Remote sensing salt marsh biomass and stress detection

A hand-held radiometer was used to gather spectral radiance data simulating bands 3, 4 and 5 of the Landsat-D Thematic Mapper. Variations in biomass of the salt marsh plant $\text{Spartina alterniflora}$ were highly correlated to changes in spectral radiance expressed as the vegetation index or the infrared index. Negative stresses like increased soil salinity and increased concentrations of copper or zinc yielded reductions in biomass which were detected spectrally. Positive stresses like freshwater and sewage effluent additions produced an increase in biomass which also were detected using spectral data. The demonstrated detection of biomass from spectral data was expanded spatially and temporally to estimate net primary productivity of a salt marsh. Remote sensing estimates of production ranged from 5 to 20% of estimates from harvest data. Future applications of this biomass estimation technique, employing data gathered from satellite platforms and from the ground, are discussed for salt marsh systems.     

Spaceborne quantitative assessment of dissolved organic carbon fluxes in the Kara Sea

An advanced algorithm for retrieval of phytoplankton chlorophyll (CHL) and dissolved organic carbon (DOC) concentrations from MERIS images of the Kara Sea is presented. The supply of DOC of terrestrial origin into the Kara Sea is numerically assessed from satellite data on DOC and historical records of river discharge rates. It exceeds the historical in situ values only by 25%. Satellite data on CHL were exploited for calculating the phytoplankton columnar biomass and the total phytoplankton biomass in the Kara Sea. Remote sensing and in situ data were used to calculate the value of the coefficient (K_PH) for calculation from phytoplankton biomass of autochthonous production of DOC. K_PH proved to be 142 ± 8 gC/gPH/month and exhibited only slight interannual variations. The coefficient K_PH was employed for the first time to evaluate the production of autochthonous DOC in the Kara Sea and to correct the value of the allochthonous DOC flux initially retrieved from space across the Kara Sea.     

Satellite ocean colour algorithm for Prochlorococcus, Synechococcus, and picoeukaryotes concentration retrieval in the South China Sea

An algorithm for retrieval of surface waters cell concentrations (in cell/ml) for three picophytoplankton components, Prochlorococcus (Pro), Synechococcus (Syn), and picoeukaryotes (Peuk) in the South China Sea (SCS), from ocean colour satellite data was developed and tested. Level 3 merged multisensor Ocean Colour Climate Change Initiative satellite data is used. Training is performed using in situ data on abundances of the three phytoplankton components. Several predictors derived from satellite reflectance data were tested. The regression form that assures the highest accuracy of the algorithm was chosen based on cross-validation (CV). According to the CV on test data subset, the algorithm performance is characterized by the r value 0.89, 0.72, and 0.73 and MAPD 38, 71 and 51% for Peuk, Pro, and Syn respectively. This is one of the few studies aimed at the Peuk, Pro, and Syn distribution research in the northern SCS using ocean colour satellite data. This is the only research providing algorithm with accuracy estimates of the Peuk, Pro, and Syn concentrations retrieval from the ocean colour data. Analysis of the developed algorithm allows us to conclude that both mechanisms (specific spectral features caused by pigments composition and spectrum features sensitive to general primary productivity, e.g. band ratios in 443–510?nm range and spectrum absolute values) are important for getting accurate information on the picophytoplankton composition.     

Advances on Technology and Application of Ocean Color Remote Sensing in China (2004 - 2006)

China has great progress in the technology and application of ocean color remote sensing during 2004-2006. In this report, firstly, four major technical advances are displaying, including (1) the vector radiative transfer numerical model of coupled ocean-atmosphere system; (2) the atmospheric correction algorithm specialized on Chinese high turbid water; (3) systematical research of hyper-spectrum ocean color remote sensing; (4) local algorithms of oceanic parameters, like ocean color components, ocean primary productivity, water transparency, water quality parameters, etc. On the foundation of technical advances, ocean color remote sensing takes effect on ocean environment monitoring, with four major kinds of application systems, namely, (1) the automatic multi-satellites data receiving, processing and application system; (2) the shipboard satellite data receiving and processing system for fishery ground information; (3) Coastal water quality monitoring system, integrating satellite and airborne remote sensing technology and ship measurement; (4) the preliminary system of airborne ocean color remote sensing application system. Finally, the prospective development of Chinese ocean color remote sensing is brought forward. With Chinese second ocean color satellite (HY-1B) orbiting, great strides will take place in Chinese ocean color information accumulation and application.     

Monitoring the changing aereal extent of irrigated lands of the gefara plain,libya

The inventory of large often non-homogeneous tracts of land by resource agencies has led to the development of estimation methods and sampling strategies that produce estimates of the aereal extent of various features from ‘limited’ observations of the universe of interest. Landsat data has furnished a tool that allows for potential improvement in estimates of resource parameters over extensive areas. This paper examines the methodology and results of a procedure which uses an economical sampling procedure allied with the large area covering qualities of the satellite imaging system to make improved estimates of irrigated land in a more timely, efficient and ‘accurate’ manner.     

Energy deposition in the polar ionosphere as determined by measurements aboard ‘INTERCOSMOS-BULGARIA-1300’ satellite

Data were obtained from the measurements of optical emissions, ion drift, DC magnetic field and energetic particles, on board INTERCOSMOS - BULGARIA - 1300 satellite. In two cases of night-time passes through auroral oval, an estimate has been made of the energy input by particle precipitation and Joule heating. In order to determine the Joule heating, the Pedersen currents flowing in the lower ionosphere were determined. In orbits 231 and 203 Pedersen currents of 0.94 Am^?1 and 0.71 am^?1 were observed. From these values estimates of Joule heating rates of2 × 10^?7Wm^?3 and8 × 10^?7Wm^?3 were obtained. The integral energy deposited by the precipitated particles was also estimated in the current systems regions. The possibility for identification of the auroral electrojet based only on satellite data is pointed out.     

A simple closed aquatic ecosystem (CAES) for space

A closed aquatic ecosystem (CAES) was developed to study the effects of microgravity on the function of closed ecosystems aboard the Chinese retrieved satellite and on the spacecraft SHENZHOU-II. These systems housed a small freshwater snail (Bulinus australianus) and an autotrophic green algae (Chlorella pyrenoidosa). The results of the test on the satellite were that the concentration of algae changed little, but that the snails died during the experiments. We then sought to optimize the function of the control system, the cultural conditions and the data acquisition system and carried out an experiment on the spacecraft SHENZHOU-II. Using various sensors to monitor the CAES, real-time data regarding the operation of the CAES in microgravity was acquired. In addition, an on-board 1g centrifuge was included to identify gravity-related factors. It was found that microgravity is the major factor affecting the operation of the CAES in space. The change in biomass of the primary producer during each day in microgravity was larger than that of the control groups. The mean biomass concentration per day in the microgravity group decreased, but that of the control groups increased for several days and then leveled off. Space effects on the biomass of a primary producer may be a result of microgravity effects leading to increasing metabolic rates of the consumer combined with decreases in photosynthesis.     

Nostoc sphaeroides Kützing,an excellent candidate producer for CELSS

Some phytoplankton can be regarded as possible candidates in the establishment of Controlled Ecological Life Support System (CELSS) for some intrinsic characteristics, the first characteristic is that they should grow rapidly, secondly, they should be able to endure some stress factors and develop some corresponding adaptive strategies; also it is very important that they could provide food rich in nutritious protein and vitamins for the crew; the last but not the least is they can also fulfill the other main functions of CELSS, including supplying oxygen, removing carbon dioxide and recycling the metabolic waste. According to these characteristics, Nostoc sphaeroides, a potential healthy food in China, was selected as the potential producer in CELSS. It was found that the oxygen average evolution rate of this algae is about 150 μmol O₂ mg⁻¹ h⁻¹, and the size of them are ranged from 2 to 20 mm. Also it can be cultured with high population density, which indicated that the potential productivity of Nostoc sphaeroides is higher than other algae in limited volume. We measured the nutrient contents of the cyanobacterium and concluded it was a good food for the crew. Based on above advantages, Nostoc sphaeroides was assumed to a suitable phytoplankton for the establishment of Controlled Ecological Life Support System. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food in future space missions.     

Vertical crustal motion derived from satellite altimetry and tide gauges,and comparisons with DORIS measurements

A somewhat unorthodox method for determining vertical crustal motion at a tide-gauge location is to difference the sea level time series with an equivalent time series determined from satellite altimetry. To the extent that both instruments measure an identical ocean signal, the difference will be dominated by vertical land motion at the gauge. We revisit this technique by analyzing sea level signals at 28 tide gauges that are colocated with DORIS geodetic stations. Comparisons of altimeter-gauge vertical rates with DORIS rates yield a median difference of 1.8 mm yr⁻¹ and a weighted root-mean-square difference of 2.7 mm yr⁻¹. The latter suggests that our uncertainty estimates, which are primarily based on an assumed AR(1) noise process in all time series, underestimates the true errors. Several sources of additional error are discussed, including possible scale errors in the terrestrial reference frame to which altimeter-gauge rates are mostly insensitive. One of our stations, Malè, Maldives, which has been the subject of some uninformed arguments about sea-level rise, is found to have almost no vertical motion, and thus is vulnerable to rising sea levels.     

Semi-annual variations of chlorophyll concentration on the Eastern Tropical Pacific coast of Mexico

An analysis of the main remotly sensed oceanographic variables was conducted to characterize the dominant drivers that modulate the spatial-temporal variability of coastal phytoplankton biomass in the northern limit of the Eastern Tropical Pacific. The phytoplankton biomass was analyzed using monthly average satellite chlorophyll (Chlo) concentration data from MODIS sensors for the period 2003–2017. Oceanographic conditions were analyzed by considering (i) Sea Surface Temperature (SST) high-resolution data from the GHRSST project, (ii) wind stress calculated with data from the zonal and meridional components of the CCMP product, (iii) climatological precipitation, and (iv) climatological river flow. Chlo time series and spatial variability were analyzed using Hovmöller diagrams and Empirical Orthogonal Functions (EOF), respectively. A strong semi-annual signal in Chlo concentration along the coast was observed: the first peak occurs in winter-spring (5.0 mg·m⁻³) and a second one in summer-autumn (6.5 mg·m⁻³). A high year-round average of Chlo concentration (3.0–15.0 mg·m⁻³) was maintained by a 10 km wide along-shore coast, with maximum values spatially associated with river mouths, of which Santiago river registered the highest Chlo values (20.0 mg·m⁻³). Surface oceanographic conditions showed a marked annual cycle with warmer conditions (30–31 °C) from July to October and colder ones (23–24 °C) from December to April; during the cold period, seasonal wind stress stimulated coastal upwelling. The EOF showed that 70% of Chlo concentration variability was controlled by the semi-annual pattern, which responded to coastal upwelling conditions during cold period, while rivers outflows influenced high Chlo concentration during the warm period. These results highlighted the importance for land-ocean interface to sustain coastal ecosystems' biological production and the major role of watersheds as sources of nutrients to maintain high biological production during warm periods in transitional tropical-subtropical zones.     

Remote sensing techniques for monitoring and managing irrigated lands

Agriculture in semi-arid tracts of the world depends on water to sustain its irrigation systems. Such agricultural systems either derive from government investments in the control of surface flow or they have been developed through the exploitation of groundwater sometimes by a large community of unsupervised individuals seeking to maximise their own advantage without concern for the resource upon which they depend in the medium and long term. In both cases government agencies need data on the area irrigated and the volume of water used. In countries with highly developed scientific and agricultural institutions the contribution of remote sensing, though significant, may only provide between five and ten per cent of the data required to guide regional and national managers. In countries without such institutions the proportion contributed by remote sensing can be very much higher, as shown in a recent study in North Africa. The paper will emphasise the importance of carefully structured sampling procedures, both to improve the areal estimates from satellite imagery and the estimates of water use based upon them. The role of satellite imagery in providing information on the status of water resources, on trends in water use and in the implementation of policies to extend or diminish irrigated land are discussed.     

Effects of solar UV-B radiation on aquatic ecosystems.

Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position phytoplankton will be exposed to solar ultraviolet radiation. This radiation has been shown to affect growth, photosynthesis, nitrogen incorporation and enzyme activity. Other targets of solar UV irradiation are proteins and pigments involved in photosynthesis. Whether or not screening pigments can be induced in phytoplankton to effectively shield the organisms from excessive UV irradiation needs to be determined. Macroalgae show a distinct pattern of vertical distribution in their habitat. They have developed mechanisms to regulate their photosynthetic activity to adapt to the changing light regime and protect themselves from excessive radiation. A broad survey was carried out to understand photosynthesis in aquatic ecosystems and the different adaptation strategies to solar radiation of ecologically important species of green, red and brown algae from the North Sea, Baltic Sea, Mediterranean, Atlantic, polar and tropical oceans. Photoinhibition was quantified by oxygen exchange and by PAM (pulse amplitude modulated) fluorescence measurements based on transient changes of chlorophyll fluorescence.     

Application of CZCS data to productivity and water quality studies in the Northern Adriatic Sea

The Northern Adriatic Sea is a shallow ocean basin with considerable fresh water input and presents some unique water-optical features realted to:- suspended matter input caused by rivers and resuspension of bottom sediments;- phytoplankton production because of nutrient input from rivers and bottom;- dissolved organic matter (yellow substance) production by decomposition processes of the organic material.All these features influence the spectral reflectance of the water and make the algorithms for CZCS data interpretation quite different from those used in open ocean (type I) water. Therefore, special test-site specific algorithms must be derived from in-situ measurements of water-optical parameters and the water constituents. The results from such measurements are presented together with the algorithms and the evaluated CZCS data obtained from them. It is then discussed how the experimental and evaluated satellite data can be used to evaluate standing crop and productivity.     

不连续观测数据对计算的原子钟稳定度影响研究

为评估原子钟稳定度,通常采用连续的、均匀的采样数据计算阿伦方差或哈达玛方差。在实际工程计算中,由于观测粗差剔除、测量仪器中断、卫星不可见等原因,经常导致原子钟的观测数据在时间上不连续,给原子钟稳定度评估带来影响。文中比较了不连续观测数据的几种常用处理方法,包括线性插值补齐、B样条插值补齐、不插值直接计算哈达玛方差等方法,分析了各处理方法对阿伦方差和哈达玛方差的计算影响,研究中断数据长度与稳定度评估的影响关系。采用的氢钟观测数据,对不连续观测数据的影响和处理效果进行统计和分析,将稳定度计算结果、计算精度损失比与理论分析进行对照和检验,得出了有益的结论。     

Cross testing of ionosphere models IRI-2001 and IRI-2007, data from satellite altimeters (Topex/Poseidon and Jason-1) and global ionosphere maps

In this study, we use a great body of statistical data covering the entire 23rd solar cycle to cross test data of satellite altimeters, Global Ionosphere Maps and the International Reference Ionosphere models, IRI-2001 and IRI-2007. It is revealed that experimental TEC values of the satellite altimeters regularly exceed the model ones by ∼3 TECU (1 TECU = 10¹⁶ m⁻²). The best possible value of difference between TECs obtained from altimeter and GIM-map data significantly differs for different laboratories: the maximum for CODG data falls on 2.5 TECU, ESAG – 3 TECU, JPLG – 0 TECU, UPCG – 2 TECU. The dependence of experimental and model data root-mean-square deviation on the F10.7 index is shown to be nearly linear. IRI-2001 and IRI-2007 relative errors are characterized by considerable 11-year and annual variations. Given the geomagnetic planetary index K_p under 7, IRI-2001 and IRI-2007 reproduce TEC in the ionosphere with an accuracy of ∼30% relative to measurement data from satellite altimeters. The amplitude of absolute error variations resulting from the difference in ionization enhancement between the model and the real ionosphere during the morning solar terminator transit is ∼5 TECU.     

Controlled Ecological Life Support Systems (CELSS) flight experimentation.

The NASA CELSS program has the goal of developing life support systems for humans in space based on the use of higher plants. The program has supported research at universities with a primary focus of increasing the productivity of candidate crop plants. To understand the effects of the space environment on plant productivity, the CELSS Test Facility (CTF) has been been conceived as an instrument that will permit the evaluation of plant productivity on Space Station Freedom. The CTF will maintain specific environmental conditions and collect data on gas exchange rates and biomass accumulation over the growth period of several crop plants grown sequentially from seed to harvest. The science requirements of the CTF will be described, as will current design concepts and specific technology requirements for operation in micro-gravity.     

The effect of cannibalism intensity on net primary production and dynamics of trophic links in aquatic ecosystems.

A mathematical model was used to investigate the effect of cannibalism intensity on the net primary production and the dynamics of trophic links in an aquatic ecosystem characterized by cannibalism at the upper trophic level. A mathematical model of an aquatic ecosystem has been constructed, with the following principal trophic links: limiting nutrient concentration, producers (phytoplankton), nonpredatory and predatory zooplankton. The model takes into account the age structure of the predator and includes two age groups (the young and adults). The adult predators are cannibals feeding on both nonpredatory zooplankton and their own young, which consume phytoplankton. It has been found that when cannibalism intensity increases above a certain level, the concentrations of both adults and the young of the predators decrease. At the same time, the concentrations of the nonpredatory zooplankton and of nutrients increase, while the biomass of producers decreases. When the cannibalism intensity is low, the net primary production of the system increases to a certain level correlated with the increase in cannibalism intensity and drops sharply when the level of consumption of young is high. There is an optimal intensity of cannibalism, at which the productivity in the photosynthesis link is maximal.     

Validation of nimbus-7 temperature-humidity infrared radiometer estimates of cloud type and amount

Estimates of clear and low, middle and high cloud amount in fixed geographical regions approximately (160km)² are being made routinely from 11.5μm radiance measurements of the Nimbus-7 Temperature-Humidity Infrared Radiometer (THIR). The purpose of validation is to determine the accuracy of the THIR cloud estimates. Validation requires that a comparison be made between the THIR estimates of cloudiness and the “true” cloudiness. The validation results reported in this paper use human analysis of concurrent but independent satellite images with surface meteorological and radiosonde observations to approximate the “true” cloudiness. Regression and error analyses are used to estimate the systematic and random errors of THIR derived clear amount.     

Distribution of chlorophyll and harmful algal blooms (HABs): A review on space based studies in the coastal environments of Chinese marginal seas

Monitoring of spatial and temporal distribution of chlorophyll (Chl-a) concentrations in the aquatic milieu is always challenging and often interesting. However, the recent advancements in satellite digital data play a significant role in providing outstanding results for the marine environmental investigations. The present paper is aimed to review ‘remote sensing research in Chinese seas’ within the period of 24 years from 1978 to 2002. Owing to generalized distributional pattern, the Chl-a concentrations are recognized high towards northern Chinese seas than the southern. Moreover, the coastal waters, estuaries, and upwelling zones always exhibit relatively high Chl-a concentrations compared with offshore waters. On the basis of marine Chl-a estimates obtained from satellite and other field measured environmental parameters, we have further discussed on the applications of satellite remote sensing in the fields of harmful algal blooms (HABs), primary production and physical oceanographic currents of the regional seas. Concerned with studies of HABs, satellite remote sensing proved more advantageous than any other conventional methods for large-scale applications. Probably, it may be the only source of authentic information responsible for the evaluation of new research methodologies to detect HABs. At present, studies using remote sensing methods are mostly confined to observe algal bloom occurrences, hence, it is essential to coordinate the mechanism of marine ecological and oceanographic dynamic processes of HABs using satellite remote sensing data with in situ measurements of marine environmental parameters. The satellite remote sensing on marine environment and HABs is believed to have a great improvement with popular application of technology.     

The longwave radiation estimated from NOAA polar orbiting satellites: An update and comparison with Nimbus-7 ERB results

The planetary outgoing longwave radiation has been estimated since 1974 from two different series of NOAA operational polar spacecraft. The first series provided data from June 1974 through February 1978 and was designated “SR” for the scaning radiometers used at that time. This data set has been used in a variety of radiation budget and climate studies, such as that by Ohring and Gruber, 1983. The second satellite system is the currently operational TIROS-N series of satellites. Data from this series began in January 1979 and are continuing. In both systems, estimates of the outgoing longwave radiation are obtained from narrow spectral interval (10–12 μm) window radiances. A comparison is made of the estimates from the two different series of satellites in order to arrive at an assessment of their compatibility. This is important since the SR observations were taken at approximately 0900 and 2100 local times, while the TIROS-N data alternate between 0730-1930 and 0300-1500 local times. In addition, there is a period of overlap between the TIROS-N data and the broad band (5–50 μm) Nimbus 7 EArth radiation budget data. A comparison of those two data sets indiciate excellent agreement generally within about 1–2 Wm^?2 on the monthly means on global and hemispherical scales. Comparisons of zonal averages indicate maximum differences as large as 9 Wm^?2.Evidence is presented to suggest that observations taken at different local observing times may be biased by the diurnal variation of emitted flux, even on global scales.