Ground-Based Observations

Between balloon and aircraft campaigns, the MkIV instrument is used to make ground-based observations. Although these measurements lack the vertical resolution that is attainable from balloon platforms, ground-based observations can nevertheless be made much more frequently - MkIV has averaged over 50 days of observation per year recently. Ground-based observations are an accurate method of ascertaining whether the composition of the Earth's atmosphere is changing, which is the main purpose of NDACC.


MkIV Ground-based Vertical Column Abundances 1985-2015

Individual Column Abundances: (89 columns, 4229 rows) m4_avg_1985_2015.vav
Individual Column Abundances: (Ames-1001 format) m4_avg_1985_2015.vav.ames
Daily Average Column Abundances: (89 cols, 1090 rows) m4_avg_1985_2015.vad
List of windows: (265 rows) all_mols_mir_1985_2015.gnd
Window-to-window biases: m4_avg_1985_2015.vav.cew

MkIV Ground-based Vertical Column Abundances 1985-2014

Individual Column Abundances: (85 columns, 3939 rows) m4_avg_1985_2014.vav
Individual Column Abundances: (Ames-1001 format) m4_avg_1985_2014.vav.ames
Daily Average Column Abundances: (85 cols, 1027 rows) m4_avg_1985_2014.vad
List of windows: (242 rows) all_mols_mir_1985_2014.gnd
Window-to-window biases: m4_avg_1985_2014.vav.cew

MkIV Ground-based Vertical Column Abundances 1985-2013

Individual Column Abundances: (83 columns, 3417 rows) mkiv_gnd_avg_1985_2013.vav
Individual Column Abundances: (Ames-1001 format) mkiv_gnd_avg_1985_2013.vav.ames
Daily Average Column Abundances: (83 cols, 923 rows) mkiv_gnd_avg_1985_2013.vad
List of windows: (225 rows) mkiv_gnd_avg_1985_2013.windows
Window-to-window biases: mkiv_gnd_avg_1985_2013.vav.cew

IMPORTANT: These files contain data from the 12 different locations tabulated below. It was felt that the benefits of keeping all the MkIV data together in one file outweigh any possible confusion. The files all contain lat/long/alt information for each observation, so it is simple to filter for a particular site.

Ground-based Sites and Observations (1985-2015)

LocationKeyNobsNdayLatitude
(deg.)
Longitude
(deg.)
Altitude
(km)
Esrange, Sweden ESN 160 32 +67.889 +21.085 0.271
Ft Wainwright, Fairbanks, Alaska FAI 124 46 +64.830 -147.614 0.182
Lynn Lake, Manitoba, Canada LYL 20 5 +56.858 -101.066 0.354
Mt. Barcroft, California MTB 1369 255 +37.584 -118.235 3.801
ARC, Mountain View, California ARC 7 4 +37.430 -122.080 0.010
Daggett, California DAG 33 21 +34.856 -116.790 0.626
Ft Sumner, New Mexico FTS 216 71 +34.480 -104.220 1.260
TMF, Wrightwood, California TMF 475 45 +34.382 -117.678 2.257
JPL B183, Pasadena, California JPL 1709 577 +34.199 -118.174 0.345
JPL Mesa, Pasadena, California JPL 20 5 +34.205 -118.171 0.460
NSBF, Palestine, Texas PAL 4 3 +31.780 -95.700 0.100
McMurdo, Antarctica MCM 37 20 -77.847 +166.728 0.100
+ve Latitude = N; +ve Longitude = E
Nobs = Number of Observations.   Nday = Number of Observation Days
Grand totals: Observations = 4167      Observation Days = 1090

Measurement Quantities:

Auxiliary Data: Year, Day, Hour, Run, Lat, long, zobs, zmin, asza, azim, osds, opd, fovi, graw, tins, pins, tout, pout, hout

Vertical column abundances (molec.cm-2): H2O, CO2, O3, N2O, CO, CH4, NO, NO2, NH3, HNO3, HF, HCl, ClO, OCS, H2CO, ClNO3, HCN, CFC-12, COF2, C2H6, C2H4, C2H2, N2, HCFC-22, HDO, and SF6

Instrument Description:

The MkIV interferometer is a high resolution FTIR spectrometer designed and built at JPL in the early 1980's for solar absorption measurements. The MkIV employes a double-passed optical configuration for compactness and to provide passive shear compensation. Two parallel detectors, an HgCdTe photoconductor covering 650-1950 cm-1 and an InSb photodiode covering 1850-5650 cm-1, allow the entire mid-infrared spectrum to be measured simultaneously. For ground-based observations an optical path difference of 117 cm is usually employed, which takes about 3 minutes per scan sampling every fringe of a .633 um He:Ne laser at 10kHz.

Algorithm Description:

Column abundances were derived using the GFIT algorithm, developed at JPL for the analysis of solar absorption spectra. Initial vertical profiles were based on balloon measurements, which were then stretched or squashed until the measured HF absorption was matched. These profiles were then scaled in order to derive the vertical column abundances. The atm.101 linelist was used for the analyses, complemented by the pseudolines for the gases CCl4, CFC-11, CFC-12, CF4, SF6, ClNO3, HCFC-22 and C2H6.

Expected Precision/Accuracy of Measurements:

The precision of these column abundances were determined from the quality of the spectral fits by the GFIT algorithm and are included in the exchange file for each measurement of each gas. Accuracies are more difficult to determine.

For each balloon flight MkIV also performed many days of ground-based observation while waiting for launch. This explains the large number of different locations from which the MkIV instrument has made measurements.

.

MkIV Observation Days from various sites

(Last update: 2004-11-06):

SiteESNFAILYLMTBARCDAGFTSTMFJPLPALMCM(DC8)Total
1985 0 0 0 0 0 0 0 0 5 0 0 0 5
1986 0 0 0 0 0 0 0 1 3 0 20 0 24
1987 0 0 0 0 0 0 0 0 4 0 0 10 14
1988 0 0 0 0 0 0 0 2 5 0 0 2 9
1989 0 0 0 0 0 0 7 0 10 3 0 10 30
1990 0 0 0 0 0 0 7 0 13 0 0 0 20
1991 0 0 0 0 3 0 7 0 40 0 0 0 50
1992 0 0 0 0 0 0 11 0 32 0 0 18 61
1993 0 0 0 0 0 21 10 0 33 0 0 0 64
1994 0 0 0 3 0 0 5 0 47 0 0 0 55
1995 0 0 0 0 0 0 0 0 72 0 0 0 72
1996 0 0 11 0 0 0 6 6 30 0 0 0 53
1997 0 47 0 0 0 0 0 0 18 0 0 0 65
1998 0 0 0 14 0 0 0 24 8 0 0 0 45
1999 1 0 0 33 0 0 0 0 16 0 0 0 50
2000 21 0 0 29 0 0 0 0 26 0 0 0 76
2001 0 0 0101 0 0 0 0 0 0 0 0 101
2002 0 0 0 78 0 0 0 0 6 0 0 0 84
2003 24 0 0 0 0 0 5 0 6 0 0 0 35
2004 0 0 0 0 0 0 4 0 9 0 0 0 13
Total 46 47 11257 3 21 62 33383 3 20 40 926


The following spectra have been (temporarily) removed due to known defects:

Year 1986, days 268 to 288: Some spectra are clipped

Year 1987, day 166-169: Time is wrong by 1 hour??. SZA and columns are wrong

Year 1989, day 177: Time is wrong by 1 hour, so SZA and columns are wrong

Year 1992, day 244: spectrum 224: CCl2F2 contamination

Year 2006, day 25: spectrum 509: Phase errors

Year 2006, day 30: All spectra have huge phase errors

Year 2009, day 292-301: Several HBr cell spectra remain

Contact Information:

G.C. Toon
Mail-Stop 183-601
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109-8099, USA
Phone: 818-354-8259
FAX: 818-354-5148
Email: Geoffrey.C.Toon@jpl.nasa.gov

J.-F. Blavier
Mail-Stop 183-601
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109-8099, USA
Phone: 818-354-6665
FAX: 818-354-5148
Email: JeanFrancois.L.Blavier@jpl.nasa.gov


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