Lobos de Afuera (Peru) Site History

History Summary

Station Name Lobos de Afuera
Country Peru
Latitude 06° 56.0' S
Longitude 080° 43.0' W
GLOSS No. None
Time Reference GMT (hours 00-23)
Contributor Direccion Hidrografia y Navegacion de la Marina
and Atlantic Oceanographic and Meteor. Lab. (AOML)
Instrument Type Standard mechanical tide gauge (1982-present)
Leupold Stevens analog-to-digital recorder (ADR)(5/1985-present) (backup)
Handar Encoder (ENC) model 436A (12/1985-present)(backup)
Site of Gauge No data
Observational Period 1982 - 1994

Reference Level

The data which were given to the AOML by the originator contained many reference level shifts. The tide staff comparison readings explained only a few of the shifts. The following shifts were adjusted by the AOML using the comparative readings, comparisons with the ADR data, and estimations based on the daily values and hourly residuals (observed data minus predicted tides):

Period
(day/month/year)
Value added
to Original(mm)
14/11/82 - 15/11/82 -150
15/11/82 - 17/11/82 -300
01/06/83 - 10/09/83 -250
11/09/83 - 22/10/83 -130
23/10/83 - 31/12/83 +120
01/01/84 - 31/12/84 +120
18/03/84 - 31/05/84 - 50
12/07/84 - 24/08/84 + 50
01/09/84 - 15/09/84 -300
16/09/84 - 22/09/84 +350
23/09/84 - 30/09/84 -250
20/10/84 - 23/10/84 - 50
01/11/84 - 05/11/84 -200
06/11/84 - 19/11/84 -350
20/11/84 - 30/11/84 -450
01/12/84 - 31/12/84 -300
01/02/85 - 28/02/85 +230
01/05/85 - 28/05/85 +328
01/08/85 - 31/08/85 +328
01/09/85 - 31/09/85 +533
01/10/85 - 31/10/85 +472
01/11/85 - 31/12/85 +625
01/01/86 - 20/01/86 +580
21/01/86 - 31/01/86 +275
01/06/86 - 13/06/86 +350
13/06/86 - 28/06/86 + 40
29/06/86 - 21/07/86 - 60
22/07/86 - 30/09/86 + 40
01/12/86 - 31/12/86 + 60
01/01/87 - 14/06/87 + 55
01/08/87 - 31/08/87 -183

The following level shifts in the analog data were adjusted by JASL based on analysis of the hourly residuals and comparisons with daily data from adjacent stations: Callao, Peru and La Libertad, Ecuador, and with daily data from the ADR and ENC sensors.

Period
((hour)day/month/year)
Value added
to Original (mm)
(00)01/07/82 - (05)26/03/83 -110
(06)01/11/83 - (13)21/11/83 - 75
(02)01/12/83 - (18)12/08/84 + 75
(04)01/09/84 - (13)20/11/84 - 70
(05)01/10/87 - (15)16/10/87 -150
(13)11/11/87 - (05)01/12/87 + 60
(06)01/12/87 - (03)16/04/88 - 60
(04)16/04/88 - (16)10/06/88 -100
(17)10/06/88 - (23)11/06/88 -240
(00)12/06/88 - (23)30/09/88 -160
(20)19/02/89 - (18)01/03/89 +75
(12)20/07/89 - (12)19/08/89 +75
(00)02/02/92 - (12)16/02/92 +75
(13)16/02/92 - (08)01/03/92 -120
(00)11/10/93 - (16)01/12/93 80

The above adjustments are uncertain to a few cm. In addition to the above adjustments, the original data from 10/1988 - 05/1994 were adjusted by -160 cm based on the overlap of August-Sept/1988 with the existing time series in the TOGA archive.

Quality Assessment by the UH Sea Level Center

The following gaps were replaced with data from the redundant sensors, primarily the ENC, which were received via satellite and quality-controlled at the UH Sea Level Center:

Period
((hour)day/month/year)
(05)01/03/86 - (10)02/04/86
(00)26/04/86 - (23)31/05/86
(00)26/06/86 - (09)01/07/86
(08)29/10/86 - (09)13/11/86
(00)29/06/87 - (20)01/08/87
(01)01/09/87 - (23)30/09/87
(05)04/10/87 - (11)05/10/87
(00)17/10/87 - (10)19/10/87
(06)10/11/87 - (11)11/11/87
(02)27/02/88 - (21)29/02/88
(00)01/06/88 - (09)02/06/88
(05)01/10/89 - (04)01/11/89
(12)05/04/90 - (04)13/04/90
(00)27/07/91 - (19)14/08/91
(13)26/12/91 - (04)01/02/92
(00)11/11/93 - (23)17/11/93

Based on differences of the data with redundant data received at the UH Sea Level Center via satellite, the accuracy of the daily values appears to be no better than ±5 cm.

Year CI (%) Missing Data Replaced Gaps or Bad Data Questionable Fluctuations
1982 46 226-229,274-280, 324-326,335-341 (17)321-(11)322 217,266
1983 86 85-134,243-244 none 239-241,251-252,256-257,260-261,264,294-296,361-362
1984 89 72-78,153-154,166-169,173-174,175-194,275-287 (23)174-(15)175
(02)230-(15)230
(01)274-(13)274
4-9,22-24,39-40,67-70,78-81,93-98,136, 139,152,160-161,164,169,238-239,251,327-332,343-344,350,355-356
1985 74 1-32,43-44,60-121 none 37,40-43,49-50,52- 53,123-125,131,155
1986 100 none none 4-6,9-10,12-13,16,29-30,96-97,258-259
1987 99 269-271 (02)137-(08)137
(10)208-(16)208
(05)305-(12)305
(13)321-(22)321
(02)322-(21)322
(10)340-(04)341
(11)351-(19)351
88,122,138-139,141, 149,151,166-167
1988 100 none (05)010-(04)011
(17)051-(01)052
(17)065-(04)066
(18)117-(00)118
(20)215-(19)216
(03)229-(12)229
(06)237-(23)237
none
1989 100 none (09)027-(18)027
(09)050-(19)050
(03)273-(10)273
63-65,160-161
1990 100 none (05)168-(04)169
(20)229-(13)230
(05)276-(14)276
(02)332-(11)332
(13)335-(01)336
(00)345-(11)345
118-119,121-125,130
1991 100 none (18)077-(04)078
(04)182-(11)182
(05)213-(13)213
(20)284-(14)285
(01)305-(12)305
(05)359-(00)360
92-119
1992 100 none (13)039-(23)039
(21)107-(04)108
(17)199-(08)200
(22)213-(23)213
(01)214-(08)214
(07)229-(17)229
(05)336-(12)336
81-82,153-182,212-213
1993 100 none none none
1994 33 none none none