Atmospheric temperature profile for a tropical region from TIROS-N microwave sounding unit

Atmospheric temperature profiles have been derived using 53·74 GHz, 54·96 GHz and 57·95 GHz channels data from the Microwave Sounding Unit onboard TIROS-N. For this purpose regression coefficients have been derived using MONEX-79 radiosonde data during the period May to July 1979. The temperature profiles derived at a few selected places were closer to radiosonde profiles than the profiles derived using standard regression coefficients for the tropical region supplied by NOAA.     

Use of satellite data for radiative energy budget study of Indian summer monsoon

In this paper satellite-derived radiative energy budget such as shortwave radiative heating, longwave radiative heating and net radiation balance have been studied for the post-onset phase of summer monsoon 1979. Since clouds play an important role in determining diabatic heating field as well as being a reflection of status of the monsoon itself, the day to day evolution of clouds from TIROS-N satellite has been made. Satellite-derived radiative heating rates from surface to 100 hPa were computed for each 100 hPa thickness layer. These heating rates were then compared with the observed latitudinal distribution of total radiative heating rates over the domain of the study. From the results of our study it was found that the characteristic features such as net radiative heating rates of the order of 0.2°C/day at upper tropospheric layer (100–200 hPa) and cooling throughout the lower tropospheric layers with relatively less cooling between 500–700 hPa layer observed in a case of satellite-derived radiative energy budget agree well with the characteristic features of observational radiative energy budget over the domain of the study. Therefore, it is suggested that radiative energy budget derived from satellite observations can be used with great potential and confidence for the evolution of the complete life cycle of the monsoon over the Indian region for different years.     

Study of thermodynamic indices in forecasting pre-monsoon thunderstorms over Kolkata during STORM pilot phase 2006–2008

The pre-monsoon convective atmosphere over Kolkata (22.52°N, 88.37°E) during STORM field phase 2006–2008 is investigated using 12 UTC radiosonde data and thermodynamic indices. In the present study, an attempt has been made to assess the skill of various indices and parameters and to propose suitable threshold values in forecasting the occurrence of thunderstorm activity at Kolkata. The thermodynamic indices and parameters used in the present study are lifted index (LI), K index (KI), severe weather threat index (SWEAT), total totals index (TTI), convective available potential energy (CAPE), deep convection index (DCI), humidity index (HI), Boyden index (BI), dew point temperature at 850 hpa (DEW), relative humidity at 700 hpa (RH), and bulk Richardson number (BRN). Validation of the suggested threshold values of indices was conducted on the days of thunderstorm activity. It was found that one index alone cannot predict the occurrence of thunderstorm over Kolkata region. The present study suggests that the indices with highest skill for thunderstorm prediction are KI, DCI, SWEAT, DEW, HI, RH, LI, TTI, while the prediction efficiency is poor for CAPE, BRN, and BI. Observed values of these indices also reveal that scattered, multi-cellular thunderstorms are possible over Kolkata during pre-monsoon months.     

青藏铁路通风路基边界条件研究

In permafrost regions, many methods about active cooling embankment are put forward, one of these representations is ventilated embankment, its cooling effect is the result of the air convection in the duct, and this leads to reducing the annual average ground temperature. The present work in this article is to determine the boundary conditions of the ventilated embankment and natural ground in numerical work. There are several effects which influence boundary conditions, they are: radiation, evaporation,phase change, convection and embankment material etc. Radiation and convection are the main effects in those. We mainly consider sun radiation in this article. The added-surface effect in ventilated embankment lowers its temperature, so the temperature on the wall of the ventilated embankment is different from the temperature in atmosphere. There are two methods in determining the surface temperature, experimental method and experiential method. Detailed research is discussed in the article.     

基于冠层温度的作物缺水研究进展

冠导温度信息可以很好地反映作物的水分状况。自20世纪70年代以来，基于冠层温度的作物缺水指标的研究经历了三个阶段，即单纯研究冠层温度本身变化特征的第一阶段、以冠层能量平衡原理为基础的作物水分胁迫指数的第二阶段和考虑冠层和土壤的复合温度的水分亏缺指数的第三阶段。指标的局长也由使用手持式红外辐射仪信息扩大到使用航空和卫星遥感信息。这一类指标在点和区域尺度上均可应用。加强这一类指标的研究对于我国北方地区农作物的有效灌溉和区域水资源的管理都有重要意义。     

Parameter estimation based on vertical heat transport in the surficial zone

Measured groundwater temperatures in the surficial zone are dependent on the properties of porous media and vertical flow velocity. Sensitivity analyses, collinear diagnostics and an inverse numerical solution to the one-dimensional heat-transport equation are used to determine which parameters can be estimated from temperature measurements in the surficial zone. This is done for heat transport in the saturated zone considering a constant vertical flow velocity. The use of temperature profiles, temperature time-series and temperature envelopes are considered. There is an important difference between a conduction and a convection dominated system. Sensitivity analysis shows that temperature measurements are sensitive to effective thermal conductivity and heat capacity and are insensitive to effective porosity and thermal dispersivity. In a conduction dominated system, temperature is also insensitive for vertical velocity. Collinear diagnostics show that in a conduction dominated system, only the combination of heat capacity and effective thermal conductivity, the thermal diffusivity, can be derived. In a convection dominated system, both the vertical velocity and the effective thermal conductivity can, theoretically, be derived.     

Statistically downscaled climate change projections of surface temperature over Northern Italy for the periods 2021–2050 and 2070–2099

Future changes of seasonal minimum and maximum temperature over Northern Italy are assessed for the periods 2021–2050 and 2070–2099 against 1961–1990. A statistical downscaling technique, applied to the ENSEMBLES-Stream1 and CIRCE global simulations (A1B scenario), is used to reach this objective. The statistical scheme consists of a multivariate regression based on Canonical Correlation Analysis. The set-up of the statistical scheme is done using large-scale fields (predictors) derived from ERA40 reanalysis and seasonal mean minimum and maximum temperature (predictands) derived from observational data at around 75 stations, distributed over Northern Italy, over the period 1960–2002. A similar technique is also applied to the number of frost days and ice days at a reduced number of stations in order to construct projections on change of the selected extreme temperature indices for the two future periods. The evaluation of future projections for these extreme indices is relevant due to its impacts on transports, health, and agriculture. The downscaling scheme constructed using observed data is then applied to large-scale fields simulated by global models (A1B scenario), in order to construct scenarios on future change of seasonal temperature, mean and extreme indices, at local scale. The significance of changes is tested from the statistical point of view. The results show that significant increases could be expected to occur under scenario conditions in both minimum and maximum temperature, associated with a decrease in the number of frost and ice days in both periods and more intense to the end of the century.     

Application of meteorological and vegetation indices for evaluation of drought impact: a case study for Rajasthan, India

Drought is a serious climatic condition that affects nearly all climatic zones worldwide, with semi-arid regions being especially susceptible to drought conditions because of their low annual precipitation and sensitivity to climate changes. Drought indices such as the standardized precipitation index (SPI) using meteorological data and vegetation indices from satellite data were developed for quantifying drought conditions. Remote sensing of semi-arid vegetation can provide vegetation indices which can be used to link drought conditions when correlated with various meteorological data based drought indices. The present study was carried out for drought monitoring for three districts namely Bhilwara, Kota and Udaipur of Rajasthan state in India using SPI, normalized difference vegetation index (NDVI), water supply vegetation index (WSVI) and vegetation condition index (VCI) derived from the Advanced Very High resolution Radiometer (AVHRR). The SPI was computed at different time scales of 1, 2, 3, 6, 9 and 12 months using monthly rainfall data. The NDVI and WSVI were correlated to the SPI and it was observed that for the three stations, the correlation coefficient was high for different time scales. Bhilwara district having the best correlation for the 9-month time scale shows late response while Kota district having the best correlation for 1-month shows fast response. On the basis of the SPI analysis, it was found that the area was worst affected by drought in the year 2002. This was validated on the basis of NDVI, WSVI and VCI. The study clearly shows that integrated analysis of ground measured data and satellite data has a great potential in drought monitoring.     

Horizontal moisture distribution from TIROS-N high resolution infrared sounder (HIRS)

A direct linear relationship between water vapour content of lower, middle and upper-middle troposphere respectively with the radiances for 8.3, 7.3 and 6.7 μm spectral observations has been attempted. From the atmospheric simulations such a relationship is found to exist with a good degree of correlation and is seen to be quite insensitive to temperature changes. Such an approach is used to interpret the water vapour imageries obtained from TIROS-N sounder through construction of detailed water vapour distribution maps.     

卫星降雨数据在高山峡谷地区的代表性与可靠性

以长江上游金沙江流域典型高山峡谷地区为研究对象,用该区域地面观测降雨量数据对TRMM PR 3B42 V6产品进行了3 h、日、月3个时间尺度的有效性评估,旨在为开展区域卫星与地面降水数据融合的流域水文模拟及预报奠定数据基础。分别采用了线性回归方法分析降雨量相关性、经验正交函数-奇异值分解方法(EOF-SVD)分析降雨量主要模态空间分布特征、相对偏差B_ias、错报率R_FA和探测率P_D指标对该卫星产品进行了精度评定。研究结果表明:研究区该卫星产品与地面观测数据在3个时间尺度存在显著的线性时间和空间相关性,但相关程度随时间尺度的减小而减弱;二者在空间分布上总体具有一致性特征,但在高海拔、大坡度区域表现出较为显著的差异;相对偏差指标显示2008-2010年降雨量均值相对偏差在±10%的概率密度百分数为36.08%;随高程的增加,卫星数据R_FA呈逐渐增加趋势变化,P_D呈逐渐减小趋势变化;总体上小雨对误差的贡献最大,大雨峰值误差贡献次之,时段降雨量偏差随时间尺度的增加逐渐减小,而随高程的增加卫星数据的探测精度下降。因此,对于类似的高山峡谷流域,要应用该卫星产品进行日、3 h尺度水文模拟及预报,有必要对流域卫星数据和地面观测数据进行融合,充分发挥两种数据的优势。     

Localization of temperature anomalies in the Upper Rhine Graben: insights from geophysics and neotectonic activity

The European Cenozoic Rift System hosts major temperature anomalies in Central Europe. In its central segment, the Upper Rhine Graben (URG), temperatures range from 75°C to nearly 150°C at a depth of 2000 m. Different hypotheses have been suggested to explain the localization of these anomalies. Our review and comprehensive interpretation of gravimetric and magnetic data, as well as neotectonic activity patterns, suggests that low-density, mostly magnetic and fractured granitic basement is systematically associated with major temperature anomalies. Further analyses provide insight into different heat transport processes contributing to the localization of these anomalies. Magnetic and gravity anomalies are known to represent lithological variations associated with the pre-Permian. We show their spatial relationship with positive temperature anomalies in the URG. Correlation between magnetics and temperature reveal a mean contribution of heat production to the temperature anomaly of about 10–15°C. A slightly higher mean value is obtained from correlation between gravity and temperature, which may be attributed to effects resulting from fracture porosity. The spatial relationship between temperature anomalies and neotectonic patterns indicates compressional shear and uplift regime for the major anomalies of the central segment of the URG. This is in agreement with different numerical models indicating free convection on fracture zones linked to faults. Our findings show that about 15–25% of the temperature anomaly can be attributed to variation in heat production. Hydrothermal circulation convection along faults, activated by the tectonic context, may explain the remaining 75–85% of the temperature anomalies.     

Study of land surface temperature and spectral emissivity using multi-sensor satellite data

In this study, an attempt has been made to estimate land surface temperatures (LST) and spectral emissivities over a hard rock terrain using multi-sensor satellite data. The study area, of about 6000 km², is a part of Singhbhum-Orissa craton situated in the eastern part of India. TIR data from ASTER, MODIS and Landsat ETM+ have been used in the present study. Telatemp Model AG-42D Portable Infrared Thermometer was used for ground measurements to validate the results derived from satellite (MODIS/ASTER) data. LSTs derived using Landsat ETM+ data of two different dates have been compared with the satellite data (ASTER and MODIS) of those two dates. Various techniques, viz., temperature and emissivity separation (TES) algorithm, gray body adjustment approach in TES algorithm, Split-Window algorithms and Single Channel algorithm along with NDVI based emissivity approach have been used. LSTs derived from bands 31 and 32 of MODIS data using Split-Window algorithms with higher viewing angle (50°) (LST1 and LST2) are found to have closer agreement with ground temperature measurements (ground LST) over waterbody, Dalma forest and Simlipal forest, than that derived from ASTER data (TES with AST 13). However, over agriculture land, there is some uncertainty and difference between the measured and the estimated LSTs for both validation dates for all the derived LSTs. LST obtained using Single Channel algorithm with NDVI based emissivity method in channel 13 of ASTER data has yielded closer agreement with ground measurements recorded over vegetation and mixed lands of low spectral contrast. LST results obtained with TIR band 6 of Landsat ETM+ using Single Channel algorithm show close agreement over Dalma forest, Simlipal forest and waterbody with LSTs obtained using MODIS and ASTER data for a different date. Comparison of LSTs shows good agreement with ground measurements in thermally homogeneous area. However, results in agriculture area with less homogeneity show difference of LST up to 2°C. The results of the present study indicate that continuous monitoring of LST and emissivity can be undertaken with the aid of multi-sensor satellite data over a thermally homogeneous region.     

New ASTER derived thermal indices to delineate mineralogy of different granitoids of an Archaean Craton and analysis of their potentials with reference to Ninomiya's indices for delineating quartz and mafic minerals of granitoids—An analysis in Dharwar Craton,India

We processed five thermal infrared (TIR) bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) “at-sensor radiance” (Level 1B) data to derive few new indices to delineate variation in quartz, feldspar and mafic minerals in three different variants of granitoid; commonly occurring quartz bearing intrusive rock group. In this regard, three indices named as quartz-bearing rock index (QRI), feldspar-bearing rock index (FRI) and mafic-bearing rock index(MRI) were proposed.QRI index was derived using band 10, band 12 and band 13((band 10/band 12) 1 (band 13/band 12)) of ASTER radiance image. MRI index was derived using band 12, band 13 and band 14 ((band 12/band 13) 1 (band 13/band 14)) of ASTER radiance bands while band 10, band 11 were combined to derive FRI ((band 10/band 11) index. Three indices were combined in false colour composite image (FCC) and three-dimensional scatter plot to delineate granite, alkali granite and mafic rich granodioritic gneiss from each other as these granitoids had variable abundances of quartz, feldspar and mafic minerals. QRI and MRI were compared with the corresponding quartz and mafic indices proposed by Ninomiya (2005). It was observed from the respective ratio images and their regression plots that MRI and Ninomiya's mafic index (NMI) were complementary to each other. On the other hand, QRI image was better in enhancing quartz enrichment in alkali granites than Ninomiya's quartz index (NQI).However, QRI index was comparable with the quartz index proposed by Rockwall and Hofstra (2008) in terms of delineating quartz enrichment in alkali granite. Mutual exclusive nature of mafic minerals and quartz in granitoids was also evident from the negative correlation between MRI and QRI indices of the granitoids. On the other hand, FRI and QRI were negatively correlated with low regression value. This was resulted due to the combined effect of inverse relation of abundance of two dominant feldspars with quartz in different granitoids. In granitoids, abundance of plagioclase is known to increase with decreasing quartz content in granodiorite and tonalite although alkali feldspar bearing granites are characterised with high silica content. Results of discrimination of granitoids using proposed indices were validated based on deriving emissivity spectra of rocks and comparing them with ASTER TIR band resampled laboratory spectra of respective granitoids in addition to use geological map of the study area. Emissivity spectra of granitoids were derived from emissivity image (derived using emissivity normalisation method) after geospatially tagging it with QRI–FRI–MRI image composite; which was used to delineate exposures of granitoids. Further, we also found that the QRI, MRI and FRI indices had poor temperature dependence; when these indices were compared with relative surface temperature image derived from radiance bands using emissivity normalisation algorithm. Therefore, proposed indices can be implemented for delineating mineralogical variations of granitoids irrespective of surface temperature condition. Hence, proposed indices may be used successfully to delineate different granitic intrusions and relating their mineralogical variations with metallogeny.     

热水沉积作用的研究历史、现状及展望

热水沉积作用的研究已经历70余年,目前初步统一了热水沉积及其沉积岩的相关概念。按照形成矿物的温度和颜色特征及类型,将热水沉积作用分为白烟囱型和黑烟囱型,前者主要是在较低温度(100～320℃)下形成硅酸盐、硫酸盐等浅色矿物,后者主要在较高温度(320～400℃)下形成硫化物、氧化物等暗色矿物。大陆的热水沉积热液与海洋热液在温度与物理化学性质方面存在明显差异,大陆热水温度比海洋低,变化范围较海洋大;pH均值比海洋高,变化范围较海洋热水小;Na+K离子浓度与海洋接近,Ca离子与Cl离子浓度比海洋高,但它们的变化范围较海洋大。初步建立了一些关于热水沉积的沉积模式,如海底热液对流模式、盆地压实卤水对流模式、洋中脊岩浆热液—海水混合循环对流模式、热液溢流—喷流—溢流模式。由于热水沉积作用及热水沉积岩的分布具有特殊性和局限性,目前的研究程度较低,对热水沉积的化学过程和热力学过程、热流体成因、物质来源、热水沉积分异、热水沉积机理还不十分清楚,有待于进一步深入系统研究。     

Synoptic features and environmental conditions of the tornado outbreak on March 22, 2013 at Brahmanbaria in the east-central region of Bangladesh

This study evaluates the synoptic features and environmental conditions of Brahmanbaria tornado event that caused 36 fatalities, 388 injuries and huge damages of properties on 22 March, 2013. Various factors for initiation of that terrific event are investigated through analysis JRA-55 reanalysis (50 km horizontal resolution) data and Multi-functional Transport Satellite images by Japan Meteorological Agency. In addition, radar images, radiosonde data and three hourly synoptic data of Bangladesh Meteorological Department are used to verify the reanalysis data. The genesis of the tornadic storm is identifiable in the most unstable part of the study region. The satellite observations are found to useful to identify the location of convection occurrence region. The half hourly satellite images identify that the convection initiation started at the convergence area and the systems intensify and organize by the continuous moisture supply from the Bay of Bengal. Lower-level convergence coupled with strong wind shear and humidity gradient lift moist air aloft to trigger deep convection and the severe storm occurred. Energy Helicity Index seems a good predictor parameter for this specific case study.     

Identifying spatial patterns of synchronization between NDVI and climatic determinants using joint recurrence plots

Ten-day series of the Normalized Difference Vegetation Index (NDVI) derived from multi-temporal satellite imagery (1998–2008) was employed as a surrogate for the surface vegetation cover to investigate synchronization of the climatic determinants and its spatial patterns in China. The results, both of the spatiotemporal patterns of joint probability of recurrence (JPR) index and lag time of maximal JPR, clearly suggest that the synchronous relationships of NDVI–climate are site specific and spatially heterogeneous. Higher JPR values of NDVI–temperature are found in Northern China, indicating stronger synchronization in these areas, while higher JPR values of NDVI–precipitation are found in semi-arid and semi-humid regions, which suggest that the moisture factor has a significant influence on NDVI in these areas. Whether lagged or advanced relationship, the phase difference of NDVI–temperature is smaller in Southern China, while is bigger in Northern China. In contrast, the phase difference of NDVI–precipitation is smaller in the semi-arid and sub-humid areas, which means that precipitation has a significant and immediate influence on vegetation in these areas. Overall, the JPR values for NDVI–temperature are higher than those for NDVI–precipitation, suggest that the synchronization between NDVI and temperature is stronger than that between NDVI and precipitation in most areas of China. The results indicate that joint recurrence quantification analysis is a good candidate method for identifying the synchronization between NDVI and climatic determinants.     

使用MODIS和MOPITT卫星数据监测震前异常

地震前温度异常以及CH4、CO2等气体的含量增加已经被人们逐渐认识,目前较多的研究集中在使用卫星热红外数据研究震前的温度异常,震前CH4、 CO2等气体含量的增加却一直未能从卫星观测中实现。使用MODIS数据研究了2002年1月15日台湾5级地震前的海上温度异常,使用MOPITT数据研究了2002年3月31日台湾7.5级强震前的CO异常以及温度异常。研究发现温度异常区和CO高值区吻合,因此认为这种温度异常可能是由于地球排气作用而导致。     

Changes in Global Monsoon Circulations Since 1950

We examined changes in several independent intensity indices of four majortropical monsoonal circulations for the period 1950–1998. Theseintensity indices included observed land surface precipitation andobserved ocean surface pressure in the monsoon regions aswell as upper-level divergence calculated at severalstandard levels from the NCAR/NCEP reanalysis. These values wereaveraged seasonally over appropriate regions of southeastern Asian, western Africa, eastern Africa and the Australia/Maritime continent and adjacent ocean areas. Asa consistency check we also examined two secondary indices: mean sea level pressure trends and low level convergence both from theNCEP reanalysis.We find that in each of the four regions examined, a consistentpicture emerges indicating significantly diminished monsoonalcirculations over the period of record, evidence of diminished spatialmaxima in the global hydrological cycle since 1950. Trends since 1979,the period of strongest reported surface warming, do not indicate any change inmonsoon circulations. When strong ENSO years are removed from each of the time series the trends still show a general, significant reduction of monsoon intensity indicating that ENSO variability is not the direct cause for the observed weakening.Most previously reported model simulations of theeffects of rising CO₂ show an increase in monsoonal activity withrising global surface temperature. We find no support in these datafor an increasing hydrological cycle or increasing extremes as hypothesized bygreenhouse warming scenarios.     

Precise temperature monitoring in boreholes: evidence for oscillatory convection? Part II: theory and interpretation

In the previous part of this work (Cermak, Safanda and Bodri, this volume p.MMM) we have described experimental data and quantified the heterogeneity features of the microtemperature time series. The spectral analysis and the local growth of the second moment technique revealed scaling structure of all observed time series generally similar and suggested the presence of two temperature forming processes. The longer-scale part can be attributed to the heat conduction in compositional and structural heterogeneous solid rocks, further affected by various local conditions. Short-scale temperature oscillations are produced by the intra-hole fluid convection due to inherent instability of water column filling the hole. Here we present how the observational evidence is supported by the results of the computer simulations. The exact modes of intra-hole convection may be different, ranging from quasi-periodic (“quiescent”) state to close of turbulence. As demonstrated by numerical modeling and referred on laboratory experiments, at higher Rayleigh numbers the periodic character of oscillation characteristic for “quiescent” regime is superseded by stochastic features. This so called “oscillatory” convection occurs due to instability within the horizontal boundary layers between the individual convectional cells. In spite of the fact that the basic convective cell motion is maintained and convection is characterized by slow motion, the oscillatory intra-hole flow and corresponding temperature patterns exhibit typical features of turbulence. The idea of boundary layer instability as a source of stochastic temperature fluctuations could explain many distinct features of borehole temperatures that previously cannot be interpreted.     

利用卫星遥感资料反演感热和潜热通量的研究综述

区域平均感热和潜热通量是气象、水文、生态模式中的关键物理因子，卫星遥感反演为观测区域平均感热和潜热通量提供了可能。对利用卫星遥感资料反演地气通量的方法进行了总结和评述。首先描述了现在常用的反演方法，分析了方法中的各种假定对反演结果的影响，并对不同的模式反演结果进行了比较。还指出了评价卫星反演通量的精度时需要注意的问题。最后对该领域内现存的问题与发展方向进行探讨。