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1.
春季南海北部上混合层的数值模拟与数值实验 总被引：5，自引：0，他引：5
根据 1 998年南海季风实验 (SCSMEX)北部“实验 3号”调查船的观测资料 ,采用一维湍动能模式 (TKE模式 ) ,对春季南海北部的SST及混合层随时间变化特征进行了数值模拟和数值试验。结果表明 ,TKE模式能够很好地模拟南海北部的海表面温度SST和上混合层深度随时间变化基本特征。在南海 5— 6月 ,SST的日振荡主要依赖于短波辐射的日变化 ,短波辐射是SST的主要维持机制 ;短波辐射会使SST升高 1— 4℃ ;风的垂直混合作用主要是抑制了SST的日周期振荡。春季南海海面潜热通量和感热通量与短波辐射和风应力相比较 ,是一个对SST影响较小的量。南海北部 5月份混合层深度的变化趋势和振荡特征受风应力和短波辐射共同控制 ,风应力使混合层深度加深 5— 1 0m ,短波辐射使混合层深度平均变浅 5— 1 0m。而 6月份南海北部 ,在夏季风爆发后短波辐射较小 ,短波辐射的作用只能使混合层深度变浅1— 2m ,潜热通量和感热通量对混合层的作用会使混合层的深度加深 1— 2m ,混合层深度主要受风应力控制。 相似文献
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BCC_CSM对北极海冰的模拟:CMIP5和CMIP6历史试验比较 总被引：1，自引：1，他引：0
本文利用北京气候中心气候系统模式(BCC_CSM)在最近两个耦合模式比较计划(CMIP5和CMIP6)的历史试验模拟结果，对北极海冰范围和冰厚的模拟性能进行了比较，结果表明:(1) CMIP6改善了CMIP5模拟海冰范围季节变化过大的问题，总体上更接近观测结果；(2)两个CMIP试验阶段中BCC_CSM模拟的海冰厚度都偏小，但CMIP6试验对夏季海冰厚度过薄问题有所改进。通过对影响海冰生消过程的冰面和冰底热收支的分析，我们探讨了上述模拟偏差以及CMIP6模拟结果改善的成因。分析表明，8?9月海洋热通量、向下短波辐射和反照率对模拟结果的误差影响较大，CMIP6试验在这些方面有较大改善；而12月至翌年2月，CMIP5模拟的北极海冰范围偏大主要是海洋热通量偏低所导致，CMIP6模拟的海洋热通量较CMIP5大，但北大西洋表层海流的改善才是巴芬湾附近海冰外缘线位置改善的主要原因。CMIP试验模拟的夏季海冰厚度偏薄主要是因为6?8月海洋热通量和冰面热收支都偏大，而CMIP6试验模拟的夏季海冰厚度有所改善主要是由于海洋热通量和净短波辐射的改善。海冰模拟结果的改善与CMIP6海冰模块和大气模块参数化的改进有直接和间接的关系，通过改变短波辐射、冰面反照率和海洋热通量，使BCC_CSM模式对北极海冰的模拟性能也得到有效提高。 相似文献
3.
2007年在南黄海进行了3个航次的热通量观测,包括长、短波辐射,近海表空气温度、湿度,风速,海表皮温等观测数据。依据计算的冬季、春季、秋季三个航次的海气热通量分析了热通量不同季节特征,南黄海海域冬季、春季和秋季平均潜热通量分别为80.7W/m2,5.6W/m2和142.1W/m2,感热通量分别为32.0W/m2,-12.5W/m2和18.9W/m2(海洋向大气传递为正)。将国际较为通用的OAflux数据集与3个季节观测数据做了逐点的比对,作为对OAflux数据集在南黄海海域的评估,结果显示:OAflux数据集热通量结果与观测数据在2006—2007年冬季最为接近,感热和潜热通量均方差是15.3W/m2和21.4W/m2。春季的潜热通量存在明显偏差,均方差为28.4W/m2。秋季的感热和潜热通量均存在显著偏差,均方差分别为20.5W/m2和57.5W/m2。导致春季偏差的主要原因是OAflux数据集和现场观测的近海表空气湿度差异,而秋季偏差则应主要归因于海表温度的偏差。 相似文献
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5.
冬季风期(11月—翌年3月)南海显著的气候特点是盛行东北季风并频繁地发生冷涌天气过程。使用2008年10月到2009年4月在西沙群岛永兴岛近海进行的海-气通量观测试验资料,分析了西沙海域冬季风期,尤其是冷涌时段的海-气通量交换和热量收支特征。结果表明:冬季风前期由于海-气温差增大,感热通量比西南季风期稍增加;潜热通量平均值与西南季风期接近;太阳总辐射明显降低,大气长波辐射减小,海洋热量净收入成为负值,使得秋季之后海面温度不断降低。冷涌期间海-气之间的感热通量高于冬季风期平均值,潜热通量大部分(1月份之前)也高于冬季风期平均值;由于潜热通量增大和太阳短波辐射减小,1月份之前的冷涌过程海洋热量净收支普遍出现较大负值,海洋失热量强于冬季风期,甚至强于2008年台风过程平均值。到了冬季后期太阳总辐射增强,海洋热量净收入转为正值,海水温度又逐渐升高。季节之间比较,观测区感热通量以冬季风期间最大,秋季次之,春季最小;而潜热通量夏季风期出现最大值,冬季次之,秋季最小。 相似文献
6.
海表二氧化碳分压(pCO2)是指海洋表层水和大气之间的二氧化碳(CO2)交换处于动态平衡时CO2的含量, 是描述海-气CO2交换的一个主要因子。本文利用2008—2014年覆盖南海大部分海域的海表pCO2观测资料, 结合现场海表温度和海表盐度以及卫星观测的叶绿素a数据, 构建了基于多元线性回归方法的分区域反演模型。模型在水深浅于30m的区域均方根误差为5.3μatm, 其余海区均方根误差为10.8μatm, 与前人基于个别航次的有限区域反演结果的均方根误差相当。利用该模型公式和HYbrid Coordinate Ocean Model(HYCOM)再分析海表温、盐数据及MODIS-Aqua卫星观测的叶绿素a数据进行反演, 得到了时空分辨率为5'×5'的2004—2016年的逐月南海海表pCO2数据。该数据能较好地反映南海海表pCO2在海表温度影响下, 春夏高、秋冬低的季节变化特征, 与前人基于航次观测的研究结果相似, 表明反演模型具有较高的可信度。进一步分析发现, 南海及邻近海域平均海表pCO2具有显著的准十年振荡特征: 2012年附近出现了极小值, 之前表现为降低的趋势, 之后略有升高的趋势。受海表pCO2的影响, 南海海盆平均海-气CO2通量在2012年之前出现了显著降低的趋势, 表明南海释放到大气中的CO2减少, 并在2007年之后的冬季出现了负值(从碳源变为碳汇), 2012年之后变化较为平缓。热带太平洋年代际振荡引起的南海区域海表盐度变化是造成海表pCO2及海-气CO2通量准十年变化的主要原因。分区分析的结果表明, 南海北部海表pCO2变化最为显著, 在南海海表pCO2的季节和准十年变化中都起到非常重要的作用。 相似文献
7.
南海西南季风期NCEP2湍流热通量的质量分析 总被引：3，自引：2，他引：3
以5次南海现场观测试验数据(Xisha2002,Xisha2000,Xisha1998,Kexue 1和Shiyan 3)为参照,对NCEP2再分析资料中湍流热通量在南海西南季风期的精度进行了评估.结果表明NCEP2估算的潜热通量的平均值在试验Xisha2000,Xisha1998,Kexue 1和Shiyan 3期间分别高估了6(11%),2(2%),7(7%)和13W/m2(16%),而在Xisha2002试验中低估了10 W/m2(11%).在5个试验中低估的感热通量分别为7(130%),3(64%),7(170%),5(53%)和5 W/m2(72%).NCEP2与5个现场观测试验的时间序列的相关系数均没有达到95%的置信度.模式中湍流热通量损失的误差来源于基本变量和算法,基本变量中以海表温度和海面风速的误差产生的影响最大.应用COARE2.6a算法和NCEP2的基本变量重新计算的湍流热通量更加符合物理意义. 相似文献
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南海北部春季非水华期的CO_2分压及其调控 总被引：1，自引：0，他引：1
针对南海北部和吕宋海峡附近海域的海-气CO2通量及其调控问题,研究了2009年3月底至4月中旬在这些海域通过走航观测的方法取得的海-气CO2分压和海表温度、盐度等相关数据。结果表明,在河口、沿岸流以外的南海北部开阔海域,与大气平衡的CO2分压分布在368~380μatm,南低北高,平均值为371μatm;而海表CO2分压分布在293~405μatm,南高北低。南海北部开阔海域的海表CO2分压主要受温度效应调控,也在一定程度上受水团混合、海-气交换、生物活动等非温度效应的影响。在相同水温条件下,黑潮区的海表CO2分压比南海北部的海表CO2分压低。本研究和大多数前人研究的结果都表明,南海北部海盆区域和吕宋海峡西侧海域在春季与大气CO2接近源汇平衡,而非大气CO2的显著源区。 相似文献
9.
春季南海南部上混合层数值模拟与数值实验 总被引：1，自引：1，他引：1
采用一维湍动能模式对南海南部的 SST及混合层进行数值模拟和数值试验。结果表明 :TKE模式能够模拟南海南部的海表面温度 SST以及除南海南部 5月中旬以外的上混合层深度随时间变化基本特征。在 5～ 6月 ,SST的日振荡主要依赖于短波辐射的日变化 ,风的混合作用抑制了 SST的日周期振荡。春季夏季风爆发期间 ,南海海面潜热通量和感热通量与短波辐射和风应力相比较 ,是一个对 SST和混合层影响较小的量。在春季南海南部 ,短波辐射作用能使 SST升高的最大值约为 4℃ ;潜热和感热通量能使 SST的下降的最大值为 3℃。风应力对南海混合层深度随时间变化趋势起着决定的作用 ,并能使其深度加深 2 0～ 30 m,而短波辐射则使混合层的深度变浅2～ 3m,潜热和感热通量会使混合层的深度加深 1～ 2 m。在春季南海南部 ,热通量对混合层深度的影响与风应力相比要小得多 相似文献
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利用实测的海洋气象资料研究了青岛沿海海气间能通量和水汽交换情况,分析了青岛沿海40a间(1961-2000)海面风应力、海-气热通量、水汽通量的大小以及时变特征。结果表明:青岛沿海风应力冬夏季大,春秋季小,6月和12月出现峰值,分别为2.9×10-3N/m2和5.8×10-3N/m2。海面净热通量全年呈单峰变化,7月份最大,为140.4W/m2;11月份最小,为-115.0W/m2;年平均海表净热通量为23.5W/m2。海面热量收支的季节分布特征是:海面吸收的太阳短波辐射夏季大、冬季小;海表有效辐射冬季大、夏季小;海-气潜热交换季节变化呈双峰分布,极大值出现在5月和9月;海-气感热交换受海气温差控制,冬季为正,热量由海洋传向大气,夏季为负,热量由大气传向海洋。受云量影响,海面吸收的太阳短波辐射从上世纪90年代以来有所增加;海-气潜热交换的年际变化显著,40a间变动范围达33.7W/m2。海-气净热通量的年际变化也很明显,40a间变动范围达41.7W/m2,且自80年代以来呈现上升的趋势。青岛沿海年平均蒸发量大于降水量,量值分别为888.0mm和677.2mm,年平均净水汽通量为-210.8mm;蒸发量的季节分布呈双峰变化,5月和9月达极大值;多年平均7,8两个月份降水多于蒸发,其余月份蒸发多于降水。 相似文献
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Observations of downward radiative flux at the sea surface generally contain uncertainty due to limited numbers of observations and limitations of auxiliary equipment. The lack of shading from direct solar radiation and ventilation systems causes bias or random errors. To evaluate the error of radiation measurements at buoys, downward shortwave and longwave radiative fluxes are compared with International Satellite Cloud Climatology Project (ISCCP), Japanese 55-year Reanalysis (JRA55), and Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved model calculations of 3-h and daytime averages. Cloud masking is evaluated by a combination of MTSAT-1R and in situ observations. Coincident observations from a land-surface station located near the buoy observatories are compared with satellite and reanalysis products. The bias at buoys, compared with retrievals, approximately over- and under-estimate for longwave and shortwave fluxes, respectively. The bias at buoys is larger and smaller than the land by 23–34 W m?2 for longwave and 13–51 W m?2 for shortwave radiation using 3-h averages under clear-sky conditions. The differences in bias decrease when using daytime averages for longwave, but the difference for shortwave increases with daytime averages. To evaluate the effect of environmental factors on buoy observations, we compared rainfall, wind speed, and solar zenith angle with the biases. We found that rainfall and wind speed affect buoy pyrgeometers such that they overestimate the longwave flux. The cosine of solar zenith angle does not cause overestimation for longwave flux, and the effect of dome heating is small. The strong wind causes underestimation of the shortwave radiative flux due to tilting. The effect of wind is reduced when daily averages are used. 相似文献
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Over the past decades, sea ice in the polar regions has been significantly affecting local and even hemispheric climate through a positive ice albedo feedback mechanism. The role of fast ice, as opposed to drift ice, has not been well-studied due to its relatively small coverage over the earth. In this paper, the optical properties and surface energy balance of land fast ice in spring are studied using in situ observations in Barrow, Alaska. The results show that the albedo of the fast ice varied between 0.57 and 0.85 while the transmittance increased from 1.3×10?3 to 4.1×10?3 during the observation period. Snowfall and air temperature affected the albedo and absorbance of sea ice, but the transmittance had no obvious relationship with precipitation or snow cover. Net solar shortwave radiation contributes to the surface energy balance with a positive 99.2% of the incident flux, with sensible heat flux for the remaining 0.8%. Meanwhile, the ice surface loses energy through the net longwave radiation by 18.7% of the total emission, while the latent heat flux accounts for only 0.1%. Heat conduction is also an important factor in the overall energy budget of sea ice, contributing 81.2% of the energy loss. Results of the radiative transfer model reveal that the spectral transmittance of the fast ice is determined by the thickness of snow and sea ice as well as the amount of inclusions. As major inclusions, the ice biota and particulates have a significant influence on the magnitude and distribution of the spectral transmittance. Based on the radiative transfer model, concentrations of chlorophyll and particulate in the fast ice are estimated at 5.51 mg/m2 and 95.79 g/m2, which are typical values in the spring in Barrow. 相似文献
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Long term in situ atmospheric observation of the landfast ice nearby Zhongshan Station in the Prydz Bay was performed from April to November 2016. The in situ observation, including the conventional meteorological elements and turbulent flux, enabled this study to evaluate the sea ice surface energy budget process. Using in situ observations, three different reanalysis datasets from the European Centre for Medium-Range Weather Forecasts Interim Re-analysis(ERA-Interim), National Centers for Environmental Prediction Reanalysis2(NCEP R2), and Japanese 55-year Reanalysis(JRA55), and the Los Alamos sea ice model, CICE, output for surface fluxes were evaluated. The observed sensible heat flux(SH) and net longwave radiation showed seasonal variation with increasing temperature. Air temperature rose from the middle of October as the solar elevation angle increased.The ice surface lost more energy by outgoing longwave radiation as temperature increased, while the shortwave radiation showed obvious increases from the middle of October. The oceanic heat flux demonstrated seasonal variation and decreased with time, where the average values were 21 W/m~2 and 11 W/m~2, before and after August,respectively. The comparisons with in situ observations show that, SH and LE(latent heat flux) of JRA55 dataset had the smallest bias and mean absolute error(MAE), and those of NCEP R2 data show the largest differences.The ERA-Interim dataset had the highest spatial resolution, but performance was modest with bias and MAE between JRA55 and NCEP R2 compare with in situ observation. The CICE results(SH and LE) were consistent with the observed data but did not demonstrate the amplitude of inner seasonal variation. The comparison revealed better shortwave and longwave radiation stimulation based on the ERA-Interim forcing in CICE than the radiation of ERA-Interim. The average sea ice temperature decreased in June and July and increased after September,which was similar to the temperature measured by buoys, with a bias and MAE of 0.9°C and 1.0°C, respectively. 相似文献
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The seasonal variabilities of a latent-heat flux (LHF), a sensible-heat flux (SHF) and net surface heat flux are examined in the northern South China Sea (NSCS), including their spatial characteristics, using the in situ data collected by ship from 2006 to 2007. The spatial distribution of LHF in the NSCS is mostly controlled by wind in summer and autumn owing to the lower vertical gradient of air humidity, but is influenced by both wind and near-surface air humidity vertical gradient in spring and winter. The largest area-averaged LHF is in autumn, with the value of 197.25 W/m 2 , followed by that in winter; the third and the forth are in summer and spring, respectively. The net heat flux is positive in spring and summer, so the NSCS absorbs heat; and the solar shortwave radiation plays the most important role in the surface heat budget. In autumn and winter, the net heat flux is negative in most of the observation region, so the NSCS loses heat; and the LHF plays the most important role in the surface heat budget. The net heating is mainly a result of the offsetting between heating due to the shortwave radiation and cooling due to the LHF and the upward (outgoing) long wave radiation, since the role of SHF is negligible. The ratio of the magnitudes of the three terms (shortwave radiation to LHF to long-wave radiation) averaged over the entire year is roughly 3:2:1, and the role of SHF is the smallest. 相似文献
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基于Icepack一维海冰柱模式,以2014年中国第6次北极科学考察长期冰站ICE06的3个融池的辐射参量和气象参量的连续观测作为大气强迫数据,对融池反照率及相关参量进行了模拟。本文引入观测的融池深度及海冰厚度作为初始条件,通过考虑融池覆盖率的作用,改进了平整冰融池参数化方案中海冰干舷的计算,修正了冰上可允许的最大融池深度,成功实现了对融池参数变化的模拟;同时,还修正了入射辐射分量比例系数与对应反照率分量权重系数不一致的问题。标准试验中,模拟的3个融池的反照率与观测结果之间的平均误差分别为0.01、0.05和0.13;入射辐射比例的敏感性试验结果表明,当可见光辐射比例增大8%时,融池反照率的模拟结果增大了6%～8%;融池表面再冻结试验的结果显示,当再冻结冰层厚度小于2 cm时,模拟冰面反照率的增加不足0.006,由此引起的表面能量收支减少了约1.1 W/m2。本文研究指出,准确的入射辐射比例对于改善北极海冰反照率模拟是必要的;并指出目前模式仍存在融池表面再冻结参数化、热收支计算、表面吹雪效应等有待解决的问题。 相似文献
16.
The purpose of this study is to validate and improve satellite-derived downward surface shortwave radiation (DSSR) over the northwestern Pacific Ocean using abundant in situ data. The DSSR derivation model used here assumes that the reduction of solar radiation by clouds is proportional to the product of satellite-measured albedo and a cloud attenuation coefficient. DSSR is calculated from Geostationary Meteorological Satellite-5/Visible Infrared Spin-Scan Radiometer data in 0.05° × 0.05° grids. The authors first compare the satellite DSSR derived with a cloud attenuation coefficient table determined in past research with in situ values. Although the hourly satellite DSSR agrees well with land in situ values in Japan, it has a bias of +13∼+34 W/m2 over the ocean and the bias is especially large in the low latitudes. The authors then improve the coefficient table using the ocean in situ data. Usage of the new table successfully reduces the bias of the satellite DSSR over the ocean. The cloud attenuation coefficient for low-albedo cases over the ocean needs to be larger in the low latitudes than past research has indicated. Daily and hourly DSSR can be evaluated from the satellite data with RMS errors of 11–14% and 30–33%, respectively, over a wide region of the ocean by this model. It is also shown that the cloud attenuation coefficient over land needs to be smaller than over the ocean because the effect of the radiation reflected by the land surface cannot be ignored. 相似文献
17.
一种海冰热力过程参数化方案 总被引：5，自引：1，他引：4
由于海冰热力过程太复杂,难于精确计算冰面和水面热量收支方程中的每一项,并且净热量收支比每项小得多,因此难以确定海冰热力一动力模式中的净热通量。本文根据渤海的水文气象观测,详细分析了太阳短波辐射、长波辐射、云量、感热和潜热等对海冰热力增长函数的贡献,给出了一种海冰热力过程的参数化方案。并选取２个典型的个例进行了对比研究。模拟结果表明,该参数化方案能较好地模拟渤海海冰的热力过程。 相似文献
18.
南海西沙海区5～6月份辐射通量研究--整体公式建立 总被引：4，自引：0，他引：4
将南海西沙海区2000年5～6月海面辐射通量（包括太阳短波辐射、海面反射辐射、大气逆辐射和海面长波辐射）与云量、海温、气温、水汽压等气象要素进行了对比分析,发现它们之间存在一定的相关关系,利用这些关系建立了适合于计算南海西沙海区的太阳短波辐射、大气逆辐射、海面长波辐射和海面反照度的经验公式.分析结果表明,采用本文经验公式计算的各辐射通量值与实测资料的误差较一般常用经验公式的计算误差均有不同程度的减小,计算结果与实测结果在变化趋势上也具有较好的一致性. 相似文献
19.
利用"中国近海海洋综合调查与评价"2007年北黄海春季航次的资料,综合分析了短波、长波辐射及海面短波、长波反射辐射特征及与云量、气温、水汽压、海面红外温度等的对应关系。结果显示海面太阳入射辐射远大于海面反射辐射,二者相差约1个量级;海面长波辐射总体上大于大气逆辐射,二者相差约40 W/m2,平均净辐射为153.1 W/m2。观测期间大气透射率约为0.45,并据此分析探讨了云对太阳辐射传输的影响,建立了考虑总云量、低云量及水汽压等因素的海面太阳短波辐射经验估算公式,计算结果与实测结果具有较好一致性,均方根误差为11.3 W/m2。最后讨论了太阳辐射船基观测由于船体晃动可能造成的误差影响。 相似文献