Last Interglacial changes in sea level on Aldabra, western Indian Ocean

The Pleistocene limestones on the island of Aldabra in the western Indian Ocean preserve a detailed record of the Last Interglacial interval. Sedimentological analysis has revealed that this interval, formerly regarded as reflecting rapid sea‐level rise, during global warming, followed by a more gradual fall towards the low sea level of the Last Glacial Maximum, in fact shows much greater variation. Although data do not support an accurate chronology, there is evidence that reversals in sea‐level trend caused both pauses in deposition and concurrent erosion during sea‐level rise, and both stillstands and erosion during sea‐level fall. Data include sea‐level related variations in coral morphology, discontinuities and boundaries within depositional sequences, and changes in biofacies. These may explain inconsistencies in the radiometric ages of deposits within the unit, but question the nature of the interglacial cycle, the mechanisms driving it and, in particular, whether comparable variation occurred elsewhere

Microwave remote sensing from space

Spaceborne microwave remote sensors provide perspectives of the earth surface and atmosphere which are of unique value in scientific studies of geomorphology, oceanic waves and topography, atmospheric water vapor and temperatures, vegetation classification and stress, ice types and dynamics, and hydrological characteristics. Microwave radars and radiometers offer enhanced sensitivities to the geometrical characteristics of the earth's surface and its cover, to water in all its forms--soil and vegetation moisture, ice, wetlands, oceans, and atmospheric water vapor, and can provide high-resolution imagery of the earth's surface independent of cloud cover or sun angle. A brief review of the historical development and principles of active and passive microwave remote sensing is presented, with emphasis on the unique characteristics of the information obtainable in the microwave spectrum and the value of this information to global geoscientific studies. Various spaceborne microwave remote sensors are described, with applications to geology, planetology, oceanography, glaciology, land biology, meteorology, and hydrology. A discussion of future microwave remote sensor technological developments and challenges is presented, along with a summary of future missions being planned by several countries

기후대에 따른 연안 먹이망 구조 및 기능: 강화 염습지, 새만금 갯벌, 주강하구 맹그로브 숲, 남극 마리안소만 사례 연구

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 지구환경과학부, 2023. 8. 김종성.연안에 집중된 인간 활동은 생태학적 가치가 높은 다양한 연안 서식지 환경을 변화시키고 기능을 감소시켰다. 그러나, 다양한 요인에 의해 발생된 연안 서식지 환경 변화에 대한 생물들의 생태학적 반응 연구는 여전히 부족한 실정이다. 서식지 환경 변화가 연안 생물에게 미치는 생태학적 영향은 연안 먹이망 구조와 기능의 평가를 통해 확인할 수 있다. 따라서 연안 먹이망 구조와 기능 연구는 생태학적 가치가 높은 다양한 연안 서식지의 보존과 관리에 사용될 수 있다. 본 연구는 탄소 및 질소 안정동위원소비 분석을 기반으로 한국 염습지 갯벌, 남중국 맹그로브 숲, 남극 연안에서 다양한 요인(퇴적물 특성, 식생 분포, 댐 방류수 영향, 빙하 및 해빙의 분포 변화)에 따른 시·공간적 서식지 환경 변화에 대해 먹이망 구조와 기능의 변화를 평가하였다. 본 연구의 목적은 1) 생태학적 가치가 높은 연안 서식지의 먹이망 구조와 기능을 밝히고, 2) 연안 서식지 환경 변화에 대한 생물의 시·공간적 생태 반응을 평가하는 것이다. 또한, 3) 연안 서식지에서 관찰된 탄소 및 질소 안정동위원소비 자료를 비교해 기후대별 연안 먹이망의 특성(먹이원 다양성 및 인위적 활동의 영향 정도)을 규명하는 것에 있다. 온대지역의 한국 염습지 갯벌과 열대지역의 남중국 맹그로브 숲은 지난 세기 동안 진행된 간척 사업으로 심각하게 훼손되었다. 따라서, 효율적인 연안 서식지 보존 관리를 위해 먹이망 구조와 기능에 대한 연구는 필수적이다. 이를 위해 한국의 대표적인 강화도 염습지에서 연구가 먼저 진행되었다. 강화도 염습지에 서식하는 저서생물의 탄소 안정동위원소비는 퇴적물 니질함량과 우점 염생식물(갈대, 칠면초)의 분포에 영향을 받는 것으로 나타났다. 퇴적물식자는 비식생 갯벌에서 저서미세조류 섭취가 증가했고, 염생식물 서식지에서는 13C 함량이 적은 유기물 섭취가 증가했다. 결과적으로, 서식지 환경의 특성(퇴적물 또는 염생식물)별로 다양한 유기물 분포가 한국 갯벌 먹이망 내 국소적 영양 흐름 변화를 야기함을 확인하였다. 세계 최장 방조제가 위치한 한국 새만금 갯벌에서는 방조제 배수갑문을 통해 배출되는 부영양 하수가 시·공간적 먹이망 역학에 미치는 영향을 확인하였다. 부영양 방류수 배출은 외측 갯벌 수·저층 환경의 영양염과 유기입자의 질소안정동위원소비 분포에 영향을 미쳤다. 이에 따라 배수갑문 근처 증가된 총질소 농도는 저서미세조류의 생물량 증가를 야기했으며, 저서생물의 저서미세조류 활용을 증가시켰다. 본 결과를 통해 인간 활동에 의한 환경 변화가 갯벌 먹이망 구조와 기능 변화에 영향을 준다는 것을 확인했다. 열대 지역 맹그로브 생태계 보전 및 관리를 위해 주강 하구에서 맹그로브 숲의 먹이망 구조와 기능을 평가한 결과, 우기에 주강 하구에 서식하는 어류의 영양 지위가 증가하는 것을 확인했다. 저서동물은 모든 계절에 지속적으로 좁은 영양 지위를 나타냈다. 두 소비자는 모두 계절에 따른 먹이원 활용 변화를 나타냈으며, 건기에 맹그로브 및 염생식물 기원의 유기물 활용이 증가했고, 우기에 수층 입자의 활용이 증가했다. 문헌 비교 결과 주강 하구 먹이망은 중국의 다른 염습지에 비해 가벼운 탄소 및 무거운 질소 안정 동위원소비 분포 특징을 보여 맹그로브 유래 유기물과 대도시 하수의 유입이 많다는 것을 확인하였다. 남극 연안 생태계는 기후변화에 따른 다양한 변화를 겪고 있으며, 특히 장기간에 걸쳐 나타나는 빙하와 해빙의 변화가 먹이망 역학에 미치는 영향은 대부분 파악되지 않은 실정이다. 따라서, 지구온난화에 따른 빙하 후퇴가 가장 심각한 남극 반도에 위치한 마리안 소만에서 먹이망 영양역학을 평가하였다. 마리안 소만 빙벽으로부터 거리에 따른 5개 정점에서 저서 및 표영성 소비자와 먹이원을 채집하였다. 빙벽 근처에서 먹이원부터 소비자까지 무겁게 나타난 탄소 안정동위원소비는 마리안 소만 환경이 빙벽과의 거리에 따라 이질성을 가진다는 것을 보여주었다. 또한, 마리안 소만 삿갓조개의 현재 먹이원 활용을 10년 전과 비교한 결과, 주요 먹이원이 저서미세조류에서 해조류로 변화함을 확인하였다. 문헌 비교 결과 서·동남극 연안에서 10년 이상 장기간 나타난 해빙 면적 감소 및 증가가 두 지역의 대조적인 먹이망 영양역학 변화를 만드는 것을 확인하였다. 따라서, 남극 연안 먹이원의 다양성 감소는 계속되는 기후 변화 상황에서 남극 해양생태계 전체에 위협을 가할 수 있음을 시사하였다. 기후대별 주요 연안 서식지 환경 변화에 대해 먹이망 내 저서 및 표영성 생물의 생태학적 반응(먹이원 활용 및 생태적 지위)을 종합 평가하였다. 열대 및 남극 연안 먹이망에서 관찰된 먹이원의 넓은 탄소 안정동위원소비 분포는 다양한 기원의 유기물이 유입되는 것을 확인시켜 주었으며, 이는 온대지역과 대조되는 특징을 보였다. 기후대별 연안 서식지 먹이망 구조 및 기능을 비교한 결과, 각 기후대에서 생산력이 높은 먹이원(식물플랑크톤, 저서미세조류, 맹그로브 등)이 연안 소비자의 먹이 활동에 크게 영향을 주는 것을 확인하였다. 반면, 각 연안 서식지 내에서는 계절적인 강우량 변화가 다른 요인(퇴적물 특성 및 식생의 분포 등)에 비해 생물의 먹이활동에 큰 영향을 주었다. 온대 및 열대 연안 서식지 먹이망에서 무겁게 (> 10 ‰) 관찰된 질소 안정동위원소비의 분포는 인간활동에 따른 하수 영향을 확인시켜 주었다. 반면 남극 먹이망은 가벼운 질소 안정동위원소비 분포를 보여, 남극 연안환경에서 인간활동 영향은 크지 않았다는 것을 확인시켜 주었다. 본 연구는 기후대별 다양한 연안 서식지 먹이망 영양역학의 변화 예측에 대한 통찰력을 제공하며 향후 연안 생태계 기반 관리 및 보존에 활용될 수 있음에 의의를 가진다.Ecologically important coastal habitats have been severely degraded and destroyed by the cumulative pressures of anthropogenic activities combined with the effects of climate change. The effects of habitat degradation can be assessed through the ecological responses of organisms in the coastal food web. Food web studies can therefore be used for the conservation and management of coastal habitats. The present study used stable isotope analysis to investigate the food web responses to natural, anthropogenic, and climate change-driven environmental changes in four coastal habitats (salt marsh; tidal flat; mangrove forest; Antarctic coast) along the three climate zones. The objectives of the present study were 1) to reveal the overall structure of the food web, 2) to determine the spatiotemporal ecological responses of coastal organisms to environmental changes, and finally, 3) to characterise the coastal food web in terms of food diversity and anthropogenic impacts by comparing the stable isotope distributions along the climate zones. Salt marshes, tidal flats and mangrove forests have been severely degraded by reclamation projects in Korea and China over the past century. In order to better understand the food web structures and functions of such habitats, seasonal sampling was first conducted in Korean Ganghwa tidal flats with different habitat conditions (sediment bottom types and vegetation). Stable isotope analysis revealed that deposit feeders consumed more microphytobenthos (MPB) on bare sites, whereas they actively utilised 13C-depleted organic matter on vegetated sites. Altogether, the results suggest that the distribution of organic matter through habitat diversity can alter the trophic function of the tidal flat at mesoscale spatial scales. Second, the food web dynamics under eutrophic water discharge from a dike were elucidated in the Korean Saemangeum tidal flat. High total nitrogen concentrations near the water gates increased the biomass and production of MPB and its subsequent utilisation by benthos, revealing the indirect effect of water discharge on the food web function. The results showed that environmental changes caused by human activities have altered the structure and function of the food web in the Saemangeum tidal flat. In the torrid zone, the seasonal food web dynamics in the Pearl River Estuary (PRE) were elucidated by analysing the stable isotope signatures of diet and consumers. Fish had a large niche space during the monsoon summer, reflecting their increased trophic role. In contrast, benthos had consistent trophic positions across seasons. They used mainly plant organic matter in the dry season and particulate organic matter in the wet season. Literature reviews characterised the food web with a high contribution of mangrove-derived organic carbon and sewage input in the PRE. Compared to other coastal habitats, the Antarctic coast is experiencing intense impacts of climate change. However, the long-term responses of the food web to the ice dynamics remain unresolved. Stable isotope signatures of diet and organisms in the Antarctic coast revealed the influence of glacier and sea ice dynamics on the coastal food web. The δ13C enrichment near the glacier revealed environmental heterogeneity along the Marian Cove (MC) with meltwater intrusion. The primary diet of limpets shifted from microalgae to macroalgae with a decadal increase in macroalgal production due to increased light penetration and glacial nutrient input. Literature reviews revealed contrasting functional changes between the western and eastern Antarctic coasts with sea ice polarisation over a decade. These results warn of a future climate crisis in the simplified Antarctic coastal ecosystem. Overall, this series of studies has provided the first evidence of the ecological responses of organisms to environmental change in coastal habitats along the climate zones. The large δ13C distributions in the coastal food web in the torrid and frigid zones revealed the diverse origin of organic matter inputs in contrast to the temperate zone. Comparisons of the coastal food webs along the climate zones showed that spatial differences in primary production influenced the dietary priorities of consumers. In contrast, within coastal habitats, seasonal flooding strongly influenced the distribution of organic matter compared to other factors (i.e., sediment type and vegetation). Furthermore, the δ15N distribution in the food webs revealed the strong influence of anthropogenic discharges in the temperate and torrid habitats, but the influence was minor on the Antarctic coast. The present study provides comprehensive insights for predicting food web dynamics under increasing human impact and climate change, which can be used for future management and conservation of coastal habitats.ABSTRACT I–II TABLE OF CONTENTS III–V LIST OF ABBREVIATIONS VI–VII LIST OF TABLES VIII–XI LIST OF FIGURES XII– XIX CHAPTER 1. Introduction 1–9 1.1. Backgrounds 2 1.2. Objectives 8 CHAPTER 2. Food web structure of Ganghwa salt marsh in Korea with sediment and halophyte distribution 10–40 2.1. Introduction 11 2.2. Materials and methods 13 2.2.1. Study area and data collection 13 2.2.2. Sample collection and preparation 16 2.2.3. Stable isotope analysis 19 2.2.4. Trophic level 20 2.2.5. Statistical analysis 21 2.3. Results and discussion 22 2.3.1. Spatial distribution of sedimentary organic matter 22 2.3.2. Benthic food web structure 28 2.3.3. Spatial variation in the stable isotopes of deposit feeders 35 CHAPTER 3. Food web structure of Saemangeum tidal flat in Korea with water discharge from a dike 41–97 3.1. Introduction 42 3.2. Materials and methods 45 3.2.1. Sample collection and preparation 45 3.2.2. Stable isotope analysis 48 3.2.3. Trophic level 49 3.2.4. Statistical analysis 50 3.3. Results and discussion 67 3.3.1. Water environmental conditions 67 3.3.2. Sediment environmental conditions 74 3.3.3. Food web structure 81 3.3.4. Spatiotemporal stable isotopic dynamics 87 3.3.5. Comparison of trophic characteristics to other Korean tidal flat 95 CHAPTER 4. Food web structure of mangrove forest in Pearl River Estuary in China with seasonal flood dynamics 98–142 4.1. Introduction 99 4.2. Materials and methods 101 4.2.1. Study area 101 4.2.2. Sample collection and preparation 103 4.2.3. Stable isotope analysis 118 4.2.4. Trophic level 119 4.2.5. Statistical analysis 120 4.3. Results and discussion 121 4.3.1. Environmental conditions 121 4.3.2. Food web structure 123 4.3.3. Seasonal stable isotopic dynamics 129 4.3.4. Comparision of trophic characteristics to other Chinese coastal ecosystem 139 CHAPTER 5. Food web structure of Marian Cove in Antarctic peninsula with glacier retreat 143–181 5.1. Introduction 144 5.2. Materials and methods 146 5.2.1. Sample and data collection 146 5.2.2. Stable isotope analysis 159 5.2.3. Trophic level 160 5.2.4. Statistical analysis 161 5.3. Results and discussion 162 5.3.1. Environment in Marian Cove (MC), King George Island 162 5.3.2. Food web structure in MC 163 5.3.3. Spatial stable isotopic distribution of producers and consumers in MC 167 5.3.4. Decadal changes in the structure and function of Antarctic limpet in MC 170 5.3.5. Influence of multi-decadal changes to sea ice extent on the spatial variation of stable isotopes for producers and consumers in Antarctica 174 CHAPTER 6. Conclusions 182–192 6.1. Summary 183 6.2. Ecological implications 187 6.3. Limitations and future research directions 191 BIBLIOGRAPHY 193–217 ABSTRACT (IN KOREAN) 218–220박

A Reconciled Estimation of the State of Cryospheric Components in the Southern Andes and California Using Geospatial Techniques

Glaciers are the essential source of fresh water not only to human sustenance, but it is also vital for all lifeforms on earth. Glaciers are also key components in understanding rapid changes in climate. This makes understanding of glacier mass, extent, and overall state essential. In this dissertation, the objective was to analyze the state of snow and ice masses in the mid (California) and low latitude (Chile/Argentina) western American regions using geospatial technology. This study also analyzed the effects of anomalies in snow mass on the regional agricultural practices in California’s Central Valley. In the Southern Andes, the digital elevation models from Shuttle Radar Topographic Mission (SRTM) (the year 2000) were compared with the elevation footprints from the Geoscience Laser Altimeter System (GLAS) campaign for the years 2004 through 2008. Generally, in all sub-regions, the elevation values were lower than the elevation for the year 2000, which demarcates continuous recession of ice mass in the Andean region. Also, this study quantified snow cover extent and mass balance variation in the Sierra Nevada and Mt. Shasta regions in California. To unearth anomalies in snow mass, study used digital elevation models generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) between the year 2000 and 2015. A remarkable reduction in snow cover extent of about 80% was observed in the studied watersheds of California. Lastly, the impacts of snow mass anomalies on the total water storage (TWS) and agriculture land cover in the California’s Central Valley were quantified and geo-visualized. The study noticed the change in the land cover area of about 20% (6993 sq.km) due to the alteration of Agriculture land to impervious land covers. Most of the change in the agriculture land cover of about 4402 sq.km occurred in the San Joaquin and Tulare Basins of southern Central Valley region. This dissertation concludes that the increased temperature in the Andes and California has adversely impacted Cryosphere components in the region in the past decade. Besides, it provides valuable insights into the changing state of cryosphere components and highlights impacts of anomalies in TWS on a billion-dollar agricultural industry

NASA Oceanic Processes Program, Fiscal Year 1981

Summaries are included for Nimbus 7, Seasat, TIROS-N, Altimetry, Color Radiometry, in situ data collection systems, Synthetic Aperture Radar (SAR)/Open Ocean, SAR/Sea Ice, Scatterometry, National Oceanic Satellite System, Free Flying Imaging Radar Experiment, TIROS-N/Scatterometer and/or ocean color scanner, and Ocean Topography Experiment. Summaries of individual research projects sponsored by the Ocean Processes Program are given. Twelve investigations for which contracting services are provided by NOAA are included

SEASAT Global Ocean Monitoring System

General information and descriptive material about the SEASAT program is given. This is the central document covering the program

SAR (Synthetic Aperture Radar). Earth observing system. Volume 2F: Instrument panel report

The scientific and engineering requirements for the Earth Observing System (EOS) imaging radar are provided. The radar is based on Shuttle Imaging Radar-C (SIR-C), and would include three frequencies: 1.25 GHz, 5.3 GHz, and 9.6 GHz; selectable polarizations for both transmit and receive channels; and selectable incidence angles from 15 to 55 deg. There would be three main viewing modes: a local high-resolution mode with typically 25 m resolution and 50 km swath width; a regional mapping mode with 100 m resolution and up to 200 km swath width; and a global mapping mode with typically 500 m resolution and up to 700 km swath width. The last mode allows global coverage in three days. The EOS SAR will be the first orbital imaging radar to provide multifrequency, multipolarization, multiple incidence angle observations of the entire Earth. Combined with Canadian and Japanese satellites, continuous radar observation capability will be possible. Major applications in the areas of glaciology, hydrology, vegetation science, oceanography, geology, and data and information systems are described

Space-Based Remote Sensing of the Earth: A Report to the Congress

The commercialization of the LANDSAT Satellites, remote sensing research and development as applied to the Earth and its atmosphere as studied by NASA and NOAA is presented. Major gaps in the knowledge of the Earth and its atmosphere are identified and a series of space based measurement objectives are derived. The near-term space observations programs of the United States and other countries are detailed. The start is presented of the planning process to develop an integrated national program for research and development in Earth remote sensing for the remainder of this century and the many existing and proposed satellite and sensor systems that the program may include are described

Submarine sedimentary basin analyses for the Aurora and Wilkes Subglacial Basins and the Sabrina Coast Continental Shelf, east Antarctica

textThis dissertation focuses on the Wilkes Land region of the East Antarctic Ice Sheet (EAIS) that is predominantly characterized by two large subglacial basins, the Aurora Subglacial Basin (ASB) to the east and the Wilkes Subglacial Basin (WSB) to the west and immediately adjacent to the Transantarctic Mountains (TAM). The ASB and WSB are expansive covering an estimated 750,000 and 980,000 square kilometers, respectively. In addition, their bedrock geometry places them an average of 1.25 km below present day sea level, raising the possibility of fundamental instability through grounding line retreat. Subglacial sediment deformation has long been known to facilitate faster ice flow and significantly impact basal ice conditions including geothermal heat flux, groundwater flow, and frictional heat flux. Recently acquired aerogeophysical data over the interior ASB and WSB document extensive subglacial sedimentary basins that can be distinguished as smaller subbasins, each associated with adjacent topographic highlands and EAIS dynamics. The volumes of these interior subglacial subbasins vary between 26,349 +/- 10,885 km³ and 398,082 +/- 164,454 km³ in the ASB and 7,188 +/- 2,940 km³ and 128,094 +/- 52,399 km³ in the WSB (based upon 20% porosity values). Notably, the character of the basins varies substantially between the more southern ASB and WSB interiors and the more marginal, northern ASB and WSB reflective of different dynamic ice histories across geologic time. ASB sedimentary basin volumes, derived from airborne gravity and magnetic data with ice-penetrating radar constraints, are contrasted with recently acquired highresolution marine seismic sequence stratigraphy collected on the Sabrina Coast continental shelf. With targeted geologic sampling of outcropping strata, megasequence sediment volumes are estimated for a finite area adjacent to the Totten Glacier/Moscow University Ice Shelf catchment draining the ASB interior. Preglacial, temperate/polythermal glacial, and polar glacial sediment volumes of 278.6 +/- 148.8 km³ , 570.6 +/-51.9 km³ , and 1,658 +/- 389 km³, respectively, combined with a multitude of diagnostic glacial tunnel valleys, unconformities, and geologic data, reinforce recent dynamic Pliocene EAIS hypotheses for the Wilkes Land margin.Geological Science

Technology and Oceanography: An Assessment of Federal Technologies for Oceanographic Research and Monitoring

A report by the Office of Technology Assessment (OTA) that "describes the status of technologies in use today, such as research ships, submersibles, buoy systems, aircraft, and satellites" (Foreward)