Discussion on Observation Targeting

1. Discussion on Observation Targeting TTISS, Monterey, September, 2009

2. Main Objectives of the Discussion • There is a wide range of views about the value of targeting. Why? • Are the different views are due to different results or different interpretation of similar results? • Is there a set of well-defined science problems that we should further investigate to bring the differing views closer to each other? • Should observation targeting play an important role in future THORPEX activities? • What are the most important future research issues in observation targeting?

3. Suggested Approach for Assessment • See whether we can come to an agreement on the effect of the targeted data on the forecasts? (Should be possible looking at the results.) • Then, debate whether the improvements justify the cost of targeting (highly subjective in the absence of relevant SERA research)

4. Question 1 There seems to be a consensus that • Targeted observations have, on average, larger impact on the forecasts than non-targeted observations • Targeted data improve the average skill of the short-range forecast of the the selected weather events by 10-20% (improvements in individual cases can be larger or smaller, even negative or neutral in 20-30% of the cases) • Because of their relatively small numbers, the larger scale impact of the targeted observations is small Do we all agree with this assessment?

5. Question 2 Do we fully understand why there are some discrepancies between the predicted targeted observation impact and the actual observed impact? (Florence Rabier)

6. Question 3 Can we improve the assimilation of satellite observations over oceanic regions, where current analysis uncertainty is much greater*(~2x) than over continental areas? Should oceanic areas be "targeted” for specific types of new satellite observations to compensate for the general lack of in-situ observations?*Ref: Langland et al., 2008: "Uncertainty in atmospheric temperature analyses," Tellus, 60A, 598-603. (Rolf Langland)

7. Question 4 • To what extent can we use targeting to define necessary mobile sensor capabilities? For example, if one is interested in process A (say, the MJO), what observations, at what levels, on how many platforms, with what range, and moving at what speed are necessary to constrain thestate to the desired degree? (Jim Hansen)

8. Question 5 Is there value in targeted improvement of initial conditions for medium-range forecasts? What techniques can be used to identify possible locations of key initial condition errors that may influence medium-range forecasts? (Rolf Langland)

9. Question 6 Does operational targeting have economic benefits? Cost-benefit analysis needs to be done for different regions – SERA research. Are there differences between Pacific (NA) & Atlantic (Europe)? (Zoltan)

10. Question 7 Can similar or better results be achieved with cheaper observing systems? Observing systems of opportunity: targeted processing of satellite data, AMDAR, UAVs? (Zoltan)