Satellite Measurements of Volcanic Carbon Monoxide from Mount Nyiragongo (DR Congo) Abstract #A331­0272 Sara Martínez­Alonso1, Merritt N. Deeter1, Helen M. Worden1, John C. Gille1 (1)Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO, United States.

INTRODUCTION QUANTIFYING NYIRAGONGO GAS EMISSIONS FROM SATELLITE VOLCANIC GAS COMPOSITION: Satellite measurements of volcanic gas emissions are relevant to Volcanic gas emissions before, during, and after terrestrial eruptions commonly include H2O, CO2, SO2, HCl, H2S, SATELLITE VS. IN SITU CO:SO RATIOS answering basic scientific questions regarding degassing rate and S2, H2, HF, CO, and SiF4 [1]. Volcanic gases were traditionally measured in situ and, subsequently, in airborne 2 relative composition. These are key to understanding the eruptive campaigns; both are spatially and temporally constricted as well as hazardous. Satellite detection of volcanic Nyiragongo style and to volcanic activity prediction [1,2]. Furthermore, some gases has been achieved for only a few species. Due to its relative high abundance in volcanic plumes and very 3 volcanic gases (H O, CO , CO) have a direct or indirect positive (Error bars from MOPITT 2 2 low background levels, volcanic SO2 is routinely analyzed from satellite data [5, and references therein]. Other 2.5 estimated errors) R² = 0.44 Column E o radiative forcing and thus impact climate [3]. volcanic species such as HCl [6], H2S [7], and CO [4] have also been successfully identified from satellites. i

t 2 a Symonds et al. (1994) R ? We focus our efforts in the Nyiragongo region (Democratic Republic We have analyzed satellite 2 1.5 O Sawyer et al. (2008) S of the Congo) because, according to in situ measurements [1], CO observations acquired : 1 O

C This Study emissions here are one to three orders of magnitude higher than those simultaneously (or quasi­ 0.5 simultaneously) by the MOPITT, LinearEruption (This Study) measured in volcanoes elsewhere. 0 MODIS, and OMI instruments over 1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007 2011 2015 Time Here we report the first satellite detection of volcanic CO the Nyiragongo region: emissions from Nyiragongo. We contrast CO and SO satellite 2 Iceland (Eijafjallajökull, Grímsvötn) ● measurements from this volcano (this work) and others in Iceland [4]. TIR, day­only, cloud free, 3 otherwise unfiltered MOPITT E E E G We derive CO:SO ratios and compare them to relevant in situ 2.5 2 data from the entire mission o measurements from the literature. Finally, we discuss vertical i Column D

t 2

(2000 to present) to detect a R distribution of CO as shown by the MOPITT vertical profiles. ? 2 1.5 and quantify volcanic CO. Symonds et al. (1994) O S Nyiragongo is one of several active volcanoes : 1 ● O along the East African Rift, where the African MODIS color images to locate C Martinez-Alonso et al. and contrast 0.5 (2012) Plate is splitting into two new plates. Mount volcanic plumes MODIS false color them with anomalous CO values. RGB=24 (thermal infrared), 4 (green), 3 (blue) 0 Eruption Nyiragongo contains the largest persistent lava 1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007 2011 2015 MODIS­Terra (8:30AM) Time lake in the world, known since late­19th ● MODIS aerosol optical MODIS­Terra (8:30AM) MOPITT­Terra (8:30AM) MODIS­Terra (8:30AM) century. Its steep stratovolcano slopes and thickness products derived We have derived preliminary CO:SO2 ratios from MOPITT and OMI satellite extremely fluid magma resulted in many from 0.55 µm radiances to measurements for Nyiragongo (this study) and Iceland [4]. The ranges of these fatalities in the 1977 and 2002 eruptions. further characterize the ratios are in general agreement with (very scarce) in situ measurements [1, 8]. plumes. Nyiragongo satellite­derived CO:SO ratios show an increasing trend since 2004, Volcanic plumes are common sight at 2 Mount Nyiragongo; clear skies are ● whose meaning and possible relationship to eruptive behaviour remains unclear, not (photo: Carsten Peter/ National OMI data (2004­present) to Geographic) detect and quantify anomalous due in good part to the lack of data during/between previous Nyiragongo eruptions. SO2 values, diagnostic of volcanic activity. While relevant, these satellite­derived ratios are approximate:

● MODIS Fire Mask products to ­ the MOPITT CO and OMI SO2 measuremements are acquired ~2 hours apart, due to further investigate the origin the overpass times of the Terra and Aura satellites.

of anomalously high CO values. ­ total OMI SO2 column values for Nyiragongo were derived assuming a 5­km high volcanic plume, a reasonable approximation based on data from [9]. Unlike for Nyiragongo Despite persistent (3,470 m) meteorological clouds we have Iceland, in situ plume height measurements are unavailable for Nyiragongo. identified volcanic CALIPSO data will be analyzed to further constrain this variable and thus refine our SO2 values. In 1977 and 2002 anomalies/plumes in coeval MODIS­Terra (8:30AM) OMI­Aura (10:48AM) MODIS­Aqua (11:20AM) Nyiragongo lava flows reaching speeds of up to MOPITT, MODIS, and OMI data in Despite these limitations, these satellite measurements and derived ratios Persistent lava lake perched in the crater Volcanic emissions from Mount Nyiragongo on 21 February 2005 included gases and aerosols; no lava flows were reported. 60­100 km/h invaded the (maps: U. S. Geological Survey) of Mount Nyiragongo. The outermost rim is city of Goma, 18 km 17 separate dates. Nyiragongo Volcano is indicated with a white triangle, country boundaries and lakes are shown by white lines. Mount Nyamuragira, substantially improve our knowledge of degassing rates and relative composition ~1.3 km across (photo: Carsten Peter/ south of the volcano. another active volcano nearby, is shown by a yellow triangle in the first panel only. National Geographic) (photo: source unknown) in the environments analyzed.

INFORMATION IN MOPITT CO VERTICAL PROFILES DISCUSSION

MOPITT provides total CO column values as well as vertical profiles of tropospheric CO, thus allowing ­to some degree­ for ● comparison with ground and satellite observations. We report the first satellite measurements of volcanic CO from Nyiragongo. High SO2, Iceland, 2010 and 2011 eruptions: The height of the maximum MOPITT CO Nyiragongo, 02.21.2005: MOPITT and MODIS data show two distinct aerosol optical thickness, and visible/infrared imagery confirm that these CO emissions enhancement (MOPITT COplume­MOPITT CObackground) in the vertical profiles plumes (see maps above). The first plume starts at the volcano are volcanic in origin. [4] is consistent with the volcanic plume's height [10, 11] (bias and coincides with high OMI SO2, indicative of a volcanic ● between ­2 and 16%). origin. The second plume starts further north, coinciding with Volcanic CO:SO2 ratios derived from satellite measurements are in general agreement high­confidence anomalies in the MODIS Fire Mask product but no The MOPITT averaging kernels (which quantify the sensitivity of the high SO2; this is consistent with a biomass burning origin. with ratios derived from (very scarce) in situ measurements. retrievals to the true state) indicate peak sensitivity between 800 MOPITT CO profiles from the two plumes differ in the height and and 300 hPa, but are very coarse, indicating weak vertical resolution. ● magnitude of their maxima. The volcanic plume peaks near/above Nyiragongo CO:SO2 ratios appear to have been increasing since 2004. CO2:SO2 ratios The retrieved profiles show no dependency on the a priori profiles. Nyiragongo's summit and locally reaches ~650 ppbv. The fire elsewhere increase prior to an eruption [12]; volcanic CO and CO2 are correlated to some plume (<220 ppbv) peaks closer to the average regional surface. Eyjafjallajökull, 2010 04 19 Eyjafjallajökull, 2010 05 07 Grímsvötn, 2011 05 22 degree, regardless of tectonic setting [4]. Further efforts will be made to determine if ) ) ) The MOPITT averaging kernels show better vertical resolution m m m k 0 k 0 k 0 ( ( ( h h h than those from Iceland. CO:SO2 and CO2:SO2 ratios behave similarly with respect to eruptive activity. 100 15.5 100 15.5 100 15.5 200 11.1 200 11.1 200 11.1 While fire plume vertical profiles are strongly influenced by ● Despite its limited vertical resolution, there is 300 300 300 relevant information in the MOPITT 8.5 8.5 8.5 the a priori, these from the volcanic plume are not. ) ) ) 400 400 a a a 400 6.7 6.7 6.7 P P P h h h ( ( ( CO vertical profiles. However, close attention must be paid to retrieval parameters (a

500 5.1 500 5.1 500 5.1 e e e Vertical resolution might improve r r r Nyiragongo, 02 21 2005 u u u s s s s s s 600 4.0 600 4.0 600 4.0 e e e ) r r r

by using MOPITT multispectral m priori profiles, averaging kernels) to recognize potential artifacts. P P P k

700 2.8 700 2.8 700 2.8 0 ( retrievals. Further work will help h 800 2.0 800 2.0 800 2.0 discern if the shape of the MOPITT 100 17.2 ● Measuring volcanic CO (and other gases) from satellites is relevant to climate 900 0.9 900 0.9 900 0.9 vertical profiles from the 200 12.2 1000 0.0 1000 0.0 1000 0.0 300 9.3 models as well as to understanding, monitoring, and predicting volcanic activity. 20 40 60 80 100 120 140 160 180 200 220 20 40 60 80 100 120 140 160 180 200 20 40 60 80 100 120 140 160 180 volcanic plumes are controlled by MOPITT CO (ppbv) MOPITT CO (ppbv) MOPITT CO (ppbv) 400 7.2 ) a

the vertical sensitivity of the P locally This is particularly important in the Nyiragongo region, due to difficult access h ( mean plume mean background mean plume mean background mean plume mean background 500 5.6 e ~650 r

. a priori plume a priori backgrounda a priori plume a priori background a priori plume a priori background instrument or by actual CO u 6 s

s ppbv 5 e

r 4.3 9 600 and proximity to densely populated areas. P 1 distribution.

, 700 3.2 ” w o GLOSSARY [4] Martínez­Alonso, S. et al., Geophys. Res. Lett., 39, L21809 (2012). l 800 2.2 l e MOPITT: Measurements of Pollution in the Troposphere instrument, on EOS/Terra. [5] Oppenheimer, C. et al. Rev. Mineral. Geochem., 73, 363­421 (2011). Y

900 1.4 d MODIS: Moderate Resolution Imaging Spectroradiometer, on EOS/Terra and EOS/Aqua. [6] Prata, A. J. et al., Atmos. Chem. Phys., 7, 5093–5103 (2007). n a

1000 0.0 OMI: Ozone Monitoring Instrument, on EOS/Aura. [7] Clarisse, L. et al., Geophys. Res. Lett., 38, L10804 (2011). e

g 40 60 80 100 120 140 160 180 200 220 240 n [8] Sawyer, G. M. et al., Geochem. Geophys. Geosyst., 9, Q02017 (2008). a r MOPITT CO (ppbv) REFERENCES O [9] Carn, S. A., Acta Vulcanologica, 14, 75­86(2004). “

[1] Symonds, R.B. et al., Rev. Mineral. Geochem., 30, 1­66 (1994). o mean fire mean volcano mean background [10] Arason et al., Earth. Syst. Sci. Data, 3, 9­17 (2011). k h a priori fire a priori volcano a priori background [2] Thomas, H.E. et al., Nat. Hazards, 54, 323­354 (2010).

t [11] Jakobsdóttir et al., Grímsvötn Volcano Status Report, 22 May 2011 (2011). o

R [3] Forster, P. et al., Cambridge University Press (2007).

[12] Aiuppa, A. et al., Geology, 35, 1115­1118 (2007). k r a M