DOI: 10.5061/dryad.ghx3ffc34
title: Seasonal landfill methane emissions driven by temperature and pressure

description: More than a quarter of anthropogenic global warming has been attributed to
 methane growth in the atmosphere. Landfills account for 17 % of estimated
 methane emissions in the United States of America (USA), according to the
 Environmental Protection Agency (EPA), but studies show that many
 landfills emit more than reported. We developed a novel method to
 calculate monthly methane emissions from an active landfill using
 atmospheric methane mixing ratios observed from a single tower in New
 Jersey, USA. The tower method provides two and a half years of
 semi-continuous measurements and therefore observes more of the
 variability of methane emissions and lacks the sampling bias present in
 other methods. Time-specific comparison of tower-based methane emissions
 against those observed from summertime aircraft sampling and year-round
 mobile ground-based platforms showed good agreement. Estimated methane
 emissions for 2023 were five times greater than those reported to the EPA.
 We observed a strong seasonality in methane emissions, with a peak in the
 winter and a minimum in the summer. This seasonal cycle was driven by a
 strong negative dependence on air temperature and the change in
 atmospheric pressure. Our results highlight the importance of observations
 in non-ideal weather conditions (such as declining pressure and
 near-freezing temperatures) when methane emissions are largest. We suggest
 that this methodology could be applied to other suitable landfills to
 improve estimates of methane emissions.
description: # Seasonal landfill methane emissions driven by temperature and pressure
 Dataset DOI:
 [10.5061/dryad.ghx3ffc34](https://doi.org/10.5061/dryad.ghx3ffc34) ##
 Description of the data and file structure The file tower_observations_30s
 contains the 30-second merged dataset for all observations at the PAMS
 tower site (40.46228, -74.42932) taken at 20 m height above ground level.
 Gas concentration data were calibrated and merged to 30-seconds using the
 calibration method described in the associated manuscript. Wind data have
 a native 30-second resolution, while insolation has a native 1-minute
 resolution. PBL height comes from NOAA’s hourly High Resolution Rapid
 Refresh model, and atmospheric pressure and temperature are measured every
 5 minutes. Those values have been linearly interpolated to the 30-second
 resolution of the wind measurements. Data from the New Jersey Mesonet site
 in East Brunswick, NJ (40.473318, -74.393765) are also provided. These
 have a native 5-minute resolution and columns have the prefix “EB”
 attached to indicate the East Brunswick site. Column names contain units
 at the end (e.g., CH4.g.m3 is methane measured in grams per cubic meter).
 The file pressure_dependence_results.csv contains the tower, aircraft, and
 mobile-based estimates for methane emissions (in kg/hour) along with
 corresponding 6-hour pressure change (for the tower). Similarly, the file
 temperature_dependence_results.csv contains the same but with the
 corresponding temperatures. The file monthly_results.csv has estimated
 emissions in kg/hour for each month using the tower data. ### Files and
 variables #### File: tower_observations_30s.csv **Description:**  #####
 Variables * utctime: Time in UTC * CH4.ppbv: Calibrated methane
 measurement from the Picarro G2401, in parts per billion by volume *
 CO.ppbv: Calibrated carbon monoxide measurement from the Picarro G2401, in
 parts per billion by volume * CO2.ppmv: Calibrated carbon dioxide
 measurement from the Picarro G2401, in parts per million by volume *
 H2O.ppthv: Calibrated humidity measurement from the Picarro G2401, in
 parts per thousand by volume * C2H6.ppbv: Calibrated ethane measurement
 from the Aeris MIRA Ultra, in parts per billion by volume *
 N2O.ppbv: Calibrated nitrous oxide measurement from the Aeris MIRA Ultra,
 in parts per billion by volume * wind.speed.m/s: Wind speed from the EPA
 PAMS site at 20 meters height, in meters per second *
 wind.direction.degrees: Wind direction from the EPA PAMS site at 20 meters
 height, in degrees * temp.C: Temperature measured at the EPA PAMS site at
 20 meters height, in Celsius * pressure.hPa: Barometric pressure measured
 at the EPA PAMS site at 2 meters height, in hectopascals *
 insolation.W.m2: Shortwave insolation measured at the EPA PAMS site, in
 Watts per square meter * PBL.m: Planetary Boundary Layer height from the
 NOAA High Resolution Rapid Refresh model, taken from the grid box nearest
 the PAMS site * CH4.g.m3: Calibrated methane measurement from the Picarro
 G2401, in grams per cubic meter * CH4.enhancement.g.m3: Methane
 enhancement above background, in grams per cubic meter *
 mean.wind.direction.degrees: Mean wind direction over the preceding amount
 of time corresponding to the transit time between the landfill and the
 PAMS site, from the 20-meter PAMS site measurement, in degrees *
 mean.wind.speed.m/s: Mean wind speed over the preceding amount of time
 corresponding to the transit time between the landfill and the PAMS site,
 from the 20-meter PAMS site measurement, in meters per second *
 mean.insolation.W.m2: Mean insolation over the preceding amount of time
 corresponding to the transit time between the landfill and the PAMS site,
 from the PAMS site measurement, in Watts per square meter *
 EB.wind.direction.degrees: Wind direction from the New Jersey Mesonet site
 in East Brunswick located next to the landfill, in degrees *
 EB.wind.speed.m/s: Wind speed from the New Jersey Mesonet site in East
 Brunswick located next to the landfill, in meters per second *
 EB.pressure.hPa: Barometric pressure from the New Jersey Mesonet site in
 East Brunswick located next to the landfill, in hectopascals * EB.temp.C:
 Temperature from the New Jersey Mesonet site in East Brunswick located
 next to the landfill, in Celsius #### File:
 temperature_dependence_results.csv **Description:**  ##### Variables *
 temperature.C: Center of the corresponding temperature range (for the
 tower data, using the measurement at the New Jersey Mesonet site) or
 instantaneous temperature (for the aircraft and mobile data), in Celsius *
 mean.flux.estimate: Mean estimate of the flux for that temperature or
 temperature range, in kg/hour * median.flux.estimate: Median estimate of
 the flux for that temperature or temperature range, in kg/hour *
 higher.bound.estimate: Upper bound estimate of the flux for that
 temperature or temperature range, in kg/hour  *
 lower.bound.estimate: Lower bound estimate of the flux for that
 temperature or temperature range, in kg/hour  * type: Categorical variable
 describing the type of flux estimate: tower-based, aircraft, or mobile
 drive #### File: pressure_dependence_results.csv **Description:**  #####
 Variables * pressure.change.hPa/hour: Center of the corresponding 6-hour
 pressure change range (for the tower data, using the measurement at the
 New Jersey Mesonet site) or pressure change over the preceding 6-hours
 (for the aircraft and mobile data), in hectopascals per hour *
 mean.flux.estimate: Mean estimate of the flux for that pressure or
 pressure range, in kg/hour  * median.flux.estimate: Median estimate of the
 flux for that pressure or pressure range, in kg/hour  *
 higher.bound.estimate: Upper bound estimate of the flux for that pressure
 or pressure range, in kg/hour  * lower.bound.estimate: Lower bound
 estimate of the flux for that pressure or pressure range, in kg/hour  *
 type: Categorical variable describing the type of flux estimate:
 tower-based, aircraft, or mobile drive #### File: monthly_results.csv
 **Description:**  ##### Variables * year: Year the measurements occurred *
 month: Month the measurements occurred * day: Day the measurements
 occurred. Since tower measurements include data for the entire month, the
 day is left NA * mean.estimate: Mean estimate of the flux, in kg/hour  *
 lower.bound.estimate: Lower bound estimate of the flux, in kg/hour  *
 upper.bound.estimate: Upper bound estimate of the flux, in kg/hour  *
 type: Categorical variable describing the type of flux estimate:
 tower-based, aircraft, or mobile drive ## Code/software All files are .csv
 format and can be opened with any spreadsheet software or coding language.