Mesoscale Observing Challenges: One Perspective with Emphasis on the Urban Zone
presentation to the:
NSF Observing Facilities Users Workshop
24-26 September 2007
NCAR
Boulder, CO
presentation to the:
NSF Observing Facilities Users Workshop
24-26 September 2007
NCAR
Boulder, CO
Walt Dabberdt
Director, Strategic Research
Vaisala - Boulder, Colorado
©Vaisala | date | Ref. code | Page 2
Presentation Outline
• Urban Demographics & Challenges
• Importance of the PBL
• Measurement Systems
• Mesoscale Networks and Testbeds
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Presentation Outline
• Urban Demographics & Challenges
• Importance of the PBL
• Measurement Systems
• Mesoscale Networks and Testbeds
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Ten(10) Largest Cities in 1000A.D. (M-Inhabitants)
Cordova Spain 0.450
Kaifeng China 0.400
Constantinople Turkey 0.300
Angkor Cambodia 0.200
Kyoto Japan 0.175
Cairo Egypt 0.135
Baghdad Iraq 0.125 (1.25???)
Nishapur Iran 0.125
Al-Hasa Saudi Arabia 0.110
Patan India 0.100
Source: Tertius Chandler: “4,000 Years of Urban Growth” (1987)
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1950
2000
2015
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Growth of Mega-Cities
City-2015 PopulationTokyoMumbaiLagosDhakaSao PauloKarachiMexico CityShanghaiNew YorkJakartaKolkataDelhiMetro ManilaLos AngelesBuenos AiresCairoIstanbulBeijingRio de JaneiroOsakaTianjinHyderabadBangkok
26.426.123.221.120.419.219.219.117.417.317.316.814.814.114.113.812.512.311.911.010.710.510.1
379.3 (23)Source: UN Population Division, March 2000
most mega-cities are in the less
developed regions (16)
blue = coastal city
green = inland city
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The March of Urbanization in the World (% global population)
World MDR LDR
1950 29.8 54.9 17.8
1975 37.9 70.0 26.8
2000 47.2 75.4 40.4
2030 60.2 82.6 56.4
MDR = more developed regions
LDR = less developed regions source: UNPD, 2001
Today, 1.3 million people are moving to the cities every week!
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Growth by City Size
Contrary to popular belief, the
bulk of urban population growth is likely to occur in smaller cities and towns of less than
500,000.
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Some Relevant City Factoids (source: Arnulf Gruber, 2004)
• ~50% world population (~2007)
• > 80(?)% world GDP (few data)
• > 80(?)% world electricity
[wfd: ~ CO2 eq. emissions?; no good data]
• ~ 95% world internet sites and internet traffic (good data)
• 78% mega-cities are coastal [wfd]
• 70% mega-cities are in less-developed regions [wfd]
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Warm Season Events • Tornadoes• Mesoscale boundaries• Mesoscale systems• Convection (localized)• Hurricanes/Tropical storms• Flash floods and main-stem
flooding• Fire weather events• Air quality episodes (O3)• Heat waves• Toxic plumes
Winter Season Events• Fronts/short-waves• Liquid/freezing/frozen boundaries• Ice storms• Orographic (e.g., lake effect
storms)• Blizzards/Wind chill• Coastal Gales• Air quality episodes (PM)• Cold air outbreaks• Toxic plumes
Examples of Mesoscale Events That Impact Human Well-Being and/or Have Major Economic Impacts
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Tornado – Ft. Worth, TX
Source: North Central Texas Council of Governmentssimulation
March 28, 2000
Path Length: Approximately 3 miles Path Width: 1/4 mileF-Scale: F1 (73-112mph) to F2 (113-157mph)
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MODIS Imagery: France Heat Wave -- August 13-28, 2003
Source: Zaitchik et al., 2006
Vegetation index anomaly Surface temperature anomaly
Solid lines demarcate conventional climate zones.
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Three Recent Heat Waves
Event Year Location Fatalities
Heat wave 1987 Athens ~900 deaths
Heat wave 1995 Chicago ~700 deaths
Heat wave 2003 France ~15,000 deaths
Source: Earth Science and Applications from Space: National Imperatives for the
Next Decade and Beyond (2007)
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Hurricane Katrina (2005) Tracks: Forecasts and Actual
Courtesy of James
Franklin, NHC
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Mega-City Smog -- Beijing
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Presentation Outline
• Urban Demographics & Challenges
• Importance of the PBL
• Measurement Systems
• Mesoscale Networks and Testbeds
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Bi-directional physical problem with feedbacks:
•Weather and Climate Impacts on the City •Quality of life •Economy•Human health and mortality
•Urban effects on the atmosphereDirect: Indirect: sensible heat urban heat island runoff and latent heat human heat stress thermal conductivity and heat capacity PBL & ML structure aerodynamic roughness cloud cover & precip. zero-plane displacement insolation and radiation gaseous and particulate loading balance sun shading local circulations
City-Atmosphere Interactions
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Why the Planetary Boundary Layer?
PBL contains the
Depth of cold air in winter to tops of stratocumulus
Low-level jet
for weather
Courtesy of Fed Carr, NAOS
Layer of air containing the roots of
summertime convection
Fog and low clouds under nocturnal
inversion
Convective events in well mixed layer
during daytime heating
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The Need for Mesoscale Observations -- as Reported by the North American Observing System (NAOS) Study*
• Need to measure mesoscale phenomena at resolution that is high enough to accurately represent these mesoscale features in the initial conditions of a mesoscale model
• If using 6-8 grid points per wavelength criterion, then the needed resolution can be estimated as follows:
– 20-30 km resolution for jet streams, IPV details, etc.– But 0.1 – 1 km resolution to observe thunderstorm updrafts
and downdrafts
* Courtesy of: Fred Carr, Univ. Oklahoma
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Tropopause (8~13 km)• Jet Stream
Mid Troposphere (2~8 km)• Location/intensity of short waves
PBL (Sfc~2 km)• Ageostrophic• Orographic• Temp, Moisture, Wind, Precipitation• Surface/sub-surface conditions
PBL has largest unmet need for improved observations
(assuming that next-generation satellite sensors measure V, T and q at needed resolutions and
precision above the PBL)
Critical to get forcing correct in PBL, and
short waves in troposphere
Tropopause
Mid-Troposphere
Planetary BoundaryLayer (PBL)
Courtesy of: Fred Carr, Univ. Oklahoma
What Additional Observations Are Needed? (source: NAOS)
Satellite imagery & soundings
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The greatest need in future mesoscale observing capability is high vertical resolution of T, q and wind in the PBL.
Slight variations in these values will have a major impact on:
thunderstorm vs. severe thunderstorm vs. squall line vs. MCC,
and subsequent forecasts of flooding, winds, temperatures, etc.,
and consequent impacts on health, safety, agriculture, transportation, energy, etc.
~2kmNeed 100-200m resolution!
Courtesy of: Fred Carr, Univ. Oklahoma
Why the PBL? (source: NAOS)
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Diurnal Boundary-Layer Evolution (after Stull)
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Urban Boundary Layer: Scales & Layers
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Near-Surface Layer: Scales & Layers
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1 mm 1 cm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km
Horizontal grid spacing
ModelingGap
Raw
inso
nd
es
ACARS
RADARDaytime Boundary Layer
SfcObs
Building Urban Storm Fronts Synoptic
Surface Layer
Measurement Capabilities: Transport & Diffusion Scales
Slide courtesy Walter Bach, ARO
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1 mm 1 cm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km
Horizontal grid spacing
ModelingGap
Raw
inso
nd
es
ACARS
RADARNocturnal
Boundary Layer
SfcObs
Building Urban Storm Fronts Synoptic
Surface Layer
Measurement Capabilities: Transport & Diffusion Scales
Slide modified after Walter Bach, ARO
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(MacDonald et al., 2001)
SCOS-97 mixing depths, September 4, 1997
Mixing Depth – Spatial and Temporal Variability
0300LST
1400LST
L.A. Basin
(Plate, 2004)
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Emergence of Urban-Based Mesoscale Initiatives
• U.S. Weather Research Program PDT-10 on Urban Forecasting (1998)
• U.S. Weather Research Program PDT-11 on Air Quality Forecasting (2001) and subsequent AQF Workshop (2003)
• U.S. Weather Research Program Community Workshop on Multifunctional Mesoscale Observing Systems (2003)
• U.S. Environmental Protection Agency Recommendations on Air Quality Forecasting and the Role of Urban Testbeds (2004)
• Helsinki Mesoscale Testbed (in operation since 2005)
• U.S. National Academies’ Panel on Multi-Functional Mesoscale Networks (midway through an 18-month study; completion 1Q 2008)
• U.S. Multi-Agency New Study of Urban Meteorological Testbeds (ongoing; completion 1Q 2008)
• American Meteorological Society’s New Panel on Partnerships and Mesoscale Networks (midway through an 18-month study; no completion target as yet)
• Canadian Research on Improved Urban Weather and Air Quality Forecasting (started in 2006 a 3-Year Study)
• U.S. National Science Foundation Study on Urban Meteorology (started a 5-year study in 2006)
• Beijing Mesoscale Network (in advanced implementation stage)
• London Mesoscale Network (in early planning stage)
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Common Themes from Four USWRP Workshops & PDTs
PDT-10 PDT-11 WKSHOP WKSHOPFUZ AQF AQF MESOMS
Impacts of visibility & icing on transportation X Improved understanding & forecasting of winter storms X X Improved understanding & forecasting of convective storms X X Improved understanding & measurement of clouds &cloud processes X X Intense/severe lightning X X PBL understanding and measurement X X X X Land surface processes X X X Mesoscale weather forecasting for emergency response X X X X Mesoscale weather forecasting for air quality forecasting X X X X Hydrological modeling X X Optimized observing system design for urban needs X X X X Data assimilation X X X X Uncertainty and predictability X X Tailor forecast and data products to user needs X X X X Improved access to data and forecast products X X X X Need for testbeds X X X Develop strong outreach programs to end users X
Themes
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One Very Relevant Study of the US Weather Research Program
BAMS 86(7), 2005
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Recommendations re: Modeling & Data Assimilation
Current observations are not sufficient for mesoscale applications. The following observations are needed to most effectively address deficiencies in current observing networks: More accurate precipitation rates with good quality control; Three-dimensional hydrometeor fields; Three-dimensional mass, wind, and moisture fields 10-km horizontal resolution in the lower troposphere 10-100 km in the upper troposphere; Three-dimensional cloud fields and cloud diabatic heating rate profiles; Daily land (sea) surface features Soil moisture and temperature profiles, Snow cover and depth, Land and sea-surface temperature (SST), Emissivity Vegetation type and state; Turbulent flow, fluxes, and stability measured from Earth’s surface to 2 km 15 min. intervals and 100-200m vertical resolution; PBL height and characteristics of convective rolls; Tropopause topology with 10 km horizontal resolution; O3, CO2, water vapor, & cloud distributions req’d for radiative transfer models;
Aerosols and chemical tracer concentrations
Observational Recommendations from the Modeling & Data Assimilation Community (mesoscale workshop)Observational Recommendations from the Modeling & Data Assimilation Community
• 3D high-resolution fie
lds
• Precipitation, hyrdometeors and clouds
• Surface characterization
• PBL structure
• Chemical species and PM
• Testbeds are crucial
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Recommendations re: Nowcasting
Top mesonet recommendation:
Establish a national mesonetwork of surface stations. NOAA should take the lead to establish this network, and set standards for data quality. Resolution needed: <10-25km and 5-15min.
Remote sensing recommendations: Addition of dual polarization capability to the WSR-88D network. Pursue integration of other radars into the national radar network. Investigate improving boundary-layer coverage through the use of
closely spaced X-band radars. Vigorously pursue national expansion of the NOAA Profiler Network
with emphasis on boundary-layer observations. Test the utility of radar refractivity measurements to improve
nowcasting.
Observational Recommendations from the Nowcasting Community (mesoscale workshop)Observational Recommendations from the Nowcasting Community (from the Mesoscale Workshop)
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Recommendations re: Nowcasting
Other priority recommendations: Conduct research aimed at using total lightning data to improve severe
weather warnings and nowcasts. Demonstrate added value of high-resolution water vapor fields for
improve nowcasting. Establish testbeds for very short period forecasting (0-6 hr, nowcasting)
of high-impact weather. Tasks should include: siting recommendations; identification of leveraged funding sources; identification of public/private partners; specification of nowcasting systems and products; involvement of potential clients and users; and conducting impact and benefits studies.
Observational Recommendations from the Nowcasting Community (mesoscale workshop)Observational Recommendations from the Nowcasting Community (from the Mesoscale Workshop)
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Recent Supporting Studies of the USWRPTwo Other Relevant USWRP Studies on AQF
BAMS 87(2), 2006
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BLD C&A M&M OAQF S&SI Total
Boundary-Layer Structure & Modeling 2 1 1 - 4
Surface-Atm. Interface & Emissions 1 2 3 1 - 7
Clouds & Aerosol Microphysics 2 3 2 2 - 9
Establish AQ Regional Testbeds 5 3 2 - - 10
Instrumentation & Measurements 4 3 5 2 - 14
Data Assimilation 1 2 2 1 - 6
Models & Modeling - 9 8 4 - 21
Forecaster & End-User Products - - - 2 1 3
Outreach - - - 1 10 11
85
Recommendations per Working GroupResearch Theme:
Organization of RecommendationsScope of AQF Workshop Recommendations
BLD = Boundary-layer Dynamics WGC&A = Clouds and Aerosols WGM&M = Measurements and Modeling WGOAQF = Operational Air Quality Forecasting WGS&SI = Stakeholders and Societal Impacts WG
Recommendations focus equally on measurement &
modeling
Recommendations focus equally on measurement &
modeling
©Vaisala | date | Ref. code | Page 44U+ extremely urgentU urgentI important
U+ extremely urgentU urgentI important
Some Specific Recommendations from the USWRP AQF Workshop (29 April - 1 May 2003)
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Presentation Outline
• Urban Demographics & Challenges
• Importance of the PBL
• Measurement Systems
• Mesoscale Networks and Testbeds
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Science
Measurement Technology & Environmental Prediction
Modeling
Computing
Observations
Improved atmospheric measurements are central to improved environmental analyses and forecasts
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• Weather radar: reflectivity; velocity, polarization; refractivity
• Wind profilers: radar, sodar; lidar; tethersondes; aircraft
• Thermodynamic soundings: RAOBS, aircraft; tethersondes; lidar
• Lightning detection: CG; total• Radiometers: microwave -- scanning;
multi-wavelength• GPS receivers: precipitable water vapor --
column integrated; maybe slant path and 3D
• Surface mesonets: PTU; V; LW, SW, net radiation; energy & momentum fluxes
• Satellites: geostationary; POES; LEO
Candidate Measurement Systems
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•Elevation angles between 0.5 and 20 degrees
•Earth surface curvature effect
•“Cone of silence” & “pyramid of silence”
•Much less coverage at the low levels/in PBL where features such as thunderstorm outflows, convergence boundaries are crucially important
•Resolution degrades further away from radar
•~75-85% of PBL is not observed
Courtesy of: Fred Carr, Univ. Oklahoma
WSR-88D Radar Network Coverage – PBL Limitations
CONE OF SILENCE
PYRAMID OF
SILENCE
0.5deg
20deg
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CASA
Price target equivalent to a mid-to-high-end automobile
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Estimating Mixing Depth
Cn2
VerticalVelocity
SpectralWidth
Mixing Depth – Data and MethodsMixing Depth – Radar Wind Profiler
0 local time 24
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Mixing Depth – Ceilometer vs. RAOB Sounding (2000)CT25K Backscatter 28-29-Mar-2000
Local Time (h)
Alt
itude (
m)
10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 20 22 00
500
1000
1500
2000
2500
3000
0 5 100200400600800
100012001400160018002000Radiosonde Sounding 29-Mar-2000 @ 11:44
Potential Temperature (°C)
Alt
itude (
m)
102 103 1040200400600800
100012001400160018002000CT25K Backscatter 29-Mar-2000 @ 11:44
Backscatter (a.u.)
Alt
itude (
m)
1m
CT25K BSL
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Mixing Depth – Ceilometer vs. RAOB Sounding (2006)
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Summary of Selected Mesoscale/Urban Challenges
PBL observations with high vertical and temporal resolution radar wind profilers lidars & laser ceilometers x-band radars aircraft
Dynamic characterization of land surface
Acquire & assimilate 4D meteorological and chemical data
High-resolution surface networks: <10km and 5min resolution
Augmentation of weather radar network dual polarization radars of opportunity high-density, low-power radar networks total lightning observations – merge with radar data adaptive radar calibration
Testbeds -- a vehicle to evaluate alternative measurement, modeling and implementation strategies
Optimal network design
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Presentation Outline
• Urban Demographics & Challenges
• Importance of the PBL
• Measurement Systems
• Mesoscale Networks and Testbeds
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Some Definitions
APPLICATION
Mesoscale networks measure the three-dimensional, time-dependent structure of the lower atmosphere using an integrated observing system that incorporates in situ and remote sensing systems, deployed on/from the ground and aloft.
“Mesonets” are a subset of mesoscale networks that consist of high-density surface stations.
Mesoscale networks measure the three-dimensional, time-dependent structure of the lower atmosphere using an integrated observing system that incorporates in situ and remote sensing systems, deployed on/from the ground and aloft.
“Mesonets” are a subset of mesoscale networks that consist of high-density surface stations.
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General applications
• Analysis/description of current atmospheric state – research or ops
• Nowcasting/very short-range forecasting (0+ to ~2 hrs)
• Short-range mesoscale prediction (~3 to 48 hrs)
Site of interest
Are
a (r
el.)
analysis
mesoscale prediction
nowcasting
Schematic
illustrationSchematic
illustration
Time (rel.)
As the timescale of the prediction increases, so does the commonality of the observing systems needed to make the prediction (i.e. they become less application-specific).
As the timescale of the prediction decreases -- toward analysis and short- term nowcasting – the observing requirements become more application-specific
As the timescale of the prediction increases, so does the commonality of the observing systems needed to make the prediction (i.e. they become less application-specific).
As the timescale of the prediction decreases -- toward analysis and short- term nowcasting – the observing requirements become more application-specific
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Mesoscale Weather Forecasting -- Testbeds
Testbed Definition: “A working relationship in quasi-operational framework among forecasters, researchers, private-sector, and government agencies aimed at solving operational and practical regional problems with a strong connection to end-users.”
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Testbed Criteria
A successful testbed must satisfy the following criteria: Address the detection, monitoring, and prediction of regional
phenomena of particular interest Define expected outcomes Provide special observing networks needed for pilot studies and
research Define strategies for achieving the expected outcomes Engage experts in the phenomena of interest Involve stakeholders in planning, operation, and evaluation of the
testbeds Expedite R2O: transitioning research to operations
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Testbed Concept
Testbeds provide the infrastructure for transitioning from R&D to operations. Testbeds need the flexibility to test many new ideas, the expertise to judge which of them are viable, and the infrastructure to harden the sensors, algorithms and models that will generate new products for operations.
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Status of some Mesoscale Testbeds
• Helsinki Testbed Phase I (observations) started August 2005; Phase II (applications) started August 2007
• Beijing Olympics 2008 enhanced mesoscale observing-and-forecasting underway
• Shanghai 2010 World Expo enhanced meso- and micro-scale multi-functional observing-and-forecasting system in advanced planning
• U.S. preparations/planning underway• DHS – Homeland Security limited urban nets in New York and WDC• OFCM urban testbeds under consideration• Multi-agency planning in early stage – NRC/BASC study (completion early
2008)
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Two Approaches to Designing Networks
Designing
Mesoscale
Meteorological
Observing
NetworksEmpirical
Methods
(current
state-of-the-art)
Analytical
Methods
(in development)
Team of experts (Wx & AQ):• Forecasters• Modelers• Observationalists• Other ‘stakeholders’
Numerical tools:• OSSEs• OSEs• Data denial experiments• Observational testbeds
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