atmos: Index | Files

package wesely1989

import ""

Package wesely1989 implements an algorithm for surface resistance to dry deposition.

Citation for the original article, followed by citation for an article with some corrections which have been incorporated here:

M. L. Wesely, Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models, Atmos. Environ. 23, 1293–1304 (1989),

J. Walmsley, and M. L. Wesely, Modification of coded parametrizations of surface resistances to gaseous dry deposition, Atmos. Environ. 30(7), 1181–1188 (1996),

The abstract of the original article:

Methods for estimating the dry deposition velocities of atmospheric gases in the U.S. and surrounding areas have been improved and incorporated into a revised computer code module for use in numerical models of atmospheric transport and deposition of pollutants over regional scales. The key improvement is the computation of bulk surface resistances along three distinct pathways of mass transfer to sites of deposition at the upper portions of vegetative canopies or structures, the lower portions, and the ground (or water surface). This approach replaces the previous technique of providing simple look-up tables of bulk surface resistances. With the surface resistances divided explicitly into distinct pathways, the bulk surface resistances for a large number of gases in addition IO those usually addressed in acid deposition models (SO2, O3, NOx, and HNO3) can be computed, if estimates of the effective Henry’s Law constants and appropriate measures of the chemical reactiiity of the various substances are known. This has been accomnlished successfullv for H2O2, HCHO, CH3CHO (to represent other aldehydes CH3O2H (to represent organic peroxides), CH3C(O)O2H, HCOOH (to represent organic acids), NH3, CH3C(O)O2NO2, and HNO2. Other factors considered include surface temperature, stomatal response to environmental parameters, the wetting of surfaces by dew and rain, and the covering of surfaces by snow. Surface emission of gases and variations of uptake characteristics by individual plant species within the landuse types are not considered explicitly.


Package Files

data.go doc.go surfaceresistance.go


var (
    So2Data = &GasData{1.9, 1.e5, 0}
    O3Data  = &GasData{1.6, 0.01, 1}
    No2Data = &GasData{1.6, 0.01, 0.1} // Wesely (1989) suggests that,
    // in general, the sum of NO and NO2 should be considered rather
    // than NO2 alone because rapid in-air chemical reactions can cause
    // a significant change of NO and NO2 vertical fluxes between the
    // surface and the point at which deposition velocities are applied,
    // but the sum of NO and NO2 fluxes should be practically unchanged.
    NoData   = &GasData{1.3, 3.e-3, 0} // Changed according to Walmsley (1996)
    Hno3Data = &GasData{1.9, 1.e14, 0}
    H2o2Data = &GasData{1.4, 1.e5, 1}
    AldData  = &GasData{1.6, 15, 0}     // Acetaldehyde (aldehyde class)
    HchoData = &GasData{1.3, 6.e3, 0}   // Formaldehyde
    OpData   = &GasData{1.6, 240, 0.1}  // Methyl hydroperoxide (organic peroxide class)
    PaaData  = &GasData{2.0, 540, 0.1}  // Peroxyacetyl nitrate
    OraData  = &GasData{1.6, 4.e6, 0}   // Formic acid (organic acid class)
    Nh3Data  = &GasData{0.97, 2.e4, 0}  // Changed according to Walmsley (1996)
    PanData  = &GasData{2.6, 3.6, 0.1}  // Peroxyacetyl nitrate
    Hno2Data = &GasData{1.6, 1.e5, 0.1} // Nitrous acid

Properties of various gases from Wesely (1989) Table 2.

func SurfaceResistance Uses

func SurfaceResistance(gasData *GasData, G, Ts, Θ float64,
    iSeason SeasonCategory, iLandUse LandUseCategory,
    rain, dew, isSO2, isO3 bool) (r_c float64)

Calculates surface resistance to dry depostion [s m-1] based on Wesely (1989) equation 2 when given information on the chemical of interest (gasData), solar irradiation (G [W m-2]), the surface air temperature (Ts [°C]), the slope of the local terrain (Θ [radians]), the season index (iSeason), the land use index (iLandUse), whether there is currently rain or dew, and whether the chemical of interest is either SO2 (isSO2) or O3 (isO3).

From Wesely (1989) regarding rain and dew inputs:

"A direct computation of the surface wetness would be most desirable, e.g.
by estimating the amount of free surface water accumulated and then
evaporated. Alternatively, surface relative humidity might be a useful
index. After dewfall and rainfall events are completed, surface wetness
often disappears as a result of evaporation after approximately 2
hours of good atmospheric mixing, the period of time recommended earlier
(Sheih et al., 1986)".

type GasData Uses

type GasData struct {
    Dh2oPerDx float64 // ratio of water to chemical-of-interest diffusivities [-]
    Hstar     float64 // effective Henry's law coefficient [M atm-1]
    Fo        float64 // reactivity factor [-]

Holder for gas properties from Wesely (1989) Table 2.

type LandUseCategory Uses

type LandUseCategory int
const (
    Urban        LandUseCategory = iota // 0: Urban land
    Agricultural                        // 1: Agricultural land
    Range                               // 2: Range land
    Deciduous                           // 3: Deciduous forest
    Coniferous                          // 4: Coniferous forest
    MixedForest                         // 5: Mixed forest including wetland
    Water                               // 6: Water, both salt and fresh
    Barren                              // 7: Barren land, mostly desert
    Wetland                             // 8: Nonforested wetland
    RangeAg                             // 9: Mixed agricultural and range land
    RockyShrubs                         // 10: Rocky open areas with low-growing shrubs

type SeasonCategory Uses

type SeasonCategory int
const (
    Midsummer    SeasonCategory = iota // 0: Midsummer with lush vegetation
    Autumn                             // 1: Autumn with unharvested cropland
    LateAutumn                         // 2: Late autumn after frost, no snow
    Winter                             // 3: Winter, snow on ground and subfreezing
    Transitional                       // 4: Transitional spring with partially green short annuals

Package wesely1989 imports 1 packages (graph) and is imported by 2 packages. Updated 2016-07-24. Refresh now. Tools for package owners.