CRYOSPHERE & HYDROLOGY

Transcription

1 CRYOSPHERE & HYDROLOGY M.Menenti, X. LI, J. WANG, H. Vereecken, Jiren LI, M. Mancini, Q.LIU, L.JIA, Jing LI, C.Kuenzer, S. HUANG, H.Yesou, J.WEN, Y. Kerr, X. CHENG, N. Gourmelen, C. KE, R.Ludwig, H. LIN, M. Eineder, Y. MA and Z. B. SU

2 Results highlights: Cryosphere Glacier flow velocity: regional patterns within Karakoram, Himalayas, Qinghai Tibet; patterns within larger glaciers; seasonality General pattern of glacier slowdown in the entire Himalayan region driven by glacier thinning. In the Pamir, Hindukush and Karakoram the variation of velocity is dominated by internal dynamics (surging) General pattern is a climatic response: glaciers are getting thinner and surface flow slower; Glacier flow velocity: optical vs. SAR feature tracking and L-band InSAR; annual velocity better with optical data, also because of extended archive at appropriate spatial resolution over 40 years; Changes in glacier elevation: GLAS, CryoSat, bistatic InSAR, stereo-imaging, in-situ mass balance; further work required to understand which target CryoSat picks up within a glacier with significant elevation range;

3 Results highlights: Cryosphere Glacier mass balance: changes between old and new glacier inventory; regional (GRACE) vs. local mass balance No proper way to determine from space mass balance of mountain glaciers and for the entire Karakoram, Himalayas, Tibet region; GLAS results convincing but spatial sampling and temporal coverage insufficient; need to integrate modeling of glacier dynamics with available observations; Changes in lakes extent and water level: attribution to glacier mass balance vs. precipitation Specialized processors available (PISTACH) for Jason and (PEACHE) Altika, needed for CryoSat to observe inland waters and mountain glaciers; Analysis of entire Landsat archive led to map changes in lakes extent since 1970 in the KHT region; integration with RA led to determine changes in lake water volume ; use of multiple satellites can improve spatial and temporal sampling;

4 Results highlights: Cryosphere Sea ice: retrieval of extent, thickness and drift vs. classification; optical vs. SAR The sea ice toolbox has been extended, containing components for sea ice classification, drift and deformation analysis, and thickness retrieval. The algorithms were used for identification of potential hazards and for developing time series of ice extent in the Bohai Sea. Merging different data is useful, but sea ice is very dynamic. Sea ice: data sources, spatial resolution vs. size of structures to be identified Merging data from different SAR systems (ASAR, PALSAR, RS-1 and RS-2, TSX) and sensors working in the visible and thermal range has been investigated for improving classification (minimizing ambiguities) and process studies (e. g. polynja evolutions). The combination of different spatial scales and the related information content was analysed.

5 Results highlights: Hydrology River basin hydrology: Satellite data products generated and evaluated on all terms of water balance; assimilation of multiple hydrological data products improves accuracy of higher level data products: this enables model prediction on the terrestrial water cycle; Validation by extensive field campaigns in different river basin environments River basin hydrology: modeling water and energy balance; model calibration by LST and water level; in-situ river discharge measurements remain necessary; Soil moisture data products: comparative evaluation of data products; scaling laws; SSM/I soil moisture climatology shows an increase in soil moisture across the central part of the Tibetan Plateau during the monsoon season, while during freeze-thaw transitions is spread across the Tibetan Plateau.

6 Results highlights: Hydrology Soil moisture: Large differences across products variable across regions; sources of errors not well understood, e.g. vegetation; might be addressed by better retrieval algorithms; sensing depth should be better characterized; ASAR soil moisture retrieval for the Tibetan Plateau is possible at specified uncertainty; Sentinel-1 is a great improvement and hold potential, but challenges the community in terms of data processing Hydrologic data products: energy and water balance; Sub-pixel topography and hemispherical cloud distribution to be taken to estimate at-surface irradiance Time series analysis, modeling and reconstruction;:lst and Tb-37GHz; Monitoring flooded areas; System operational for merging several different optical data; products for energy and water balance modeling can be generated globally; System operational for ET data products across a range of spatial and temporal resolutions; validated against EC measurements in China and Europe;

7 Results highlights: Hydrology Dynamic of wetland environments : extended time series analyzed on water extent and on relative abundance of favourable and unfavourable habitat; Conflict between protection of wetland ecosystem and exploitation of land and water resources; attribution of observed changes to stressors; Methods to delineate water bodies are sensor independent and have been applied to different sensors; available SAR data over a wide range od spatial resolution; Sentinel 1 makes analysis of very fast changes feasible; Integration of in-situ measurements with multi source satellite data for habitat assessment;

8 Seed questions: Science and Applications What are the remaining issues concerning the exploitation of current mission data? Specialized processors for inland waters and mountain glaciers elevation; Sentinel 1 data products are very massive and could be easier to process by a wider community if available split by polarization and sub swath in addition to current formats; Acquisition of Sentinel 1 data over Dragon test sites should be improved and secured; So far the potential of Chinese EO satellites has not been fully exploited, both in China and Europe, especially of high resolution sensor systems; Use of ESA receiving stations to acquire GF-1 and 2 data in Europe and Africa should be explored What are the new science findings in the domain? - Regional patterns in glacier flow velocity and climatic response of glaciers - Long term changes in lake extent and response to climate - Characterization of the land surface response to radiative forcing across temporal scales by using extended LST time series

9 Seed questions: Science and Applications What is the general performance and what are the limitations of geophysical parameters retrieval? - Freeze thaw assessment and rejection of microwave radiometer observations for retrieval of SM, - Most retrieval algorithms assume homogeneity of observed target, this assumption applies to high resolution observations, much less to low spatial resolution; - Large difference across SM data products and unrealistic retrievals in some regions, e.g. desert; - RFI on SMOS observations still an issue in China EO data synergy: is there scope for data synergy and if so which EO missions/sensors are required? - Virtual constellations for sea ice monitoring are beneficial: Sentinel-1, Radarsat- Constellation); merging different data types (Sentinel-2, Sentinel-3) Validation : Have the necessary validation data been collected and shared? - Better physics of remote sensing vs. in-situ measurements needed for robust validation; - Permanent validation sites are necessary beyond project based efforts;

10 Seed questions: New mission exploitation What are the new domains where further research is needed? - Constraining models of glacier dynamics with satellite observations, e.g. surface flow velocity; use of observed snow cover and SWE as input to glacier mass balance models; - Use of bi-directional AATSR and SLSTR data to model land surface energy and mass fluxes; - Integrate vertical soil water flow model in the retrieval algorithms to match retrieval to a realistic current sensing depth; - Integration of water level and water extent for wetlands and water bodies in flatter environments should be pursued to assess trends and changes in water volumes; this would make easier the linkage with water use and water resources vulnerability; - Water volume is a better observation for the calibration and validation of hydrological models; - Identification and monitoring of frozen ground should be improved; Sentinel 1 has a significant potential in this direction;

11 Seed questions: New mission exploitation What are the synergy between Europe and China new missions to be exploited? -The observations by the intended Chinese Water Cycle Mission (WCOM) with a dual frequency dual polarized microwave radiometer would fill a gap in current European observations and would be highly relevant to monitoring of water resources. The mission will provide observations of SWE, precipitation and soil moisture. - Spatial and temporal coverage can be significantly improved by integrating China and Europe multispectral observations at HR and VHR ; the full resolution PROBA V observations should be considered in this context; What complementarity in the operational use of the current / future missions (planning, observations, etc.) could be improved to allow better data exploitation? CBERS 4 TIR, Landsat 8 and ASTER acquisitions should be programmed to guarantee data availability for hydrological assessments on water use and water stress; Sentinel 3 data will fill a gap in current observations, especially as regards spectrometry (OLCI) and land surface radiometry (SLSTR) as well as altimetry; Large part of acquired Landsat images since 1970 is neither at USGS or ESA; would be useful whether additional images are stored in the Chinese archive;

12 Recommendations: Cryosphere Glacier mass balance in high elevation Asia should be explored by bistatic InSAR and spatial patterns characterised, especially in the context of extending local studies to evaluations for the entire KHT region; A glacier hydrological model for endhoreic and exhoreic basins should be established to assess and understand impacts on fresh water resources; The deformation of the permafrost active layer should be further studied by InSAR using the 6-days Sentinel 1 repeat and its role in the terrestrial water cycle better understood. The planned WCOM will provide new and better observations of the terrestrial water cycle and of the cryosphere and should become part of the space infrastructure supporting the next phase of Dragon. In high elevation area the use of high resolution image data to assess changes in the extent of glaciers and lakes and the combination with laser and radar altimetry should be further developed focusing on smaller glaciers and lakes; Parameterization of models of glacier dynamics might be improved by using satellite observations, e.g. surface flow velocity; use of observed snow cover and SWE as input to glacier mass balance models; Sea ice: extend the work on long-time series of sea ice conditions in the Bohai Sea to assess potential hazards for marine traffic and offshore operations.

13 Recommendations: Hydrology Observations of water level have not yet been used to their full potential to understand the dynamic of inland water bodies, particularly in combination with measurements of water extent over the available 40 years data record. Current precipitation data products should be improved by assimilating active and passive microwave measurements, e.g. by WCOM, in cloud resolving atmospheric models, Acquisition of Sentinel 1 data over Dragon test sites / study area should be improved and secured; Global hydrological data products can be generated taking advantage of the synergies of European and Chinese data assets, but this requires improved accessibility and standardization of Chinese data products and archive. To document and improve the quality of data products on the terrestrial water cycle permanent validation sites in both Europe and China are necessary beyond project based efforts;

14 Recommendations: Hydrology Models and data products generated under the current phase of Dragon should be used more systematically to assess water use and water productivity; The accumulated body of knowledge on wetlands dynamics and wetlands ecosystem should be expanded by characterizing the linkage between the terrestrial water cycle over the watershed and wetlands. This applies to both lowlands and high elevation areas. The extended data record on extreme events (floods and droughts) should be better exploited to characterize the probability of occurrence and duration, both in lowlands and high elevation areas.

15 Seed questions: Evolution of Dragon cooperation What are your recommendations for continuity and improved cooperation under Dragon 4? - The Dragon community interested in the terrestrial water cycle and water resources has built shared interests and capabilities through the subsequent cycles of the program and is ready to provide a collective and significant contribution to the next cycle. - The Young Scientist program has been successful and should be continued, but attention should be dedicated to make use of existing funding sources for this purpose, such as the ESA / ALCANTARA program and the CSC and MOST / CAS programs for the exchange of PhD students and postdocs. How would you structure your thematic areas to generate a combined proposal under Dragon 4? Theme: Assessment of fresh water resources and of their productivity and security Suggested topics: High elevation terrestrial water cycle Wetlands water use and vulnerability Integrated water management in river basins

16 Common Interests Hydrological modelling / data assimilation of remote sensing data Hydrology products from remote sensing Soil mositure products Soil-Plant- Atmosphere interactions climate change Glaciers mass changes Flood dynamics from remote sensing Water quality from remote sensing Land use changes, biodiversity from remote sensing Heihe river basin Yangtze river basin ID10649: Water Cycle & River Basins ID10664: Yangtze River Basin Hydrology China Tibetan Plateau Himalayan Yigong Zangbo & Parlung Zangbo Tibetan Plateau Tibetan Plateau & Himalayan ID10680: Hydrology Products ID10611: SMOS CalVal and Soil Moisture ID10302: Himalayan Glacier Dynamics ID10612: Glaciers & Hydrological Dynamics ID Cryosphere Dynamics ID10603: CEOP-TPE Poyang and Donting Lakes, Anhui province, Napahai, Rouergai in Qinghai plateau Donting Lake ID10557: Wetlands Monitoring ID10697: Dongting Lake Flood Dynamics

17 Thank you!