NOAA's Role in Space-Based Global Precipitation Estimation and Application (2007) / Chapter Skim
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3 Precipitation Data in NOAA Operations
3 Precipitation Data in NOAA Operations
Pages 33-71
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From page 33... ...
Finally, this chapter outlines the applications of space-based precipitation data in general and the potential applications of GPM mission data specifically. NOAA MISSION REQUIREMENTS FOR PRECIPITATION DATA AND RELATED PRODUCTS Global observation of precipitation on a range of time and space scales is essential to achieving NOAA's mission objectives related to the monitoring and prediction of weather, climate monitoring, many aspects of hydrologic monitoring and prediction, climate data set development, and more (Box 3.1)
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. NCEP's operational needs for global precipitation data include initialization of atmospheric and surface hydrologic (soil moisture)
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The Climate Program Office supports several projects dealing with the development and use of satellite precipitation data sets. These projects include the Climate Change and Detection Project, the Applied Research Center for Data Set Development for transition of Climate Change and Detection Data Projects to NOAA operations, and the Scientific Data Stewardship Program, which governs the production of climate data records.
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From page 36... ...
NOAA's Ability to Fulfill Its Precipitation Measurement Requirements Increasingly comprehensive and higher-quality satellite precipitation data and data products have become available during the past several years as a consequence of the launch of the Tropical Rainfall Measuring Mission (TRMM) and a number of polar-orbiting satellites carrying passive microwave sensors.
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From page 37... ...
As the GPM core and constellation satellites supplement these sources, they will benefit from being validated against data from a robust ground-based network. This section reviews the status and attributes of ground-based and satellite sources and makes recommendations for improvements that will benefit GPM in particular and global precipitation estimation in general.
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From page 38... ...
The data from these multiple sources undergo quality control and are incorporated in near real time to form an extensive rainfall database. The data are analyzed to map precipitation distribution, determine the potential extent of flooding, and calibrate and validate radar and satellite precipitation estimates.
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Recommendation 3.1: NOAA should explore collaborative efforts to augment the existing rain gauge network with additional resources coming online through mesonets that are increasingly used by local, state, and federal agencies to quantify precipitation for many near real-time applications. NOAA should maintain rigorous quality con trol and integrate the resultant rain gauge data sets into GPM cali bration and validation efforts.
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40 FIGURE 3.3 Location of NOAA WSR-88D NEXRAD radar sites in the continental United States and the distribution of coverage at altitudes of 4,000, 6,000, and 10,000 feet (tan, orange, and blue circles, respectively)
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. NEXRAD data are crucial during rapidly evolving summer thunderstorm events as well as for prolonged and extreme events such as landfalling tropical cyclones.
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NOAA should integrate NEXRAD data sets into GPM calibration and validation efforts. Satellite Sources Satellite sensors mitigate several weaknesses in rain gauge and ground-based radar data sets; thus, the combination of gauge, radar, and satellite precipitation data provides a powerful tool for multiple applications.
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From page 43... ...
Although cloud-top temperatures, cloud-top heights, and cloud type are not highly correlated with instantaneous rain rates, the correlation is strongest for warm-season convective systems that frequent the eastern and midwestern continental United States. Operational geostationary visible-infrared digital data sets cover the globe between 60 degrees latitude North and South and are routinely available for near-real-time applications.
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For example, TRMM provided both the TRMM Microwave Imager and Precipitation Radar, launched in 1997. TRMM was followed by the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E)
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. Planned Satellite Precipitation and Related Missions That Contribute to the Global Precipitation Constellation In general, the geostationary constellation health will markedly improve in the next 5 years, while the opposite is true for passive microwave imagers on low-orbiting platforms.
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From page 46... ...
However, the reduction from six to three sensors and the current launch schedule significantly impact the global mix of microwave imagers available for precipitation monitoring. Temporal sampling will be hindered because fewer sensors equate to less frequent observations and imply that enhanced reliance will be placed on "merged or blended" precipitation techniques using both passive microwave and visible-infrared data sets.
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From page 47... ...
mission satellite, which would have global coverage and carry a radar in addition to a microwave imager and would target light rainfall and light-to-medium snowfall. Although this is potentially a unique and central contributor to the overall precipitation constellation, the uncertain status of EGPM and the lack of funding mean it cannot be relied on as a contributor to future precipitation measurements.
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This mission follows in the footsteps of the Advanced Earth Observing System program that carried the AMSR-E sensor. Finding: Availability of the NPOESS microwave imagers in both proposed NPOESS orbits is essential to any precipitation measuring constellation.
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to construct near-real-time global and regional precipitation analyses on a regular time-space grid from satellite-inferred precipitation, and (2) to initialize the operational analysis-forecast cycle of atmospheric and land-surface components of NWP models through direct assimilation of satellite precipitation information such as precipitation estimates or radiances.
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Microwave imagers use external "hot" and "cold" load sources that provide vital calibration functions for inferring precipitation rates. These reference temperatures are critical to accurately quantify measured radiances.
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Recommendation 3.5: NOAA should lead the international satellite community by proposing specific actions for the accurate cali bration of all microwave imagers and sounders through cross calibration and standard reference data sets and by implementing internal calibrations on all future microwave sensors. Physically based precipitation estimates from microwave sensors (using frequencies that are sensitive to hydrometeors)
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, and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) uses geostationary and TRMM Microwave Imager data and incorporates a neural network approach (Sorooshian et al., 2000)
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From page 53... ...
The novel ways of combining geostationary infrared and passive microwave observations each have their own inherent strengths and point the way forward to significant improvements in the GPM era. However, the error characteristics of the high-resolution products have yet to be adequately described, and opportunities for improvement by combining the various methodologies are only in the initial stages of development.
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54 TABLE 3.2 Suite of Satellite-based Rain Rate Techniques Produced by NOAA or Available in Near Real Time for Comparisons, Validation, and/or Technical Idea Exchangea Self-calibrating Naval Multisatellite Multivariate Research Precipitation Precipitation Retrieval Hydro-E CMORPH PERSIANN Laboratory Analysis (SCaMPR) Spatial 4-5 km 8 km 25 km 0.10 degree 0.25 by 0.25 4 km resolution 5 km soon degrees Temporal 15 minutes, uses 30 minutes, but 30 minutes Instantaneous, but 3 hours 15 minutes resolution ETA RH/TPW finest time scale finest time scale fields to adjust output is 3 hours output is infrared rain 3 hours Data latencyb 15 minutes 15 hours 1-4 hours soon 1-4 hours 10 hours 1-4 hours (low-Earth orbit)
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Sensors Used Geostationary Yes Yes Yes Yes Yes Yes infrared Passive microwave No Yes Yes Yes Yes Yes TRMM No No No Yes No No Precipitation Radar SSMI No Yes Yes Yes Yes Yes AMSU No Yes Yes Yes Yes Yes AMSR-E No Yes Yes Yes Yes No SSMIS No Soon No Yes No No aAll algorithms are routinely run and digitally accessed through automated routines at NOAA, NASA, DOD, and other institutions. bDelay in availability of product.
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From page 56... ...
describing the components of GSICS, the roles of participating agencies, a timetable for implementing the program, and coordination with other international programs was under review by the Coordina tion Group of Meteorological Satellites. GSICS will be implemented beginning in 2007, long before launch of the GPM core satellite.
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From page 57... ...
At NASA's Goddard Space Flight Center, an inversion-based retrieval algorithm has been developed to estimate vertical profiles of precipitation ice water content and liquid water content in tropical cyclones from combined TRMM Precipitation Radar and Microwave Imager data (Jiang and Zipser, 2006)
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They processed TRMM Microwave Imager data for multiple years covering six ocean basins (Atlantic, East and West Pacific, North and South Indian Ocean, and South Pacific) and included all tropical cyclones of tropical storm strength or greater.
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Products are now routinely produced from the NASA GPCP and the NCEP Climate Prediction Center Merged Analysis of Precipitation. In a focused application of TRMM data to tropical cyclone rain rates, NASA used Multisatellite Precipitation Analysis to quantify the climatology of rainfall distribution in tropical cyclones that made landfall on the Gulf Coast during 1998-2004 (Jiang et al., 2006, and two unpublished papers7)
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In addition, forecast performance in the Southern Hemisphere is now comparable to that in the Northern Hemisphere, despite the grossly unequal distribution of high-quality radiosonde data, largely due to the availability of global satellite sounder radiances. Assimilation of satellite precipitation information (i.e., precipitation estimates or radiances)
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difficulty validating satellite precipitation retrievals; (7) inability to accurately map threedimensional rain rate structure and fully understand resultant latent heating profiles; and (8)
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Remotely sensed precipitation and soil moisture information is used increasingly in LDAS that may be coupled with atmospheric NWP models (e.g., Rizvi et al., 2002; Drusch et al., 2005)
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In the NCEP regional analysis (i.e., North American Model) , precipitation estimates from SSMI, TRMM Microwave Imager, and rain gauges and ground-based radar (over the continental United States)
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. Doppler radar radial wind and precipitable water and rain rate derived from the microwave radiometer on SSMI, TRMM Microwave Imager, and Aqua AMSR-E are used in the mesoscale model.
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From page 65... ...
Large brightness temperature contrasts permit microwave imagers and sounders with 85-91 GHz channels (i.e., SSMI, SSMIS, TRMM Microwave Imager, AMSR-E, AMSU-B) to supply vital tropical cyclone information (Lee et al., 1999, 2002; Hawkins et al., 2001; Simpson, 2003)
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The GPM mission has advantages over the TRMM mission for data assimilation and NWP: the improved precipitation rate estimates of the dual-frequency precipitation radar on the GPM core satellite (particularly for light rain) (see Chapter 2)
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For example, although rain rates can be inferred from microwave imager and sounder data, only radar can actually retrieve vertical profiles. The TRMM precipitation radar is the first satellite sensor to demonstrate that rain rate profiles are feasible from satellite observations (Chapter 2)
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In addition, GPM will have a direct and measurable positive impact in supporting NOAA's goal to protect life and property from tropical cyclone damage in the continental United States and countries that rely on U.S.-derived information by improved forecasts of landfall location and intensity. Microwave measurements from GPM's precipitation radar and microwave imager will give analysts cloud-free views of tropical cyclone structure.
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From page 69... ...
GPM precipitation data have the potential to contribute to both the further development and the operational application of regional and global LDAS components through improved input and validation of precipitation. GPM data will likely have the greatest impact on global LDAS by improving the quality of the high-resolution precipitation analysis products for the large land areas of the world where surface observations are sparse or not available in a timely manner.
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From page 70... ...
. Nevertheless, because of the previous meager level of knowledge, TRMM Microwave Imager data have been extremely valuable for describing the large-scale features of the tropical and subtropical precipitation regimes, including individual realizations of the El Niño-Southern Oscillation cycle.
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From page 71... ...
SUMMARY The best operational uses of GPM data at NOAA will be weather forecasting, hydrologic applications, climate applications, and global precipitation climate data records. Prior to the launch of the GPM core satellite, NOAA can initiate improvements in current sources of precipitation data and improvements in data products to enhance the operational benefits of the GPM mission.
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