GMD Site Description: THD


  • Country: United States Country Flag
  • Latitude: 41.0541° North
  • Longitude: 124.151° West
  • Elevation: 107.00 masl
  • Time Zone: Local Time + 8.0 hour(s) = UTC


  • Contact Name: Mike Ives
  • Address: HSU Marine Lab
    570 Ewing St
    Trinidad Head, California, 95570, United States
  • Phone: (707) 826-3705
  • Fax: (707) 826-3682


Cooperating Agencies


Trinidad Head is located on a point jutting into the ocean along the remote north coast of California. Much of the time the site experiences baseline conditions, but it also allows for the monitoring of regionally influenced air, affected mainly by forested lands, but to a lesser extent, air having a small urban influence.

An instrument trailer was installed in April 2002 to measure aerosols, surface ozone, radiation, and flask sampling for halocarbons and carbon cycle gases. Bi-weekly airborne vertical profile measurements of carbon cycle gases are collected in flasks above and upwind of Trinidad Head. GMD's measurements provide a continuous baseline of pollution and climate forcing agents in air entering the U.S. Co-located with the Trinidad Head Observatory, the Scripps Institution of Oceanography operates two in situ instruments, one as part of the Advanced Global Atmospheric Gases Experiment (AGAGE), the other for measuring changes in atmospheric oxygen concentrations.

GMD Projects at Trinidad Head, California

Carbon Cycle Surface Flasks

Parameter Formula First Sample Date Status
Carbon Dioxide CO2 2002-04-19 Ongoing
Methane CH4 2002-04-19 Ongoing
Carbon Monoxide CO 2002-04-19 Ongoing
Molecular Hydrogen H2 2002-04-19 Ongoing
Nitrous Oxide N2O 2002-04-19 Ongoing
Sulfur Hexafluoride SF6 2002-04-19 Ongoing
Carbon-13/Carbon-12 in Carbon Dioxide d13C (CO2) 2002-04-19 Ongoing
Oxygen-18/Oxygen-16 in Carbon Dioxide d18O (CO2) 2002-04-19 Ongoing
Methyl Chloride CH3Cl 2004-10-07 Ongoing
Benzene C6H6 2004-10-07 Ongoing
toluene C7H8 2004-10-07 Ongoing
ethane C2H6 2004-10-07 Ongoing
ethene C2H4 2004-10-07 Ongoing
propane C3H8 2004-10-07 Ongoing
propene C3H6 2004-10-07 Ongoing
i-butane i-C4H10 2004-10-07 Ongoing
n-butane n-C4H10 2004-10-07 Ongoing
i-pentane i-C5H12 2004-10-07 Ongoing
n-pentane n-C5H12 2004-10-07 Ongoing
n-hexane n-C6H14 2004-10-07 Ongoing
Wind Speed ws 2002-04-19 Ongoing
Wind Direction wd 2002-04-19 Ongoing
Temperature temp 2004-08-20 Terminated - 2004-09-22
isoprene C5H8 2004-10-07 Ongoing
Acetylene C2H2 2004-10-07 Ongoing

Carbon Cycle Airborne Flasks

Parameter Formula First Sample Date Status
Carbon Dioxide CO2 2003-09-02 Ongoing
Methane CH4 2003-09-02 Ongoing
Carbon Monoxide CO 2003-09-02 Ongoing
Molecular Hydrogen H2 2003-09-02 Ongoing
Nitrous Oxide N2O 2003-09-02 Ongoing
Sulfur Hexafluoride SF6 2014-09-27 Ongoing
Sulfur Hexafluoride SF6 2003-09-02 Ongoing
Carbon-13/Carbon-12 in Carbon Dioxide d13C (CO2) 2003-10-08 Ongoing
Oxygen-18/Oxygen-16 in Carbon Dioxide d18O (CO2) 2003-10-08 Ongoing
HFC-134a CH2FCF3 2004-11-12 Ongoing
HCFC-22 CHF2Cl 2004-11-12 Ongoing
CFC-12 CCl2F2 2004-11-12 Ongoing
Methyl Chloride CH3Cl 2004-11-12 Ongoing
CFC-114 and CFC-114a (combined) CFC-114 and CFC-114a (combined) 2004-11-12 Ongoing
HCFC-142b CH3CF2Cl 2004-11-12 Ongoing
Halon-1211 CBrClF2 2004-11-12 Ongoing
methyl bromide CH3Br 2004-11-12 Ongoing
CFC-11 (ion 101) CCl3F (ion 101) 2004-11-12 Ongoing
CFC-11 (ion 103) CCl3F (ion 103) 2010-05-23 Ongoing
HCFC-141b CH3CCl2F 2004-11-12 Ongoing
methyl iodide CH3I 2004-11-12 Ongoing
CFC-113 CCl2FCClF2 2004-11-12 Ongoing
dichloromethane CH2Cl2 2004-11-12 Ongoing
chloroform CHCl3 2004-11-12 Ongoing
methyl chloroform (ion 97) CH3CCl3 2004-11-12 Ongoing
methyl chloroform (ion 99) CH3CCl3 2010-05-23 Terminated - 2012-10-04
carbon tetrachloride CCl4 2004-11-12 Ongoing
dibromomethane CH2Br2 2004-11-12 Ongoing
tetrachloroethylene C2Cl4 2004-11-12 Ongoing
bromoform CHBr3 2004-11-12 Ongoing
Benzene C6H6 2004-11-12 Ongoing
carbonyl sulfide COS 2004-11-12 Ongoing
HCFC-21 CHCl2F 2015-10-15 Ongoing
HFC-152a CH3CHF2 2004-11-12 Ongoing
HCFC-124 CHClFCF3 2004-11-12 Ongoing
toluene C7H8 2007-07-25 Ongoing
carbonyl disulfide CS2 2004-11-12 Ongoing
Sample Pressure press 2007-06-09 Terminated - 2010-06-20
ethane C2H6 2014-09-27 Ongoing
ethene C2H4 2014-09-27 Ongoing
propane C3H8 2007-06-09 Ongoing
propene C3H6 2014-09-27 Ongoing
i-butane i-C4H10 2014-09-27 Ongoing
n-butane n-C4H10 2007-06-09 Ongoing
i-pentane i-C5H12 2007-06-09 Ongoing
n-pentane n-C5H12 2007-06-09 Ongoing
n-hexane n-C6H14 2014-09-27 Ongoing
Temperature temp 2003-09-02 Ongoing
Ambient Pressure press 2004-01-22 Terminated - 2013-04-18
Relative Humidity rh 2003-09-02 Ongoing
Halon 1301 CF3Br 2007-06-09 Ongoing
Halon 2402 CBrF2CBrF2 2007-06-09 Ongoing
HFC-143a CH3CF3 2007-06-09 Ongoing
HFC-227ea CF3CHFCF3 2007-06-09 Ongoing
HFC-365mfc CH3CF2CH2CF3 2007-06-09 Ongoing
CFC-115 CClF2CF3 2007-06-09 Ongoing
HFC-125 CHF2CF3 2007-06-09 Ongoing
CFC-13 CClF3 2007-06-09 Ongoing
Chloroethane CH3CH2Cl 2007-06-09 Terminated - 2014-05-11
HFC-23 CHF3 2007-06-09 Ongoing
Perfluoropropane C3F8 2008-03-22 Ongoing
Acetylene C2H2 2008-03-22 Ongoing
HFC-32 CH2F2 2009-04-04 Ongoing
HFC-134 CHF2CHF2 2009-04-04 Ongoing
CH2BrCl CH2BrCl 2014-09-27 Ongoing
tetrafluoromethane CF4 2014-09-27 Ongoing
hexafluoroethane CF3CF3 2014-09-27 Ongoing
nitrogen trifluoride NF3 2015-10-15 Ongoing
sulfuryl fluoride SO2F2 2014-09-27 Ongoing
HFC-236fa CF3CH2CF3 2014-09-27 Ongoing
HCFC-133a CH2ClCF3 2015-10-15 Ongoing
CFC-112 CCl3CClF2 2014-09-27 Ongoing
C2HCl3 C2HCl3 2014-09-27 Ongoing
HFO-1234yf CH2=CFCF3 2016-09-17 Ongoing
HFO-1234ze CHF=CHCF3 2016-09-17 Ongoing

HATS Flask Sampling

Parameter Formula First Sample Date Status
HFC-134a CH2FCF3 2002-02-26 Ongoing
HCFC-22 CHF2Cl 2002-03-06 Ongoing
Methyl Chloride CH3Cl 2002-03-06 Ongoing
HCFC-142b CH3CF2Cl 2002-02-26 Ongoing
Halon-1211 CBrClF2 2002-02-26 Ongoing
methyl bromide CH3Br 2002-03-06 Ongoing
HCFC-141b CH3CCl2F 2002-02-26 Ongoing
CFC-113 CCl2FCClF2 2002-02-26 Ongoing
dichloromethane CH2Cl2 2002-03-06 Ongoing
tetrachloroethylene C2Cl4 2002-03-06 Ongoing
carbonyl sulfide COS 2002-04-03 Ongoing
HFC-152a CH3CHF2 2002-02-26 Ongoing
Halon 1301 CF3Br 2004-02-26 Ongoing
Halon 2402 CBrF2CBrF2 2004-02-26 Ongoing
HFC-143a CH3CF3 2007-01-17 Ongoing
HFC-227ea CF3CHFCF3 2011-06-19 Ongoing
HFC-365mfc CH3CF2CH2CF3 2009-08-10 Ongoing
HFC-125 CHF2CF3 2007-01-17 Ongoing
HFC-32 CH2F2 2009-03-14 Ongoing
Methyl Chloroform CH3CCl3 2002-02-26 Ongoing

Aerosol Surface In-Situ

Parameter Formula First Sample Date Status
Light Scattering Coefficient σsp 2002-01-01 Ongoing
Light Absorption Coefficient σap 2002-01-01 Ongoing
Particle Number Concentration Nt 2002-01-01 Ongoing
Aerosol Chemical Composition 2002-01-01 Ongoing
Aerosol Hygroscopic Growth f(RH) 2002-01-01 Ongoing

Radiation In-Situ Observatory

Parameter Formula First Sample Date Status
Direct Beam 2002-04-10 Ongoing
Shortwave Global 2002-04-10 Ongoing
Diffuse 2002-04-10 Ongoing
Downward Longwave 2003-05-20 Ongoing

Surface Ozone

Parameter Formula First Sample Date Status
Ozone O3 2002-04-18 Ongoing





Parameter Formula First Sample Date Status
Wind Speed ws 2002-06-29 Ongoing
Wind Direction wd 2002-06-29 Ongoing
Temperature temp 2002-04-10 Ongoing
Ambient Pressure press 2002-04-10 Ongoing
Relative Humidity rh 2002-04-10 Ongoing

Ozone Airborne

Trace gases Airborne Flasks