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TRMM Tropical Rainfall Measurement (Mission). Why TRMM? n Tropical Rainfall Measuring Mission (TRMM) is a joint US-Japan study initiated in 1997 to study.

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Presentation on theme: "TRMM Tropical Rainfall Measurement (Mission). Why TRMM? n Tropical Rainfall Measuring Mission (TRMM) is a joint US-Japan study initiated in 1997 to study."— Presentation transcript:

1 TRMM Tropical Rainfall Measurement (Mission)

2 Why TRMM? n Tropical Rainfall Measuring Mission (TRMM) is a joint US-Japan study initiated in 1997 to study tropical and subtropical precipitation. n 2/3 of global rainfall occurs in the tropics n ¾ of atmosphere’s heat energy is formed from the release of latent heat of condensation n Precipitation in the tropical and subtropical area affect global weather and circulation n TRMM provides the first spaceborn rain radar and microwave radar data that will measure the vertical distribution of precipitation over the tropics in a band between ± 35' in latitude

3 TRMM Objectives n To obtain and study science data sets over several years of tropical and subtropical rainfall measurements n To understand how interactions between the sea, air and land masses produce changes in global rainfall and climate n To help improve modeling of tropical rainfall processes and their influence on global circulation in order to predict rainfall and variability at various time scale intervals n To test, evaluate, and improve the performance of satellite rainfall estimates measurements and techniques. n * Allows for examination through the cloud, to the ground, making this all possible.

4 TRMM Specifications n Relatively low orbit of 350km ( can resolve cloud images to a small scale) n 35 degree inclination angle (tropics and subtropics) n 1100 watts of power n Weighs 3620kg - why so much? n Provides mostly monthly rainfall rates

5 n TMI - Tropical Microwave Imager n VIRS - Visible and Infrared Scanner n PR - Precipitation Radar n LIS - Lightning Imaging Sensor n CERES - Clouds and Earth’s Radiant Energy System

6 TMI - Tropical Microwave Imager n - multichannel radiometer, whose signals in combination can measure rainfall quite accurately over oceans and somewhat less accurately over the land n - passive microwave sensor measures wave radiation n - measures radiation intensity at 5 different frequencies: 10.7, 19.4, 21.3, 37.0, and 85.5 GHz n - similar to SSM/I, but with the addition of the 10.7 that gives better linear rainfall rates n - evaluates integrated cloud precipitation content, cloud liquid water, cloud ice, rain intensity, and rainfall types convective/stratoform n - basis for calculation is Planck’s law, how much energy a body radiates based on its temperature n 6-50km horizontal resolution

7 VIRS - Visible and Infrared Scanner n - measures radiance in five bandwidths,.63, 1.6, 3.75, 10.8, and 12.0 um n - variation of intensities are used to determine brightness or temperature of the source n - can be used to determine cloud tops based on wavelength received (cirrus vs. convective) n - the various channels help to differentiate between clouds, giving an indication of rainfall intensities n - used as an indirect indicator of rainfall n - serves as a transfer standard to other measurements that are made from POES and GOES satellites n - also used to detect fires n - 2km resolution

8 PR - Precipitation Radar n - 3-dimensional Radar n - determines the vertical distribution from the ground to 15km of precipitation by measuring the radar reflectivity of the clouds and the weakening of a signal as it passes through the precipitation n - compensates for attenuation by separating rain echoes for vertical sample sizes of 250m when looking straight down n - measurement of rain over land is better than other satellite systems, where passive microwave channels have more difficulty n - 4km resolution

9 LIS - Lightning Imaging Sensor n - investigates the distribution and variability of both atmospheric and cloud-to-ground lightning, and their correlation to convective rainfall n - spatial, temporal, and spectral filtering is processed to produce the clearest images of lightning possible n - sensitive optical lenses that remove background illumination allow for lightning detection even when weak and during brightest times of the day n - detects rate, location, radiant energy, and duration of lightning related to convective storms n - 4km resolution

10 CERES - Clouds and Earth’s Radiant Energy System n - visible/infrared sensor designed especially to measure energy rising from the surface of the Earth and the atmosphere including its constituents (e.g., clouds and aerosols) n - evaluates the earth’s “radiation budget”, how much radiation received by the earth, and then re-emitted n - three channels in each radiometer: Total radiance (0.3 to >100 µm); Shortwave (0.3 to 5 µm); Window (8 to 12 µm) n - measures radiation at all levels of the atmosphere, focusing on upper levels and the surface n - contributes to the extended range forecast n - combines with VIRS to produce cloud properties n - examines cloud top height, fractional area, cloud liquid water path, droplet size, and other cloud properties that are consistent with the radiative fluxes

11 Processing the Information - Crazy flow chart of algorithms - TRMM algorithms combine data from the TMI, VIRS, and PR to produce the best rain estimates - Algorithms involving VIRS and CERES process the cloud data - TRMM has its own unique Science Data and Information System (TSDIS) - TSDIS analyzes the rainfall data and also provides validation from nearly hundreds of ground radar sites The connection between precipitation rates (TMI and PR) and cloud-top temperatures (VIRS) derived from TRMM should improve estimates of tropical precipitation rates using data from visible and infrared satellite instruments in the eras both before and after the TRMM mission

12 Final Product

13 TRMM Example with TMI 85 GHz

14 TRMM Composite with TMI 37 GHz

15 TRMM Composite with PR

16 TRMM Composite with LIS

17 TRMM Composite with VIRS



20 References n - n - n - n - n -

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