Assessment of the Benefits of Extending the Tropical Rainfall Measuring Mission A Perspective from the Research and Operations Communities: Interim Report (2006) / Chapter Skim
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4 Anticipated Contributions of TRMM
4 Anticipated Contributions of TRMM
Pages 43-60
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From page 43... ...
The TRMM objectives and goals, however, evolve as more is learned about how to make use of TRMM data -- on their own as well as integrated with other observations and numerical weather prediction and cloud-resolving models. For example, learning from peculiar differences in how TRMM Microwave Imager (TMI)
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From page 44... ...
The elaborations in this chapter, working from the specific to the general, mirror the outline of Table 4-1. ANTICIPATED CONTRIBUTIONS WHEN CONTROLLED REENTRY IS STILL POSSIBLE Anticipated Operational Contributions Another Year of PR and TMI Data for Tropical Storm Monitoring and Forecasting Another year's worth of TMI and PR data would be valuable to the National Oceanic and Atmospheric Administration (NOAA)
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From page 45... ...
· Longer TRMM record needed for climate research* · Foster improving moist physics parameterization for climate models, numerical weather prediction, and related assimilation systems by evaluating models of clouds and precipitation physics*
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From page 46... ...
Realizing the Potential to Use PR as a Global Rainfall Reference Standard The use of TRMM data as the global reference against which data from spaceborne microwave sensors are adjusted is the subject of ongoing research. The combination of TRMM's unique sensor suite and orbit underpins this approach.
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From page 47... ...
This is important for Global Precipitation Measurement algorithm development, in particular through validation of these algorithms for higher-latitude precipitation. Overlap with Coriolis WindSat Mission The Coriolis WindSat polarimetric radiometer's launch in January 2003 produced the next step in spaceborne passive microwave radiometers.
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From page 48... ...
This program will investigate tropical cloud systems and their environmental feedback. The initiative seeks innovative approaches that use NASA's observational data for investigations of tropical cyclones, the effect of cirrus clouds on atmospheric cycles of water and energy, and related feedbacks on the radiative, compositional, and dynamic attributes of the upper troposphere and lower stratosphere.
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From page 49... ...
. TRMM's Precipitation Radar Provides a Calibration Reference for the Current GPM-like Constellation The combination of TRMM's TMI and PR with the microwave sensors on other satellites provides many of the key elements of a Global Precipitation Measurement constellation concept.
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From page 50... ...
Passive microwave imagers such as TMI can view tropical cyclone inner-core structure often obscured by upper-level clouds and thus masked in visible and infrared imagery. Intense tropical cyclones typically have a central dense overcast expanding from the central eyewall outward, sometimes clouding over the eye as well.
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From page 51... ...
Over the first six years of TRMM data, the TMI instrument passes within 750 km of storm centers during one of every eight orbits, whereas PR observes within 250 km of the center during one of every 25 orbits.5 The narrow swath of the PR and the rare occurrence and great variability of tropical cyclone structure, intensity, and precipitation amount strongly argues for mission extension to increase sample sizes for statistical analyses. The PR on TRMM has already provided more data on the vertical structure of precipitation in tropical cyclones than a quarter century of aircraft penetrations into hurricanes in the Atlantic and the Caribbean.6 The vertical structure information from the PR indicates the distribution of latent heat release in tropical cyclones.
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From page 52... ...
In addition to developing mesoscale tropical cyclone models, forecasters are developing models that predict precipitation as a function of the development stage of the storm (from weak tropical depressions on up in intensity to Category 5 hurricanes or Super Typhoons) .8 With improved accuracy of forecast track and storm propagation speed, rain accumulation forecasts have recently become operational based on the published climatology using the early TRMM data (Lonfat et al., 2004)
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From page 53... ...
Foster Improving Moist Physics Parameterization for Climate Models, Numerical Weather Prediction, and Related Assimilation Systems by Evaluating Models of Clouds and Precipitation Physics Global cloud models are advancing and will become a reality in the next 5 to 10 years (Randall et al., 2003; Stephens, 2004)
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From page 54... ...
(2001) , who demonstrate how assimilation of TMI-retrieved rainfall, integrated water vapor, and sea surface temperature into a mesoscale numerical weather prediction model yielded improved nine-hour forecasts of radar reflectivity cross-sections compared with coincident observations from the PR.
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From page 55... ...
, which plans to focus on the use of cloud and precipitation information. Keeping the TRMM satellite in orbit for as long as possible, therefore, will contribute to the further development of advanced data assimilation schemes that will be needed for the Global Precipitation Measurement era.
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From page 56... ...
Whereas research aircraft radar can provide some data of similar resolution, a satellite-based system is required to validate the precipitation during all stages in the hurricane life cycle and in regions where research aircraft are not available. Seamless Transition into the Global Precipitation Measurement Mission There are obvious merits to achieving this goal, for the many reasons stated in the previous section about extending datasets and, in particular, the crosscalibration value of overlap of TRMM sensors with the Global Precipitation Measurement sensors.
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From page 57... ...
If TRMM were extended until the true core satellite launch there would be a seamless transition of radar-calibrated global precipitation measurements into the Global Precipitation Measurement era. Avoiding Researchers Being Ill Prepared for the Global Precipitation Measurement Mission The success of TRMM and its unique combination of sensors and special orbit has encouraged development of a cadre of graduate students and researchers now well versed in the intricacies of using a rain radar and a multichannel microwave radiometer in synergy with infrared and visible cloud sensors.
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From page 58... ...
Continuous TRMM observations from 1997 into the Global Precipitation Measurement era would provide a unique and valuable continuous record for the ongoing study and characterization of the ENSO cycle. CONCLUSIONS CONCLUSION 4.1: The material in this report provides science and operations information needed as input for a qualitative evaluation of the balance between the risk inherent in an uncontrolled reentry and the contribution through operations and research to the protection of life and property of an extension of the TRMM mission.
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From page 59... ...
For example, over the first six years of TRMM data, the TMI instrument passes within 750 km of storm centers during one of every eight orbits, whereas PR observes within 250 km of the center during one of every 25 orbits. The narrow swath of the PR and the rare occurrence and great variability of tropical cyclone structure, intensity, and precipitation amount strongly argues for mission extension to increase sample sizes for statistical analyses.
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From page 60... ...
Having them available in near real time for an extensive period of time would foster investment of time and effort to make full use of PR data in the forecasting process. CONCLUSION 4.5: Considering the past and expected scientific and operational contributions presented in this report, important benefits would be obtained if TRMM were extended until it runs out of fuel.
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