Data communication status of the ARGO floats

Hiroyuki NAKAJIMA*1 Yasushi TAKATUKI*2 Keisuke MIZUNO*2 Kensuke TAKEUCHI*3 Nobuyuki SHIKAMA*3

Abstract

We investigate the data communication status of the ARGO floats, that deployed until February 2001 in the seas adjacent to Japan. The mean receive rate of the data via the ARGOS system, which calculated from the periods while floats flies overhead of the float, is 52%. The mean error rate of the transferred data, which detected by the CRC code in the data, is 21%. These rate varied according to the float position and the periods during the float stayed at the sea surface. East of Japan (35-40N,140-145E)was the worst 5 degrees-grid area in communication status, where the receive rate is 7% lower than the average and 3% higher than the average. The worst 6-hour period is 12:00-18:00 in JST, when the receive rate is 9% lower than the average and the error rate is 4% higher than the average. The communication status seemed to be affected by interferences of the radio were around Japan. The second-generation Argos instruments have about 10% higher receive rate than the first-generation ones, but no difference found in the error rate. Considering the orbits of the ARGOS satellites, most effective periods for data communication from the ARGOS floats in the seas adjacent to the Japan is 00:00-08:00 in JST.

Keywords : ARGO float, data communication, ARGOS system

*1 Marine Works Japan Ltd.
*2 Ocean Observational Research Department
*3 Frontier Observational Research System for Global Change


1. Introduction

2. Data communication status of the Argo floats

WMO ID
ARGOS ID
CTD sensor
Parking Depth(m)
Average time of the float staying at the sea surface(hour)
Periods of the float staying at the sea surface(JST)
Observation cycle
Repetition rate(sec)
Float deployed day(JST)
29032
28935
SBE
1500
19
17h~12h
(18h~13h)
28日
90
2000/3/22
29033
28936
SBE
1500
19
17h~12h
(10h~05h)
14日
90
2000/3/22
29034
28938
SBE
2000
21
22h~19h
10日
90
2000/10/21
29035
28940
FSI
2000
21
22h~19h
10日
90
2000/10/21
29042
06496
SBE
2000
8
02h~10h
10日
44
2001/2/16
29043
06495
SBE
2000
8
06h~14h
10日
44
2001/2/16
29044
06498
SBE
2000
8
10h~18h
10日
44
2001/2/16
29045
06497
SBE
2000
8
12h~20h
10日
44
2001/2/16
29046
06500
SBE
2000
8
16h~24h
10日
44
2001/2/16
29047
06499
SBE
2000
8
18h~02h
10日
44
2001/2/16
29048
06503
SBE
2000
8
21h~05h
10日
44
2001/2/16
29049
06502
SBE
2000
8
00h~08h
10日
44
2001/2/17
29050
06504
SBE
2000
8
04h~12h
10日
44
2001/2/17
29051
06505
SBE
2000
8
10h~18h
10日
44
2001/2/17
29052
06506
SBE
2000
8
14h~22h
10日
44
2001/2/17
29053
06507
SBE
2000
8
21h~05h
10日
44
2001/2/17
29054
06510
SBE
2000
8
01h~09h
10日
44
2001/2/18
Table 1 Summary of the ARGOS floats deployed before February 2001 by JAMSTEC/FORSGC.


Fig. 1 Example of ARGOS satellite tracks which possible to communicate with ARGO float.
Lite blue star indicates the ARGO float position.
Black and red crosses on the satellite track show the ARGOS satellite positions when satellite received data from the float without error and with error, respectively.
Red stars show the satellite positions when float position fixed.

2.1 Status of the data communication via ARGOS system in each 5 degrees-grid


Fig. 2 Status of the data communication via ARGOS system in each 5 degrees-grid.

Satellite Name
Band-width
(KHz)
Receiver
(dBm)
Proc.Units
Link Speed
(bits/sec)
NOAA-D
24
-128~-108
4
720
NOAA-H
24
-128~-108
4
960
NOAA-J
24
-128~-108
4
1200
NOAA-K
80
-131~-108
8
2560
NOAA-L
80
-131~-108
8
2560
Table 2 Characteristics of the ARGOS instruments on the NOAA satellites.

2.2 Status of the data communication via ARGOS system in each 6 hours period


Fig. 3 Status of the data communication via ARGOS system in each 6 hours period.

2.3 Status of the data communication every 3 months for the float 29032 and 29033 from April 2000 to June 2001


Fig. 4 Status of the data communication every 3 months for the float 29032 and 29033 from April 2000 to June 2001.

2.4 Correlation between the status of the sea surface and of the data communication


Fig. 5 The receive rate(red triangle)and the error rate(green circle) vs. wave height where floats stayed.

2.5 Correlation between the receive level of the satellites and the status of the data communication


Fig. 6 The receive rate, the error rate(upper panel)and the receive level(middle panel)for each float from Mar. 17, 2001 to Jun. 7, 2001. Periods of the float stayed at the sea surface for each float are also shown in lower panel.


Fig. 7 Communication status in each receive level for the 1st generation satellites(Argos-I;D,H,J).


Fig. 8 Same as Fig.7 except for the 2nd generation satellites(Argos-II;K,L).

3. Consideration

 
JAMSTEC/FORSGC
University of Washington
 
The way of calculation by JAMSTEC/FORSGC
The way of calculation by University of Washington
Japan Sea
Atlantic
Receive rate(%)
52
88
86
85
Error rate(%)
21
17
17
Number of data
193
2564
537
Table 3 The receive rate and the error rate for the floats operated by JAMSTEC/FORSGC and University of Washington.


Fig. 9 Orbits of NOAA POES(Polar Orbiting Environmental Satellites) used for the Argos system

 

4. Summary