• 検索結果がありません。

Installation and observation results of the Argos system at the Angkor Wat Meteorological Observation Station

N/A
N/A
Protected

Academic year: 2021

シェア "Installation and observation results of the Argos system at the Angkor Wat Meteorological Observation Station"

Copied!
8
0
0

読み込み中.... (全文を見る)

全文

(1)

to monitor climatic data in a continuous manner is re-quired to obtain continuous climatic data.

Therefore, we decided to install a new monitoring sys-tem, Argos system. The Argos system is a transmission and reception system that intermediates signals between polar orbiters and observation objects. It is possible for this system to obtain positioning data from all over the world, if the objects have a platform transmitter terminal (PTT). Although it is difficult to monitor objects in real time, the Argos system can be used for one day monitor-ing. Thus, installation of the Argos system for AMOS was planned and performed. This paper reports on the obser-vation data since 2011, in addition to the outline of the Ar-gos system and feasibilities of physical geographical usage.

Argos system and its installation at AMOS Description of the Argos system

The Argos system is a system that estimates the posi-tion of an object and collects various data transmitted from the PTT through polar orbiters. It uses the Doppler effects to estimate the position of the object. The PTT is mainly placed on mobile objects, such as wild animals (e.g., Haneda et al., 2017), sea ices, glaciers (e.g., Inoue et Introduction

In order to analyze the progress of weathering of stone-built temples such as the Angkor monuments in Cambo-dia, we established a meteorological station called Angkor Wat Meteorological Observation Station (AMOS) at the Angkor Wat temple in December 2010 (Waragai et al., 2013). A climatic dataset of AMOS confirmed the temper-ature differences between the green belt and the stone-built temples that were designated as the world heritage status by UNESCO. The dataset also offers explanations for the climatic environment of an area of the Angkor monuments.

However, it was observed that AMOS occasionally stopped working. Since an observation field of AMOS is situated under a tropical environment, the reason for its malfunctioning can be attributed to insects such as spi-ders and termites and an overgrown grasses in addition to aging of the equipment. Monitoring of equipment and weeding in the observation field were done by the Author-ity for the Protection and Management of Angkor and the Region of Siem Reap (APSARA) that supervises the Ang-kor monuments in Cambodia. However, it is difficult to predict undetectable faults such as those of a sensor by aging. We strongly believe that a new system that is able

As a new meteorological monitoring system, in 2014, the Argos system was successfully installed at the Angkor Wat Meteorological Observation Station (AMOS) in Cambodia. The Argos system has been utilized as a tool for collecting and relaying meteorological and oceanographic data and animal track data from around the world. The system is suitable for remote areas with no communication networks. This paper reports on the meteorological observation data since 2011, in addition to the outline of the Argos system and feasibilities of physical geographical usage. Since the time of its installation at AMOS, no trouble due to communication condition has encountered up to September 2017. Therefore, it is believed that transmission and reception of data are stable with this semi-real time monitoring. However, it is necessary to improve for obtaining high accurate elevation data.

Keywords : Argos system, Automatic weather station, Angkor Wat, Cambodia

Installation and observation results of the Argos system at

the Angkor Wat Meteorological Observation Station

Tetsuya WARAGAI

(Accepted November 30, 2017)

 * Department of Geography, College of Humanities and Sciences, Nihon University: 3-25-40 Sakurajyosui, Setagaya-ku, Tokyo, 156-8550 Japan

(2)

al.,2010;Alford et al., 2016), buoys (e.g., Roemmich et al., 2009), or weather stations, located in remote areas in order to collect in situ atmospheric data.

The Argos system was created in 1978 under a Memo-randum of Understanding by the French Space Agency (CNES), the National Aeronautics and Space Administra-tion (NASA), and the NaAdministra-tional Oceanic and Atmospheric Administration (NOAA) originally as a scientific tool for collecting and relaying meteorological and oceanographic data around the world (Argos HP). Recently, other inter-national space agencies such as the European Organiza-tion of the ExploitaOrganiza-tion of Meteorological Satellites (EUMETSAT) and the Indian Space Research Organiza-tion (ISRO) have also participated in the Argos system. Since 2016, the Argos system has been utilized six polar orbiting environmental satellites (NOAA-15, -18, -N, METOP-A, -B, and SARAL).

Data that the satellites receive from the PTT are distrib-uted to researchers through the receiving stations, pro-cessing centers, and finally user service centers. In 1986, CNES created a subsidiary Collecte Localisation Satellite (CLS), to operate, maintain, and commercialize the sys-tem. Cubic-i Ltd serves as an agent for the Argos system in Japan.

Accuracy of the object position in the Argos system de-pends on the angle of satellite elevation, number of signals received from the PTT, and so on (Haneda et al., 2017). In surfaces such as air or marine surface wherein sky view factor is high, high accuracy data is obtained as there is a small probability for radio interference between the PTT and satellites. The accuracy is classified based on the Argos location using the Doppler effects: Class 0: ≥ 1500 m; Class 1: 500–1000 m; Class 2: 250–500 m; and Class 3: <250 m (CLS, Argos User’s Manual, 2016). Al-though the Argos system was mainly utilized for tracking wild animals since 1983 (e.g., Oi et al., 2002, Yamazaki et al., 2008, Hino and Ishida, 2012, Haneda et al., 2017), in the case of objects that travel long distance such as migra-tory birds or marine organisms, an error of the position estimated is negligible. This makes the system unsuitable for the estimation of position of objects in faraway dis-tance with high accuracy. Therefore, we fix a global posi-tioning system (GPS) to objects and transmit data to the satellite through the PTT, enabling the system to obtain data with <100 m accuracy (Class G). However, it is

diffi-cult to estimate elevation of the object with high accuracy since the system uses DEM data based on USGS GTO-PO30.

Installation of the Argos system for AMOS

The AMOS (N13°24′48.1′′, E103°51′44.7′′, altitude; 29 m) is located at the Angkor Wat temple and was installed on December 22, 2010 after obtaining the approval of the APSARA Authority and cooperation of Sophia University Asia Center for Research and Human Development (Fig. 1). The installed equipment includes a temperature and hu-midity probe, an anemoscope, anemometers, pyranome-ter, solar panel, and measurement and control module. A tipping bucket rain gauge was also set in the observation field. The quantities measured include air temperature, relative humidity, rainfall, wind direction, wind speed, and insolation. These are measured by the respective sensors at ten-minute intervals.

AMOS is in the range of mobile phone communication in Cambodia. However, with the usage of this network, non-residents face the problems of subscription proce-dures and payment. In addition, we suppose a semi-real-time monitoring of a one-hour unit although climatic data have been collected at a 10-minute interval at AMOS. Be-cause the PTT does not transmit large chunks of data, it is believed that the Argos system is suitable for AMOS. A module of transmission and reception for Argos-3 (PMT YTR-3000, Kenwood) was installed at AMOS on Decem-ber 27, 2014 (Fig. 1). The module with dimensions of 25 × 80 × 60 mm and 160 g weight was connected to a data logger (CR-1000, Campbell Scientific, Inc.) of AMOS and was housed inside a measurement box. A communication antenna usually installs outside of the box. However, the antenna is unable to fix outside the box due to the precinct of Angkor Wat temple. Therefore, a downsized antenna was placed inside the box (Fig. 1). A communica-tion program was made by Climatec Inc for the satellites. Results

Since the installation of the Argos system on December 27, 2014, no trouble due to communication condition has encountered up to September 2017. Hence, it is believed that transmission and reception of data are stable.

Waragai et al. (2013) has reported preliminary results observed between December 23, 2010, and March 17,

(3)

2012. Although the Argos system was installed in the month of December in 2014, this report concludes with the results observed between January 1, 2011, and De-cember 31, 2016. Daily climatic data such as average wind speed (m/sec), average wind direction (degree), average temperature (ºC), average humidity (%), accumulated in-solation (MJ), and rainfall (mm) are shown in Table 1. Due to a fault of sensor or exchange of equipment, their missing data are eliminated from this Table 1.1).

Table 1 also shows the daily averages of the observed parameters between 2011 and 2016 and the averages of each year. The highest average daily temperature (abso-lute max.) was recorded to be 41.3ºC in April 2016 and the lowest was 13.9ºC (absolute min.) in January 2014 (Table 1). The maximum temperature (absolute max.) showed the lowest value of 36.1ºC in March 2011, with the annual temperature of the year being low as well. In contrast, the maximum of daily minimum temperature (absolute min.) was 18.2ºC in January 2012, with the temperature of dry season in this year being warmer than that in other years

during the observation period.

Annual precipitation has ranged between 1161.5 mm (2015) and 2065 mm (2011). This indicates that the annu-al precipitation significantly fluctuated during the obser-vation period, for example, number of rainy days of ≥1 mm was 124 days in 2011 but it was 80 days in 2015. In addi-tion, in October 2011, the daily maximum rainfall of 98.5 mm was recorded.

Monthly averages of some climatic elements from 2011 to 2016 are shown in Table 2. Annually, the mean temper-ature was 27.3ºC, mean humidity was 79.0%, and mean precipitation was 1633.6 mm during the observation peri-od. Regarding temperature fluctuation, it was found that high temperature season is from March to May and low temperature season is December to January. It is be-lieved that other periods, June to November and February are transaction periods between high and low seasons. On the basis of progress of monthly precipitation, it is be-lieved that the rainy season (having >200 mm rainfall per month) starts from June to October and the dry season Fig. 1 Location of AMOS (A) and installation equipment of the Argos system (B and C).

(4)

Table 1 Results of daily observation from 2011 to 2016.

Wind speed

(m/sec) Wind direction (degree) Air temperature (℃ ) Rerative humidity (%) Insolation (MJ) Rainfall (mm)

Daily statics fr om 2011 to 2016 Average 0.44 143.44 27.27 78.97 17.58 4.46 Standard error 0.01 1.69 0.08 0.39 0.11 0.30 Median 0.47 142.99 27.20 79.62 17.48 2.37 Standard deviation 0.15 32.29 1.55 7.49 2.14 5.78 Variance 0.02 1042.78 2.41 56.04 4.57 33.44 Range 0.75 172.26 7.26 33.39 12.91 33.83 Minimum 0.16 63.96 23.43 60.26 10.60 0.00 Maximum 0.91 236.22 30.69 93.65 23.52 33.83 Total 162.23 52500.30 9980.08 28903.02 6434.13 1633.57 Sample number 366 366 366 366 366 366 Confidence interval (95.0%) 0.02 3.32 0.16 0.77 0.22 0.59 2016/1/1~12/31 Absolute max 10.25 357.60 41.33 99.20 26.02 81.00 Appearance 22 Apr 26 Jan 11 Apr 28 Sep 2 Jun 6 Jul

Absolute min 0.00 0.00 14.29 14.90 2.79 0.00

Appearance − − 26 Jan 14 Apr 27 Aug −

Range 10.25 357.60 27.04 84.30 23.23 81.00

Total − − − − − 1442.00

Number of rainy day

(≥ 1mm/day) − − − − − 105/366 days

Average − − 28.02 76.50 − −

2015/1/1~12/31

1)

Absolute max 10.03 342.20 40.74 98.00 25.82 74.00 Appearance 26 May 12 Jan 20 Apr 15 Jul 11 May 10 Sep

Absolute min 0.00 0.00 15.40 24.43 4.82 0.00

Appearance − − 17 Jan 4 Apr 9 Jul −

Range 10.03 342.20 25.34 73.57 21.00 74.00

Total − − − − − 1161.50

Number of rainy day

(≥ 1mm/day) − − − − − 80/364 days

Average − − 27.60 73.54 − −

2014/1/1~9/11

Absolute max 9.35 237.13 37.83 98.60 25.83 77.00 Appearance 3 Jun 9 Jul 26 Apr 12 Sep 23 May 4 Sep

Absolute min 0.00 0.00 13.87 30.50 6.71 0.00

Appearance − − 25 Jan 23 Mar 1 Sep −

Range 9.35 237.13 23.96 68.10 19.11 77.00

Total − − − − − 1022.50

Number of rainy day

(≥ 1mm/day) − − − − − 72/254 days

Average − − 27.32 77.73 − −

2013/1/1~12/31

Absolute max 8.82 268.75 39.24 99.70 25.67 80.00 Appearance 22 Jun 18 Sep 7 Apr 28 Oct 1 May 11 Jun

Absolute min 0.00 0.00 14.53 30.22 4.66 0.00

Appearance − − 28 Dec 17 Jan 17 Sep −

Range 8.82 268.75 24.71 69.48 21.01 80.00

Total − − − − − 1973.00

Number of rainy day

(≥ 1mm/day) − − − − − 122/365 days

Average − − 27.02 80.00 − −

2012/1/1~12/31

Absolute max 10.55 257.32 38.34 98.70 25.28 57.50 Appearance 30 Jul 22 Jul 25 Apr 14 Sep 3 May 28 Aug Absolute min 0.00 25.98 18.21 33.02 6.33 0.00

Appearance − 25 Nov 9 Jan 11 Feb 18 Sep −

Range 10.55 231.34 20.13 65.68 18.95 57.50

Total − − − − − 1580.00

Number of rainy day

(≥ 1mm/day) − − − − − 113/366 days

Average − − 27.42 80.14 − −

2011/1/1~12/31

Absolute max 10.77 256.45 36.11 98.80 25.04 98.50 Appearance 14 May 22 Jun 20 Mar 25 Sep 3 Jul 14 Oct

Absolute min 2.00 38.86 15.33 28.81 2.68 0.00 Appearance 8 Oct 22 Nov 12 Dec 20 Jan 19 Sep −

Range 8.77 217.59 20.78 69.99 22.37 98.50

Total − − − − − 2065.00

Number of rainy day

(≥ 1mm/day) − − − − − 124/365 days

Average − − 26.56 79.54 − −

1) Missing data: Temperature 2015/3/2, 5/26, 6/7, 6/8, 7/6, 7/14, 7/15, 7/26, 7/27, 8/3, 8/4, 8/8, 12/25.Humidity 8/15 ∼12/24. -: no counting

(5)

2, 3, and 4. The average daily temperature was maximum (30.7ºC) in April and minimum (23.4ºC) in December (Fig. 2). Fluctuations of daily precipitation and daily mean humidity are shown in Figure 3. Rainfall is very seldom ( ≥ 20 mm/month) starts from December to February.

November and the period of March to May are alternative seasons in rainfall.

Fluctuations of daily mean value are shown in Figures

Table 2 Average Montly data of AMOS from 2011 to 2016.

Temperature (℃) Relative humidity (%) Mean Insolation (MJ) Total Insolation (MJ) Precipitation (mm) Jan 24.9 72.9 16.9 523.2 0.8 Feb 26.8 70.1 17.4 505.7 0.1 Mar 28.8 68.2 18.7 580.6 35.0 Apr 29.6 70.5 19.7 591.2 71.0 May 29.3 75.7 20.4 632.4 121.9 Jun 28.1 80.9 17.7 530.4 242.9 Jul 27.4 83.7 17.1 529.2 221.8 Aug 27.4 84.7 18.0 558.3 256.1 Sep 26.8 89.0 15.7 472.0 357.5 Oct 26.6 88.4 16.6 516.0 243.9 Nov 26.7 84.9 16.4 492.7 66.8 Dec 25.0 78.4 16.2 502.5 15.7 Annual mean 27.3 79.0 17.6 536.2 136.1 Annual total 327.4 947.4 210.8 6434.1 1633.6

(6)

Fig. 3 Daily fluctuations of rainfall and relative humidity. Moving average is calculated from 10 days.

(7)

tion and elevation data.

Fixed meteorological observation does not demonstrate the performance of the Argos system completely but one merit of the system is semi-real time monitoring. In par-ticular, it is suitable for remote areas with no communica-tion networks. Alford et al. (2016) used this system to monitor glaciers in mountains and obtained high accurate position data using GPS positioning. Regarding accuracy of the elevation, a virtual reference station needs to be set in the remote area, which is tedious. Despite increasing volume of communication data, by transmitting stereo im-ages to the satellite, it is possible to monitor and obtain el-evation data by photographic surveying.

Acknowledgements

The author would like to thank Mr. Y. Hiki for system installation in the observation field. In order to install the Argos system for AMOS, JSPS KAKENHI (Grant Number JP 26300008) financially supported this work. In addition, the Research fund of College of Humanities and Sciences of Nihon University (2017) also supported making this re-port.

Finally, the author is grateful to Professor K. Mizushi-ma for imparting his expertise on the geographical re-search.

observed in the period from December to February. However, it starts raining infrequently after March; rain-fall shows small peaks (>60 mm per day) in June and then large peaks (>70 mm per month) from August to Septem-ber. Humidity is caused due to temperature and rainfall is minimum from March to April and maximum in October. Daily averages of wind speed and wind direction are shown in Figure 4. The wind speed becomes high from April to September and low from October to December. In particular, the wind speed corresponds to small peaks of rainfall and is found to be maximum in the end of June. Regarding the wind direction, it may be affected by the green belt located in the north of AMOS.

Concluding remarks

The Argos system is used for the monitoring environ-ments of remote area and also for ecological analysis of wild animals. Accuracy of the position data is improved by fixing a GPS unit on the PTT. However, regarding ele-vation, it is difficult to obtain data with high accuracy as the system uses DEM data. Therefore, the system is use-ful to obtain meteorological observations and environ-mental measurements at the surfaces of the sea and/or lake in remote areas. Physical geographical utilization of the system may be restricted as it requires absolute

posi-1) All observation data between September 12 and Decem-ber 31, 2014 were eliminated. In addition, following data of temperature and humidity in 2015 were eliminated; Tem-perature: March 2, May 26, June 7 and 8, July 6, 14, 15, 26,

Notes

27, August 3, 4, 8 and December 25; Humidity: from Au-gust 15 to December 24. Causes of missing observation were faults of a data logger (CR10 X) in 2014 and the tem-perature and humidity sensor in 2015.

Alford, D.L., Archer, D.R., Bookhagen, B., Grabs, W., Halvor-son, S.J., Hewitt, K., Immerzeel, W., Kamp, U., Krumwie-de, B.S. (2016): Monitoring of glaciers, climate, and runoff

in the Hindu Kush-Himalaya mountains. Washington,

D.C.: World Bank Group. http://documents.worldbank. org/curated/en/127761468197388108/Monitoring-of-gla- ciers-climate-and-runoff-in-the-Hindu-Kush-Himalaya-mountains.

CLS (2016): Argos User’s Manual, 60pages (http://www.argos-system.org/wp-content/uploads/2016/08/r363_9_argos_ users_manual-v1.6.6.pdf). Accessed 18 Aug, 2017.

References

Oi, T., Otani, T., Miura S., Tujimoto, T., Fujiwara, C., Fujimura, M. and Akatsuka, K. (2002): A preliminary study of satel-lite tracking of the Asiatic black bear by the Argos system.

Mammalian Science, 42, 123-128 (in Japanese with

Eng-lish abstract).

Haneda, T., Kobayashi, M., Tamura, Z., Takada, K. and Ogawa, I. (2017): Coastal use patterns of Japanese harbor seals (Phoca vitulina stejnegeri) in Akkeshi Bay in Hokkaido during the spring season. Mammalian Science, 57, 35-43

(in Japanese with English abstract).

(8)

movements of Great Cormorants Phalacrocorax carbo in the Tokai area, based on GPS-Argos tracking. Japanese

journal of Ornithology, 61, 17–28 (in Japanese with English

abstract).

Inoue, J., Ogita, Y., Hori, M. and Kikuchi, T. (2010): Toward the operation of portable ice-drifting buoys-Trial use in the Arctic expedition-. Bulletin journal of the Meteorological

Society of Japan (TENKI), 57,33-35 (in Japanese).

Roemmich, D., Johnson, G.C., Riser, S., Davis, R., Gilson, J., Owens, W.B., Garzoli, S.L., Schmid, C. and Ignaszewski, M. (2009): The Argo Program: Obser ving the global

ocean with profiling floats. Oceanography, 22 (2), 34–43.

Waragai, T., Morishima, W. and Hada, A. (2013): Angkor Wat meteorological observation station (AMOS): Installation of monitoring system and preliminary results of observa-tion at Angkor Wat temple, Cambodia. Proceedings of the

Institute of Natural Sciences, Nihon University, 48, 35-48.

Yamazaki, K., Hayashi, N., Yokoyama, K., Hosokawa, S., Kofuji, K., Kinoshita, S. Kozakai, C. and Koike, S. (2008): Semi-re-al time tracking system of Japanese black bears using low earth orbit satellite communications. Mammalian

Table 1 also shows the daily averages of the observed  parameters between 2011 and 2016 and the averages of  each year
Table 1 Results of daily observation from 2011 to 2016. Wind speed
Fig. 2 Daily fluctuations of average temperature and insolation. Moving averages are calculated from 10 days.
Fig. 3 Daily fluctuations of rainfall and relative humidity. Moving average is calculated from 10 days.

参照

関連したドキュメント

Here we continue this line of research and study a quasistatic frictionless contact problem for an electro-viscoelastic material, in the framework of the MTCM, when the foundation

For further analysis of the effects of seasonality, three chaotic attractors as well as a Poincar´e section the Poincar´e section is a classical technique for analyzing dynamic

Then it follows immediately from a suitable version of “Hensel’s Lemma” [cf., e.g., the argument of [4], Lemma 2.1] that S may be obtained, as the notation suggests, as the m A

In order to be able to apply the Cartan–K¨ ahler theorem to prove existence of solutions in the real-analytic category, one needs a stronger result than Proposition 2.3; one needs

[Mag3] , Painlev´ e-type differential equations for the recurrence coefficients of semi- classical orthogonal polynomials, J. Zaslavsky , Asymptotic expansions of ratios of

Henson, “Global dynamics of some periodically forced, monotone difference equations,” Journal of Di ff erence Equations and Applications, vol. Henson, “A periodically

1) DO NOT make more than two applications of ARGOS HERBICIDE per year. oz./A in a single application and not more than 9 fl.oz./A of ARGOS HERBICIDE per year. 3) DO NOT harvest

[r]