# Presentation: 815227

## For NWP
ATOVS 
SSM/I and SSMIS 
satellite winds
Quikscat 
AIRS/IASI
GPS radio occultation
GPS total water vapour 
NWP SAF  

- ATOVS
- SSM/I and SSMIS
- satellite winds
- Quikscat
- AIRS/IASI
- GPS radio occultation
- GPS total water vapour
- NWP SAF

- Progress on the use of satellite data at the Met Office
- John Eyre

- For nowcasting
-   Meteosat Second Generation
-   volcanic ash detection
- For climate monitoring
-    SST  - ATSR and AATSR

## Satellite data currently assimilated - global NWP

- ATOVS
- HIRS (NOAA-16+17: Chs 4-8, 10-12, 15)
- AMSU-A (NOAA-15+16+17: Chs 4-12; 6-12 only over land and sea ice except 30E-130E 50N-70N)
- AMSU-B (NOAA-15+16+17: Chs 18-20 over sea only; note Ch. 19 on NOAA-15 not used)
*Note: AMSU-A and AMSU-B mapped to HIRS grid and thinned to ~150 km*
- SSM/I (DMSP F13+15):   windspeed from 1D-Var, over sea
*Note: SSM/I thinned to: one obs in 25 in S.Hem, one obs in N.Hem.*
- Quikscat/Seawinds:   ambiguous retrieved winds
- Satellite winds:  Meteosat, GOES, GMS
- AVHRR SSTs
- SSM/I sea-ice, via NCEP analysis

## ATOVS

Key events
March 1999:   NOAA-15 ATOVS replaces NOAA-11 TOVS
October 1999:   Direct radiance assimilation replaces assimilation of 1D-Var retrievals
April 2001:   NOAA-16 ATOVS replaces NOAA-14 TOVS
April 2001:   NOAA-15 and NOAA-16 AMSU-B used
October 2002:   NOAA-17 added (= 3 ATOVS)
Plans
More use over land and sea ice
Improved treatment of cloudy radiances

- Key events
- March 1999:   NOAA-15 ATOVS replaces NOAA-11 TOVS
- October 1999:   Direct radiance assimilation replaces assimilation of 1D-Var retrievals
- April 2001:   NOAA-16 ATOVS replaces NOAA-14 TOVS
- April 2001:   NOAA-15 and NOAA-16 AMSU-B used
- October 2002:   NOAA-17 added (= 3 ATOVS)
- Plans
- More use over land and sea ice
- Improved treatment of cloudy radiances

## Blue = NOAA-15+16 

- Blue = NOAA-15+16
- Green = NOAA-   15+16+17
- Red=NOAA-16+17
- Note: All trial versions - bias tuning not optimised for NOAA-17

## Moisture - single control variable ? ...

- ... or separate control variables for specific humidity, cloud liquid water, etc.?
- Define total water as Qt = Qv + Ql + [...]

- Comparison of using Qt and separate Qv, Ql control variables for AMSU channel 5 (left) and channel 6 (right)

## Microwave imagery for forecasters

## SSMIS

- SSMIS launch expected mid 2003
- SSMIS over-samples.  Therefore we plan to “super-ob” the measurements to create a lower resolution, lower noise radiance product
- Treatment of SSM/I-like channels will change from current 1D-Var approach to direct radiance assimilation
- Mesospheric channels will be not be used (those peaking above 1 hPa) - so Zeeman effect will also be ignored

## Satellite winds

- Recent operational changes
-    Doubling of satwind observation errors (Oct 2001).
-    Switch from Meteosat low-density SATOBs to thinned high-density BUFR winds (Dec 2002).
- Current and future work
-    Real-time trial of MODIS polar winds.
-    Superobbing O-B method for assimilating high density satwinds -  to be tested with new GOES BUFR winds.
-    Use of Meteosat-6 rapid scan winds in the Mesoscale model.
-    Prepare for new satellites (GOES-12, GOES-9, MSG, MTSAT).
-    Bias correction
-    Continue updates and produce second analysis report for the NWP SAF satellite wind web page: http://www.metoffice.com/research/interproj/nwpsaf/satwind_report

## Scatterometer data

## Scatterometers:  PDFs to penalty functions

- uo1

- uo2

**Notes:**
1. P is the prob distribution function that given state u we observe Uo. Ie represents most likely values for u
transform to cost function it drops out as 
a quadratic (assuming gaussian distribution). Note ob error

2. Two winds - equal likelihood more complex - can be applied up to N winds per ob. 

3. Based on retrieval info we could vary the heights of each maxima ie the prior probability. ERS-2 no skill, Quikscat yes.

4. What does the function look like in practice....

## Quikscat assimilation3D-Var:u-windincrements

## Quikscat:short-range verification

- Comparison of observations with T+6  forecasts: % reduction in observation increments on adding Seawinds

**Notes:**
Ocean stations - the impacts described earlier were over land and sea.
Here we concentrate on the impact around low lying islands.

## Forecast impact for Quikscat, against observations

- N Hemisphere   |  Tropics       |    S Hemisphere

- Index Change v obs +0.5 June , 0.0 Sept

**Notes:**
In general the results from different centres converge. encouraging

1. ECMWF found improvements in 7day range in their experiments
and simlar short range improvements as our work

2. The american study
has reduced impact - poor dealiasing in sensitive areas?  Good NSCAT
result highlights wider swath.

3. HIRLAM large impact iin using two scats. Again pointing to coverage
Also highlighted importance of resolution  

## Exploitation of AIRS data

- Data (324 channels) have been flowing into the Met Office from NESDIS since 10 October 2002
- These data are compared with 6hr forecast radiances from the Met Office global model
- Results from these comparisons are placed on monitoring pages on the www (but password protected)
- Developments now underway are:
- Variational cloud detection (“Day 1” system in place)
- Bias correction (under development)
- Running data assimilation trials (to start in March 2003)

**HIRS-12**

- NOAA-16/HIRS vs Aqua/AIRS

- O-B ‘clear’ maps

**AIRS-1803 1569 cm****-1**

## O-B biases and standard deviations: (post-launch ISRF,extrapolating forecast above 15hPa)

- O-B biases and standard deviations: (post-launch ISRF,extrapolating forecast above 15hPa)

- 15m CO2
- Band

- O3
- (not in Met
-  Office model)

- 4.3m CO2 Band
- (non-LTE & spectroscopic errors)

- H2O

- Windows

- AMSU 1&2
- (surface emissivity
-  wrong)

## “Tartan plots”:  SD of O-B clear

- H2O

- O3

- CO2

- CO2

- AMSU
-  1&2

**Channel number**

## Initial comparisons between measured and background HIRS channel 8 BTs suggest that the background skin temperature might be good enough to support IR sounding over land at certain times of the day but require an estimate of surface emissivity.

Reasonable agreement between newly-developed surface emissivity atlas and MODIS split-window product.

Plan to incorporate a retrieval of IR surface emissivity (~10 EOFs) within 1DVar pre-processor for AIRS.  First-guess emissivity provided by IGBP surface type atlas. 

- Reasonable agreement between newly-developed surface emissivity atlas and MODIS split-window product.
- Plan to incorporate a retrieval of IR surface emissivity (~10 EOFs) within 1DVar pre-processor for AIRS.  First-guess emissivity provided by IGBP surface type atlas.

- Extending use of IR radiances over land

## Extended IGBP land cover classification

## July 2001

**11 microns**

**12 microns**

**Atlas for first-guess**

**MODIS**

## Radio occultation: measurement geometry

- GPS

- LEO

- Tangent point

- Bending angle

- Impact parameter

## Assimilation options for RO data

- Options:
- (1)  assimilate retrieved profiles of temperature and humidity
- (2)  assimilate retrieved profile of refractivity, N(z)
- (3)  assimilate measured refracted angles, α(a), directly
- Special problems with RO data:
-   non-separability of temperature and humidity
-   addressed by (2) and (3)
-   limited horizontal resolution / problems of horizontal gradients
-   partially addressed by (3)

## RO forward model: accuracy

- Comparisons against a 3D ray tracer for simulations in the domain of the
- Met Office mesoscale model. 160 cases.
- Healy and Eyre,
- in preparation.

- Largest source of error - using impact parameter to derive tangent
- point height.

## Comparisons of CHAMP retrievals with 

- Met Office global operational model analyses

- June 2001.       780 collocations.
- Similar bias found at 10 hPa against GPS/MET data in 1995.

## Comparison of CHAMP retrievals with 

- Comparison of CHAMP retrievals with
- Met Office stratospheric model analyses

- June 2001.    230 collocations.
- Data from Lydia Henderson and Mike Keil, Met Office

## Information content: RO and IASI

- Collard and Healy, submitted to QJRMS 2002

## GPS satellite-to-ground total water vapour

- European GPS WV network

## NWP SAF

- SAF = “Satellite Application Facility”
- EUMETSAT-sponsored collaboration: Met Office led, with partners ECMWF, KNMI and Météo-France
- Objective: to improve and support the interface between satellite data/products and European activities in global and regional NWP.
- R+D  (mainly) software packages for use in NWP assimilation systems.
- World-wide user community for some deliverables

## NWP SAF deliverables

- RTTOV (v7 released, v8 expected Jan 2004)
- AAPP (v3.4 released, v4 expected Apr 2003)
- ICI:  NWP-independent ATOVS retrieval package
- SeaWinds processing software (prototype)
- 1D-Var for SSMI, SSMI(S) and AMSU
- 1D-Var for AIRS/IASI
- Web-based monitoring reports (radiances, AMVs, scatterometer products)
- Reports (e.g.  Visiting scientist reports)

## SSM/I + SSMIS

- 1D-Var
- SSM/I, SSMIS, AMSU
- RTM which handles precipitation
- Monitoring

## MVIRI/SEVIRI

- Integrated monitoring report for satellite winds

- First analysis report issued

## NWP SAF plans

- 5-year “development phase” ends Feb 2004
- Follow-on “operational phase” proposed.
- More work on existing instruments
- New satellites/instruments:
- e.g. METOP, NPP / IASI, ASCAT, ATMS, CrIS, ...
- Increased data monitoring role
- For more information about the NWP SAF, see www.metoffice.com/research/interproj/nwpsaf/

## Meteosat Second Generation (MSG)

- New European geostationary at 0W,  operated by EUMETSAT (www.eumetsat.de)

## MSG

- Replaces Meteosat series (1977 to ~2005)
- MSG1 launched 28 August 2002 at 22:45 UTC
- Operational data expected from ~Dec 2003
- MSG-2 due for launch early 2005
- Initially 3 satellites in series, 4th being considered
- Measuring missions: SEVIRI 12-channel imager + GERB broadband radiance

## Comparison between Meteosat and MSG

## First MSG image

- Ch 1,2,3 composite
- 28 Nov 2002, 12.15 UTC
- Note: MSG now at 10W; final station will be 0W

- © EUMETSAT 2002

## Satellite imagery is used in the Volcanic Ash Advisory Centre to advise aircraft about the presence of volcanic ash
AVHRR ch4 (10.8 m) - ch5 (12.0 m) images are automatically generated within the Met Office

AVHRR ch4-ch5 imagery has been successfully used to monitor two eruptions of Etna in near real-time
The development of a volcanic ash detection system using the greater spectral, spatial and temporal information from SEVIRI data on MSG is underway

- AVHRR ch4 (10.8 m) - ch5 (12.0 m) images are automatically generated within the Met Office
- AVHRR ch4-ch5 imagery has been successfully used to monitor two eruptions of Etna in near real-time
- The development of a volcanic ash detection system using the greater spectral, spatial and temporal information from SEVIRI data on MSG is underway

- Volcanic ash detection

- AVHRR ch4-ch5 (BT10.8 - BT12.0) < 0 volcanic ash
- AVHRR ch4-ch5 (BT10.8 - BT12.0) > 0 water & ice

## Eruption of Mount Etna

- 27 October 2002 0958 UTC

- 28 October 2002 1316 UTC

- 30 October 2002 1254 UTC

- 29 October 2002 1305 UTC

## Eruption of Mount Spurr

- The ash cloud could be tracked for over 60 hours, until it was over Greenland

- Minimum of -19.2 K occurred 48 hours after eruption

## AATSR Processing in real time 

**AATSR Processing in real time**

## AATSR SST - buoy SST

- coverage so far =1860
- weekly coverage ~130

- Means for period 19 Aug - 27 Nov 2002
- all data = 0.03 K(s.d. 0.53 K)
- night only = 0.02 K(s.d. 0.42 K)
- day only = 0.03 K(s.d. 0.60 K)

- Moored buoys
- Drifting buoys

## Slide 43