Real time analysis with the Medspiration HR-DDS (High Resolution Diagnostic Data Sets) David J. S. Poulter, National Oceanography Centre, UK

Transcription

1 Real time analysis with the Medspiration HR-DDS (High Resolution Diagnostic Data Sets) David J. S. Poulter, National Oceanography Centre, UK

2 Outline 1. Outline 2. Description of the HR-DDS system 3. Time Series Analysis Pages 4. Spatial Comparison Pages 5. Anomaly Analysis Pages 6. Global analysis examples 7. Use in diurnal variability studies 8. METOP-A SST validation study 9. Developments for wave products

3 HR-DDS Description GDAC MMR-FR MMR L2P MDB internet Internet Users External data centres L2 Internet L2P Archiving system MDB records Collocation L2P, UHR/L4 in situ data HR-DDS HR-DDS extraction HR-DDS extraction Product consolidation Optimal interpolation DV correction L2 L2P L2P L2P UHR/L4 Ancillary Ancillary data data

4 HR-DDS Description Within GHRSST / Medspiration: Archive of subsets from L2, L2P and L4 products Collected at 250 sites across the ocean Common format Common grid Open access via FTP and OPeNDAP

5 HR-DDS Description Location of HR-DDS Sites: Polar 3 rd Party Lakes & Seas Glob Colour Other In situ

6 HR-DDS Description Within GHRSST / Medspiration: Data Archive of subsets Common format Access Access via OPeNDAP Access via FTP Users Expert users

7 HR-DDS Description Modified by MERSEA / NCOF: Data User Archive Configure of subsets Common Database format lookups Quick looks Dynamic graphics Access CSV Table Access Download via OPeNDAP Access via FTP Dynamic TAR file Statistical Values Users Educational Expert users Users Research Users Operational Users

8 HR-DDS Description An example of use: 1. Observe an error in time series 2. Confirm and or identify the cause 3. Identify impacts 4. Report or notify

9 Time Series Analysis Quickly identify problem data: In this case an OSTIA SST seems 2.5 K too cool

10 Time Series Analysis Quickly identify problem data: Re-plot graph instantly for mean, median, maximum, minimum, skew, kurtosis and standard deviation statistics from each field Re-plot graph to show ancillary fields (i.e. wind speed, salinity, aerosol optical depth etc.) Download a C.S.V. file containing all the data from the plot

11 Spatial Comparison Plots Confirm and investigate the problem: Move forward or backward a day, a week or a month

12 Spatial Comparison Plots Confirm and investigate the problem: Move forward or backward a day, a week or a month

13 Spatial Comparison Plots We identify a problem in other data from the day before: Problem traced to a bad QC evaluation for a drifter observation Cold bias also present in NCDC AVHRR SST

14 Spatial Comparison Plots We can also look at a time series of comparisons: In this example poor quality AMSR observations have introduced what could be misinterpreted as mesoscale features into the NCDC daily merged analysis.

15 Anomaly Analysis Plots Any quick-look image can be compared against any other, or against a whole days worth. Each plot produced is clickable and the website provides background statistics. In the following example AATSR and TWO versions of METOP- A data are displayed (observations 45 minutes apart)

16 Anomaly Analysis Plots Perhaps of more interest is the differences between two products from the same instrument. This example from the same day compares METOP-A global 5 km SST against METOP-A North Atlantic Region (NAR) 2 km. These are the SAME observations from the SAME instrument with the SAME SST algorithm. Similar effects are visible in all AVHRR products.

17 Match-up analysis example I AATSR AVHRR GAC (left) AATSR AVHRR LAC (right) Same observations, different errors!

18 Match-up analysis example II Mean Bias of OSTIA to AATSR (0.01 K)

19 Use in diurnal variability studies The HR-DDS can be used in many ways, for example in characterizing the distribution of diurnal variability. The HR-DDS has also been used to develop a primitive diurnal variability correction based on localised look-up tables. It has shown why global LUTs will fail.

20 Use in diurnal variability studies The HR-DDS can be used in many ways, for example in characterizing the distribution of diurnal variability. The HR-DDS has also been used to develop a primitive diurnal variability correction based on localised look-up tables. It has shown why global LUTs will fail.

21 A METOP-A Case Study The HR-DDS system was recently used to identify the cause of a cold bias appearing in Arctic METOP-A SSTs. Using the HR-DDS the problem was found to be caused by occasional large errors (up to 5 K).

22 A METOP-A Case Study It was noticed that the error occurred only on the evening overpass. Using the HR-DDS, the error was linked to a range of solar-zenith angles.

23 A METOP-A Case Study

24 A METOP-A Case Study

25 User services Users may register at the website and record default preferences, for example: Number of days to display in time series Apply / deny error (bias) correction Plot error bars Minimum SST coverage for a granule to be displayed

26 Collaborative Tools (in development)

27 Future development (MyOcean) For MyOcean we will develop Pixies : User defined notifications For example an (or RSS) alert when a criterion is matched, i.e. the SST from METOP-A is more than 1 K from AATSR Bulletins The global / regional performance of an instrument published weekly by RSS

28 Future developments Take Ocean Colour HR-DDS online Improve existing wave product HR-DDS Possibly develop a Sea Ice HR-DDS

29 The End Thank you for your attention! Please visit the HR-DDS.

30 HR DDS status report In situ SSTs: ARGO and drifter SST and salinity. Moored buoys SST (Soon to include wave and atmospheric data GHRSST PP IX, France,

31 HR DDS status report Wave DDS: Produced a prototype wave DDS. To include spectral data GHRSST PP IX, France,

32 HR DDS status report Scatter plots: X Y scatter plots are back! There are many possible improvements to this, we are looking at several improvements for the various GHRSST working groups GHRSST PP IX, France,

33 HR DDS status report Inter comparison framework We are working on a comprehensive inter comparison framework for users This example shows METOP A bias from OSTIA binned by solar zenith angle (See Steinar s talk for more on this example) GHRSST PP IX, France,

34 HR DDS status report Detailed analysis of biases This example shows the change from AATSR in AMSRE SSTs GHRSST PP IX, France,

35 HR DDS status report We have introduced services for the DV working group This shows an area where we might have a chance with DV GHRSST PP IX, France,

36 HR DDS status report This is the Benguela region.. GHRSST PP IX, France,

37 HR DDS status report We have introduced user registration services: Users can set various default parameters for the plotting of data We are working on facebook like collaborative features GHRSST PP IX, France,

38 HR DDS status report The HR DDS is moving into the MyOCEAN project: Far greater focus on User Services Implementation of pixies automated analysis web pages / RSS updates etc. GHRSST PP IX, France,