GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAF

Helga NitscheDeutscher Wetterdienst, D-63067 Offenbach

Content:

•The CM-SAF (short overview)

•The HCP: product definition and specification

•Validation of Input Data

•Gridding and Interpolation

•„Merging“ of satellite-derived precipitable water: the concept

•User Requirements for HCP

•User Requirements of HCP for GRAS-SAF

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFThe CM-SAF: Overview

•5 Scientific Work Packages

•Products connected to the Energy and Water Budget of the Earth

•Regional Products

•Product Groups:

•Cloud Parameters

•Surface Radiation

•TOA fluxes

•Surface Ocean Stress

•Humidity Composite Product

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The HumidityCompositeProduct of the CM-SAFThe CM-SAF: The Products

Product Acronym ResolutionSpatial Temporal

Daily Weekly Monthly MonthlyMeanDiurnalCycle

Fractional cloud cover CFC 15 km 1

Cloud type CTY 15 km 1

Cloud top temperature and height CTT,CTH

15 km 1

Cloud optical thickness COT 15 km 1

Cloud phase CPH 15 km 1

Cloud water path CWP 15 km 1

Surface incoming shortwave radiation SIS 15 km 1

Surface albedo SAL 15 km

Surface net shortwave radiation SNS 15 km 1

Surface outgoing longwave radiation SOL 15 km 1

Surface downward longwave radiation SDL 15 km 1

Surface net longwave radiation SNL 15 km 1

Surface radiation budget SRB 15 km 1

Incoming solar radiative flux at the top of theatmosphere

TIS 50 km

Reflected solar radiative flux at the top of theatmosphere

TRS 70 km

Emitted thermal radiative flux at the top of theatmosphere

TET 70 km

Surface Ocean Stress SOS 50 km

Total precipitable water TPW 1 degree

Layer precipitable water LPW 1 degree 3 layers

Table 1: Overview of CM-SAF products ( 1 :only for MSG based products)

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The HumidityCompositeProduct of the CM-SAFThe CM-SAF: The Processing Area

GMTMay 4 14:49:21 2001 OMC - kk+w 0 10002000

km

Inner Arctic Circle

MSG Area

Initial Baseline Area

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFThe HCP: Productdefinition

•an independent water vapour profile data set

•based on merged satellite products only

• validated with sophisticated in-situ observations

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•Precipitable water; total column and Layers between pressure levels

•Physical units: g/kg resp. mm

•Spatial resolution: <= 1 degree (0.5); >= 3 layers (5-6)

•Temporal resolution: daily, monthly

•Meta data: Input data sources, QC-Flags, Validation results, Merging Algorithm

•First operational product: July 2005

•Duration: Operational long term product

The HumidityCompositeProduct of the CM-SAFProductspecification:

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The HumidityCompositeProduct of the CM-SAF

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The HumidityCompositeProduct of the CM-SAFValidation Topics:

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAF Validation Data: operational Networks:

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFValidation Data: Reference Stations:

Site Description of Lindenberg:

Geographic coordinates: 52 0 13 ì North and 14 0 07 i East; approximately 60 km eastward ofBerlin.

Station height (radiosonde): 112 m NN.Natural Region: “Ostbrandenburgische Platte”.History: Meteorological Observatory since 1905.Representativeness: for frequent passages of mature cyclones.Additional information: The Meteorological Observatory Lindenberg (MOL) is a reference

station within the GEWEX Water Vapour Programme (GVaP)

1. Operational Radiosonde Station (4 ascents per day; humidity calibrated and corrected withweekly ascents of a reference radiosonde)

2. Microwave Radiometer3. Microwave Profiler4. GPS-Receiver5. Ceilometer6. Sunspectrometer7. Starspectrometer8. Cloud Radar9. Differential Absorption LIDAR (Coorperation with the MPI, Hamburg)

Instrumentation:

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFGridding and Interpolation:

„Raw“ Data: Values and postions as reportet originally

Interpolation in time:

linearly; values within a choicable radius

Gridding: values „binned“ into the grid (0.5x0.5 degrees)

Spatial Interpolation: inverse distance method (SPHEREMAP)

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFSpatial and Temporal Resolution of Input:

Data/Instrument Time Resolution Spacing horizontally Spacing verticallyATOVS-GTS(=SATEM) 2/d/satellite Ca 250 km 3 layers (1000-700; 700-

500, 500-300 hPa)ATOVS-BUFR 2/d/satellite 3-4 times denser than

ATOVS-GTS15 Standard pressurelevels up to 300 hPa

SEVIRI (LPW) 24/d Pixel (ca 5 km) 3 layers appx likeATOVS-GTS

IASI/AIRS 2/d/satellite Ca 40 km 20 LayersGRAS 1/d 300-500 km 1-2 km

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The HumidityCompositeProduct of the CM-SAFMerging:

Applicable models:

1) NVaP (NASAWater Vapour Programme), Randel et.al.

2) GPCC Huffman et.al.

Basic Idea:

•Daily mean values on the Grid from Interpolation for the polar orbiter satellites (ATOVS-data from NOAA, METOP)

•Bias Correction for TPW, biases from Validation

•Profile Information from ATOVS, IASI: relative profiles (%)

•improve horizontal resolution by SEVIRI

•improve daily mean by SEVIRI

•extension to Upper Troposphere/Lower Stratosphere with GRAS

• perhaps additional constraints: DEM und TRP

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The HumidityCompositeProduct of the CM-SAFUser Requirements for HCP

•Horizontal spatial resolution: < 10 .... 5000 km

•vertical resolution: 3-8 Layers

•time resolution: </= 1/h...1/d

•parameters: precipitable water (& absolute/specific humidity)

•area extension to MSG: yes

•area extenstion to inner arctic circle: no/yes

•accuracy: </= 10 % (</=5 %)

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFUser Requirements for HCP

Possible Applications

•Reference Data Set

•Background Data Set for Numerical Modeling

•Validation Purposes

•Process Studies

•Input into Climate Monitoring Products

GRAS-SAF User Workshop June 2003

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The HumidityCompositeProduct of the CM-SAFUser Requirements of HCP for GRAS-SAF

•Vertical Extent: at least up to the Lower Stratosphere

•Metadata: extensive Metadata together with each Profile, including Time of Measurement, Horizontal Representativeness , Reliability/Representativeness of the Lowest Level, method/model used for the retrieval

•Reprocessing Capability? Unlimited Archive of the Measurements and Metadata

•individual profiles

•highest possible absolute accuracy

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The HumidityCompositeProduct of the CM-SAFVertical Profiles of Precipitable Water