Variability of coastal upwelling south of Madagascar

Madagascar’s southern coastal marine zone is a region of high biological productivity which supports a wide range of marine ecosystems, including fisheries. This high biological productivity is attributed to coastal upwelling. The thesis seeks to characterise the variability of the coastal upwelling south of Madagascar. The first part of the thesis provides new insights on the structure, variability and drivers of the coastal upwelling south of Madagascar. Satellite remote sensing is used to characterize the spatial extent and strength of the coastal upwelling. A front detection algorithm is applied to thirteen years of Multi-scale Ultra-high Resolution (MUR) Sea Surface Temperatures (SST) and an upwelling index is calculated. The influence of winds and ocean currents as drivers of the upwelling are investigated using satellite, in-situ observations, and a numerical model. Results reveal the presence of two well-defined upwelling cells. The first cell (Core 1) is located in the southeastern corner of Madagascar, and the second cell (Core 2) is west of the southern tip of Madagascar. These two cores are characterized by different seasonal variability, different intensities, different upwelled water mass origins, and distinct forcing mechanisms. Core 1 is associated with a dynamical upwelling forced by the detachment of the East Madagascar Current (EMC), which is reinforced by upwelling favourable winds. Core 2 which appears to be primarily forced by upwelling favourable winds, is also influenced by a poleward eastern boundary flow coming from the Mozambique Channel. This intrusion of Mozambique Channel warm waters could result in an asynchronicity in seasonality between upwelling surface signature and upwelling favourables winds. The second part of the thesis focuses on the interaction between the intrusion of warm water from Mozambique channel and the upwelling cell in Core 2. Cruise datasets, satellite remote sensing observations and model data analyses are combined to highlight the existence of a coastal surface poleward flow in the south-west of Madagascar: the South-west MAdagascar iv Coastal Current (SMACC). The SMACC is a relatively shallow (Coastal Current (SMACC). The SMACC is a relatively shallow (<300 m) and narrow (<100km wide) warm and salty coastal surface current, which flows along the south western coast of Madagascar toward the south, opposite to the dominant winds. The warm water surface signature of the SMACC extends from 22◦S (upstream) to 26.4◦S (downstream). The SMACC exhibits a seasonal variability: more intense in summer and reduced in winter. The average volume transport of its core is about 1.3 Sv with a mean summer maximum of 2.1 Sv. It is forced by a strong cyclonic wind stress curl associated with the bending of the trade winds along the southern tip of Madagascar. The SMACC directly influences the coastal upwelling regions south of Madagascar. Its existence is likely to influence local fisheries and larval transportpatterns, as well as the connectivity with the Agulhas Current, affecting the returning branch of the global overturning circulation. The last part of the thesis provides a holistic understanding of the inter-annual variability of the upwelling cells associated with the multiple forcing mechanisms defined in the first two parts of this work. Results reveal that the upwelling cells, Core 1 and Core 2, have different inter-annual variabilities. Inter-annual variability of Core 1 is associated with the East Madagascar Current (EMC) while Core 2 is linked with the South-west MAdagascar Coastal Current (SMACC). Inter-annual changes in the EMC occur as a result of oscillations in the South Equatorial Current (SEC) bifurcation off Madagascar, while the inter-annual variability in the SMACC is influenced by the cyclonic wind stress curl inter-annual variability. The upwelling is also linked with global/regional climate modes. Both Cores are highly correlated with the Subtropical Indian Ocean Dipole (SIOD). Core 2 is also correlated to the Indian Ocean Dipole (IOD). Both cores are significantly correlated with the El Ni˜no-Southern Oscillation (ENSO) after 12 months lag

Satellite remote sensing of surface winds, waves, and currents: Where are we now?

This review paper reports on the state-of-the-art concerning observations of surface winds, waves, and currents from space and their use for scientific research and subsequent applications. The development of observations of sea state parameters from space dates back to the 1970s, with a significant increase in the number and diversity of space missions since the 1990s. Sensors used to monitor the sea-state parameters from space are mainly based on microwave techniques. They are either specifically designed to monitor surface parameters or are used for their abilities to provide opportunistic measurements complementary to their primary purpose. The principles on which is based on the estimation of the sea surface parameters are first described, including the performance and limitations of each method. Numerous examples and references on the use of these observations for scientific and operational applications are then given. The richness and diversity of these applications are linked to the importance of knowledge of the sea state in many fields. Firstly, surface wind, waves, and currents are significant factors influencing exchanges at the air/sea interface, impacting oceanic and atmospheric boundary layers, contributing to sea level rise at the coasts, and interacting with the sea-ice formation or destruction in the polar zones. Secondly, ocean surface currents combined with wind- and wave- induced drift contribute to the transport of heat, salt, and pollutants. Waves and surface currents also impact sediment transport and erosion in coastal areas. For operational applications, observations of surface parameters are necessary on the one hand to constrain the numerical solutions of predictive models (numerical wave, oceanic, or atmospheric models), and on the other hand to validate their results. In turn, these predictive models are used to guarantee safe, efficient, and successful offshore operations, including the commercial shipping and energy sector, as well as tourism and coastal activities. Long-time series of global sea-state observations are also becoming increasingly important to analyze the impact of climate change on our environment. All these aspects are recalled in the article, relating to both historical and contemporary activities in these fields

EPS/Metop-SG Scatterometer Mission Science Plan

89 pages, figures, tablesThis Science Plan describes the heritage, background, processing and control of C-band scatterometer data and its remaining exploitation challenges in view of SCA on EPS/MetOp-SGPeer reviewe

Community Review of Southern Ocean Satellite Data Needs

This review represents the Southern Ocean community’s satellite data needs for the coming decade. Developed through widespread engagement, and incorporating perspectives from a range of stakeholders (both research and operational), it is designed as an important community-driven strategy paper that provides the rationale and information required for future planning and investment. The Southern Ocean is vast but globally connected, and the communities that require satellite-derived data in the region are diverse. This review includes many observable variables, including sea-ice properties, sea-surface temperature, sea-surface height, atmospheric parameters, marine biology (both micro and macro) and related activities, terrestrial cryospheric connections, sea-surface salinity, and a discussion of coincident and in situ data collection. Recommendations include commitment to data continuity, increase in particular capabilities (sensor types, spatial, temporal), improvements in dissemination of data/products/uncertainties, and innovation in calibration/validation capabilities. Full recommendations are detailed by variable as well as summarized. This review provides a starting point for scientists to understand more about Southern Ocean processes and their global roles, for funders to understand the desires of the community, for commercial operators to safely conduct their activities in the Southern Ocean, and for space agencies to gain greater impact from Southern Ocean-related acquisitions and missions.The authors acknowledge the Climate at the Cryosphere program and the Southern Ocean Observing System for initiating this community effort, WCRP, SCAR, and SCOR for endorsing the effort, and CliC, SOOS, and SCAR for supporting authors’ travel for collaboration on the review. Jamie Shutler’s time on this review was funded by the European Space Agency project OceanFlux Greenhouse Gases Evolution (Contract number 4000112091/14/I-LG)

Wind Resource Assessment Using the Numerical Weather Prediction Model to Identify the Offshore Wind Resource in the Philippines

Developing nations need to build their economies in order to reach the millennium goals of the world. Energy is an essential resource for economic development but the conventional fuel at present is not a sustainable energy source. Thus, these countries must seek for renewable energy sources so that they can develop in a sustainable manner. Wind energy is found to be a potential source for power generation especially, the offshore locations. There are many developing countries in the low-latitude areas that have open waters close to them. So, offshore wind energy may be a possible source for power but there are limited data available to make a reliable wind resource assessment (WRA). This study aims to develop a wind characterisation methodthat can be useful for coastal and small island areas with no or few in-situ wind observations. The study area is focused in Palawan Province of the Philippines because it has similar characteristics as small island nations and coastal areas in the low-latitude regions. The research found that numerical weather prediction is an alternative for in-situ wind measurements for WRA. A technique that involves coupling mesoscale model to microscale model is employed in this work in order to produce wind maps. The results found that a combination of mesoscale model and microscale model can be a good method for wind profiling areas without or few wind observations. The mesoscale model is deemed sufficient for open water areas while coastal areas are better represented by microscale models especially the low wind speed conditions

On the role of the Agulhas Current on weather and climate of South Africa

The Agulhas Current is the strongest western boundary current of the Southern Hemisphere. The aim of this thesis is to understand the impact of ocean-atmosphere interaction in the Agulhas Current on the atmosphere and to investigate its importance for Southern African rainfall. This warm Current creates a high temperature gradient with the surrounding ocean, leading to a large turbulent flux of moisture from ocean to atmosphere (also called the turbulent latent heat flux). The dynamics of ocean-atmosphere interaction above the Agulhas Current and its impact on the weather and climate of Southern Africa are not well known. This is due to a) climate reanalyses that do not include the Agulhas Current and b) the lack of regional capacity in ocean-atmosphere modeling. I use ocean observations, various climate reanalyses, and several satellite remote sensing data sets to find out if the new reanalyses (cited below) do represent the intense exchange of moisture that occurs above the Agulhas Current and the Agulhas Retroflection region. The largest turbulent latent heat flux is found in the Retroflection region in winter, while the lowest is off Port Elizabeth in summer. The Climate Forecast System Reanalysis (CFSR) and the ModernEra Retrospective analysis for Research and Applications version-2 (MERRA-2) do represent the turbulent latent heat flux well when compared to high-resolution satellite data. ERA-Interim Reanalysis underestimates the turbulent latent heat flux due to reduced wind speeds. The observation-based National Oceanography Centre Southampton (NOCS) is different from the satellites and the reanalysis products because its annual cycle is reversed, and NOCS underestimates the turbulent latent heat flux compared to the former products. The study of the satellite product air-sea turbulent fluxes (SEAFLUX) shows that east of the Agulhas Current, the specific humidity difference is the main driver of the annual cycle variations of turbulent latent heat flux, while the main driver in the Retroflection is the wind speed and both the specific humidity difference and the wind speed in between (around Port Elizabeth). I use high-resolution annual mean observations from satellites, atmospheric reanalysis, and the Weather Research and Forecasting (WRF) model to show that the warm core of the Agulhas Current drives a band of precipitation along the east coast of South Africa when the Current is adjacent to the coast. To do that, I conduct a classic modeling experiment with one configuration representing the sea surface temperature (SST) of the Agulhas Current relatively well. This WRF experiment reproduces the turbulent latent heat flux well. The second simulation is with SST of the Agulhas Current reduced by up to 2°C compared to the first experiment. From a diagnostic of the pressure adjustment mechanism, results show that the warm SST of the Agulhas Current enhances the formation of coastal precipitation along and above the Current. Finally, I look at the seasonality of oceanatmosphere interaction in the Agulhas Current and its impact on Southern African precipitation. In winter, the impact of the Agulhas Current is confined to the atmosphere above it and mechanisms are similar to those described for annual mean. In summer and autumn, SST differences between the two simulations where the Agulhas Current system is more than 25°C, leads to differences in geopotential height above the ocean, extending along the eastern coast and over the land area. The higher temperature of the control simulation leads to cyclonic circulation anomalies and larger moisture flux anomalies from the Agulhas Current to the continent from the south. The analysis of the high-level moisture flux indicates that the Agulhas Current influences the rainfall and humidity flux of Southern Africa. More moisture flux is then brought inland at a higher level. In the northeast of the region, there is an export of moisture anomalies from land to the ocean, and an import of moisture anomalies from above the Agulhas Current to the landmass. This is due to the wind anomalies between the two simulations. However, the overall result leads to more precipitation over the interior of the continent. The study shows that it is important to integrate the fine structure of the ocean temperature of the Agulhas Current in modeling studies and climate reanalyses. Results of this thesis have implications for the prediction of South African weather and climate, and for understanding past and present climate

Earth Observations for Addressing Global Challenges

"Earth Observations for Addressing Global Challenges" presents the results of cutting-edge research related to innovative techniques and approaches based on satellite remote sensing data, the acquisition of earth observations, and their applications in the contemporary practice of sustainable development. Addressing the urgent tasks of adaptation to climate change is one of the biggest global challenges for humanity. As His Excellency António Guterres, Secretary-General of the United Nations, said, "Climate change is the defining issue of our time—and we are at a defining moment. We face a direct existential threat." For many years, scientists from around the world have been conducting research on earth observations collecting vital data about the state of the earth environment. Evidence of the rapidly changing climate is alarming: according to the World Meteorological Organization, the past two decades included 18 of the warmest years since 1850, when records began. Thus, Group on Earth Observations (GEO) has launched initiatives across multiple societal benefit areas (agriculture, biodiversity, climate, disasters, ecosystems, energy, health, water, and weather), such as the Global Forest Observations Initiative, the GEO Carbon and GHG Initiative, the GEO Biodiversity Observation Network, and the GEO Blue Planet, among others. The results of research that addressed strategic priorities of these important initiatives are presented in the monograph

Status of the Global Observing System for Climate

Status of the Global Observing System for Climat

State of the Climate in 2010

Several large-scale climate patterns influenced climate conditions and weather patterns across the globe during 2010. The transition from a warm El Niño phase at the beginning of the year to a cool La Niña phase by July contributed to many notable events, ranging from record wetness across much of Australia to historically low Eastern Pacific basin and near-record high North Atlantic basin hurricane activity. The remaining five main hurricane basins experienced below- to well-below-normal tropical cyclone activity. The negative phase of the Arctic Oscillation was a major driver of Northern Hemisphere temperature patterns during 2009/10 winter and again in late 2010. It contributed to record snowfall and unusually low temperatures over much of northern Eurasia and parts of the United States, while bringing above-normal temperatures to the high northern latitudes. The February Arctic Oscillation Index value was the most negative since records began in 1950. The 2010 average global land and ocean surface temperature was among the two warmest years on record. The Arctic continued to warm at about twice the rate of lower latitudes. The eastern and tropical Pacific Ocean cooled about 1°C from 2009 to 2010, reflecting the transition from the 2009/10 El Niño to the 2010/11 La Niña. Ocean heat fluxes contributed to warm sea surface temperature anomalies in the North Atlantic and the tropical Indian and western Pacific Oceans. Global integrals of upper ocean heat content for the past several years have reached values consistently higher than for all prior times in the record, demonstrating the dominant role of the ocean in the Earth’s energy budget. Deep and abyssal waters of Antarctic origin have also trended warmer on average since the early 1990s. Lower tropospheric temperatures typically lag ENSO surface fluctuations by two to four months, thus the 2010 temperature was dominated by the warm phase El Niño conditions that occurred during the latter half of 2009 and early 2010 and was second warmest on record. The stratosphere continued to be anomalously cool. Annual global precipitation over land areas was about five percent above normal. Precipitation over the ocean was drier than normal after a wet year in 2009. Overall, saltier (higher evaporation) regions of the ocean surface continue to be anomalously salty, and fresher (higher precipitation) regions continue to be anomalously fresh. This salinity pattern, which has held since at least 2004, suggests an increase in the hydrological cycle. Sea ice conditions in the Arctic were significantly different than those in the Antarctic during the year. The annual minimum ice extent in the Arctic—reached in September—was the third lowest on record since 1979. In the Antarctic, zonally averaged sea ice extent reached an all-time record maximum from mid-June through late August and again from mid-November through early December. Corresponding record positive Southern Hemisphere Annular Mode Indices influenced the Antarctic sea ice extents. Greenland glaciers lost more mass than any other year in the decade-long record. The Greenland Ice Sheet lost a record amount of mass, as the melt rate was the highest since at least 1958, and the area and duration of the melting was greater than any year since at least 1978. High summer air temperatures and a longer melt season also caused a continued increase in the rate of ice mass loss from small glaciers and ice caps in the Canadian Arctic. Coastal sites in Alaska show continuous permafrost warming and sites in Alaska, Canada, and Russia indicate more significant warming in relatively cold permafrost than in warm permafrost in the same geographical area. With regional differences, permafrost temperatures are now up to 2°C warmer than they were 20 to 30 years ago. Preliminary data indicate there is a high probability that 2010 will be the 20th consecutive year that alpine glaciers have lost mass. Atmospheric greenhouse gas concentrations continued to rise and ozone depleting substances continued to decrease. Carbon dioxide increased by 2.60 ppm in 2010, a rate above both the 2009 and the 1980–2010 average rates. The global ocean carbon dioxide uptake for the 2009 transition period from La Niña to El Niño conditions, the most recent period for which analyzed data are available, is estimated to be similar to the long-term average. The 2010 Antarctic ozone hole was among the lowest 20% compared with other years since 1990, a result of warmer-than-average temperatures in the Antarctic stratosphere during austral winter between mid-July and early September. List of authors and affiliations... .3 Abstract 16 1. Introduction 17 2. Global Climate 27 a. Overview .. 27 b. Temperature 36; 1. Surface temperature .. 36; 2. Lower tropospheric temperatures 37; 3. Lower stratospheric temperatures .. 38; 4. Lake temperature 39 c. Hydrologic cycle .. 40; I. Surface humidity .. 40; 2. Total column water vapor .41; 3. Precipitation . 42; 4. Northern Hemisphere continental snow cover extent ... 44; 5. Global cloudiness 45; 6. River discharge . 46; 7. Permafrost thermal state . 48; 8. Groundwater and terrestrial water storage .. 49; 9. Soil moisture ..52; 10. Lake levels 53 d. Atmospheric circulation 55; 1. Mean sea level pressure . 55; 2. Ocean surface wind speed 56 e. Earth radiation budget at top-of-atmosphere ... 58 f. Atmosphere composition ...59; 1. Atmosphere chemical composition ...59; 2. Aerosols 65; 3. Stratospheric ozone 67 g. Land surface properties . 68; 1. Alpine glaciers and ice sheets .. 68; 2. Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) ... 72; 3. Biomass burning ... 72; 4. Forest biomass and biomass change .74 3. Global Oceans 77 a. Overview .. 77 b. Sea surface temperatures .. 78 c. Ocean heat content .81 d. Global ocean heat fluxes ... 84 e. Sea surface salinity .. 86 f. Subsurface salinity ... 88 g. Surface currents ... 92; 1. Pacific Ocean 93; 2. Indian Ocean 94; 3. Atlantic Ocean . 95 h. Meridional overturning circulation observations in the subtropical North Atlantic . 95 i. Sea level variations ... 98 j. The global ocean carbon cycle 100; 1. Air-sea carbon dioxide fluxes 100; 2. Subsurface carbon inventory . 102; 3. Global ocean phytoplankton . 105 4. Tropics ... 109 a. Overview 109 b. ENSO and the tropical Pacific 109; 1. Oceanic conditions ... 109; 2. Atmospheric circulation: Tropics .110; 3. Atmospheric circulation: Extratropics ...112; 4. ENSO temperature and precipitation impacts .113 c. Tropical intraseasonal activity .113 d. Tropical cyclones 114; 1. Overview .114; 2. Atlantic basin ...115; 3. Eastern North Pacific basin .121; 4. Western North Pacific basin .. 123; 5. Indian Ocean basins .. 127; 6. Southwest Pacific basin 129; 7. Australian region basin 130 e. Tropical cyclone heat potential .. 132 f. Intertropical Convergence Zones . 134; 1. Pacific ... 134; 2. Atlantic 136 g. Atlantic multidecadal oscillation 137 h. Indian Ocean Dipole . 138 5. The arctic ... 143 a. Overview 143 b. Atmosphere 143 c. Ocean .. 145; 1. Wind-driven circulation . 145; 2. Ocean temperature and salinity 145; 3. Biology and geochemistry .. 146; 4. Sea level .. 148 d. Sea ice cover ... 148; 1. Sea ice extent . 148; 2. Sea ice age ... 149; 3. Sea ice thickness 150 e. Land .. 150; 1. Vegetation ... 150; 2. Permafrost ... 152; 3. River discharge ... 153; 4. Terrestrial snow 154; 5. Glaciers outside Greenland 155 f. Greenland ... 156; 1. Coastal surface air temperature . 156; 2. Upper air temperatures . 158; 3. Atmospheric circulation . 158; 4. Surface melt extent and duration and albedo . 159; 5. Surface mass balance along the K-Transect .. 159; 6. Total Greenland mass loss from GRACE . 160; 7. Marine-terminating glacier area changes .. 160 6. ANTARCTICA ..161 a. Overview .161 b. Circulation ...161 c. Surface manned and automatic weather station observations 163 d. Net precipitation ... 164 e. 2009/10 Seasonal melt extent and duration . 167 f. Sea ice extent and concentration .. 167 g. Ozone depletion 170 7. Regional climates ... 173 a. Overview 173 b. North America ... 173; 1. Canada 173; 2. United States .. 175; 3. México . 179 c. Central America and the Caribbean .. 182; 1. Central America 182; 2. The Caribbean ... 183 d. South America .. 186; 1. Northern South America and the Tropical Andes . 186; 2. Tropical South America east of the Andes .. 187; 3. Southern South America 190 e. Africa 192; 1. Northern Africa 192; 2. Western Africa .. 193; 3. Eastern Africa . 194; 4. Southern Africa .. 196; 5. Western Indian Ocean countries 198 f. Europe . 199; 1. Overview 199; 2. Central and Western Europe 202; 3. The Nordic and Baltic countries . 203; 4. Iberia 205; 5. Mediterranean, Italian, and Balkan Peninsulas .206; 6. Eastern Europe .. 207; 7. Middle East ..208 g. Asia ... 210; 1. Russia ... 210; 2. East Asia ..215; 3. South Asia 217; 4. Southwest Asia ...219 h. Oceania ...222; 1. Southwest Pacific ..222; 2. Northwest Pacific, Micronesia .. 224; 3. Australia .. 227; 4. New Zealand .. 229 8. SEASONAL SUMMARIES ... 233 Acknowledgments 237 Appendix: Acronyms and Abbreviations 238 References . 24