|Name||GRENE-ei CAAM 0.05°×0.05° Grid Daily Precipitation in Thailand (prototype)|
|Organization||Tokyo Metropolitan University|
|Organization||Tokyo Metropolitan University|
|Organization||Japan Agency for Marine-Earth Science and Technology|
This is a prototype of 0.05°(lat) x 0.05°(lon) gridded data set of spatially-interpolated daily precipitation made from station precipitation in Thailand. Most of the data are obtained from the Thai Meteorological Department (TMD) by Prof. Jun Matsumoto (Tokyo Metropolitan University/JAMSTEC). We have not taken account of topographical effects, nor systematic errors of raingauges. In our product, data are given on grid boxes over land whose altitude is below 500 m only. Furthermore, those grid boxes which are far from any observing stations to be void of data. The threshold distance is predetermined by subjective decision of the analyst. The production of this data set is also a part of GRENE-ei (Green Network of Excellence, environmental information) CAAM (Climatic Changes and Evaluation of Their Effects on Agriculture in Asian Monsoon Region) of MEXT (the Ministry of Education, Culture, Sports, Science and Technology in Japan).
|North bound latitude||20.5|
|West bound longitude||97|
|South bound latitude||5.5|
|Dimension Name||Dimension Size (slice number of the dimension)||Resolution Unit|
|Keyword Type||Keyword||Keyword thesaurus Name|
|theme||Atmosphere > Precipitation > Precipitation Amount||GCMD_science|
|theme||HYDROLOGY > Precipitation, ATMOSPHERIC PROCESSES > Precipitation||AGU|
|place||Asia > South Eastern Asia > Thailand||Country|
GRENE-ei CAAM webpage : https://grene.agrid.org/
file download : https://data.diasjp.net/dl/storages/filelist/dataset:233
Maps of daily precipitation plots at stations and the gridded data (this product) : http://macroscope.world.coocan.jp/en/browse/grene/
[Processing environment]: programs written by the data set creator in Fortran 77 and Awk, Fortran 77 program "Spheremap" version 99.8a from the University of Delaware, and Generic Mapping Tools (GMT) version 4.3.1 (Wessel and Smith), on Intel PC running Linux OS. [Data format]: The data are stored in a format of ".grd" files in each day. They are made by "xyz2grd" command of GMT.
This is a prototype of gridded data set of spatially-interpolated daily precipitation made from station precipitation in Thailand.
As the algorithm for interpolation, “Spheremap”of Willmott et al. (1985) is used. This is originally the two-dimensional spatial interpolation algorithm by Shepard (1968) which is a kind of weighted average method, but modified to work with the spherical coordinates. The algorithm is also used by Global
Precipitation Climatology Centre (GPCC, located in the German Weather Bureau) in production of their gridded data set of precipitation.
We have not taken account of topographical effects, nor systematic errors of raingauges.
In our product, data are given on grid boxes over land whose altitude is below 500 m only. Furthermore, those grid boxes which are far from any observing stations to be void of data. The threshold distance is predetermined by subjective decision of the analyst.
Note: This dataset is a "prototype" one, and it is possible to modify the data in a final version of dataset.
* We checked the source data and partially modified before entering them to the production.
* The following convention is assumed when monthly precipitation is calculated.
– Trace precipitation is assumed to be the same as zero.
* The selection of stations which are used for interpolation into the grid is as follows:
– Such stations that are off the region of the grid to be produced by more than 2 degrees of latitude or longitude are excluded.
* The following masking is done after spatial interpolation to the grid.
– Only those grid boxes which correspond to land whose altitude is below 500 m are considered valid, in order to escape an effect of mountains on precipitation. The distinction between land and sea follows that of the GPCC (Global Precipitation Climatology Centre) data set ("Monitoring Product" as of 2004). That is, we put the missing-value flag to grid boxes which are considered as oceanic boxes by GPCC.
– The value in such grid boxes that are more than a certain distance farther from any stations with valid values are considered as missing. The threshold distance is defined to be equal to the difference of 1.6 degrees latitude along a meridian.
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Shepard, D., 1968. A two-dimensional interpolation function for irregularly-spaced data. Proceedings, 1968 ACM National Conference, 517 – 524. (Reference of spatial interpolation algorithm)
Willmott, C.J., Rowe, C.M. and Philpot, W.D. 1985. Small-scale climate maps: a sensitivity analysis of some common assumptions associated with grid-point interpolation and contouring. The American Cartographer, 12, 5 – 16. (Reference of spatial interpolation algorithm)