Long Term Baseline Atmospheric
M a r k A. G o l d m a n 1
University of Hawaii Cloud Physics Observato~y Hilo, 96720
Monitoring
Are man's activities making significant and lasting changes in the earth's atmosphere (1, 2)? The answer to this question requires determination of the background concentration of the principal physical and chemical constituents of the atmosphere. Background baseline measurements currently are being carried out by the Geophysical Monitoring for Climatic Chanee (GMCC). nroeram .. of the National h a n k and ~ t m o & h & i r Administration. l'nited States D e ~ a n m e n tof Commerce ( 3 , . The .nmeram " is designed to measure the normal concentrations of certain chemical and physical parameters of the atmosphere so that quantitative estimates may be made of loc& regional, and global pollution. The ultimate goal of the program is to determine how baseline values may be changing, if indeed they are, and how such changes may affect the earth. Several isolated locations have been selected as sites for "benchmark" monitorina. Stations are currentlv located in Alaska, the ~ n t a r c t i c a ,American Samoa, and Hawaii, with others planned. The purpose of this note is to discuss some of the activities a t Mauna Loa Observatory (MLO), Hawaii 14, 5) (Fig. 1). Located a t 4 km above sea level on the NNW slope of the volcanic mountain Mauna Loa, the Observatory was originally established as a weather research station in 1956 16). The measurements currently being made at MLO are listed in the table. There is a characteristic diurnal wind circulation at MLO, the uniformity and regularity of which contribute significantly to the study of the aerosol composition of the atmosphere. Upslope, northerly winds dominate the airflow during the day, while downslope, southerly winds usually occur a t night (7). The chemical analysis of collected aerosols (8) has shown that the downslope air is predominantly of continental origin and thus suitable for baseline atmospheric measurements. On the other hand, the upslope airflow during the day is maritime in nature and is affected by the ocean and local biosphere (9, 10). Electron microphrobe analysis (11) of individual giant aerosol particles ( d > IF; Z > 10) reveals no difference in cation content in the upslope and downslope air masses. This suggests, therefore, that it is the anion content which determines the chemical effects that aerosols have on weather and climate. MLO is well known as the site of the longest continuous measurement of atmospheric COz (12). Figure 2 shows the variation in COz concentration from 1961 through 1972. At the present rate, the concentration of atmospheric COz will increase about 1% of the current amount every three years (13, 14). The COa concentration also exhibits a seasonal cycle, with a maximum in the spring and a minimum in the fall. This cycle reflects the withdrawal of COz by growing plants in the spring and summer and the release of COz in fall and winter. The exact temporal occurrence of the maximum and minimum COz concentrations is a function of latitude (15). Since long term changes in temperature (2), and therefore climate, may be related to changes in COz and aerosol concentrations f16), it is necessary to constantly moni-
ISLAND OF HAWAlI
t
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'Present Address: Hilo Coast Ptocessing Co., P.O. Box 18, Pepeekeo, Hawaii 96783.
E N T O M lTERWL l ln
Figure 1. Island of Hawaii showing the location of Mama Loa Observatory (MLO).
Parameters Monitored at Manua Lea Obrervatorv
7. Lidsr (biwkkly and ssneeded) 8. Total On (Dabson. 3 timeedailv) 9. surf& oDconcentration(eontiouous) 10. Direct solar spectral irradiance (Emley,continuous)
14. Erythema s g t r u m (continuous) 15. Atmosoherie extinction coefficient 12 wavelencths: EPA ohotorneter.
tor these quantities to determine their variations with time. The total incident solar radiation has long been monitored a t MLO. Such measurements have provided the first good estimate of the lifetime of injected stratospheric material (17). After the explosive eruption in 1963 at Mt. Agung in the Phillipines, it took approximately seven years for the haseline solar radiation to return to its pre-Agung value (Fig. 3). Subsequent volcanic eruptions, such as Trident, Surtsey, etc., were of much smaller magVolume 52, Number 6,June 1975 / 365
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Figure 3. A p p a r e n t t r a n s m i t t a n c e of solar radiation: 1958-1970. After E l l i s a n d P u e s c h e l (61.
Literature Cited Time Figure 2. A t m o s p h e r i c CO? c o n c e n t r a t i o n : 1961-1972.
nitude than Agung and, therefore, did not significantly modify the transmission curve shown in Fig. 3 (18). Since 1970 the Environmental Protection Agency has been monitoring NOz, SO2 and particulate matter a t MLO. It is still too early to establish adequate baselines for these species. However, comparing recent measurements of NO2 with measurements made in Hawaii in the 1950's (19) indicates that the background concentration of NOz may be increasing (20). Many of the measurements taken at MLO have been published (1, 3-14, 17, 20-22) while other projects listed in the table are new and sufficient data for publication has not yet been collected; for example, the chemical analysis of rainfall, surface freon, CCla, etc. The awarding of a Presidential Internship a t MLO to the author and the editorial assistance of Dr. C. M. Fullerton are greatly appreciated.
366 / Journal of Chemical Education
(I) ~ a r r e t f E. . w., ~ueschel,R. F.. ~ u h n P, . M..and Wickmann. H. K., ESSA Tach. Rppt ERL 185-APCL 15. Sept 1970. (2) Hobbs. P.V.. Harrison.H., andR0binson.E.. Science, 183,903 (1974). (31 Miller. J. M.. (Editor). Geophysical Monitoring for Climatic Change No. 1. (Summary Repoit-1972). NOAA. ERL. Boulder. Colarsdo. (41 Chin. J. F. S.. Ellis. H . T . , Mondonea. B. G., Pmrehel. R. F., and Simpron, H.J.. NOAATech. MemoERLAPCL-13, July 1971. (5) Machfa. L.. Bull. Amer M e t . .For.,53.402(1972). . 1. (1959). (61 Price. S.. and Palaa.J.C.. Mon Weo R D U 87. (71 Mendoncs.B.. J A p p l . Met.. 8,533 (19691. (8) Simpson. H.J.. NOAATech.Repoit, ERL248-APCL21(1972I. (9) Puenehel. R.F.,andMendonca. B.G., Tellw. 24, l39(19721. (101 Mendonca.B.G.,and Pue~ehelR.F.. J A D P I . M & IZ(l), 156, (1973). (11) Pueschel. R. F., Parungo. F. P.. and Goldman. M. A,. Bull. Amar. Met. Soc.. 54, l,"G,,Qm,
(121 P a l a , S.,andKelin& C.D., J Goophys Ros., 70,6053 (19ffil. (131 Goldmsn, M . A . J . Geophys. Re8,79.4550(19741. (141 Keeline. C. D..Bainbridee. A. E.. Ekdah1.C A . Guenthor.P.. Chin, J. F. S., T d i w ,
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(15) Bolin, B., and Keeling, C. D . . J G ~ o p h y sR. e s , 6.9.3899(1963). ,161 Levy n. H.$cilnce. 173. 138(19711. (17) Ellis. H.T.. andpueschel, R . F . Srirnca. 172.845l1971). I181 Ellis. H.T.. ptivafecommunication. 1974. (191 Junge. C., Tdlus. 9.528 119571. (201 Goidman. M. A,, Tellus. 27. (19751, inpress. (21) Komhyr. W. D., Barreit. E. W . . Sloeum. G.. and Weickmann H. K.. Noluw. 232. A
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