1. Introduction
Transcription
1. Introduction
NRT Core Services [email protected] KNMI scatterometer team [email protected] Vongfong, 8 October 2014 Outline Scatterometer wind services Nowcasting Global NWP Regional NWP Satellite Wind at Sea Services NWP SAF software users • • • • 24/7 Wind product services (OSI SAF) – Constellation of satellites – Africa High quality winds, QC – China Timeliness 30 min. – 2 hours – Europa Service messages India – Other QA, monitoring Asia Russia services (NWP SAF) Software America – South Portable Wind Processors USA – Weather model comparison Organisations involved: KNMI, EUMETSAT, EU, ESA, NASA, NOAA, ISRO, SOA, WMO, CEOS, .. Users: NHC, JTWC, ECMWF, NOAA, NASA, NRL, BoM, UK MetO, M.France, DWD, CMA, JMA, CPTEC, NCAR, NL, . . . More information: www.knmi.nl/scatterometer Wind Scatterometer Help Desk Email: [email protected] What we do, R&D • Help build a constellation for increased temporal coverage • Cal/val, NWP ocean calibration, e.g., OSCAT, HY2A, ASCAT-B, RapidScat OSI SAF Wind Products ASCAT-A 25-km winds • QC, e.g., QC near rain (AS Marcos Portabella) Operational status ASCAT-A 12.5-km winds status • First VH GMF in extreme winds to support Operational EPS-SG ASCAT-A coastal winds Operational status 25-km winds • Analysis of C-band GMF at extreme winds ASCAT-B Operational status ASCAT-B coastal winds Operational status • First analysis of structures at sea Oceansat-2 winds Discontinued status QuikSCAT winds • Increased resolution (EUM NWP SAF) Discontinued status Wind Products Processing Status • FA with EUMETSAT and Un. Vienna on “coastal” soil Other Wind Services at KNMI ASCAT-A 25-km winds (EARS) moisture Operational status ASCAT-A 12.5-km winds (EARS) Operational status • CDR sampling error ASCAT-B 25-km winds (EARS) Operational status ASCAT-B 12.5-km winds (EARS) • Stress-equivalent winds (EU MyOcean) Operational status 4 www.knmi.nl/scatterometer [email protected] OSI SAF User Workshop | November 2014 ERS-2 winds (EARS) Discontinued status Scatterometer work at KNMI RapidScat Mounted last week! Data in 2015 (Copernicus) www.jpl.nasa.gov/news/ne ws.php?feature=4325 OceanSat-2 scatterometer OSCAT International collaboration and lead cal/val team Exchange of resources, support to increase temporal sampling Winds at ~12 and ~00 LST HY2A Scatterometer Evaluation [email protected] Anton Verhoef Same approach as for OSCAT Data exchange Offer expert and GS support At ~6:00 and ~12 LST Independent Verification • Compare products with other producers • Product improvements • Standards (speed scale) Naoto Ebuchi, Tokai Un., Japan coaps.fsu.edu/scatterometry/ meeting/past.php#2013 OSI SAF User Workshop | November 2014 F ASCAT High Resolution Processing Workshop M A MetOp • Investigate ASCAT Spatial Response Functions, SRF • Detect structures • Improve knowledge of aggregated SRFs for geophysical processing [email protected] Stress-equivalent wind U10N: equivalent-neutral 10m wind For the same U10N, cold heavy air will produce more stress (and roughness) than lighter warmer air. This effect is expressed by the surface stress equation. The surface wind stress τ = ρ u*2 indeed depends on the air density ρ. Assuming that σ 0 measurements are more a measure of τ than U10N, the ρ correction for U10N takes the form where U10S denotes the current set of stress-equivalent scatterometer wind retrievals and <ρ> is the average air density as defined in a standard atmosphere (≈1.225 kg/m3). ρ variations, which depend on surface pressure, air temperature, and humidity, are generally small (1-2%) and can exceptionally increase locally in cases such as cold air outflow. Hurricane wind extremes Discussion on highest ever peak winds from tyfoon Haiyan in the media, but impossible to measure! Maximum 1-minute sustained winds are difficult to know, but used for category! Scatterometer winds are mentioned in 20% of ALL NHC TC discussions Scatterometers measure 25-km scale winds and are thus much lower extremes than 1-minute peak winds Current scatterometers either capture rain and/or saturate at 40 m/s; The impact of a hurricane surge is catastrophic and depends on wind speed, wind direction, wind duration and wind fetch, less on maximum 1minute peak wind (Sandy) TC Rita ASCAT hits on Vongfong 50 ASCAT B ASCAT A 40 30 710 -1 4 710 00: 12 -1 4 710 12: 03 -1 4 710 12: 51 -1 4 810 23: 51 -1 4 910 00: 42 -1 4 910 12: 09 -1 4 13 :0 3 20 Peak around midnight on 7/8 October 2014 of 42 m/s (150 km/h) ASCAT-A appears low as compared to ASCAT-B Current calibration bias B-A of 0.1 dB (0.1 m/s) Required accuracy is 0.2 dB Due to GMF saturation, 0.1 dB at 40 m/s is 4 m/s ! For extremes more careful instrument calibration is needed Trends in extreme wind speed Trend in 90th Percentile QuikSCAT Trend in Wind Speed (in 0.1 m/s per 10 year) Figure by Jason Keefer and Mark Bourassa, FSU Controversy in trends of mean and extremes Wentz, F. J., and L. Ricciardulli, 2011, Science Young, I. R., S. Zieger, and A. V. Babanin, 2011: Science QuikScat CDR: unexplained 0.1 m/s decadal falling trend of mean wind ? Go out there! Key Flight level PS dropsonde With the NOAA hurricane hunters Time (UTC) SFMR WS Feb 4, 2010 HF drops HF SFMR High Winds Research • validation set for remotely sensed winds •ASCAT, OceanSat-2, future instruments • NWP forecast models • Instrumentation •GPS dropsondes, Step Freq. Mirowave Radiometer UMASS Imaging Wind AGU andOcean Rain Air-borne Profiler (IWRAP) Feb•23, 2010 Sciences 2010, Portland, OR 14 SFMR versus ASCAT Distance to centre [km] Distance to centre [km] CMOD5 winds are lower than SFMR (VV pol) add ln(VASCAT) However, CMOD5 winds equal buoy winds for 15 to 20 m/s; which to trust? SFMR winds go up when it rains -ln(RR); NOAA is recalibrating Calibration strategy 1. GPS dropsondes provide true measure of local wind 2. GPS dropsondes calibrate SFMR on its basic footprint 3. Calibrated SFMR data are integrated over a scatterometer WVC length to provide a resource for satellite scatterometer calibration Error attribution in all steps CEOS Virtual Constellation http://ceos.org/ourwork/virtual-constellations/osvw/ Winds when it matters high water Delfzijl 0.5 m underpredicted surge (NL) by HiRLAM (blue) and ECMWF winds (green) OSI SAF QuikScat winds (red) are stronger and/or more directed into the harbour NRT needed R&D on mesoscales needed 1/11/’06 4:03 1/11/’06 6:14 Requirement for visualisation 14:42Z Weersverwachtingen worden steeds beter NH ZH Beter gebruik van waarnemingen Grotere computers Verbeterde weermodellen 21 Substantial NWP Forecast Error Reduction by Scatterometers The sensitivity to observations measures the impactto of the observations on the short-range forecast (24 hours). • forecast Great success of OSCAT; grateful ISRO The forecast sensitivity tool developed at ECMWF computes the Forecast Error Contribution (FEC) that is a measure (%) Much ofinformation inthrough datathe assimilation; only a assimilated few % observations. used of •the variation the forecast erroris (aslost defined dry energy norm) due to the May 2013 versus May 2012 12% Smaller Global FcError 2% FcError Reduction due to GOS [C. Cardinali ] OSI SAF User Workshop | November 2014 From plume to probability eSurge UCM3 2015 Improve meteorology? Greg.J. Tripoli, Un. Wisconsin Why high resolution? Example: Simulation of a storm in 1990 HARMONIE ERA-Interim High resolution modelling affects more than just the coastal zone Baas and De Waal, 2012 25 from R. Boers, KNMI WMO CGMS International Winds Working group • See also https://groups.ssec.wisc.edu/groups/iwwg/activities/high-resolutionwinds-1/nwp-data-assimilation Relevant scatterometer splinter group actions: • All: Share experimental results among participants. Further experiments on timing errors, thinning, more aggressive QC in inner/outer loops and background error structure are encouraged. • NWP SAF (KNMI): Investigate 2DVar sensitivity to: timing errors, thinning, QC, background error structure, background (provided by participants) with the aim to provide guidance to NWP centres. • NWP SAF: Make above points more prominent on web site: bias correction guidance, guidance, data and tools (as is) on spatial/spectral analyses and triple collocation. • NWP SAF: Organize NWP SAF workshop on scatterometer data assimilation. HARMONIE WW, 13-16/10/2014, Santander NRT Core Storm Service Provides basic underlying information when alarm codes turn red Real-time for deterministic nowcasting Satellite winds are successfully used in global NWP; global NWP provides probabilistic ensemble forecasts Use of satellite winds is challenging in regional NWP; coordinated effort in IWWg Consistent provision of core winds, waves and surges for Disaster Risk Reduction in a one-stop shop? Both observations and models? One-stop shop portal? www.storm-surge.info Haiyan