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Where to Find Precipitation Products, Including TOVAS George J. Huffman

Where to Find Precipitation Products, Including TOVAS George J. Huffman NASA/GSFC Laboratory for Atmospheres and Science Systems and Applications, Inc. Outline 1. So Many Data Sets, So Little Time! 2. Using the Tables of Data Sets Choosing Data Sets TOVAS.

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Where to Find Precipitation Products, Including TOVAS George J. Huffman

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  1. Where to Find Precipitation Products, Including TOVAS George J. Huffman NASA/GSFC Laboratory for Atmospheres and Science Systems and Applications, Inc. Outline 1. So Many Data Sets, So Little Time! 2. Using the Tables of Data Sets Choosing Data Sets TOVAS

  2. 1. SO MANY DATA SETS, SO LITTLE TIME There are lots of different precipitation data sets, and no standard because - The field is pretty young (GPCP Monthly is only 10 years old) - No single approach solves the problem - Various approaches are best in different places, for different users Requires users to work harder than some other variables

  3. 2. USING THE TABLES OF DATA SETS • The focus is on operational, (quasi-) global, freely available data • Data sets separated by input data types: • Table 1: single satellite sensor type (may be multiple satellites); doesn’t include gauge data sets • Table 2: multiple satellite sensor types • Table 3: multiple satellite sensor types and gauge analysis • Active sites hosting and/or linking to multiple global precipitation data sets • - Frequently contain basic documentation and links to more information and the data • - Might provide updated data location information in the future • Active sites hosting interactive analysis engines • - Run computations at the site and download results, not raw data • Archive locations referenced in the the tables • - Generally have to enter subdirectories to access data, images

  4. 2. USING THE TABLES OF DATA SETS (cont.) How long after the observation time the data set is updated Region and time span covered; start date given for active data sets Short name for the algorithm/data set Kinds of data used in the data set Smallest resolved time/ space data grid box How often the data set is updated General URL of digital data set (keyed to list on last page); additional image archive also noted Shading indicates data sets not yet released

  5. 3. CHOOSING DATA SETS Attributes of different data sets fit the needs of different users Microwave-based precip estimates tend to out-perform IR-based on small time-space scales - TMI, AMSR-E, SSM/I (, SSMIS) - AMSU to a lesser extent over ocean at present Combination data sets that use both microwave-based precip estimates and gauge data tend to out-perform others All fine-scale estimates are relatively noisy at full resolution - applications that entail some explicit or implicit averaging are the most successful

  6. 4. TOVAS TRMM On-Line Visualization and Analysis Tool - Developed by NASA GSFC DISC Precipitation Data and Services Center - Became prototype for GIOVANNI, which handles several kinds of data Addresses typical challenges to use of new (to user) global data sets - Large data volume - Non-uniform data formats – steep learning curve - Distributed data locations - Analysis software required

  7. 4. TOVAS (cont.) Design goals - Serve users at different levels of sophistication - Fast and easy access - User-friendly analysis and output interface - Both graphical and text output for display and further analysis/applications Priority functions - Spatial variations - Temporal variations - Inter-comparison - Data output in various formats

  8. http://disc2.nascom.nasa.gov/Giovanni/tovas/ Link to GIOVANNI – other kinds of data Near-real-time data sets Choose a data set to analyze by clicking on its “JAVA” or “Non-JAVA” hot link After-real-time research data sets Prototype comparison tool (U.S. only)

  9. Select product (comparison only) Select region (non-JAVA must use text boxes) Select function Select time interval Create plot or text (separate window)

  10. 4. TOVAS – Sample Output Time-average maps - 31 December 2005 over West Coast of U.S. TMPA-RT Gauge analysis

  11. 4. TOVAS – Sample Output (cont.) Difference map - 31 December 2005 over West Coast of U.S. - TMPA-RT – Gauge

  12. 4. TOVAS – Sample Output (cont.) Area-average time series - 1-31 December 2005 over West Coast of U.S. - TMPA-RT (black) and Gauge (green)

  13. 4. TOVAS – Sample Output (cont.) Area-average difference time series - 1-31 December 2005 over West Coast of U.S. - TMPA-RT – Gauge

  14. 4. TOVAS – Sample Output (cont.) Scatter plot - 1-31 December 2005 over West Coast of U.S. - TMPA-RT (x) vs. Gauge (y)

  15. 4. TOVAS – Sample Output (cont.) ASCII text - Time average for 1-31 December 2005 at grid boxes over West Coast of U.S. - TMPA-RT

  16. 5. FUTURE PLANS More data sets Additional statistics along the lines of the current IPWG validation sites User-input data sets Continued user input

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