Estimation of rainfall from infrared‐microwave satellite data for basin‐scale hydrologic modelling

The infrared‐microwave rainfall algorithm (IMRA) was developed for retrieving spatial rainfall from infrared (IR) brightness temperatures (TBs) of satellite sensors to provide supplementary information to the rainfall field, and to decrease the traditional dependency on limited rain gauge data that are point measurements. In IMRA, a SLOPE technique (ST) was developed for discriminating rain/no‐rain pixels through IR image cloud‐top temperature gradient, and 243K as the IR threshold temperature for minimum detectable rainfall rate. IMRA also allows for the adjustment of rainfall derived from IR‐TB using microwave (MW) TBs. In this study, IMRA rainfall estimates were assessed on hourly and daily basis for different spatial scales (4, 12, 20, and 100 km) using NCEP stage IV gauge‐adjusted radar rainfall data, and daily rain gauge data. IMRA was assessed in terms of the accuracy of the rainfall estimates and the basin streamflow simulated by the hydrologic model, Sacramento soil moisture accounting (SAC‐SMA), driven by the rainfall data. The results show that the ST option of IMRA gave accurate satellite rainfall estimates for both light and heavy rainfall systems while the Hessian technique only gave accurate estimates for the convective systems. At daily time step, there was no improvement in IR‐satellite rainfall estimates adjusted with MW TBs. The basin‐scale streamflow simulated by SAC‐SMA driven by satellite rainfall data was marginally better than when SAC‐SMA was driven by rain gauge data, and was similar to the case using radar data, reflecting the potential applications of satellite rainfall in basin‐scale hydrologic modelling. Copyright © 2010 John Wiley & Sons, Ltd.     

遥感技术在川藏铁路车站选址中的应用

川藏铁路拟选康定车站地处高山峡谷区,地形高差大,地质环境复杂,车站选址难度极大。为研究该铁路关键节点车站选址问题,本文充分运用高分辨率遥感技术,辅以热红外、InSAR等遥感新技术,对拟选车站选址区的活动断裂、不良地质等重大工程地质问题进行了详细判释和综合分析,遴选出三道桥设站为最优方案,可以为拟选车站选址及该段方案稳定提供重要依据,并指导工程地质调绘和勘探工作。结果表明:该方法效果良好,对于类似复杂艰险山区车站选址工作具有参考价值。     

北京延庆硅化木的矿物学特征分析

通过X射线荧光、红外光谱和X射线衍射等检测方法分析了延庆硅化木的矿物学特征.结果表明:2个不同植物种属但在同一埋藏地形成硅化木标本成因相似,其颜色与所含元素种类及含量密切相关.X射线衍射分析表明,不同颜色和植物种属的硅化木主要组成物相一致,为SiO2,其他矿物极其微量.2个硅化木标本的红外吸收谱带基本一致,均显示典型的...     

吉林松原地区地震前热红外亮温异常研究

使用小波变换和功率谱估计法,利用中国静止气象卫星亮温数据研究2017年以来松原地区3次M_S＞4.5地震前的热红外异常。结果表明, 2017-07-23 M_S4.9和2018-05-28 M_S5.7地震前的异常都是沿依兰-伊通断裂和密山-敦化断裂走向逐渐扩展的,即异常存在于松辽盆地的东部边缘,地震震中不在异常区内;2019-05-18 M_S5.1地震前异常不明显,可能是由于盆地内二氧化碳和甲烷等温室气体在前2次地震前后已得到最大量的释放。     

利用层析成像方法反演近地表速度模型

由于地表条件复杂和近地表速度变化显著给近地表速度模型的反演工作带来了很大的困难。层析成像方法可以较好地模拟介质横向和纵向的速度变化,能同时考虑直达波、透射波、回折波、折射波等初至波,为确定近地表速度结构提供了有效的工具。主要介绍了层析成像的方法原理,并应用此方法反演了实际地震探区的近地表速度模型,取得了良好的应用效果。     

塔克拉玛干沙漠地表发射率及分布变化特征

通过利用便携式傅立叶变换热红外光谱仪,对冷热黑体辐射和漫反射金板辐射校正,测量波长在8–14 μm的热红外大气窗口的地表辐射光谱,计算出地表的发射率光谱,再转换成地表的发射率值(ε)。为获得塔克拉玛干沙漠精确的ε,沿着沙漠公路,从南至北穿越沙漠,平均每50 km进行一次测量,获得了沙漠地表发射率的分布变化特征。结果表明：靠近绿洲的地表发射率值最高,达到0.93,绿洲与沙漠过渡带的值为0.91–0.92,沙漠其它地区的值为0.90–0.91,而沙漠中心区接近0.89。     

Trends in the near-zero range of the minimum air-temperature distribution

This study estimated the trends in the number of days that fall within the near-zero (0?°C) range of the temperature continuum. This narrow range has importance for potential transportation hazards and freeze-thaw cycles. While the tails of the air-temperature distribution and their trends often are closely examined under the climate change context, the frequency and trend of other portions of the air-temperature distribution can be equally important, as many societal impacts are caused by events in the non-tail region, such as near-zero °C temperatures (NZT). Examining the trend of the number of NZT days over the conterminous USA for the period of 1948–1949 through 2010–2011, we found three distinct spatial clusters. The most distinctive spatial clusters are found along the West Coast (positive temperature trends leading to a decrease in NZT days), the High Plains and Northern Rockies (positive temperature trends leading to an increase in NZT days), and the southeastern USA (negative temperature trends leading to an increase in NZT days). While trends in the number of NZT days are linked to changes in mean minimum air temperature, increasing minimum temperature leads to a positive trend at NZT days only at some locations.     

Retrieval of land surface temperature from the Kalpana-1 VHRR data using a single-channel algorithm and its validation over western India

Indian geostationary satellite Kalpana-1 (K1) offers a potential to capture the diurnal cycle of land surface temperature (LST) through thermal infrared channel (10.5–12.5 μm) observations of the Very High Resolution Radiometer (VHRR) sensor. A study was carried out to retrieve LST by adapting a generalized single-channel (SC) algorithm (Jiménez-Muñoz and Sobrino, 2003) for the VHRR sensor over India. The basis of SC algorithm depends on the concept of Atmospheric Functions (AFs) that are dependent on transmissivity, upwelling and downwelling radiances of the atmosphere. In the present study AFs were computed for the VHRR sensor through the MODTRAN simulations based upon varying atmospheric and surface inputs. The AFs were fitted with the atmospheric columnar water vapour content and a set of coefficients was derived for LST retrieval. The K1-LST derived with the SC algorithm was validated with (a) in situ measurements at two sites located in western parts of India and (b) the MODIS LST products. Comparison of K1-LST with the in situ measurements demonstrated that SC algorithm was successful in capturing the prominent diurnal variations of 283–332 K in the LST at desert and agriculture experimental sites with a rmse of 1.6 K and 2.7 K, respectively. Inter comparison of K1-LST and MODIS LST showed a reasonable agreement between these two retrievals up to LST of 300 K, however a cold bias up to 7.9 K was observed in MODIS LST for higher LST values (310–330 K) over the hot desert region.     

利用三值模板模糊匹配进行手指静脉识别

针对静脉特征图像中静脉边缘和末梢模糊造成匹配困难的问题,提出了一种基于三值模板图像的模糊匹配方法。该方法将提取出的静脉特征图像分割为三值图像,值1代表目标区,0.5代表模糊区,0代表背景区。三值图像用于模板匹配时,计算模板间非0值区域之间的平均距离作为相似分数,分数越低,则模板越相似。该方法匹配能力强,不要求点与点之间的绝对位置匹配,对模糊的静脉边缘和末梢匹配具有较强的鲁棒性。对实验中采集的456张近红外手指静脉图像进行匹配,正确识别率达99.46%,表明本文方法是可行的和有效的。     

Numerical investigation of wave propagation in the Liverpool Bay, NW England

The computer model for near shore wave propagation,SWAN,was used to study wave climates in Liverpool Bay,northwest England with various input parameters,including bottom friction factor,white capping,wind drag formulation and effects of tidal modulations.Results were compared with in-situ measurements and reveal the impacts from these inputs on the predictions of wave height and propagation distributions.In particular,the model results were found very sensitive to different input formulations,and tend to underestimate the wave parameters under storm conditions in comparison with the observations.It is therefore important to further validate the model against detailed field measurements,particularly under large storms that are often of the primary concern.