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Wettzell WVR Workshop1 October 9-10, 2006 Use of NWM forecasts for converting T B to delay Arthur Niell MIT Haystack Observatory Mark Leidner AER, Inc.

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Presentation on theme: "Wettzell WVR Workshop1 October 9-10, 2006 Use of NWM forecasts for converting T B to delay Arthur Niell MIT Haystack Observatory Mark Leidner AER, Inc."— Presentation transcript:

1 Wettzell WVR Workshop1 October 9-10, 2006 Use of NWM forecasts for converting T B to delay Arthur Niell MIT Haystack Observatory Mark Leidner AER, Inc.

2 Wettzell WVR Workshop2 October 9-10, 2006 Questions Can a high resolution Numerical Weather Model forecast improve the calculation of delay from WVR brightness temperature? Can the use of NWM and WVR improve the atmosphere estimation in geodetic VLBI and GPS?

3 Wettzell WVR Workshop3 October 9-10, 2006 Mesoscale NWP Model PSU/NCAR 5 th generation nested grid mesoscale model (MM5) Horizontal spacings 81, 27, 9, and 3 km Pressure level output from surface to 10 hPa (30 levels) Initialized with NCEP global model 12 hour forecasts initialized every 6 hours

4 Wettzell WVR Workshop4 October 9-10, 2006 MM5 Analysis CONT02 (Oct 15-31, 2002)

5 Wettzell WVR Workshop5 October 9-10, 2006 Hart x-sect

6 Wettzell WVR Workshop6 October 9-10, 2006 Hart plan view

7 Wettzell WVR Workshop7 October 9-10, 2006 Model - 1

8 Wettzell WVR Workshop8 October 9-10, 2006 Model - 2 Define ratio of delay to brightness temperature from NWM If this ratio from MWM is accurate, then WVR delay is related to the true T B by:

9 Wettzell WVR Workshop9 October 9-10, 2006 Model - 3 WVR T B is related to true T B by offset and scale factor Then the delay corresponding to the brightness temperature measured by the WVR will be: and the model for the wet delay in the geodetic analysis will be: Thus in geodetic analysis estimate (in principal) only two parameters, a and b, instead of 72 ZWDs (every 20 min).

10 Wettzell WVR Workshop10 October 9-10, 2006 Questions - 1 What is the error in r n ? Are a and b constant over 24 hours? There is information in all frequencies. How can other frequencies be included? e.g. use Onsala X parameter (kge)? What horizontal resolution is needed for this to be useful?

11 Wettzell WVR Workshop11 October 9-10, 2006 Questions - 2 VLBI data will be reanalyzed many times as models improve. Is it practical to do analysis instead of forecast at 3 km resolution? Will the r n improve?

12 Wettzell WVR Workshop12 October 9-10, 2006

13 Wettzell WVR Workshop13 October 9-10, 2006 D4: 3 km grid 2-way nesting 5º 10º D1: 81 km grid 2-way nesting 5º 10º 5º 10º 5º 10º D2: 27 km grid 2-way nesting D3: 9 km grid 2-way nesting


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