APHRODITE-2 V1101EX_R1
Last
update October 5, 2018
1.Introduction
Since the release of
APHRODITE V1101 products (Yatagai et al.,2012), APHRODITE daily grid
precipitation data sets are widely used. However, except for APHRO_JP (product for
Japan), no update has not been made. The product ended in 2007, and update is
really expected for diagnosing climate variability and related hydrological
studies.
On the other hand, by getting funding
for FY2016-2018, APHRODITE-2 project has started, and one of the main targets
is to improve APHRODITE for evaluation of extreme precipitation. Now we can
release the new product V1801 for Monsoon Asia; however, to make V1801 product
takes time for quality control and judging end of the day (24-hr accumulation
time). So, according to requirements from the science community, which is to
release update APHRODITE product even it is created with the same algorithm
(V1101), we decided to release it as follows, with named V1101EX (This means
version 1101 extend).
The interpolation algorithm of V1101 and
V1101EX_R1 is the same, but using data policy is slightly changed, since our
continuous efforts of quality control (QC) flagged some data.
2. General Information
2.1 Product
We make V1101EX_R1 for 2007-2015, which
means, the year 2007 is overlapped in V1101 and V1101EX_R1. This is for the
users of careful treatment of using the two datasets. Data of Monsoon Asia
(APHRO_MA) in simple binary format that can be handled with GrADS software is
released now. Those for Middle East (APHRO_ME), Russia (APHRO_RU) and whole
Asia (APHRO_PR) will be released in a couple of months.
Each domain of the product, resolution,
file format are the same with what we have released. So, please see the "readme"
of V1101 which is attached below.
3. Reference and contact
We have not written a
document for V1101EX_R1, so when you publish a paper by using this data, please
refer Yatagai et al. (2012, BAMS) and write V1101EX_R1 is update of V1101 and
refer this page (http://aphrodite.st.hirosaki-u.ac.jp).
We welcome your
feedback. The contact postal address and email addresses are given here.
PI
of the APHRODITE-2 project
Prof. Akiyo YATAGAI (Course of Meteorology, Graduate School of Science and Technology, Hirosaki University)
3 Bunkyocho, Hirosaki City, Aomori,
036-8561, Japan
Technical
Inquiries
APHRODITE project team Aphrodite.precinfo@gmail.com
General
Inquiries
APHRODITE secretariat Aphrodite.secretary@gmail.com
README document for APHRO_V1101
(Last updated 27 September, 2018)
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.
After releasing our last product,
APHRO_V1003R1, in July 2010, we have
made continuous
efforts to collect more data and improve quality control
and analysis
method. We now release APHRO_V1101,
which includes more
rain-gauge data
and data region is changed for the Middle East product
according to the
distribution of input gauge data.
This README interprets the
structure of APHRO_V1101 data files
(sections 2-5),
explains changes from the previous versions (section 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
data over Monsoon
Asia (APHRO_MA_V1101), the Middle East (APHRO_ME_V1101),
and
Russia/Northern Eurasia (APHRO_RU_V1101).
The gridded fields of daily
precipitation are defined by interpolating
rain-gauge observations
obtained from meteorological and hydrological
stations
throughout the region. We use new
daily precipitation climatology
and interpolate
the ratio of the daily precipitation to the climatology at
a resolution of
0.05 degrees, then multiplied each gridded ratio by each
gridded
climatology value day-by-day. We
then re-gridded the 0.05-degree
analysis to both
0.5-degree and 0.25-degree grids.
Details are given in a
paper by Yatagai
et al. (2009, 2012) and other related papers listed in section 7.
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.
2.2 Spatial and Temporal Coverage
Spatial coverage : (MA) 60.0E - 150.0E, 15.0S - 55.0N
: (ME) 20.0E - 65.0E, 15.0N - 45.0N
: (RU) 15.0E - 165.0W, 34.0N
- 84.0N
Spatial resolution : 0.5 degree and 0.25 degree
latitude/longitude
Temporal coverage : January 1, 1951 - December 31, 2007 (57
years)
Temporal resolution : Daily
2.3 Units
Precipitation : mm/day
Ratio of 0.05 grid box containing
station(s) : %
2.4 Missing Code
Precipitation : -99.9
Ratio of 0.05 grid box containing
station(s) : -99.9
3. Data Files and Their Structure
The product is stored in one file
per year.
3.1 Denotation
APHRO_XX_YYYdeg_V1101.ZZZZ
XX : Region (MA/ME/RU for Monsoon Asia/Middle
East/Russia)
YYY :
Resolution (050/025 for 0.5/0.25-degree grid)
ZZZZ : The year in 4 digits (e.g. 1951, 1952,
..., 2007)
For the file in NetCDF format,
filename ends with the suffix ".nc."
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,
90 x 60 elements for APHRO_ME,
360 x 100 elements for APHRO_RU.
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 2 fields x
365 days = 73,584,000 bytes
for a non-leap
year, or 73,785,600 bytes for a leap year.
4. How to handle the dataset
4.1 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_V1101 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_V1101.ctl).
4.2 Sample Fortran 90 Program
A sample program written in
Fortran 90 (read_aphro_v1101.f90) is
available in the
directory /V1101. Note that the
little-endian byte order is
assumed in this
program.
4.3 NetCDF files
We provide NetCDF files for each
year. They are stored in /V1101/nc with suffix
".nc".
Matlab, ArcGIS and many applications can handle NetCDF.
5. References
5.1 How to cite
APHRO_V1101
Should you refer to our product in your paper/presentation,
please
cite Yatagai et
al. (2012).
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
Details on quality control method of our
product is described in Hamada et al.(2011)
Hamada, A., O. Arakawa and A.
Yatagai, 2011: An automated quality control
method for
daily rain-gauge data. Global Environmental Research, V15N2,
pp183-192.