README document for AphroTemp_V1808 (Last updated 26 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 (Yatagai et al., 2011). APHRODITE first term was finished in 2010 and APHRODITE second term has begun in 2016, in collaboration with Hirosaki University, Kyoto University and Chiba University. To develop long-term daily gridded precipitation and temperature datasets from rain-gauge observation records over Asia by international collaborations with local meteorological/hydorlogical agencies and researchers. AphroTemp_V1808 is daily mean temperature product as 0.50 and 0.25 degree gridded daily product. More data is collected and analyzed than AphroTemp_V1204R1 and data period is also extended to 2015. Topographical effect scheme is introduced to interpolation algorithm. Surface observations in India, Bhutan, Thailand, Myanmar are added to the grid analysis after AphroTemp_V1204R1 Increase of them and improvement of interpolation algorithm, climate and estimated values in South Asia show good representation in new product. This README interprets the structure of AphroTemp_V1808 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 daily mean temperature data over Monsoon Asia (APHRO_TAVE_MA_V1808). The gridded fields of daily mean temperature are defined by interpolating gauge observations obtained from meteorological stations throughout the region. The algorithm for the new product is made with a few modification on that of APHRO_V1101. We interpolate the subtraction of the daily mean temperature from the climatology at a resolution of 0.05 degrees, then add each gridded subtraction to 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 Yasutomi et al. (2011) and other related papers listed in section 7. An indicator is introduced to represent the reliability of the interpolated daily temperature 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 Spatial resolution : 0.5 degree and 0.25 degree latitude/longitude Temporal coverage : 1961-2015 Temporal resolution : Daily 2.3 Units Daily mean temperature : degC Ratio of 0.05 grid box containing station(s) : % 2.4 Missing Code Daily mean temperature : -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_MA_TAVE_YYYdeg_V1808.ZZZZ YYY : Resolution (050/025 for 0.5/0.25-degree grid) ZZZZ : The year in 4 digits (e.g. 1961, 1962, ..., 2015) 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 daily mean temperature 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 monsoon Asia. In the case of the 0.5-degree APHRO_MA_TAVE 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 temperature 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_TAVE_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. 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 AphroTemp_V1808 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_TAVE_MA_050deg_V1808.ctl). 5. Sample Fortran 90 Program A sample program written in Fortran 90 (read_aphro_v1808.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 AphroTemp_V1808 We are preparing a paper that presents our algorithm for AphroTemp_V1808. Should you refer to our product in your paper/presentation, please cite the reference paper of V1204R1(former version, Yasutomi et al., 2011) for the present. We will notice when AphroClim_V1808 reference paper is pubilshed to registered users. Yasutomi, N., A. Hamada and A. Yatagai (2011): Development of a long-term daily gridded temperature dataset and its application to rain/snow descrimination of daily precipitation, Global Environmental Research, V15N2, 165-172. When you write/publish papers, please access the "Research Activities" page of our website ( http://aphrodite.st.hirosaki-u.ac.jp/publications.html ) to obtain the latest information on our reference papers that present our algorithms and products. 6.2 Reference for the related products The following are references of the related versions. 1) Yatagai, A., K. Kamiguchi, O. Arakawa, A. Hamada, N. Yasutomi and A. Kitoh (2012): APHRODITE: Constructing a Long-term Daily Gridded Precipitation Dataset for Asia based on a Dense Network of Rain Gauges, Bulletin of American Meteorological Society, doi:10.1175/BAMS-D-11-00122.1. 2) Yasutomi, N., A. Hamada and A. Yatagai (2011): Development of a long-term daily gridded temperature dataset and its application to rain/snow descrimination of daily precipitation, Global Environmental Research, V15N2, 165-172. 3) 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. Points of concern 1) Lack of observation data (in Indonesia and Papua New Guinea) Input of daily observations over Indonesia and Papua New Guinea are lacked. A considerable number of temperature grids over New Guinea Island are missing until 1980's. Distribution of valid station observation is provided (RSTN) for each day. Users please pay attention to the density of observations. 2) Homogenization of observation We do not homogenize the observed time series of temperature data. Changes in gauges, location of the stations, and many other factors might cause discontinuity of observation data. 3) Improvement in calculation after Yasutomi et al.(2011) Anomaly interpolation method is introduced after publish of Yasutomi et al. (2011). Climatological mean temperature is based on AphroClim_V1808. First, we derive anomaly from climatology, next, anomalies are interpolated into 0.05 degree grid. Then summed up to climatology and regridded into 0.25 degree and 0.50 degree grid. 8. Contacts Please contact APHRODITE project (led by Dr. Akiyo Yatagai of Hirosaki University) for further questions regarding this product. APHRODITE's Water Resources project http://aphrodite.st.hirosaki-u.ac.jp Technical inquiries APHRODITE project team aphrodite.precinfo@gmail.com General inquiries APHRODITE secretariat aphrdite.secretary@gmail.com (Contact) Dr. Natsuko Yasutomi Disaster Prevention Research Institute, Kyoto University Gokasho, Uji, Kyoto 611-0011, Japan Principal Investigator Prof. Akiyo Yatagai Course of Meteorology, Graduate School of Science and technology, Hirosaki University