Ocean observation challenges and implications for research and applications

Transcription

1 Ocean observation challenges and implications for research and applications Detlef Stammer Centrum für Erdsystemwissenschaften und N Universität Hamburg WIGOS WOGOS, SPACE SPACE WORKSHOP WORKSHOP

2 Need for global Ocean Observations The ocean exhibits an enormous economic and social value; continuous monitoring of the oceans through in situ and satellite observations is therefore mandatory. Observations of the ocean are required for applications that include the monitoring of climate and the environment on seasonal to interannual to decadal time scale. Benefits of these observations include increased efficiency of operations at sea, improved safety to personnel and reduced damage to the environment. In particular, the availability of operational ocean observations is prerequisite for quality weather and ocean state forecasts.

3 Future of Sustained Ocean Observations OceanObs 09 identified tremendous opportunities, but also significant challenges. Called for a framework for planning and moving forward with an enhanced global sustained ocean observing system over the next decade, integrating new physical, biogeochemical, biological observations while sustaining present observations.

4 Framework for Ocean Observing Towards sustained system: requirements, observations, data management Input (Requirements) Output (Data & Products) Process (Observations)

5 Essential Ocean Variables We cannot measure everything, nor do we need to basis for including new elements of the system, for expressing requirements at a high level Driven by requirements, negotiated with feasibility Allows for innovation in the observing system over time

6 The Current Global Ocean Observing System Integrated system designed to meet many requirements: Climate Weather prediction Global and coastal ocean prediction Marine hazards warning Transportation Marine environment and ecosystem monitoring Naval applications 8 of 9 Societal Benefits Tide gauge stations Drifting Buoys Tropical Moored Buoys Profiling Floats Ships of Opportunity Ocean Reference Stations Ocean Carbon Networks Dedicated Ship Support Data & Assimilation Subsystems Management and Product Delivery Satellites -- SST, Surface Topography, Wind, Color, Sea Ice

7 Integrated Ocean Observing System... GOOS, IOC/UNESCO, see also CLIVAR Exchanges No.67, September 2015 WOGOS, SPACE 2040 WORKSHOP WIGOS SPACE 2040 WORKSHOP

8 .. from Global to Regional to Coastal Scale Time Coastal Regional Global Centuries Decadal Interannual Seasonal Daily hourly Ferryb ox Fisher Man Vessel Subsea observatories Gliders HF Radars Region Ship Time Series VOS Surface Data Moored Time series In network Floats Repeat Trans-Basin Sections 1Km 2 Regional/10 6 Km 2 Ocean bassin Globe Space

9 .. has strong satellite component. Time Coastal Regional Global Centuries Decadal Interannual Seasonal Daily hourly Ferryb ox Fisher Man Vessel Subsea observatories Gliders HF Radars Region Ship Time Series VOS Surface Data Moored Time series In network Floats Repeat Trans-Basin Sections 1Km 2 Regional/10 6 Km 2 Ocean bassin Globe Space

10 Vision for satellite ocean observations In combination with in situ observing system, deliver sustained, long term observations of essential ocean parameters that are of importance to meet the challenges of ocean and climate services as well as research.

11 Satellite Observations Major success during the last decade. Adecade of continuity and expansion in observing global oceans from space involving many innovative observations from research missions. Success led to major advances in ocean and climate science Created a foundation for operational ocean services and earth system modeling both with measurable benefit to society. The user needs for global ocean satellite observations are well established.

12 Earth Science Missions and Instruments Altimetry-FO (Formulation in FY16; Sentinel-6/Jason-CS) Earth Science Instruments on ISS: RapidScat, CATS, LIS, SAGE III (on ISS), TSIS-1, OCO-3, ECOSTRESS, GEDI, CLARREO-PF Detlef Stammer WOGOS, SPACE 2040 WORKSHOP CEN, Uni Hamburg

13 European Space Agency

14 Essential Satellite Ocean Variable Ocean surface topography and global sea level Sea ice topography and thickness, coverage, concentration, drift, melt pond fraction, albedo. Ocean currents Gravimitery. Sea surface temperature (SST) Sea surface salinity (SSS) Ocean Color: Ocean bio geochemical variables (e.g phyto plankton, sediment transport, dissolved matter, surface slick,...) Ocean wind (vector) Sea State Parameters

15 2015 ArcticSea Ice Extent WIGOS SPACE 2040 WORKSHOP WOGOS, SPACE 2040 WORKSHOP

16 2015 ArcticSea Ice Extent Monitoring Arctic Sea Ice Regional Arctic Ice Services WIGOS SPACE 2040 WORKSHOP WOGOS, SPACE 2040 WORKSHOP

17 WCRP-FPA2 Polar Challenge Be the first to complete a 2000 km continuous transect with an autonomous underwater vehicle (AUV) under the sea-ice climate.org/polarchallenge

18 WCRP-FPA2 Polar Challenge Be the first to complete a 2000 km continuous transect with an autonomous underwater vehicle (AUV) under the sea-ice climate.org/polarchallenge

19 Sea Surface Height Satellite altimetry remains the most important satellite observing systems for ocean analysis and forecasting: Dynamical Boundary conditions of the ocean circulation. Ongoing time series since 1993, 7 altimeter missions (re)processed: T/P, Jason1/2, ERS-1/2, ENVISAT & GFO; Besides JASON-3 also ongoing now CryoSat-2 and SARAL/AltiKa. Multiple mission high resolution products are readily available (e.g. SSALTO/DUACS). New MDTs from GRACE and GOCE. Very strong complementarity with Argo.

20 Sea Level ECV products Global Mean Sea Level ¼ Gridded Monthly mean Regional Trends

21 Sea Surface Temperature Longest time series in existance of large scale ocean observations. Used to observe climate variations and feed backs on regional and global scale. Use of SST data in ocean models: To correct for errors in forcing fields (heat fluxes, winds). To characterize the mesoscale variability of the upper ocean (eddies, frontal structures, surface currents) at very high resolution (a few km). Assimilation and validation. Approach today: Multi sensor approach (GHRSST)

22 Climate modeling: satellite data requirements Climate modeling is concerned with simulations and predictions of the entire climate system or parts of it. Ocean reanalyses fall under this category: ocean hind cast constrained by all available ocean observations, including satellite data. Satellite data play a major role in testing climate model solutions, For the initialization of models For improving the models Essential satellite ocean parameters: SSH, SST, sea ice Plus in situ data!!

23 Satellites and operational oceanography Operational oceanography provides near real time information about the ocean, ocean currents and many parameters for operations and research. Global, real time and high space and time (repeat) resolution, can also be directly used, e.g. for marine safety, pollution monitoring, water quality. Satellites provide key parameters (sea level and ocean currents, SST, ocean colour, sea ice, waves) needed to constrain global/regional/coastal ocean models through data assimilation and/or to validate them Always need to be complemented by in situ observing system (an integrated observing system).

24 Long term challenges for satellite ocean observations

25 Long term challenges for satellite observations Overriding considerations: Sustain measurement time series over multiple missions; focus on validation campaigns to assess error & uncertainties. Focus on determination of full error and uncertainty budgets of all remotely sensed oceanic and atmospheric variables. Continue emphasis on measuring variables needed to study processes in the climate, including feedbacks. Earth system science approach: e.g., development of synergistic missions to study the linkage of ocean, water cycle, and climate (e.g., precipitation, soil moisture, sea ice).

26 European Space Procedure to migrate from left to right? Agency

27 Long term challanges for satellite observations Spatial Resolution Improve spatial resolution of all variables: Enhancing spatial resolutions to monitor mesoscale and submesoscale variability, important to ocean dynamics, air sea fluxes, marine biology, coasts. Requirement for increased temporal sampling as small features evolve faster. More rapid sampling reduces data latency for some operational applications, such as NWP and crisis management. May require constellations of small satellites miniaturize sensors. This implies better definition and implementation of satellite constellations and convoys. There is a clear need for more consistent optimization of satellite sensor synergy in order to progress from 2D expressions to upper layer 3D interpretations. Detlef Stammer WOGOS, SPACE 2040 WORKSHOP CEN, Uni Hamburg

28 User groups Oceanography (global and coastal), operational open ocean and coastal monitoring NWP (global and regional) operational weather forecasts Seasonal to inter annual forecasting NWC operational weather and ocean nowcasts Climate global monitoring and climate change Treaty verification Future missions should be able to support all these communities (see also POST EPS Process)

29 Operational Oceanography and Climate Modeling Sea level, SST, Ocean Color, waves, sea ice and winds = backbone prognostic quantities in operational oceanography. Data needed to constrain and validate ocean models. Data also needed for applications Core operational satellite observations required for global, regional and coastal ocean monitoring and forecasting systems. Satellite high resolution SSH and SST observations are essential observations. Continuity (as in atmospheric (re)analysis)!!

30 Operational Oceanography and Climate Modeling Specific requirements : AATSR class SST needed as part of combined satellite/in situ SST measurement system to give highest absolute accuracy. A microwave SST satellite is required. 3 4 altimeters minimum required: only plausible way to initialise ocean mesoscale. Need long term series of Jason satellites (climate reference) Ocean colour increasingly important : global and coastal (at least 2 satellites) Surface winds (2 scatterometers) SAR for waves, sea ice characteristics and oil slick monitoring (at least 2 satellites) SSS needed on the longer run

31 Sea Surface Height Altimeter constellation remains fragile (far from being optimal over the past couple of years). Need to progressively infuse new technology (e.g. SAR/altimetry, SWOT): High spatial resolution swath altimeters, focus on near coastal measurements. Applications include: Sea level rise, Sea ice volume changes High resolution topography (post SWOT) (a mixture of along track and swath techniques) gradually covering also coast lines. We need in addition to climate quality to observe the SSH at high space/time resolution for operational oceanography.

32 Sea Surface Temperature Major challenges with the gap in dual view infrared radiometry since the loss of AATSR on ENVISAT. High resolution microwave radiometer, primarily for Sea Surface Temperature, needed to overcome significant sampling errors in IR SST fields caused by clouds. overcome limitations on land surface emission through side lobes of a real aperture radiometer to enable near coastal measurement. Need microwave + high accuracy reference systems (AATSR, S3) The status of passive microwave SST is fragile. 10 km resolution passive microwave sensing for global (all weather) acquisitions. A proposal (Microwat) is gradually emerging.

33 Continuation of Ocean Surface Vector Winds

34 Measuring sea surface salinity from space Soil Moisture & Ocean Salinity (SMOS) Mission by European Space Agency Nov present Aquarius/SAC D Mission by NASA & CONAE June 2011 June 2015 WIGOS SPACE 2040 WORKSHOP WOGOS, SPACE 2040 WORKSHOP

35 Measuring sea surface salinity from space Soil Moisture & Ocean Salinity (SMOS) Aquarius/SAC D Mission by NASA & Satellite SSS are complementary to in-situ Mission by European Space Agency CONAE measurements (e.g., from Argo) as well as with Nov present other satellite measurements.june 2011 June 2015 Aquarius & SMOS fill in spatial & temporal scales of SSS observations and in marginal seas & coastal oceans that are previously not possible, providing new knowledge of ocean dynamics at these scales. Elucidating the links of the ocean with climate variability and the water cycle through ocean salinity. WIGOS SPACE 2040 WORKSHOP WOGOS, SPACE 2040 WORKSHOP

36 Sea Surface Salinity Continuity of SSS measurements is needed but accuracy should be improved and requirements should be revised to take into account what we can already observe with Argo Improving accuracy of high latitude SSS measurements (Lband radiometers such as from SMOS, Aquarius, and SMAP have poor sensitivity to SSS at cold waters). SSS: Retrievals in cold water region is still a major challenge!! Low frequency scanning microwave radiometer, primarily for Sea Surface Salinity follow on for Aquarius and SMOS: High resolution needed to resolve near coastal features, rainfall events; probably requires aperture synthesis (SMOS).

37 Retrievals of SSS from NASA s Soil Moisture Active-Passive (SMAP) Mission under development

38 Animation of un-calibrated SSS from SMAP

39 SMOS and Sea Ice Thickness SMOS brightness temperatures at L Band can be used to retrieve sea ice thickness up to ~ 0.5 1m SMOS observations support monitoring of sea ice as it grows in the winter and recedes in the spring. Thin sea ice is particularly important for weather and climate as it controls the exchange of heat between ocean and atmosphere. Very useful in monitoring ice as it grows in the winter and recedes in the spring. Operational product available: Daily maps generated by University of Hamburg and disseminated with latency of 24 hours, since winter season 2010/11 till now through: Complementary with ESA s CryoSat data, being an radar altimeter measuring the free board. Combined product currently developed. Error characteristic of SMOS and CryoSat ice thickness retrieval: Synergy ice product based on SMOS and CryoSat data, combining both sensors skill under development. SMOS derived sea ice thickness for February and March (average) from 2011 to 2015 in [m]. Credit: University of Hamburg Kaleschke et al., 2010, 2012,2015

40 Optimize usage of data sets; Expand application horizon Surface Currents new variable to be considered + winds + sea ice (incl thickness) + importance of in situ observations. Sea State and Surface current: Wave current interaction has strong consequences for the upper ocean mixed layer mixing and temperature, Sea Ice Dynamics: Sea ice deformation and drift, snow on sea ice, thickness, waves in ice, heat flux versus lead statistics.

41 Example: Sea ice shear deformation rate Left: Sea ice shear deformation rate computed from SAR derived drift vectors; Right: corresponding sea ice shear deformation rate as simulated by the new nextsim Lagrangian sea ice model (using an Elasto Brittle rheology) presented in Rampal et al. (2015). Note: For this simulation a preliminary approach to initializing the damage field of the nextsim model as a function of the observed previous deformation over 3 days was used. Rampal, P., Bouillon, S., Ólason, E., and Morlighem, M. (2015): Detlef nextsim: Stammer a new Lagrangian sea ice model, The Cryosphere Discuss., 9, , doi: /tcd WOGOS, SPACE CEN, Uni Hamburg 2040 WORKSHOP

42 Surface Currents GlobeCurrent project: Global surface current obtained by integrating information from various data sets. Data interpolated to a 10 km grid at 3 hour intervals covering 12 years from 2002 to 2014 include: Surface geostrophic current (Alt, GOCE, GRACE, surface drifters) Surface and 15 m Ekman current (Scatterometer, Argo, surface drifters) Stokes drift (Wave model)

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44 Goal: Advance the quantitative estimation of ocean surface currents from satellite sensor synergy. Demonstrate impact in user led scientific, operational and commercial applications. Improveandstrengthentheuptakeofsatellite measurements.

45 Wave effects in the ocean Three wave effects have recently been implemented in NEMO at ECMWF: Coriolis Stokes forcing: sets up a current in the along wave direction. Stress: As waves grow under the influence of the wind, the waves absorb momentum which otherwise would have gone into the ocean Mixing: breaking waves inject turbulent kinetic energy is injected into the ocean mixed layer, significantly enhancing the mixing Mixing is found to have the greatest effect, with differences between a control run and the run with all wave effects amounting to 2 K difference in the extratropics (courtecy Øyvind Breivik, NERSC)

46 The Future An expanded, holistic view Earth s Ecosystems on a global scale Earth and ocean heat content and freshwater cycles Carbon cycle and climate: Satellite observations of tropical cyclones Seafloor bathymetry from altimetry Satellite Earth Observation for Atmosphere Ocean Exchange (heat, freshwater, carbon and momentum) Environmental monitoring: the health of the ocean and of coast lines

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