README document for APHRO_MA_V1101R2
(Last updated 3 April, 2013)
1. Introduction
A suite of precipitation products is being constructed by the Asian
Precipitation -- Highly-Resolved Observational Data Integration Towards
Evaluation of the Water Resources (APHRODITE's water resources) project
in collaboration with the Research Institute for Humanity and Nature and
the Meteorological Research Institute of the Japan Meteorological Agency.
We now release APHRO_V1101, which includes more rain-gauge data and is
modified in quality control processes. In addition to precipitation
product, daily mean temperature product AphroTemp_V1204R1 is released
on February 2013. To take advantage of daily, highly-resolved precipitation
and temperature product, we provide discrimination between liquid and solid
precipitation to each grid.
This product, APHRO_MA_V1101R2 consists of daily precipitation and
information that the precipitation is solid or liquid by using AphroTemp_V1204R1.
This README interprets the structure of APHRO_V1101R2 data files
(sections 2-5), explains the rain/snow discriminant (sections 6) and gives
relevant references (section 7).
2. General Information
2.1 Products
The products we release are 0.5x0.5-degree and 0.25x0.25-degree gridded
daily precipitation data and rain/snow discrimination information over
Monsoon Asia (APHRO_MA_V1101R2). Since the precipitation product is compiled
from APHRO_MA_V1101, see APHRO_V1101_readme.txt for detailed information.
An indicator is introduced to represent the reliability of the
interpolated daily precipitation fields. This indicator, named RSTN, was
calculated for each re-gridded 0.50-degree (0.25-degree) cell, by calculating
the proportion of 0.05-degree cell(s) containing station(s).
The number of input data differs from year to year. Users, interested
in long-term changes should consider this variable.
Discrimination between rain and snow is defined by daily mean temperature
(APHRO_TAVE_MA_V1204R1) and relative humidity (RH) derived from ECMWF reanalysis data,
ERA40 (1961-2002) and ERA-Interim (2002-) for each 0.05-degree cell. RH based on
reanalysis shows extreme value (over 110%...), therefore, 7-day running mean is
carried out for each RH derived from ECMWF for V1101R2.
The discriminant is based on MRI/JMA technical report (Matsuo and Sasyo, 1981a, b,
Yasutomi et al., 2011). The indicator, RSNW was the proportion of 0.05-degree cell(s)
satisfying snowing condition.
2.2 Spatial and Temporal Coverage
Spatial coverage : (MA) 60.0E - 150.0E, 15.0S - 55.0N
Spatial resolution : 0.5 degree and 0.25 degree latitude/longitude
Temporal coverage : January 1, 1961 - December 31, 2007 (47 years)
Temporal resolution : Daily
2.3 Units
Precipitation : mm
Ratio of 0.05 grid box containing station(s) : %
Ratio of 0.05 grid box satisfying snowing contidion : 0(liquid)-100%(solid)
2.4 Missing Code
Precipitation : -99.9
Ratio of 0.05 grid box containing station(s) : -99.9
Ratio of 0.05 grid box satisfying snowing condition : -99.9
3. Data Files and Their Structure
The product is stored in one file per year.
3.1 Denotation
APHRO_MA_YYYdeg_V1101R2.ZZZZ
YYY : Resolution (050/025 for 0.5/0.25-degree grid)
ZZZZ : The year in 4 digits (e.g. 1961, 1952, ..., 2007)
3.2 Structure of Data Files
Each file contains daily fields for 365 (366 for leap years) days.
These daily fields are arranged according to the Julian calendar. Daily
fields (data arrays) contain information on the precipitation amount and
ratio of 0.05-degree cells containing a rain gauge. In the case of a
0.5-degree grid file, each field consists of a data array with longitude
by latitude dimensions of 180 x 140 elements for APHRO_MA.
In the case of the 0.5-degree APHRO_MA product, the first element is a
cell at the southwest corner centered at [60.25E, 14.75S], the second
is a cell at [60.75E, 14.75S], ..., the 180th is a cell at [149.75E,
14.75S], and the 181st is a cell at [60.25E, 14.25S].
[Note for plain binary format]
The data files are written in PLAIN DIRECT ACCESS BINARY. In each
daily field, the array for precipitation comes first, followed by
information on the rain gauge. Each element (both precipitation and
rain gauge information) is written as a 4-byte floating-point number
in little endian byte order. Users should swap the byte order to
big endian if necessary. There are no 'space', 'end of record', or
'end of file' marks in between. In the case of the 0.5-degree APHRO_MA
product, the size of a file (0.5-degree grid) is
4 bytes x 180 x 140 x 3 fields x 365 days = 110,376,000 bytes
for a non-leap year, or 110,678,400 bytes for a leap year.
4. Sample of GrADS Control Files
Each data file needs a *.ctl file to be handled by the GrADS software
(http://www.iges.org/grads/). Control files for APHRO_MA_V1101R2 are available
in the same directory as for the corresponding gridded data. After saving
the control file in the same location as the downloaded data, open this file
after the "ga" prompt (e.g., ga-> open APHRO_MA_050deg_V1101R2.ctl).
5. Sample Fortran 90 Program
A sample program written in Fortran 90 (read_aphro_v1101r1.f90) is
available in the same directory as for the corresponding gridded data. Note
that the little-endian byte order is assumed in this program.
6. References
6.1 How to cite APRHO_MA_V1101R2
APHRO_MA_V1101R2 consists of precipitation data, APHRO_MA_V1101 and rain/snow
discrimination indicator derived from AphroTemp_V1204R1.
Reference paper for APHRO_MA_V1101 is,
Yatagai, A., K. Kamiguchi, O. Arakawa, A. Hamada, N. Yasutomi and
A. Kitoh, 2012: APHRODITE: constracting a long-term daukt gridded
precipitation dataset for Asia based on a dense network of rain gauges,
BAMS, doi:10.1175/BAMS-D-11-00122.1 (early online releases)
and reference paper for AphroTemp_V1204 and rain/snow discrimination is,
Yasutomi, N., A. Hamada and A. Yatagai, 2011: Development of a
long-term daily gridded temperature dataset and its application to
rain/snow discrimination of daily precipitation. Global Environmental
Research, V15N2, pp165-172.
Should you refer to our product in your paper/presentation, please cite
Yatagai et al. (2012) and Yasutomi et al. (2011).
When you write/publish papers, please access the "Research Activities"
page of our website (http://www.chikyu.ac.jp/precip/research/index.html)
to obtain the latest information on our reference papers that present our
algorithms and products.
6.2 Reference for the previous and related products
1) <APHRO_V0902 reference>
Yatagai, A., O. Arakawa, K. Kamiguchi, H. Kawamoto, M. I. Nodzu,
and A. Hamada, 2009: A 44-year daily gridded precipitation dataset
for Asia based on a dense network of rain gauges, SOLA, 5, 137-140,
doi:10.2151/sola.2009-035.
2) <APHRO_V1101 reference>
Yatagai, A., K. Kamiguchi, O. Arakawa, A. Hamada, N. Yasutomi and
A. Kitoh, 2012: APHRODITE: constracting a long-term daukt gridded
precipitation dataset for Asia based on a dense network of rain gauges,
BAMS, doi:10.1175/BAMS-D-11-00122.1 (early online releases)
3) <AphroTemp_V1204 and rain/snow discrimination reference>
Yasutomi, N., A. Hamada and A. Yatagai, 2011: Development of a
long-term daily gridded temperature dataset and its application to
rain/snow discrimination of daily precipitation. Global Environmental
Research, V15N2, pp165-172.
4) <APHRO_V1101 quality control method>
Hamada, A., O. Arakawa and A. Yatagai, 2011: An automated quality control
method for daily rain-gauge data. Global Environmental Research, V15N2,
pp183-192.
7. Contacts
Please contact APHRODITE project (led by Dr. Akiyo Yatagai of RIHN)
for further questions regarding this product.
APHRODITE's Water Resources project
aphrodite.precinfo@gmail.com
http://www.chikyu.ac.jp/precip/index.html
(Contact)
Dr. Natsuko Yasutomi
Research Institute for Humanity and Nature
457-4 Kamigamo-Motoyama, Kita-ku, Kyoto 603-8047, Japan
Tel : +81-75-707-2412 (direct)
Fax : +81-75-707-2506
Principal Investigator
Dr. Akiyo Yatagai
Kyoto University (present affiliation)