subtropical area (10－20oN, 150oE－150oW) pres-sure work turns into kinetic energy that maintains 40－50 day periodic perturbation associated with the variation in position and intensity of the mid-Pacific trough. The mean energy budget in the three-dimensional space (0－30oE, 30oE－150oW, 100－1000 hPa) indicates that the 40－50 day periodic perturbation transports kinetic energy to a seasonal mean and a transient perturbation wind field.     

Global carbon budgets and the viability of new fossil fuel projects

Policy-makers of some fossil fuel-endowed countries wish to know if a given fossil fuel supply project is consistent with the global carbon budget that would prevent a 2 °C temperature rise. But while some studies have identified fossil fuel reserves that are inconsistent with the 2 °C carbon budget, they have not shown the effect on fossil fuel production costs and market prices. Focusing on oil, we develop an oil pricing and climate test model to which we apply future carbon prices and oil consumption from several global energy-economy-emissions models that simulate the energy supply and demand effects of the 2 °C carbon budget. Our oil price model includes key oil market attributes, notably upper and lower market share boundaries for different oil producer categories, such as OPEC. Using the distribution of the global model results as an indicator of uncertainty about future carbon prices and oil demand, we estimate the probability that a new investment of a given oil source category would be economically viable under the 2 °C carbon budget. In our case study of Canada’s oil sands, we find a less than 5% probability that oil sands investments, and therefore new oil pipelines, would be economically viable over the next three decades under the 2 °C carbon budget. Our sensitivity analysis finds that if OPEC agreed to reduce its market share to 30% by 2045, a significant reduction from its steady 40–45% of the past 25 years, then the probability of viable oil sands expansion rises to 30%.     

The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes

The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79?km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70° N, the negative energy imbalance at the top of the atmosphere decreases by about 10?W/m² in both sensitivity experiments. The energy transport across 70° N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter.     

The effects of topography on the summer atmospheric energetics of the Northern Hemisphere in a low-resolution global spectral model

An analysis is made of the effects of topography on the summer atmospheric energetics of the Northern Hemisphere in a low-resolution global spectral model. The numerical mode! is a global, spectral, primitive equation model with five equally spaced sigma levels in the vertical and triangular truncation at wavenumber 10 in the horizontal. The model includes comparatively full physical processes. Each term of the energy budget equations is calculated in four specific latitudinal belts (81.11°S–11.53°S; 11.53°S–11.53°N; 11.53°N–46.24°N; 46.24°N–81.11°N) from a five-year simulation with mountains and a one-year simulation without mountains, respectively. Differences between them are compared and statistically tested. The results show that synoptical scale waves transport available potential energy and kinetic energy to long waves and increase conversion from available potential energy of the zonal flow to eddy's and from the eddy kinetic energy to the zonal kinetic energy in region 3 (11.53°N-46.24°N) due to mountains; topography intensifies the atmospheric baroclinity in region 3, consequently the baroclinic conversion of atmosphere energy is increased. The seasonal characteristics associated with the summer atmospheric energy source in region 3 are caused by seasonal variation of the solar radiation and the land-ocean contrasts and independent of topographic effects. The mechanism of topographic effects on the increase of long wave kinetic energy is also discussed.     

A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing

Snow surface and sea-ice energy budgets were measured near 87.5°N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to ?7°C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between ?50 W m^?2 and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m^?2, except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area.     

Climatic impacts of historical wetland drainage in Switzerland

The effects of historical land-use and land-cover changes on the climate of the Swiss Plateau in the different seasons were investigated. In the 19th century, a civil engineering project was initiated to reshape the lake and river system on the Swiss Plateau in order to ban the frequent flooding during extreme weather events. The landscape modifications consisted primarily of a conversion of wetlands with extended peat soils into a highly productive agricultural landscape. Historical maps (1800–1850) served as a basis for the reconstruction of the past land use. The “Lokal-Modell” of the Consortium for Small-Scale Modelling was used to conduct eight one-month long high-resolution simulations (1.5 × 1.5 km²) with present and past landscape conditions. The modified soil and surface properties led to distinctly altered energy and moisture exchanges at the surface and as a consequence affected the local and regional climate. The climatic changes show different characteristics and magnitudes in the cold (October – March) as compared to the warm season (April – September). The landscape modifications led to an average daytime cooling between −0.12 °C (January) and −0.61 °C (April) and a night-time warming of 0.19 °C−0.34 °C. The differences in the mean monthly temperatures show a warming of 0.1 °C−0.2 °C in the cold season and a cooling of similar magnitude in most of the study area in the warm season. The modification of the radiation budget and the surface energy balance distinctly affected the convective activity in the study area in the warm season, but had only a weak effect on convectivity in the cold season. The cloud coverage in the warm season is therefore distinctly reduced compared to the past.