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Measuring Global Precipitation: present and future challenges

Measuring Global Precipitation: present and future challenges. Chris Kidd & co-authors Earth System Science Interdisciplinary Center, University of Maryland, and NASA/Goddard Space Flight Center, USA chris.kidd@nasa.gov. Goddard Space Flight Center.

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Measuring Global Precipitation: present and future challenges

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  1. Measuring Global Precipitation:present and future challenges Chris Kidd & co-authors Earth System Science Interdisciplinary Center, University of Maryland, and NASA/Goddard Space Flight Center, USA chris.kidd@nasa.gov

  2. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Overview Water & precipitation - Why? Measuring Precipitation - Conventional observations to satellite products Challenges - Future directions and opportunities

  3. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Why precipitation? “Our knowledge of the time and space distributions of rainfall,soil moisture, ground water recharge, and evapotranspirationare remarkably inadequate,in part because historical data bases are point measurements from which we have attempted extrapolation to large-scale fields.” P.299 National Research Council (1991) Opportunities in the hydrologic sciences, National Academy Press “…critical atmospheric variables not adequately measured by current or planned systems [include] precipitation.” UK Met Office. NERC CEOI Workshop, 13/11/09 Precipitation is ultimately the input for all hydrological systems

  4. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Water factoids 1 mm per square metre = 1 litre (or 1 kg) 1 mm per square kilometre = 1,000,000 litres or 1000 tonnes so, Sopot has ~750 mm/yr ≡ 750,000 tonnes/yr/km2 Currently fresh water costs ~$2 per cubic metre, globally precipitation ‘contributes’ $258 trillion annually. Over the US alone, precipitation is ‘worth’ $13 trillion annually. “More than 2.8 billion people in 48 countries will face water stress or scarcity conditions by 2025.”WaterFootprint.org & WWF

  5. 20,000 Rain gauges Radarduplicates rain-gauge coverage Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Conventional Observations Precipitation is highly variable, both temporally and spatially. Satellites can provide consistent, regular observations, global coverage, real-time delivery of data

  6. Satellite precipitation observational capabilities 1959 Vanguard 2 1960 TIROS-1 1966 ATS-1 1974 SMS-1 1978 SMMR 1983 NOAA-8 25 years 1987 SSM/I 1988 WetNet 15 years 1997 TRMM 1989 AIP-1 1991 AIP-2 1994 AIP-3 1990 PIP-1 1993 PIP-2 1996 PIP-3 1998 AMSU 10 years 2002 MSG 2003 SSM/IS 2001 IPWG 2006 Cloudsat 2004 PEHRPP 2011 NPP 2011 Megha-Tropiques 2014 GPM ? Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 1960 Visible 1970 Infrared 1980 Passive Microwave 1990 2000 Active MW 2010 2020

  7. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Current precipitation-capable systems PMW-I Passive Microwave Imager PMW-S Passive Microwave Sounder AMW Active Microwave (radar) Other systems such a MODIS and even Landsat may also be used

  8. Visible (including near IR) • Reflectance, cloud top properties (size, phase) Infrared • Thermal emission – cloud top temperatures → height Passive Microwave • Natural emissions from surface and precipitation (emission and scattering) Active Microwave • Backscatter from precipitation particles Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Satellite retrieval of precipitation Note: Observations are not measurements

  9. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Surface & Satellite Observing Systems Surface Satellite Observations have different spatial/temporal characteristics

  10. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Global Precipitation Datasets e.g. CPC unified analysis, CRU gauge, GPCC analysis e.g. GPI, GPROF, HOAPS, Hydro-estimator, OPI, TAMSAT, TRMM PR e.g. CMORPH, GSMaP, NRL, TCI, TOVS, 3B40/1/2 e.g. CAMS/OPI, CMAP, GPCP, TMPA • Precipitation gauge analyses (land only) • Single-source satellite datasets • Satellite combined datasets • Combined datasets with gauge data Huffman et al – see IPWG website

  11. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Precipitation products(a selection) GSMaP CMORPH PERSIANN CPC-MMW 3B42RT NRLbld Products available quasi-operationally, nominally at 3-hourly, 0.25 degree ECMWF GPCC-0.5 Plenty of products - need for validation Annual Totals, 2009

  12. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Ground validation (GV) synergies After Turk & Arkin, BAMS 2008

  13. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 International Precipitation Working Group Near real-time inter-comparison of model & satellite estimates vs radar/gauge

  14. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 GPM Ground Validation LPVEx 21/09/2010Helsinki, Finland There is significant complementary GV activity related to the GPM mission involving ground instrumentation, aircraft (cloud particles sampling & imaging) as well as satellite observations. Aranda Jarvenpaa GCPEx Jan/Feb 2012 Ontaria, Canada Primarily frozen precipitation; Heavy lake-effect snow and light, shallow snow events

  15. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Annual Precipitation - Tropics ECMWF 3B42 TRMM PR 0 5 10 15 20 mmd-1

  16. 3B42 merged satellite product TRMM PR Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Sub-daily retrievals: Diurnal Cycle time of maximum precipitation ECMWF operational forecast UTC 00 03 06 09 12 15 18 21 no data

  17. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Climate-scale analyses Note that the mean global precipitation is relatively constant

  18. Low-level orographic Mid-latitude frontal CF WF Multi-layered Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Cloudsat: Cloud Profiling Radarproviding new insights

  19. Himalayas Occurrence of rainfall Annual total rainfall Western Ghats Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 High resolution climatologies TRMM PR data: 13 years (1997→) at ~5 km resolution. Rainfall shows significant local variability linked with relief.

  20. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Calibration of surface radar: TRMM vs NMQ PR rain vs NMQ no-rain PR no-rain vs NMQ rain

  21. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Hurricane Isaac (2012) TRMM PR 28 August 2012 17:12LT NPP VIIRS 29 August 2012 01:57LT ‘night-time visible’ - moonlight

  22. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Challenges Number of challenges/opportunities: • High latitude retrievals - light, shallow, mixed & frozen precipitation • Resolution/sampling - spatial resolution & revisit times • Errors and uncertainties - quantifying ‘range’ of estimates • Maintaining and building capabilities - planned precipitation-capable missions

  23. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 High latitude retrievals The retrieval of precipitation at higher latitudes is more challenging due to the physically diverse nature of the weather systems and surface backgrounds. Critical issues include identification and retrieval of: - light intensities (< 1 mm h-1) - shallow systems (< 1 km altitude) - mixed-phase (rain & snow co-existing) - frozen precipitation (snow – in all forms) … all over potentially frozen or snow-covered surfaces.

  24. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Distribution of light precipitation • Light precipitation becomes increasingly important towards the polar regions • COADS data shows light precipitation occurrence >80%; ~50% in mid-latitudes • European radar suggests ~85% of precipitation <1 mmh-1 (35%<0.1 mmh-1) • Accumulation of light precipitation is smaller, particularly in the Tropics Current satellite techniques do not retrieve light precipitation well

  25. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Resolution and Sampling - Spatial: precipitation contains many fine-scale features at resolutions below ~5 km (important for hydrology) - Temporal: need for rapid updates, particularly for severe storms, flash-floods and hydrology. Dependent upon number of systems available; possible to include multiple sensors, but often at the expense of greater ‘noise’ and different sensor characteristics.

  26. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Resolution: details Can we adequately resolve the peculiarities associated with the movement of precipitation? 1 km/5 min radar (much better resolution than satellites) Precipitation is (temporal and spatial) resolution critical

  27. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Quantifying Errors and Uncertainties An ever increasing number of users and applications require information on the errors and uncertainties associated with each precipitation estimate. Errors & uncertainties are a function of: • precipitation characteristics; (time; location; intensity; areal & temporal extent) • observational capability; (type – Vis/IR, MW etc; sampling; resolution) • retrieval ability. (knowledge/understanding, calibration data) A multi-dimensional problem – still understanding the question!

  28. Mission Country Launch (CEOS) MetOp-B EU 17/09/2012 DMSP-F19 US Jan 2014 GPM US Early 2014 Meteosat-11 EU Spring 2015 GOES-R US Oct.2015 (LR) EarthCARE EU/Japan (Nov. 2015) GCOM-W2 Japan (2016) MetOp-C EU Autumn 2019 (Only includes definite missions) Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Future Precipitation-Capable Missions All NOAA & NASA instruments Number of sensors Number of operating (2000-2011) and planned (2012-2020) NASA and NOAA EO (all) instruments. (Planned=funded and specified launch dates). NRC mid-term assessment (2012). Sensors are becoming more lifetime-resilient, however, it is critical to maintain or improve upon current capabilities

  29. Goddard Space Flight Center EUMETSAT conference, Sopot, Poland. 3-7 Sept 2012 Conclusions Solid foundations • 50+ years since the dawn of the satellite era • 33 years since usable observations for precipitation • 15 years since ‘first’ precipitation mission Significant progress in precipitation retrievals • nominal ~0.25° 3-hourly estimates, but also finer products • However, products generally limited to 60°N-60°S Current & future issues • High latitudes needed for global precipitation estimates • Fine resolution, multi-source retrievals – globally • Errors and uncertainties needed for estimates • Maintain (and better) current capabilities

  30. Thank you! chris.kidd@nasa.gov http://pmm.nasa.gov/ http://www.isac.cnr.it/~ipwg/

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