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) 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) 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) 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) 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)