Inertance of surface temperature variations

The index of inertance of surface temperature variations is proposed which supposedly reflects the damping effect of the ocean on the variations in atmospheric thermal conditions over the land. It is demonstrated that the climate variability and climate change are related to the index of inertance. Air temperature rose most intensively in the years of weak stabilizing effect of the ocean which restrains the climate warming. The general trend of the inertance weakening on the land in the second half of the 20th century led to the additional and more rapid warming and to the increase in climate extremity on the continents.     

Dynamic normals of surface air temperature

Cited are the latest data on the contemporary climate changes in surface air temperature (to the year 2011 inclusive). Substantiated is the necessity of extending the concept on the normals and anomalies of surface air temperature under conditions of the changing climate. Formulated is a concept of “dynamic normals” and “dynamic anomalies” of surface air temperature taking account of current trends of climate change and interseasonal variations. It is proposed to adopt this concept both for the problems of forthcoming climate change assessments and for the long-range forecasting out of the “limit of predictability.” An adaptive regression method is proposed to compute such dynamic normals as a function of the indicator of global climate changes. Presented are the skill scores of dynamic normals as of “intermediate” forecasts (an analogue of the climate forecast under a changing climate).     

Modes of variability of global sea surface temperature,free atmosphere temperature and oceanic surface energy flux

Monthly mean sea surface temperature (SST), free air temperature from satellite microwave sounding units (MSU) and oceanic surface energy fluxes are subjected to empirical orthogonal function (EOF) analysis for a common decade to investigate the physical relationships involved. The first seasonal modes of surface solar energy flux and SST show similar inter-hemispheric patterns with an annual cycle. Solar flux appears to control this pattern of SST. The first seasonal mode of MSU is similar with, additionally, land-sea differences; MSU is apparently partly controlled by absorption of solar near-infrared radiation and partly by sensible heat from the land surface. The second and third seasonal eigenvector of SST and solar flux exhibit semi-annual oscillations associated with a pattern of cloudiness in the subtropics accompanying the translation of the Hadley cell rising motion between the hemispheres. The second seasonal mode of MSU is dominated by an El Niño signal. The first nonseasonal EOFs of SST and solar flux exhibit El Niño characteristics with the solar pattern being governed by west-to-east translation of a Walker cell type pattern. The first non-seasonal EOF of MSU shows a tropical strip pattern for the El Niño mode, which is well correlated with the latent heat fluxes in the tropical east Pacific but not in the tropical west Pacific. Two possible explanations are: an increase in subsidence throughout the tropical strip driven by extra evaporation in the tropical east Pacific and consequent additional latent heat liberation; a decrease of meridional heat flux out of the tropics.     

The Prediction of winter surface air temperature

The author investigates the prediction of Northeast China’s winter surface air temperature (SAT),and first forecast the year to year increment in the predic-tand and then predict the predictand.Thus,in the first step,we determined the predictors for an increment in winter SAT by analyzing the atmospheric variability associated with an increment in winter SAT.Then,multi-linear re-gression was applied to establish a prediction model for an increment in winter SAT in Northeast China.The pre-diction model shows a high correlation coefficient (0.73) between the simulated and observed annual increments in winter SAT in Northeast China throughout the period 1965-2002,with a relative root mean square error of -7.9%.The prediction model makes a reasonable hindcast for 2003-08,with an average relative root mean square error of -7.2%.The prediction model can capture the in-creasing trend of winter SAT in Northeast China from 1965-2008.The results suggest that this approach to forecasting an annual increment in winter SAT in North-east China would be relevant in operational seasonal forecasts.     

对地面温度异常情况的处理

从众多的地面温度观测记录来看，发现了很多地面最高温度表的记录和地面最低温度表的记录，分别比下午和上午地面0cm的值偏低和偏高许多，或者下午（上午）地面0cm温度表与地面最高温度表（地面最低温度表）读数相差较大的异常情况。以下就对这些情况出现的原因及处理方法提出一些看法和见解。     

对地面温度异常情况的处理

从众多的地面温度观测记录来看,发现了很多地面最高温度表的记录和地面最低温度表的记录,分别比下午和上午地面0cm的值偏低和偏高许多,或者下午(上午)地面0cm温度表与地面最高温度表(地面最低温度表)读数相差较大的异常情况.以下就对这些情况出现的原因及处理方法提出一些看法和见解:     

Soil temperature spin-up in land surface schemes

Land surface schemes used in atmospheric and hydrologic models require the specification of initial soil-temperature profiles. However, detailed soil temperature information is generally unavailable, hence modellers sometimes recur to specifying simplified initial conditions such as vertically constant profiles, assuming that the harmonic heating at the soil surface induces a rapid equilibrium to a steady periodic state. In this paper, using both numerical and analytical approaches, it is shown that such a transition to a steady periodic state is not always very rapid. In particular, it is demonstrated that the characteristic time required to reach equilibrium is highly dependent on the precise timing of initialisation with respect to the cycle of surface heating, and that initialising at the instant coincident with the occurrence of the maximum soil heat flux is the preferred mode.     

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Using a state-of-the-art chemistry-climate model,we analyzed the atmospheric responses to increases in sea surface temperature （SST）.The results showed that increases in SST and the SST meridional gradient could intensify the subtropical westerly jets and significantly weaken the northern polar vortex.In the model runs,global uniform SST increases produced a more significant impact on the southern stratosphere than the northern stratosphere,while SST gradient increases produced a more significant impact on the northern stratosphere.The asymmetric responses of the northern and southern polar stratosphere to SST meridional gradient changes were found to be mainly due to different wave properties and transmissions in the northern and southern atmosphere.Although SST increases may give rise to stronger waves,the results showed that the effect of SST increases on the vertical propagation of tropospheric waves into the stratosphere will vary with height and latitude and be sensitive to SST meridional gradient changes.Both uniform and non-uniform SST increases accelerated the large-scale Brewer-Dobson circulation （BDC）,but the gradient increases of SST between 60°S and 60°N resulted in younger mean age-of-air in the stratosphere and a larger increase in tropical upwelling,with a much higher tropopause than from a global uniform 1.0 K SST increase.     

气象卫星遥感地表温度推算近地表气温方法研究

气温是各种植物生理、水文、气象、环境等模式或模型中的一个非常重要的近地表气象参数.多年来气温数据以离散的常规气象站点观测为主,连续分布的格点气温数据则以站点资料插值而得到,分辨率低,无法反映地形等下垫面因素对局地气温的影响,在农业气候区划等研究中具有一定的局限性.随着卫星遥感地表温度算法的日趋成熟,为探讨卫星遥感地表温度数据在气温观测中的可能性和可行性,利用全中国2340个站点1998 2007年的逐旬平均最高气温数据,以及相应时段的NOAA/AVHRR旬最高地表温度数据,以线性回归及拟合模型为主,通过考虑植被指数、土地覆盖类型、季节、风速、气压、降水等各类影响因子,建立了旬最高地表温度与旬平均最高气温间的推算模型,并利用未参与建模的2002-2003年的常规气象站点气温数据,同时与推算气温和插值气温结果进行对比分析.结果表明,利用卫星遥感地表温度数据推算的旬值气温数据可取得较高的精度,尤其在地形复杂地区以及站点稀疏地区精度明显高于插值气温结果.     

An updated evaluation of the global mean land surface air temperature and surface temperature trends based on CLSAT and CMST

Climate Dynamics - Past versions of global surface temperature (ST) datasets have been shown to have underestimated the recent warming trend over 1998–2012. This study uses a newly updated...     

大洋间海表温度遥联与中国冬季气温的关系

利用SVD方法,在年代际和年际尺度上研究了各季北大西洋和北太平洋海表温度的遥相关关系,给出了冬季两个时间尺度上的遥联指数I,并分析了它们与同期中国冬季气温及亚太冬季风的相关关系.结果表明:北大西洋和北太平洋在两个时间尺度上的海表温度遥联均与同期中国冬季气温相关;特别在年代际尺度上两大洋海表温度遥联与我国河套以南及长江中游地区冬季气温有显著正相关.其影响途径可能是两大洋海温异常引起亚太冬季风异常、继而引起我国冬季气温异常.     

Synoptic-scale anomalies of Lake Ladoga surface temperature fields

Results of studying characteristic features of variability of the water surface temperature fields of Lake Ladoga during the open water period are presented. Anomalies and extreme deviations of real spatial distributions from those typical of the scales of synoptic variability are estimated. Typical surface temperature distribution of Lake Ladoga during an open water period occupies not more than 20% of the lake area. The near-shore shallow water area is characterized as an area of most anomalous water temperature distribution. The abnormality extent changes from month to month. July is the most anomalous month of the open water period.     

On the time-varying trend in global-mean surface temperature

The Earth has warmed at an unprecedented pace in the decades of the 1980s and 1990s (IPCC in Climate change 2007: the scientific basis, Cambridge University Press, Cambridge, 2007). In Wu et al. (Proc Natl Acad Sci USA 104:14889–14894, 2007) we showed that the rapidity of the warming in the late twentieth century was a result of concurrence of a secular warming trend and the warming phase of a multidecadal (~65-year period) oscillatory variation and we estimated the contribution of the former to be about 0.08°C per decade since ~1980. Here we demonstrate the robustness of those results and discuss their physical links, considering in particular the shape of the secular trend and the spatial patterns associated with the secular trend and the multidecadal variability. The shape of the secular trend and rather globally-uniform spatial pattern associated with it are both suggestive of a response to the buildup of well-mixed greenhouse gases. In contrast, the multidecadal variability tends to be concentrated over the extratropical Northern Hemisphere and particularly over the North Atlantic, suggestive of a possible link to low frequency variations in the strength of the thermohaline circulation. Depending upon the assumed importance of the contributions of ocean dynamics and the time-varying aerosol emissions to the observed trends in global-mean surface temperature, we estimate that up to one third of the late twentieth century warming could have been a consequence of natural variability.     

Prediction of surface potential temperature over complex terrain

Based on a statistical approach, the surface potential temperature at seven observing stations in complex terrain has been examined. It is shown that the surface potential temperature depends primarily on the rate of change of slope wind and on the geostrophic-level potential temperature.     

Microscale temperature fluctuations in the atmospheric surface layer

Microscale temperature fluctuations were measured at 2 m above a grassy surface. The temperature-derivative spectrum was in general agreement with earlier results but the bump at nondimensional wavenumbers higher than 0.02 was not as pronounced as has been observed. The Obukhov-Corrsin constant for the one-dimensional temperature spectrum was evaluated to be 0.92 ± 0.05, consistent with recent results. The effects of instability and the vertical variation of temperature variance and kinetic energy dissipation are postulated to explain some of the difference with other spectra.     

Spatiotemporal scaling of surface air temperature fields in China

The characteristics of spatiotemporal variability of surface air temperature anomaly fields in China are computed from the data of instrumental observations carried out from 1907 to 2000. The fields are represented by their empirical orthogonal function expansion. The temporal variations of the coefficients of this expansion are considered at the scale range from one month to five years. It turned out that both the orthogonal function structure and the type of the temporal variability of expansion coefficients in China differ from those in Northern Eurasia. Investigating the current climate warming in China, it is enough to consider the first two empirical orthogonal functions of temperature fields only. The characteristic time of the existence of temperature anomalies described by these functions is almost the same as that of the temperature anomalies in Northern Eurasia described by the first empirical orthogonal function of the respective fields.     

On long range dependence in global surface temperature series

Long Range Dependence (LRD) scaling behavior has been argued to characterize long-term surface temperature time series. LRD is typically measured by the so-called “Hurst” coefficient, “H”. Using synthetic temperature time series generated by a simple climate model with known physics, I demonstrate that the values of H obtained for observational temperature time series can be understood in terms of the linear response to past estimated natural and anthropogenic external radiative forcing combined with the effects of random white noise weather forcing. The precise value of H is seen to depend on the particular noise realization. The overall distribution obtained over an ensemble of noise realizations is seen to be a function of the relative amplitude of external forcing and internal stochastic variability and additionally in climate “proxy” records, the amount of non-climatic noise present. There is no obvious reason to appeal to more exotic physics for an explanation of the apparent scaling behavior in observed temperature data.     

The reliability of global and hemispheric surface temperature records

The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered.These issues are discussed in the order of their importance for temperature records at these spatial scales: biases in SST data,particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time.