GAME Asian Automatic Weather Station Network (AAN) Data
Set Ver.3.0 (through year 2002)
Sugita, M1, Nohara,
D.2,3,
and
Yasunari, T.5
1 Graduate School of Life and Environmental
Sciences,
2 Terrestrial Environment Research Center,
3 Now at Meteorological Research Institute,
Tsukuba,
4 Now at
5 Now at Hydrospheric Atmospheric
I
INTRODUCTION
GEWEX Asian Monsoon Experiment, in which
GEWEX stands for Global Energy and Water cycle Experiment (GAME, Yasunari et al, 2003,
) has been implemented since 1996 to understand the role of the
Asian monsoon in the global energy and water cycle and to improve the
simulation and seasonal prediction of Asian monsoon patterns and regional water
resources. Within the framework of
GAME, Asian AWS (Automatic Weather Station) Network project was initiated with
main objective of the observation and the detection of seasonal and annual
variations of surface fluxes of momentum, heat, and radiation as well as those
of soil moisture on the continental scale. At the same time, its objective
includes a support for the regional studies of GAME carried out in
This GAME/AAN data set version 3.0 includes not only the content of version 1.0 and 2.0 CD-ROMs (Nohara et al., 2003, 2004) but also new additional data sets, figures, documentation and revision/correction that have become available since the publication of the version 2.0 data set in a single DVD-ROM. Version 3.0 set covers the data obtained from the starts of measurements (1997-1999 depending on sites) through year 2003 within the framework of GAME/AAN project, and is the exact copy of the web version of the GAME-AAN data center at as of April 1 of 2005.
II.
GAME/AAN PROJECT
2.1
Objectives
The Eurasian continent, the largest continent on the earth, plays a predominant role on the seasonal cycle of the planetary‑scale surface energy exchange and transport in the climate system. The diverse land surfaces and vegetations, however, characterize the extremely large seasonal and spatial variation of surface sensible and latent energy fluxes over the continent, which in turn may produce the regionality and asymmetries in the seasonal cycle over the continent.
The surface net radiation flux is a fundamental forcing of the sensible and latent energy fluxes. The estimation of these fluxes over the global surface was formerly carried out by Budyko (1956). This task should be updated by utilizing the satellite as well surface observations with higher quality and resolution over the whole of the continent, which is one of the major tasks of the GEWEX. The surface energy budgets are fundamental forcing of the seasonal march of the climate system. These elements are particularly important over the eastern half of the Eurasian continent, to unravel the role of the land/ocean heating contrast on the Asian winter and summer monsoon systems.
There has been, so far, a considerably dense routine observation network of surface meteorological station in the eastern half of this continent, maintained by the operational meteorological agencies of each country. However, these station data are providing only indirect measures for estimating the surface radiation and energy budgets over the broad area of the continent, based mainly upon the bulk method. In addition, the diverse and heterogeneous land surfaces of the continent make it more difficult to estimate the appropriate bulk transfer coefficients for the momentum, heat and moisture fluxes of each station.
The
satellite‑based SRB (Surface Radiation Budget), combined with the surface‑based
BSRN (Baseline Surface Radiation Network), has been continuously providing us
with data sets of surface radiation elements with continental‑scale coverage.
The long‑term monitoring of directly‑measured energy fluxes, however, was not
undertaken except at a very few micro‑meteorological stations in the beginning
of GAME project. The continental‑scale
monitoring system of surface energy fluxes and surface conditions (albedo, soil moisture, vegetation etc.), combined with the
radiation network mentioned above, will provide us with key information for
unraveling the physical processes of the recent climate change (e.g., rapid
warming over
To remedy the lack of a surface measurement network, it was important to construct a network of surface stations. Such network should have a major objective of the observation and the detection of seasonal and annual variations of surface fluxes of momentum, heat, and radiation as well as those of soil moisture on the continental scale as part of GAME scientific activities. At the same time, it's objective should have included a support for the regional studies, particularly their intensive field experiments. The latter requires the accurate determination of the above variable on a time scale of hour.
1.2
Strategy and Schedule of GAME/AAN project
Because the two major aims required different and somewhat contradictory requirements for the specification and configuration of a surface station, it was decided to organize AAN activities in two phases.
Phase I for the year 1996‑2000 would be the period for the construction, tests, and deployment of the AAN, and also for data acquisition during the intensive observations planned in 1998. For the Phase I, measurements would be made of (i) regular meteorological variables such as temperature, humidity, wind speed, etc., (ii) regular hydrologic variables such as precipitation, (iii) surface turbulent fluxes of momentum, heat and water vapor, (iv) surface radiative fluxes, and (v) soil moisture.
The subsequent Phase II (year 2000‑2004) have been designated as the long term monitoring period.
1.3
Development and selection of Automatic Weather Station (AWS)
An important function of the AWS system is to measure the radiation and energy flux components, with the surface parameters (soil moisture, snow cover etc.). At the time of GAME/AAN project planning stage in 1994-1996, AWS systems to fully satisfy this purpose are not available. Among the candidates as an AWS to be used during Phase I, a Portable Automated Mesonet (PAM) III station which were in the stage of development at National Center for Atmospheric Research (NCAR) in the U.S., was selected as a candidate, and scientists in AAN project worked closely with NCAR scientists and engineers to modify and improve the PAM III station to meet needs and requirements for AAN.
PAM III station uses a 3D sonic anemometer and a hygrothermometer to determine surface turbulent fluxes of momentum, heat and water vapor by applying an eddy correlation technique and bandpass covariance method. For GAME‑AAN, addition of second hygrothermometer and an infrared radiation thermometer was considered to allow flux evaluation by means of a Bowen ratio method, a profile method, and of a bulk method in order to increase the reliability of flux determination over a prolonged period in a remote area. In addition, sensors needed to apply time domain reflectometry (TDR) technique was added to PAM III, in order to add capability to monitor the soil moisture. Furthermore, 4-component radiometers were added to allow direct measurements of radiation budget at the surface. A novel feature of the PAM III station was its capability to transmit the data through a geostationary satellite. This function was implemented with a Japanese geostationary satellite, GMS, with permission from Japan Meteorological Agency for the real time monitoring of the status of the station as well as real time data acquisition.
Since the PAM III station may lack the capability to operate safely in a severe cold environment to be encountered in GAME as it has not been tested in such conditions, improvements of the station system as well as possibility of the development of other AWS systems specifically designed for such cold environment were carried out. These systems are similar in its measured component with main difference being lack of continuous eddy correlation measurements.
1.4
Deployment of the Station
Overall, 15 stations were established (see Fig.1) and valuable data have been accumulated. Essentially, the location of each station has been selected to fulfill the following requirements: (i) the location should represent the surrounding general area of 100 by 100 km in terms of vegetation, geomorphology, and climate. (ii) the location should allow maintenance of the station to guarantee the long-term measurements.
Fig.1 GAME/AAN station
1.5
Scientific Results
To summarize and wrap-up the Phase I
activities and to address future needs of AAN activities, the International
Workshop on GAME-AAN/Radiation was held at Phuket in
One of the issues that has emerged in the process of deploying AWSs and the data analysis is the so-called energy imbalance problem. Theoretically, the sum of latent and sensible heat fluxes should be balanced with net radiation and soil heat flux. However, in many AAN sites this turned out not to be the case, although some sites reported close to perfect balance. Current consensus appears that the closure problem is site specific and that up to 20-30% of the net radiation may not be able to account for from measurements. Possible reasons have been identified as a problem of turbulence measurements technique, sampling error of the soil heat flux and the net radiation measurements, and a mismatch of foot print of equipments used to measure energy balance components. Intensive discussions at scientific meetings, both at the international workshop and other related meetings, took place, and as a result, an additional field observation initiative has started in which 5-10 eddy flux measurement systems were installed side by side at a well maintained and controlled site, and their difference, and possible causes for the imbalance problems are being investigated.
Although Phase I is for the test and deployment of AWS systems, some initial results of a long term measurements are being reported. For example, three geographically very different locations showed difference in variations of surface energy partition regime, both in time and in magnitude (Miyazaki et al., 2001). Additionally, some interesting and encouraging results were reported with the Phase I AAN data set. Comparisons of the surface fluxes obtained from one AAN surface station and from GAME and ECMWF reanalysis data were reported in Yatagai et al., 2001. For the reanalysis data, flux values of the nearest grid were used. The comparison indicates reanalysis very good agreement of the measurements and model derived values. This tends to indicate, in the viewpoint of the surface station, that a point measurement of the station represents somehow a region surrounding the station. This is encouraging for the use of the AAN data and actually may not be too surprising given the fact that each station site was selected so as not to be too local and not to be too different from its surrounding areas. Sugita et al. (2001) and Sugita (2001) are an example of the use of AAN data for the model validation. Because AAN sites cover a wide range of geographical areas and climates, a comparison of any variables produced from a model or from a satellite against the AAN data sets should give opportunity for a thorough validation of these data (and, in turn, the model or the satellite measurements themselves).
III
Data set
3.1
Summary
The
data have been checked by each P.I. and processed for archiving at the AAN data
center at
3.2
Use of the data
[Mac and Windows User]
1. Put this DVD-ROM into the DVD-ROM drive on your computer.
2. Web browser will automatically run to show the main menu.
3. If it does not, click the DVD-ROM to open the top folder of the DVD-ROM
4. Double click 'start.html' to run web browser to show the main menu.
[Linux, FreeBSD and other UNIX users]
1. Put this DVD-ROM into the DVD-ROM drive on your computer.
2. Mount the DVD-ROM on your system.
3. Run your browser.
3. If the DVD-ROM is mounted at a mounting point "/DVDROM", then type the URL below in the location window on your browser:
file:///DVDROM/start.html
4. If you do not know how to do the above, ask your administrator.
All data are contained in ‘’./aan/datalists/’’ separated by each observational station, and these are created by csv format.
3.3
Citation of this CD-ROM data set
When data in this CD-ROM are used in scientific researches, please add the following reference to the publication.
Sugita, M, Nohara,
D.,
IV.
Concluding Remarks
The GAME/AAN data set is being updated continuously to make it more accurate, reliable, trustworthy, and user-friendly. For that we need inputs from a user of the data. Usually P.I.s are not necessarily an appropriate person to find problems. Rather, an independent user is much more suitable to do so. Thus we wait and welcome any comments/reports on the data set. Also suggestions for improvement will be greatly appreciated. You can contact us at GAME/AAN data center by e-mail at aan@suiri.tsukuba.ac.jp, or by fax +81-29-853-2530.
Acknowledgements
The data contained in this GAME/AAN data
set have been obtained, compiled and prepared by the responsible PIs of each station
through cooperation of local counterpart organizations and personnel. They are listed in the data set
documentations and we would like to thank them all for their additional time
and efforts to make their data available to the general scientific communities. Thanks are also to K. Hayashida and A. Shiwozawa at
Terrestrial Environment Research Center of University of Tsukuba, for helping
to compile the data sets. The
preparation and publication of the GAME/AAN data set have been supported, in
part, by Ministry of Education, Culture, Sports, Science and Technology through
Japan Society for the Promotion of Science (Grants-in-Aid for Publication of Scientific Research Results,
Database, no.148070 for FY 2002 and no.158071 for FY2003, no. 168070 /for FY2004)
.
References
Aoki, M., T. Chimura, K. Ishii, I. Kaihotsu, T. Kurauchi, K. Musiake, T. Nakaegawa, N.Ohte, P. Panya, S. Semmer, M. Sugita, K. Tanaka, O. Tsukamoto and T. Yasunari, 1998: Evaluation of surface fluxes over a paddy field in tropical environment: Some findings from preliminary observation of GAME, J. Japan Soc. Hydrology & Water Resour. , 11, 39-60.
Budyko, M.I., 1956: Heat Balance of the Earth's Surface (in Russian), Gidrometeoizdat,
Ma, Y., O. Tsukamoto, I. Tamagawa, J. Wang, H. Ishikawa, Z. Hu and H. Gao, 2000: The study of turbulence structure and transfer characteristics over the grass land surface of Tibetan Plateau, Chinese J. Atmos. Sci., 24, 456-464.
Miyazaki, S., O. Tsukamoto, M. Toda, N. Ohte, K. Tanaka, I. Kaihotsu, T. Miyamoto and T. Yasunari, 2001: A comparative study of seasonal variation of surface heat flux in Asian Monsoon region, Proc. Int. Workshop GAME-AAN/Radiation, GAME Public. ,No.28 ( Bull. Terrestrial Environ. Res. Cen., Univ. Tsukuba, No. 1), Pucket, Thailand, 95-97.
Nohara, D.,
Nohara, D.,
Ohta, T., K. Suzuki, Y. Kodama, J. Kubota, Y. Kominami and Y. Nakai, 1999: Characteristics of the heat balance above the canopies of evergreen and deciduous forests during the snowy season, Hydrological Processes, 13, 2383-2394.
Ohta, T., T. Hiyama, H. Tanaka, T. Kuwada, T.C. Maximov, T. Ohata and Y. Fukushima, 2001: Seasonal variation in the energy and water exchanges above and below a larch forest in Eastern Siberia, Hydrological Processes, 15, 1459-1476.
Sugita, M., 2001: Estimation of large scale evaporation by a complementary relationship with a simple ABL model. Proc. Int. Workshop GAME-AAN/Radiation, GAME Public., No.28 ( Bull. Terrestrial Environ. Res. Cen., Univ. Tsukuba, No. 1), Pucket, Thailand, 91-93.
Sugita, M., J. Usui, I. Tamagawa and I. Kaihotsu, 2001: Complementary relationship with a convective boundary layer model to estimate regional evaporation, Water Resour. Res., 37, 353-365.
Toda, M., N. Ohte,
M. Tani and K. Musiake,
2001: Observation of energy flux and evapotranspiration
over terrestrial complex land in the tropical monsoon region, J. Meteor. Soc.
Yatagai, A.,
.
Yasunari, T., K. Nakamura,A. Higuchi, and J. Asanuma, 2003: GAME Summary Reports, GAME Publication No.37. 133p.