Tracking the calibration stability and consistency of the 3.7, 11.0 and 12.0 μm channels of the NOAA-KLM AVHRR with MODIS

The NOAA-KLM satellites (NOAA-15 to 18) are the current polar-orbiting operational environmental satellites (POES) that carry the Advanced Very High Resolution Radiometer (AVHRR). This study examines the calibration stability and consistency of all three infrared channels (3.7, 11.0 and 12.0 μm) of AVHRR onboard NOAA-15 to 18. The short-term stability is examined from variations of the scan-by-scan gain response, while the long-term stability and calibration consistency are examined by tracking the trends of gain response and measured scene brightness temperatures. The relative differences of observed scene brightness temperatures among NOAA-15 to 18 AVHRR are determined using MODIS as a transfer radiometer based on observations from simultaneous nadir overpasses (SNO). Results show that variations of the scan-to-scan gain responses are within 0.10% under normal operational conditions, while long-term gain changes over six years from 2001 to 2006 vary from 2 to 4% depending on channel. Long-term trending results show that total six-year drifts in observed brightness temperature from NOAA-15 to 18 AVHRR are less than 0.5 K for a given scene temperature in the 250 to 270 K range for the 3.7, 11.0 and 12.0 μm channels, respectively. The calibration consistency is examined for a scene temperature range of 220 to 290 K. The temperature biases among NOAA-16 to 18 AVHRR are within ±0.5 K for the 11.0 and 12.0 μm channels. For NOAA-15 AVHRR, biases of –2.0 K at 11.0 μm and –1.5 K at 12.0 μm are found in comparison with others at the low end of the temperature range. For the 3.7 μm channel, relative biases up to a few degrees among NOAA-15 to 18 could be found at low brightness temperatures.     

Estimating above‐ground burned biomass and CO2 emissions for tropical Africa for the year 1990 with the NOAA–NASA Pathfinder AVHRR 8 km land dataset

Biomass burning combusts Earth's vegetation (in forests, savannas and agricultural lands) and occurs over huge areas of the Earth's surface. Global estimates of biomass burning are thus required in order to provide exact figures of the gas fluxes derived from this source. In this paper we use coarse resolution images for estimating above‐ground burned biomass and CO₂ emissions for tropical Africa for the year 1990. The burned land cover areas have been derived from burn scar and land cover maps using the global daily National Oceanic and Atmospheric Administration–National Aeronautics and Space Administration (NOAA–NASA) Pathfinder AVHRR 8?km land dataset. A burned area estimation of (742±222)?Mha has been considered. Monthly maximum Normalized Difference Vegetation Index (NDVI) composites and biomass density measurements have been used for modelling the temporal behaviour of above‐ground biomass for the main seasonal vegetation classes in Africa (humid savanna, derived humid savanna, dry savanna grassland and broadleaf savanna). The amount of above‐ground burned biomass and therefore CO₂ emissions can be estimated from burned land cover area, above‐ground biomass density, burn efficiency and emission factor of trace gas by land cover class. A total of 6494 (3675–9312) Tg for CO₂ emissions was computed for tropical Africa for the year 1990.     

Variability of chlorophyll concentration in the Arabian Sea and Bay of Bengal as observed from SeaWiFS data from 1997–2000 and its interrelationship with Sea Surface Temperature (SST) derived from NOAA AVHRR

Variability of chlorophyll concentration in the Arabian Sea and Bay of Bengal has been studied using SeaWiFS eight‐day average, 9 km processed data for the period 1997–2000. The interrelationship with sea surface temperature (SST) was studied with the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) derived, best SST product. The chlorophyll pattern shows in general high concentrations during February to March in the Arabian Sea and November to December in the Bay of Bengal. Year‐to‐year variations in temperature show an inverse relation with chlorophyll, at different locations, even on a monthly basis. However, the intraannual variability in chlorophyll at different locations shows differences in the relationship with SST. The Arabian Sea showed an inverse relationship at most of the locations, while a positive relationship was observed in the northwest region during October to December and an inverse relationship during January to April. The Bay of Bengal showed positive relationships at northeast locations, whereas no definite assessment could be made for other locations due to the narrow range of chlorophyll concentration.A longer time series (～10 years) will be required to establish a more concrete relationship but definitely consistent patterns are emerging from this study. The results form an additional dimension to the criteria for partitioning the ocean, required for global productivity or biophysical coupled modelling.     

The Red Edge Parameters Diversification Disciplinarian and Their Application in Winter Wheat

Some red edge parameters( λ red, Min λ 6oo-72o, d λ,red, d λ min, d λ red / d λ min, ∑ d λ 680-750, and λ nir) and the relationship between these parameters and the parameters of biochemistry and biophysics of winter wheat were studied by regression analysis. The results indicated that there existed some changes in these red edge parameters in the whole growth stages,and there were strong correlations between red edge parameters and pramters of biochemistry and biophysics. Thus, the red edge parameters were found valuable for assessment of wheat parameters of biochemistry and biophysics. The λ red can be used to estimate the soluble sugar content and the chlorophyll content. The d λ red was the best estimator of total nitrogen content. LAI can be estimated by Min λ 600-720 satisfactorily.     

高产冬小麦铁素吸收分配特点的研究

采用干灰化——原子吸收分光光度计法 ,测定了田间高产试验条件下冬小麦不同生育时期植株地上部各器官的铁含量 .结果表明 :麦株含铁量随生育时期呈单峰曲线变化 ,其峰顶位于返青期 ;铁吸收量随生育的时期呈双峰曲线变化 ,其峰顶分别位于拔节期和乳熟期 ,而峰谷出现在开花期 ;各生育阶段麦株体内铁始终以叶片分配比率最高 ;形成 1 0 0kg籽粒需要吸收铁 1 7.98g .     

缓/控释肥对小麦增产与提高氮肥利用率的效果研究

以不施氮肥、尿素基施和尿素基追比5:5等3个处理做对照,对3种包膜缓/控释肥处理冬小麦产量、产量相关因子、不同时期植株含氮量及肥料利用率进行了分析比较。结果表明,缓/控肥处理的以上几个指标均接近于尿素基追比5:5处理。与尿素基施相比,包膜缓/控释肥增产10.03%～11.17%,有效穗数和穗粒数增加,返青-拔节期植株含氮量明显提高,氮肥利用率提高了6.18%～11.57%。3种缓/控释肥相比较,产量、产量因子、植株含氮量及肥料利用率没有显著性差异。     

缓/控释肥对小麦增产与提高氮肥利用率的效果研究

以不施氮肥、尿素基施和尿素基追比5∶5等3个处理做对照,对3种包膜缓/控释肥处理冬小麦产量、产量相关因子、不同时期植株含氮量及肥料利用率进行了分析比较。结果表明,缓/控释肥处理的以上几个指标均接近于尿素基追比5∶5处理。与尿素基施相比,包膜缓/控释肥增产10.03%~11.17%,有效穗数和穗粒数增加,返青-拔节期植株含氮量明显提高,氮肥利用率提高了6.18%~11.57%。3种缓/控释肥相比较,产量、产量因子、植株含氮量及肥料利用率没有显著性差异。     

利用多时相NDVI 监测京郊冬小麦种植信息

物候和时相信息在农作物种植信息提取方面有十分重要的应用价值, 利用多时相L andsat TM 数据, 结合冬小麦的波谱和时相信息, 成功提取了北京地区的冬小麦种植信息。首先, 选用了2003 年4 月7 日、5 月1 日、5 月25 日、6 月18 日不同时相的4 景TM 卫星影像, 计算了不同时相的NDV I 时间谱图像数据; 其次, 结合北京地区农作物种植的实际情况, 提取并分析了北京春夏季主要植被地物(冬小麦、苜蓿、苗圃、春玉米、树林等) 的NDV I 时间谱特征; 第三, 利用不同时相的NDV I 图像数据, 通过NDV I 图像通道间的逻辑运算算法, 成功提取了2003 年北京地区的冬小麦种植信息, 提取精度达到96. 92%; 最后, 与2002 年收割小麦的统计数据相对比, 监测了北京各郊区县的冬小麦种植结构调整情况。结果表明, 多时相、多光谱遥感数据在作物种植信息的监测中有十分明显的技术优势和重要的应用潜力。     

不同pH和供Zn条件下HCO-3对冬小麦幼苗生长和锌营养的影响

采用营养液培养法,研究了不同pH和供Zn条件下高浓度HCO3-(10 mmol L-1)对小麦幼苗生长,尤其是对锌营养的影响,结果表明:当营养液起始pH为6时,HCO3-在缺Zn时对小麦根系生长的抑制作用较为明显,而正常供Zn时的影响较小。当营养液起始pH为8时,不论缺Zn还是供Zn,添加HCO3-对根系和地上部均未表现出明显的抑制作用。HCO3-在酸性营养液中能极大促进小麦植株根系和地上部尤其是根系对Zn的吸收,而在碱性条件下则抑制小麦幼苗根系和地上部对Zn的吸收。此外,HCO3-能显著抑制Zn从根系向地上部分的转运,从而造成在根系中的大量积累。HCO3-加入营养液后会生成少量的CO32-,并使营养液pH维持在较高水平上。     

施钴对冬小麦产量和蛋白质含量及土壤有效钴含量的影响

采用盆栽试验的方法,研究了石灰性褐土上不同钴施用量对冬小麦产量、蛋白质含量及土壤有效钴含量的影响。试验结果表明:施用适量的钴可以显著提高冬小麦的产量和蛋白质的含量。各施钴处理较对照增产0.98-13.73%, 生物产量增加2.01-18.47%,其中以处理Co3增产最高。在施钴量4mg kg-1以内,随着施钴量的增加,增产效应提高,但当施钴量超过4mg kg-1时,冬小麦的籽粒产量和生物产量增加,但增产效应下降。处理Co1、处理Co2的蛋白质含量分别比对照增加2.14和1.1个百分点,但处理Co3、处理Co4的蛋白质含量分别比对照减少0.07和0.21个百分点。各处理的蛋白质产量比对照增加0.06%-20.02%,其中以处理Co1增加最大,处理Co2次之。土壤有效钴含量与施钴量呈极显著正相关,小麦籽粒中钴含量与施钴量呈显著正相关。     

星载SAR在涡阳县冬小麦测产中的应用

由于雷达遥感的全天候、全天时的优势,使之成为南方大范围农业信息动态监测的最佳遥感手段。应用星载合成孔径雷达(SAR)-RadarSat-2,选择安徽省涡阳县冬小麦产区进行测产研究。利用SAR的多极化特点(HH/HV/VH/VV),针对此卫星影像比较选择VV极化,并在试验田取样,获得试验田产量,从而建立产量和后向散射系数关系的线性测产模型,在提取冬小麦种植区基础上,应用此模型对冬小麦进行大面积产量测产。通过计算,得到了超过80%精度的测产模型和冬小麦较准确的测产结果。研究结果表明:在冬小麦收割前一周左右应用SAR进行测产,从而为农保提供服务,这种思路和方法是行之有效的。     

冬小麦品质的影响因素及高光谱遥感监测方法

研究了小麦品质的分类及其构成因素与环境条件之间的关系，各品质因素之间的关系。运用相同栽培条件下不同品种品质指标间的关系和变化规律，研究了品种因素对小麦品质的影响程度以及品种因素与品质指标之间的相关性，得出相同环境条件下籽粒的蛋白质含量与湿面筋含量、沉降值、吸水率、形成时间和稳定时间之间存在极显著的相关性。并利用不同品种、不同肥水条件下的作物关键生育时期的生化参量与光谱指数进行分析，得出开花期冬小麦叶片的类胡萝卜素与叶绿素a的比值与结构不敏感植被指数(SIPI)之间存在极显著的正相关，决定系数达到0．7207，冬小麦体内的全氮含量与类胡萝卜紊与叶绿素口的比值之间存在极显著的负相关，决定系数为0．7245，并通过分析开花期冠层生化组分与籽粒品质指标间的相关性，得出开花期叶片全氮与籽粒蛋白质、湿面筋、干面筋和沉降值之间存在极显著的正相关，表面运用开花期光谱指数来反演叶片全氮含量，进而用来预测预报籽粒品质是切实可行的。     

HJ星数据在关中冬小麦种植面积遥感监测中的应用 

应用冬小麦抽穗期的环境小卫星影像对关中地区依据行政区划划分,采用多种遥感监测方法进行冬小麦种植面积提取,提取精度达95.64%。结果表明:抽穗期是关中地区提取冬小麦种植面积的最佳时相,同时也表明环境小卫星可以用来监测大范围的冬小麦种植面积,并得到很高的精度。在未来的研究中,对于地形差异较大的地区,可依据地形和冬小麦的种植结构对研究区进行划分,针对每个子研究区采用不同的遥感监测方法以提高提取精度。