TRMM Product Level 2A Precipitation Radar (PR) Rain Characteristics (2A23)

The TRMM Precipitation Radar (PR), the first of its kind in space, is an electronically scanning radar, operating at 13.8 GHz that measures the 3-D rainfall distribution over both land and ocean, and defines the layer depth of the precipitation.

The PR qualitative algorithm (2A23) inputs PR reflectivities (1C21) and returns a rain/no rain decision based on echo structure. When rain is present, a storm height is calculated. If a bright band is detected, the height of the bright band is also given.

TRMM Satellite Operating Altitude Change

The average operating altitude for TRMM was changed from 350 to 403 km during the period of August 7-24, 2001. This orbit boost maneuver extended the mission life significantly. All post-boost data products had been released by the TRMM Science Project, as of early December 2001. All TRMM data products (post- and pre-boost) are available via the TRMM data search-and-order system at http://disc.sci.gsfc.nasa.gov/data/datapool/TRMM_DP/. The time period before August 7, 2001 is referred to as pre-boost, and the time period after August 24, 2001 is referred to as post-boost.

The characteristics of the three rain instruments for pre- and post-boost are shown in following table:

Characteristics of TRMM Instruments
	Swath Width (km)		Ground Resolution (km)
	Pre-boost	Post-boost	Pre-boost	Post-boost
VIRS	720	833	2.2	2.4
TMI	760	878	4.4*	5.1*
PR	215	247	4.3	5.0
* Ground resolutions of TMI are those at 85.5 GHz (highest resolution).

The pre- and post-boost characteristics of TRMM data are different; their details are listed in the Data Characteristics table for each orbital product. Some caveats associated with post-boost TRMM Precipitation Radar (PR) products have been released by the PR algorithm scientists and are available at ftp://disc2.nascom.nasa.gov/data/TRMM/Documentation/TRMM_Boost_PR_Caveats.html.

For TRMM version 5 products, the post-boost filenames all have a "5A" in the product version part of the name, compared with a "5" in pre-boost filenames. For version 6, the filenames have no differences for pre-boost and post-boost.

Sponsor and Acknowledgement

The distribution of this data set is funded by NASA's Earth Science Enterprise (ESE). The data are not copyrighted; however, we request that when you publish data or results using these data, please acknowledge as follows: The data used in this study were acquired as part of the Tropical Rainfall Measuring Mission (TRMM). The algorithms were developed by the TRMM Science Team. The data were processed by the TRMM Science Data and Information System (TSDIS) and the TRMM Office; they are archived and distributed by the Goddard Distributed Active Archive Center. TRMM is an international project jointly sponsored by the Japan National Space Development Agency (NASDA) and the U.S. National Aeronautics and Space Administration (NASA) Office of Earth Sciences. Please send a copy of your publication to Help Desk, Goddard DAAC, Code 610.2, NASA GSFC, Greenbelt, MD 20771 or email the reference of your publication to help-disc@listserv.gsfc.nasa.gov.

Future Updates

It is expected that some of the TRMM algorithms will be refined or improved as new measurements are gathered and analyzed by the TRMM Science Team. The data products are expected to be periodically reprocessed by TSDIS in order to provide the scientific and other user communities with the most current and best available rainfall products. The exact reprocessing schedule will be set by a team designated by the TRMM Project Scientist. This document will be updated in coordination with the TRMM reprocessing schedule and whenever appropriate as determined by the Goddard DAAC Hydrology Data Support Team.

Data Flow Description

PR Level 1A ==> 1B21 PR Power ==> 1C21 PR Reflectivities ==> 2A23 PR Rain Characteristics

The data flow of all products are shown in Satellite Algorithm Flow Diagram.

Data Set Description

Data Characteristics

TRMM 2A23 Data Characteristics
	Pre-boost (before 2001-08-07)	Post-boost (after 2001-08-24)
Temporal Coverage	Start Date: 1997-12-08 Stop Date: 2001-08-07	Start Date: 2001-08-24 Stop Date: -
Geographic Coverage	Latitude: 38°S - 38°N Longitude:180°W - 180°E	Latitude: 38°S - 38°N Longitude:180°W - 180°E
Temporal Resolution	About 91.5 minutes per orbit About 16 orbits per day More information about revisit frequency	About 92.5 minutes per orbit About 16 orbits per day More information about revisit frequency
Horizontal Resolution	4.3 km	5.0 km
Scan Characteristics	Swath Width: 215 km Rays/Scan: nray = 49 Scans/Second (SS): 1/0.6 Seconds/Orbit (SO): 5490 Average Scans/Orbit: nscan = SS*SO = 9150	Swath Width: 247 km Rays/Scan: nray = 49 Scans/Second (SS): 1/0.6 Seconds/Orbit (SO): 5550 Average Scans/Orbit: nscan = SS*SO = 9250
Average File Size	Compressed: ~6.2 MB Original: ~13.6 MB	Compressed: ~6.3 MB Original: ~13.8 MB
File Type	HDF	HDF

Data Format Structure

Further information on the contents and structure of the 2A23 product can be found in Volume 4 of the "File Specifications for TSDIS Products - Level 2 and Level3" .

Data Format Structure for 2A23, PR Rain Characteristics
Name	Type	Record Size (byte)	Dim Size/ # of Records	Scaled by	Range	Unit	Description
ECS Core Metadata	Char Attribute	10,000	-	-	-	-	ECS Core Metadata
PS Metadata	Char Attribute	10,000	-	-	-	-	Product Specific Metadata
Swath Structure	Char Attribute	5,000	-	-	-	-	The specification of the swath geometry
Scan Time	Vdata Table	8	nscan	-	-	-	The time associated with the scan, expressed as 8-byte float UTC second of the day.
Geolocation	Float SDS	4	2nraynscan	-	-	degree	The earth location of the center of the IFOV at the altitude of the earth ellipsoid. The first dimension is latitude and longitude, in that order. The next dimensions are numbers of pixels and scans.
Scan Status	Vdata Table	15	nscan	-	-	-	The status of each scan.
Navigation	Vdata Table	88	nscan	-	-	-	Spacecraft geocentric information
Rain Flag	Integer SDS	1	nray*nscan	-	-	-	The rain flag is identical to the Minimum Echo Flag of 1C21. 0: no rain 10: rain possible 11: rain possible (echo greater than rain threshold #1 in clutter region) 12: rain possible (echo greater than rain threshold #2 in clutter region) 13: rain possible 15: rain possible 20: rain certain
Rain Type	Integer SDS	2	nray*nscan	-	-	-	The Rain Type Flag.
Shallow Rain Flag	Integer SDS	1	nray*nscan	-	-	-	The Warm Rain Flag is set as follows: = 10: maybe shallow, isolated = 11: shallow isolated (with confidence) = 20: maybe shallow but not isolated = 21: shallow but not isolated (with confidence) = 0: when not shallow < 0: when not rain certain or data missing
Status Flag	Integer SDS	1	nray*nscan	-	-	-	The Status Flag indicates whether the data are obtained over sea or land and the confidence.
Height of Bright Band	Integer SDS	2	nray*nscan	-	-	-	A positive Height of Bright Band is defined in meters above mean sea level. Negative values are defined as follows: -1111: No bright band -8888: No rain -9999: Data missing.
Bright Band Intensity	Integer SDS	4	nray*nscan	-	-	-	The maximum value of the bright band (dBZ) obtained from normal samples. The range is from 0.00 to 100.0 dBZ. Negative values are defined as: -1111: No bright band -8888: No rain -9999: Data missing.
Bright Band Peak Bin	Integer SDS	2	nray*nscan	-	-	-	A positive range bin number that corresponds to the peak of the bright band. This bin number is in the Level-1 bin numbering scheme (125m, see Level-1 PR description). Negative values are defined as: -1111: No bright band -8888: No rain
Bright Band Boundary	Integer SDS	2	2nraynscan	-	-	-	Positive bin number of the boundary of the bright band. The first index indicates the bottom. This bin number are in the Level-1 bin numbering scheme (125m, see Level-1 PR description). Negative values are defined as: -1111: No bright band -8888: No rain
Bright Band Width	Integer SDS	2	nray*nscan	-	-	-	The width of the bright band in meters. Negative values are defined as: -1111: No bright band -8888: No rain
Bright Band Status	Integer SDS	2	nray*nscan	-	-	-	Indicates the status of the bright band detection. This flag is a composite of three internal status flags: BB_status[j] = BB_detection_status * 16 + BB_boundary_status[j] * 4 + BB_width_status[j] where each status on the right hand side takes the following values: 1: poor, 2: fair, 3: good.
Height of Freezing Level	Integer SDS	2	nray*nscan	-	-	-	A positive Height of Freezing Level is the height of the 0°C isotherm above mean sea level in meters, estimated from climatological surface temperature data. Negative values are defined as: -5555: When error occurred in the estimation of Height of Freezing Level -8888: No rain -9999: Data missing
Height of Storm	Integer SDS	2	nray*nscan	-	-	m	A positive Height of Storm is the height of the storm top above mean sea level in meters. A positive Height of Storm is given only when rain is present with a high degree of confidence in 1C21 (i.e., the Minimum Echo Flag in 1C21 has the value of 2 [rain certain]). Negative values are defined as: -1111: Height of Storm not calculated because rain is not present with a high level of confidence in 1C21 -8888: No rain -9999: Data missing
Spare	Float SDS	2	nray*nscan	-	-	-	Spare will characterize the width of the bright band. Since this characterization requires much research, the meaning is not disclosed.

Tools for Visualizing Data

The Goddard DAAC provides the following tools to help users visualize data in the Hierarchical Data Format (HDF).

TSDIS Orbit Viewer

The TSDIS Orbit Viewer is a menu-driven graphical interface for dynamically generating images from TRMM HDF files. The viewer can display, at the full instrument resolution, TRMM satellite, Ground Validation, browse, and Coincidence Subsetted Intermediate (CSI) products, as well as other derived products.

The software runs on Microsoft Windows and UNIX.

The source code and installation instructions for the Orbit Viewer are available from the Goddard DAAC's TRMM ftp site (ftp://disc2.nascom.nasa.gov/software/trmm_software/Orbit_Viewer).

Please note: TSDIS can provide technical support for the Orbit Viewer only to certain members of the TRMM Science Team. Other users should contact the DAAC's Hydrology Data Support Team (hydrology-disc@listserv.gsfc.nasa.gov).

EOSView

EOSView is a standalone X-based data visualization tool that displays HDF files. It can be used to view data ordered from the Goddard DAAC. In addition, it provides a secondary mechanism for previewing browse files before ordering data. (The primary mechanism is the preview feature of the TRMM Data Search and Order System.) EOSView serves as a file verification tool. The contents of HDF files are displayed and individual objects can be selected for display. Displayable objects include raster images, data sets in tables, pseudocolor images of data sets, attributes, and annotations. Simple animations can be performed for a file with multiple raster images.

A unique interface has been provided for handling HDF-EOS data structures. The Swath/Point/Grid interface uses only HDF-EOS library calls. EOSView users will not see the underlying HDF structures but will be prompted for what parts of the HDF-EOS object they wish to view. The EOSView requires at least 4 megabytes of memory and a larger than 24-bit graphics board.

Download Instructions for the Software:

These tools can be downloaded via anonymous ftp using a command line ftp client, available on all Unix machines.

The source code, installation instructions, and documentation for EOSView and Orbit Viewer are available from the Goddard DAAC's TRMM ftp site (ftp://disc2.nascom.nasa.gov/software/trmm_software).

The following files should be downloaded for EOSView:

EOSView (executable)
eosview.csc (help)
eosview.uid (user interface description file)
eosview.dat (IDL commands file)

How to start EOSView:

Start EOSView by typing 'EOSView' at the command prompt. The current working directory must contain the four EOSView files.

Sample Software

TRMM HDF Data File Read Software

The Goddard DAAC Hydrology Team has developed the TRMM HDF Data File Read Software, first released in February 1999. The software reads TRMM HDF data files and writes out to flat binary files. The software has been tested with most of the TRMM standard products, as well as with some derived subset products. Both C and Fortran versions are available from ftp://disc2.nascom.nasa.gov/software/trmm_software/Read_HDF/.

TSDIS Toolkit

TSDIS developed the TSDIS Science Algorithm Toolkit to assist the TRMM Science Team's algorithm developers. The toolkit provides a library of commonly used routines, constants, and macros. It also allows seamless integration of TRMM algorithms into the TSDIS environment.

The toolkit provides routines for reading and writing data to and from the HDF files; routines are provided for Levels 1-3 products and for both satellite and GV. Each of the routines in the toolkit are callable in either C or Fortran. The toolkit also includes routines for reading land/sea data and topographical data.

Data Access Information

The Goddard DAAC maintains archives of all TRMM data products and many other Hydrology data sets. The archived data can be ordered via FTP network transfer.

Data Volume Limits By Media
CDR		FTP-Pull
Min.	Max.	Min.	Max.	Min.	Max.	Min.	Max.
0 GB	3.17 GB	0 GB	2 GB	1 GB	50 GB	1 GB	50 GB

TRMM 2A23 can be accessed and ordered using the Goddard DAAC's TRMM Data Search and Order System at http://disc.sci.gsfc.nasa.gov/data/datapool/TRMM_DP/01_Data_Products/01_Orbital/07_Rain_Type_2A_23/ .

Points of Contact

For information about or assistance in using any Goddard DAAC data, contact the DAAC Help Desk at:: GES Distributed Active Archive Center (DAAC)
Code 610.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771

Email: help-disc@listserv.gsfc.nasa.gov.
301-614-5224 (voice)
301-614-5268 (fax)

References

Tropical Rainfall Measuring Mission Science Data and Information System (TSDIS) Interface Control Specification Between the TSDIS and the TSDIS Science User (TSU)
Volume 3: File Specifications for TRMM Products - Level 1.
Volume 4: File Specifications for TRMM Products - Level 2 and Level 3.

Appendix

TRMM Navigation
Name	Format	Description
Spacecraft Geocentric Position [3]	3 X 4-byte float	The position (m) of the spacecraft in Geocentric Inertial Coordinates at the Scan mid-Time (i.e., time at the middle pixel/IFOV of the active scan period). The order of components is: x, y, and z. Geocentric Inertial Coordinates are also commonly known as Earth Centered Inertial coordinates. These coordinates will be True of Date (rather than Epoch 2000 which are also commonly used), as interpolated from the data in the Flight Dynamics Facility ephemeris files generated for TRMM.
Spacecraft Geocentric Velocity [3]	3 X 4-byte float	The velocity (ms ^-1) of the spacecraft in Geocentric Inertial Coordinates at the Scan mid-Time. The order of components is: x, y, and z.
Spacecraft Geodetic Latitude	4-byte float	The geodetic latitude (decimal degrees) of the spacecraft at the Scan mid-Time.
Spacecraft Geodetic Longitude	4-byte float	The geodetic longitude (decimal degrees) of the spacecraft at the Scan mid-Time. Range is -180 to 179.999999.
Spacecraft Geodetic Altitude	4-byte float	The altitude (m) of the spacecraft above the Earth Ellipsoid at the Scan mid-Time.
Spacecraft Attitude [3]	3 X 4-byte float	The satellite attitude Euler angles at the Scan mid-Time. The order of the components in the file is roll, pitch, and yaw. However, the angles are computed using a 3-2-1 Euler rotation sequence representing the rotation order yaw, pitch, and roll for the rotation from Orbital Coordinates to the spacecraft body coordinates. Orbital Coordinates represent an orthogonal triad in Geocentric Inertial Coordinates where the Z-axis is toward the geocentric nadir, the Y-axis is perpendicular to the spacecraft velocity opposite the orbit normal direction, and the X-axis is approximately in the velocity direction for a near circular orbit. Note this is geocentric, not geodetic, referenced, so that pitch and roll will have twice orbital frequency components due to the onboard control system following the oblate geodetic Earth horizon. Note also that the yaw value will show an orbital frequency component relative to the Earth fixed ground track due to the Earth rotation relative to inertial coordinates.
Sensor Orientation Matrix [3 X 3]	3 X 3 X 4-byte float	The rotation matrix from the instrument coordinate frame to Geocentric Inertial Coordinates at the Scan mid-Time.
Greenwich Hour Angle	4-byte float	The rotation angle (degrees) from Geocentric Inertial Coordinates to Earth Fixed Coordinates.

TRMM PR Scan Status
Name	Format	Values	Description
Missing	1-byte integer	Value and meaning	Indicates whether information is contained in the scan.
Validity	1-byte integer	Bit and meaning	A summary of status modes.
QAC	1-byte integer	0: No decoding error occurred.	The Quality and Accounting Capsule of the Science packet as it appears in Level-0 data.
Geolocation Quality	1-byte integer	Bit and Meaning	A summary of geolocation quality in the scan.
Data Quality	1-byte integer	Bit and Meaning	A summary of data quality in the scan.
Current Spacecraft Orientation	1-byte integer	Value and Meaning	Current spacecraft orientation.
Current ACS Mode	1-byte integer	Value and Meaning	Current ACS mode.
Yaw Update Status	1-byte integer	0: Inaccurate 1: Indeterminate 2: Accurate	Yaw update status.
PR Mode	1-byte integer	1: Observation Mode 2: Other Mode	PR mode.
PR Status 1	1-byte integer	0: Normal 1: A little questionable	A warning for scan data. This field is used only for NASDA's data analysis.
PR Status 2	1-byte integer	0: Not initialized 1: Initialized	Initialization in Onboard Surface Algorithm.
Fractional Orbital Number	4-byte float		The orbit number and fractional part of the orbit at Scan Time. The orbit fraction part is calculated as: (Time-Orbit Start Time)/(Orbit End Time-Orbit Start Time)

Value and Meaning of Missing
Value	Meaning
0	Scan data elements contains information
1	Scan was missing in the telemetry data
2	Scan data contains no elements with rain

Bit and Meaning of Validity
Bit	Meaning if bit=1
0	Spare (always 0)
1	Non routine spacecraft orientation (2 or 3)
2	Non routine ACS mode (other than 4)
3	Non routine yaw update status (0 or 1)
4	Non routine instrument status (other than 1)
5	Non routine QAC (non-zero)
6	Spare (always 0)
7	Spare (always 0)

Bit and Meaning of Geolocation Quality
Bit	Meaning if bit=1 for Non-routine Situation	Routine Situation
0	Latitude limit error	If all status modes are routine, all bits in Validity = 0. Routine means that scan data has been measured in the normal operational situation as far as the status modes are concerned. Validity does not assess data or geolocation quality. Validity is broken into 8 bit flags. Each bit=0 if the status is routine but the bit = 1 if the status is not routine. Bit 0 is the least significant bit (i.e., if bit i=1 and other bits = 0, the unsigned integer value is 2**i).
1	Geolocation discontinuity
2	Attitude change rate limit error
3	Attitude limit error
4	Satellite undergoing maneuvers
5	Using predictive orbit data
6	Geolocation calculation error
7	not used

Bit and Meaning of Data Quality
Bit	Meaning if bit=1	Note
0	Missing	Unless this is 0 (normal), the scan data is meaningless to higher processing. Bit 0 is the least significant bit (i.e., if bit i=1 and other bit = 0, the unsigned integer value is 2**i).
5	Geolocation quality is not normal
6	Validity is not normal

Value and Meaning of Current Spacecraft Orientation
Value	Meaning
0	+x forward
1	-x forward
2	-y forward
3	Inertial -- CERES Calibration
4	Unknown Orientation

Value and Meaning of Current ACS Mode
Value	Meaning
0	Standby
1	Sun Acquire
2	Earth Acquire
3	Yaw Acquire
4	Nominal
5	Yaw Maneuver
6	Delta-H (Thruster)
7	Delta-V (Thruster)
8	CERES Calibration

TRMM 2A23 Rain Type Flag
Value	Meaning	Conditions
100	Stratiform certain	When R_type_V = T_stra; (BB exists) and R_type_H = T_stra;
110	Stratiform certain	When R_type_V = T_stra; (BB exists) and R_type_H = T_others;
120	Probably stratiform	When R_type_V = T_others; and R_type_H = T_stra;
130	Maybe stratiform	When R_type_V = T_stra; (BB detection certain) and R_type_H = T_conv;
140	Maybe stratiform or maybe transition or something else	When R_type_V = T_others; (BB hardly expected) and R_type_H = T_stra;
152	Maybe stratiform	Shallow isolated (type of warm rain) is detected When R_type_V = T_others; R_type_H = T_stra; and shallowRain = 20 or 21;
160	Maybe stratiform, but rain hardly expected near surface	BB may exist but is not detected When R_type_V = T_others; R_type_H = T_stra;
170	Maybe stratiform, but rain hardly expected near surface	BB hardly expected. Maybe cloud only When R_type_V = T_others; R_type_H = T_stra;
200	Convective certain	When R_type_V = T_conv; (no BB) and R_type_H = T_conv;
210	Convective certain	When R_type_V = T_others; and R_type_H = T_conv;
220	Convective certain	When R_type_V = T_conv; and R_type_H = T_others;
230	Probably convective	When R_type_V = T_conv; (BB exists) and R_type_H = T_conv;
240	Maybe convective	When R_type_V = T_conv; and R_type_H = T_stra;
251	Convective	Shallow isolated is detected When R_type_V = T_conv, R_type_H = T_conv and shallowRain = 10 or 11;
252	Convective	Shallow rain (non-isolated) is detected When R_type_V = T_conv, R_type_H = T_conv and shallowRain = 20 or 21;
261	Convective	Shallow isolated is detected When R_type_V = T_conv; R_type_H = T_others; and shallowRain = 10 or 11;
262	Convective	Shallow rain (non-isolated) is detected. When R_type_V[i] = T_conv, R_type_H[i] = T_others; and shallowRain[i] = 20 or 21;
271	Convective	Shallow isolated is detected When R_type_V = T_others; R_type_H = T_conv; and shallowRain = 10 or 11;
272	Convective	Shallow isolated is detected When R_type_V = T_others; R_type_H = T_conv; and shallowRain = 20 or 21;
281	Convective	Shallow isolated is detected When R_type_V = T_conv; R_type_H = T_stra; and shallowRain = 10 or 11;
282	Convective	Shallow rain (non-isolated) is detected. When R_type_V[i] = T_conv, R_type_H[i] = T_stra; and shallowRain[i] = 20 or 21;
291	Convective	Shallow isolated is detected When R_type_V = T_others; R_type_H = T_stra; and shallowRain = 10 or 11;
300	Others	When R_type_V = T_others; and R_type_H = T_others;
312	Others	Shallow rain (non-isolated) is detected When R_type_V = T_others, R_type_H = T_others; and shallowRain = 20 or 21;
313	Others	If sidelobe clutter were not rejected, shallow isolated would be detected When R_type_V = T_others, R_type_H = T_others; and shallowRain = 20 or 21;
where R_type_V: rain type classified by the V-profile method, R_type_H: rain type classified by the H-pattern method, which is based on SHY95 developed by Prof. Houze and his group. The above assignment of numbers has the following meaning: (merged) Rain Type / 100 = 1: stratiform, 2: convective, 3: others. (merged) Rain Type Flag % 100 = Sub-category, (merged) Rain Type Flag % 10 = 0: usual, 1: shallow isolated, 2: shallow non-isolated, 3: sidelobe clutter only (once shallow isolated overwritten as sidelobe clutter only). rainTytpe % 10 = 3 occurs for type 313 only. where Rain Type Flag % 10 means MOD (Rain Type, 10) in FORTRAN. Though rainType is changed to int16, no rain and missing values remain the same, that is -88: no rain -99: data missing

TRMM 2A23 Status Flag
Value	Meaning	Where
0	good	over ocean
10	BB detection may be good	over ocean
20	R-type classification may be good (BB detection is good or BB does not exist)	over ocean
30	Both BB detection and R-type classification may be good	over ocean
50	not good (because of warnings)	over ocean
100	bad (possible data corruption)	over ocean
1	good	over land
11	BB detection may be good	over land
21	R-type classification may be good (BB detection is good or BB does not exist)	over land
31	Both BB detection and R-type classification may be good	over land
51	not good (because of warnings)	over land
101	bad (possible data corruption)	over land
2	good	over coastline
12	BB detection may be good	over coastline
22	R-type classification may be good (BB detection is good or BB does not exist)	over coastline
32	Both BB detection and R-type classification may be good	over coastline
52	not good (because of warnings)	over coastline
102	bad (possible data corruption)	over coastline
4	good	over inland lake
14	BB detection may be good	over inland lake
24	R-type classification may be good (BB detection is good or BB does not exist)	over inland lake
34	Both BB detection and R-type classification may be good	over inland lake
54	not good (because of warnings)	over inland lake
104	bad (possible data corruption)	over inland lake
9	may be good	land/sea unknown
19	BB detection may be good	land/sea unknown
29	R-type classification may be good (BB detection is good or BB does not exist)	land/sea unknown
39	Both BB detection and R-type classification may be good	land/sea unknown
59	not good (because of warnings)	land/sea unknown
109	bad (possible data corruption)	land/sea unknown
When it is "no rain" or "data missing", Status Flag contains the following values: -88: no rain -99: data missing Assignment of the above numbers are based on the following rules: When Status >= 0 Status/100 = 0: good, may be good, or not good 1: doubtful (Status/10) % 10 = 0: good, may be good when status < 100, and not good when status >= 100 1: BB detection not so confident 2: R-type classification not so confident (but BB detection is good, or when BB does not exist) 3: BB detection is not so confident and R-type classification not so confident 5: Over-all quality of the processed data for the j-th scan angle is not good (but may not be too bad to be classified as bad data) Status % 10 = 0: over ocean 1: over land 2: over coastline 4: over inland lake 9: land/sea unknown In other words, we can check the confidence level of 2A-23 by the following way: Status Flag >= 100 : bad (untrustworthy because of possible data corruption) 100 > Status Flag >= 10 : result not so confident (warning) Status Flag = 9 : may be good 9 > Status Flag >= 0 : good The last digit of Status Flag indicates over ocean, land, etc.

TRMM Frequency Analysis Result* (Number of visits for a 30-day period)
Radar Site	Latitude (°)	PR (~215 km)	VIRS (~720 km)	TMI (~760 km)
Kwajalein Atoll	8.72	9	29	31
Darwin, Australia	-12.45	10	31	32
Guam	13.50	9	32	32
Om Koi, Thailand	17.80	9	31	33
Kauai, HI	22.17	13	36	38
Sao Paolo, Brazil	-23.58	12	41	42
Taiwan	23.92	11	40	42
Key West, FL	24.67	13	41	42
Miami, FL	25.75	13	45	45
Brownsville, TX	25.97	13	43	47
Corpus Christi, TX	27.85	15	49	51
Tampa, FL	28.03	13	51	52
Melbourne, FL	28.10	15	49	53
San Antonio, TX	29.53	16	57	59
Jacksonville, FL	30.33	19	63	65
Texas A&M, TX	30.58	18	67	68
Jerusalem, Israel	31.87	20	92	102
PR: Precipitation Radar VIRS: Visible/InfraRed Scanner TMI: TRMM Microwave Imager * This analysis result was derived based on TRMM pre-boost orbital information. The revisit frequency should be slightly higher after TRMM boost (August 24, 2001). If you have questions regarding this table, please send email to: helpdesk@tsdis02.nascom.nasa.gov.

NASA Official: Steve Kempler
Website Curator: Stephen W Berrick

Last updated: April 11, 2008 15:17:36 GMT