GRIP Acidity

REFERENCES: 

Clausen, H.B., C.U. Hammer, C.S. Hvidberg, D. Dahl-Jensen, J.P. Steffensen,
J. Kipfstuhl, and M.R. Legrand. 1997. A comparison of the volcanic records
over the past 4000 years from the Greenland Ice Core Project and Dye 3
Greenland ice cores. Journal of Geophysical Research 102:26707-26723.

Wolff, E.W., J.C. Moore, H.B. Clausen, and C.U. Hammer. 1997. Climatic
implications of background acidity and other chemistry derived from
electrical studies of the Greenland Ice Core Project ice core. Journal of
Geophysical Research 102:26325-26332.

Clausen, H.B., C.U. Hammer, J. Christensen, C.S. Hvidberg, D. Dahl-Jensen,
M.R. Legrand, and J.P. Steffensen. 1995. 1250 years of global volcanism as
revealed by central Greenland ice cores. Ice Core Studies of Global
Biogeochemical cycles, annecy, France, R. Delmas (ed.). NATO Advanced
Sciences Institutes Series 1, 30:175-194.

Wolff, E.W., J.C. Moore, H.B. Clausen, C.U. Hammer, J. Kipfstuhl, and K.
Fuhrer. 1995. Long-term changes in the acid and salt concentrations of the
Greenland Ice Core Project ice core from electrical stratigraphy. Journal
of Geophysical Research 100:16249-16263.

Moore, J.C., E.W. Wolff, H.B. Clausen, C.U. Hammer, M.R. Legrand, and K.
Fuhrer. 1994. Electrical response of the Summit-Greenland ice core to
ammonium, sulphuric acid, and hydrochloric acid. Geophysical Research
Letters 21:565-568.

Moore, J.C., R. Mulvaney, and J.G. Paren. 1989. Dielectric stratigraphy of
ice: a new technique for determining total ionic concentrations in polar
ice cores. Geophysical Research Letters 16:1177-1180.

DATA DESCRIPTION: 

This file contains the GRIP acidity record, as calculated from electrical 
conductivity measurements.

The sample resolution of the record is 1 cm. 

Explanation of columns

1) Depth in m below the snow surface at a local maximum in the ECM record. 

2) Age at the local acid peak in years BP 1950

3) Number of years of high acidity at the local acid peak.

4,5) The mean acid concentration and background concentration in the years
of high acidity in micro equivalent H+ per kg of ice (ueq/kg).  The data
for the past 2000 years are shown on Fig. 3b in Clausen,et al. (1997).
Hammer, (1980) and Clausen et al., (1995) describe how the current
measured by ECM is converted into concentration of acid. 

6) These data are the difference between the data of #4 and #5. The
concentrations above the background are of course not all of volcanic
origin but they contain the candidates for the major acid producing
volcanism. 

7) The peak concentration value of strong acid detected in a 1cm sample. 

8) The amount of the volcanic acid deposited at the surface during the
years of high acidity (called VAD). The amount is calculated as kg
sulphuric acid per square kilometer over the time period of enhanced
acidity from the concentration in #6 and corrected for the effect of the
thinning of the annual layers due to glacier flow.  The VAD is calculated
as sulphuric acid, irrespective of the actual anion.  Sulphate is the
dominant anion in acid volcanic fall-out, but in some cases hydrochloric
acid and more seldom hydrofluoric acid are present, and in the case of Dye
3 presence of nitric acid, which does not have a volcanic origin. These
data are shown on Fig.  4a - 4d in Clausen et al., (1997). 

9) The magnitude of the eruption (the released amount of acid gases into
the atmosphere) is expressed in Mtons of sulphuric acid. The magnitude is
calculated by comparing the VAD to the deposited amount of total
beta-activity from known atmospheric thermonuclear tests at high northern
latitude (HNL) and low northern latitude (LNL), Refs. 4 and 5. The
calculation assumes an eruption site at HNL for comparative reasons. Some
of the data are shown in column (10) of Table 3 in Clausen et al., (1997).

DATA:

Depth (m)	Age (yr BP)	Length (yrs)	total	background	diff.	peak	deposition	
magnitude

2.66	-34	0.5	2.71	0.78	1.93	4.07	11	15
3.42	-33	0.1	3.26	1.22	2.04	3.7	1	2
4.27	-32	0.4	3.37	1.16	2.21	5.97	8	11
4.74	-31	0.4	3.54	1.07	2.47	7.56	8	12
5.25	-30	0.9	2.64	1.38	1.26	4.33	12	17
6.95	-26	0.3	2.77	1.39	1.38	3.53	5	7
8.62	-22	0.8	2.56	1.52	1.04	3.26	9	14
10.12	-18	0.9	2.35	1.41	0.94	3.09	7	10
13.84	-9	0.2	2.07	1.26	0.81	2.94	2	2
18.27	3	0.4	1.83	1.08	0.75	2.54	3	4
30.36	38	1	2.45	1.02	1.43	3.82	15	22
32.27	43	0.7	2.32	0.93	1.39	2.83	8	11
41.4	72	0.1	1.66	0.99	0.67	2.19	1	1
58.46	134	1.1	2.23	1.1	1.13	2.56	13	19
60.03	140	0.8	2.52	1.22	1.3	3.1	11	16
67.21	167	1.6	5.26	1.24	4.02	13.84	70	101
80.12	218	0.3	2.25	1.26	0.99	2.76	4	5
80.31	219	0.7	2.17	1.41	0.76	2.92	3	4
80.92	222	0.8	2.2	1.48	0.72	2.72	7	11
82.05	225	0.5	2.21	1.46	0.75	2.76	5	7
95.66	283	1.2	2.43	1.48	0.95	3.72	11	16
101.8	308	0.3	2.69	0.76	1.93	6.03	9	13
103.02	313	1.8	2.19	0.92	1.27	3.83	13	19
105.7	325	0.7	1.95	0.99	0.96	3.93	4	6
108.15	336	0.4	5.15	0.99	4.16	9.5	12	17
110.98	349	2.3	2.8	1.17	1.63	6.4	36	52
116.16	370	0.9	1.97	1.16	0.81	3.83	8	11
121.63	396	1.5	2.15	1.23	0.92	4.22	17	25
131.19	438	2.7	2.87	1.32	1.55	7.72	53	77
132.17	442	0.7	2.75	1.14	1.61	4.12	12	17
133.53	447	0.2	3.36	1.22	2.14	4.36	6	9
138.65	470	2.4	2.72	1.32	1.4	4.08	30	44
139.39	473	2.2	3.07	1.75	1.32	6.7	34	48
142.99	490	0.4	3.45	1.68	1.77	4.17	9	13
147.25	509	2.9	2.86	1.56	1.3	4	39	56
154.17	540	1.4	2.44	2.02	0.42	3.95	7	10
159.08	560	0.1	2.68	1.61	1.07	5.06	2	2
159.33	561	0.7	3.4	1.93	1.47	5.98	17	24
160.89	568	1	4.07	1.84	2.23	7.9	20	29
168.88	605	0.5	2.59	1.28	1.31	3.27	8	11
169.77	609	0.8	3.05	1.3	1.75	5.06	10	14
172.04	619	1.4	2.42	1.33	1.09	3.78	14	20
185.21	681	2.1	2.35	1.46	0.89	3.67	18	27
187.28	691	3	6.83	1.45	5.38	14.44	161	232
193.31	721	2.9	4.37	1.41	2.96	6.39	73	105
201.04	758	0.5	2.79	1.12	1.67	4.17	8	12
201.24	759	0.5	2.72	1.75	0.97	4.46	7	10
201.66	761	0.5	2.97	1.84	1.13	3.97	6	9
203.78	771	0.7	6.52	1.58	4.94	10.25	43	62
205.98	781	0.7	2.79	1.15	1.64	3.76	11	16
219.55	844	1.5	3.37	1.49	1.88	5.32	35	50
222.73	859	0.6	3.18	1.41	1.77	3.95	13	19
238.22	933	1.4	2.81	1.66	1.15	4.46	7	10
242.4	954	9.5	3.11	1.66	1.45	6.18	14	20
243	956	0.5	3.29	1.61	1.68	5.86	14	20
243.29	957	0.7	3.38	1.63	1.75	4.06	17	25
244.74	964	0.3	2.9	1.63	1.27	4.01	4	5
254.34	1007	2.5	2.63	1.24	1.39	3.87	37	53
256.14	1016	1.7	16.66	1.34	15.32	49.47	261	375
263.79	1052	1	4.39	1.41	2.98	7.28	34	49
269.41	1079	1.5	4.78	1.39	3.39	13.35	51	74
274.49	1103	0.3	2.84	1.25	1.59	4.33	5	7
275.09	1106	0.1	4.3	1.26	3.04	4.89	3	4
293.12	1193	0.6	4.39	1.31	3.08	7.44	20	29
294.88	1202	0.4	3.16	1.76	1.4	4.01	8	11
295.58	1206	1.5	3	1.51	1.49	4.65	22	32
309.68	1275	0.9	3.65	1.19	2.46	5.06	25	36
316.2	1305	3.1	2.29	1.02	1.27	4.26	40	58
320.85	1328	1.7	3.37	1.1	2.27	5.32	37	54
328.33	1366	0.8	3.25	1.35	1.9	4.8	18	25
330.3	1378	1.4	2.73	1.48	1.25	4.93	15	21
331.91	1386	0.7	3.06	1.37	1.69	4.47	8	11
338.89	1418	1.2	3.37	1.96	1.41	4.75	19	27
339.83	1423	2.1	4.64	1.63	3.01	11.52	73	105
342.63	1436	1.1	5.58	1.42	4.16	13.19	45	65
353.84	1464	0.5	3.81	1.11	2.7	6.1	14	20
413.25	1791	1	5.96	1.21	4.75	12.69	46	66
424.22	1849	0.1	3.52	1.15	2.37	4.46	4	6
429.09	1871	0.5	4.9	1.17	3.73	8.15	26	38
444.76	1947	1.5	2.92	1.68	1.24	4.42	19	27
455.36	1999	2.7	6.06	1.05	5.01	16.6	135	194
455.85	2002	1.4	2.7	1.43	1.27	5.47	19	27
469.41	2069	1.3	3.52	1.41	2.11	7.3	26	37
474.28	2097	2.1	2.96	1.78	1.18	5.76	36	52
493.04	2194	0.9	16.39	1	15.39	33.94	129	186
513.36	2300	1.1	2.83	0.84	1.99	5.3	22	32
526.7	2371	3.5	4.84	1.12	3.72	8.25	99	143
534.12	2411	0.4	2.19	0.78	1.41	2.9	8	12
538.89	2436	1.1	2.88	1.41	1.47	3.55	16	23
553.47	2519	1.7	4.24	1.15	3.09	8.5	52	74
567	2596	0.9	2.53	1.12	1.41	3.7	11	17
567.62	2599	0.7	2.31	1.31	1	3.05	4	6
569.37	2610	1.4	2.43	1.24	1.19	3.75	14	20
572.2	2626	1.4	2.43	1.23	1.2	3.18	17	25
586.02	2703	1.1	4.6	1.03	3.57	7.35	44	64
586.4	2705	2.1	4.14	1.51	2.63	7.53	53	76
586.87	2707	1	5.9	1.15	4.75	13.35	53	77
610.49	2838	2	4.75	1.07	3.68	15.52	50	73
620.55	2894	2	2.45	1.24	1.21	3.79	25	37
640.39	3013	1.4	2.38	0.93	1.45	3.33	28	40
641.74	3023	1.2	9.76	1.34	8.42	19.39	61	88
659.35	3132	1.6	2.73	0.99	1.74	3.3	30	43
661.49	3143	0.6	2.58	1.12	1.46	3.47	13	19
664.36	3158	0.6	3.15	1.14	2.01	4.39	12	18
680.83	3252	0.8	4.94	0.98	3.96	7.97	27	39
689.89	3308	0.7	2.49	1.09	1.4	3.26	11	16
691.99	3319	0.5	2.07	0.94	1.13	2.34	5	7
701.88	3375	3.1	3.66	0.87	2.79	9.09	98	141
706.35	3400	1	2.62	0.97	1.65	3.92	17	24
725.48	3516	1.9	2.79	1.02	1.77	3.58	27	39
729.52	3543	0.6	3.03	0.97	2.06	4.3	10	15
733.58	3568	1.3	5.61	1.14	4.47	13.34	37	53
736.47	3586	2.3	5.69	1.28	4.41	13.35	96	139
743.43	3627	0.9	2.37	1.26	1.11	4.42	19	28
743.89	3629	1	2.4	1.14	1.26	3.43	14	20
748.53	3657	0.3	1.86	1.11	0.75	2.09	3	4
753.76	3688	2.3	2.04	1.16	0.88	3.05	17	25
754.85	3695	1.6	2.94	1.51	1.43	3.77	26	37
761.89	3741	4.8	2.73	1.79	0.94	4.38	45	65
768.65	3780	1.2	2.13	1.17	0.96	3.06	13	19
777.02	3842	0.9	2.79	1.33	1.46	4.65	14	21
779.71	3860	0.4	3.55	1.22	2.33	5.03	9	13
784.41	3888	1.3	3.61	1.26	2.35	4.83	33	47
788.5	3914	1.9	3.32	1.28	2.04	5.53	40	58
802.73	3995	2.5	4.58	1.12	3.46	9.59	91	132