Partitioning from interval average data

The flux partitioning procedure of [SS08] emphasizes the use of high-frequency eddy covariance data because it may be necessary to filter the data to satisfy variance similarity assumptions and obtain a physically consistent partitioning. However, once the filter has been applied (or if a filter is not required on a particular data set), the partitioning calculation is actually made using interval average values for Fq=<w’q’>, Fc=<w’c’>, var(q), var(c), corr(q,c), and WUE.

In fluxpart, the partitioning calculation using interval average values is made in fluxpart.partition.fvspart_interval().

Example: Palatella et al. [PRV14] (Table 1) reported the following quantities for an hour time interval:

stddev(q)

0.411163 g/m^3

stddev(c)

5.182580 mg/m^3

<w’q’>

0.033140 g/m^2/s

<w’c’>

-0.472108 mg/m^2/s

corr(q, c)

-0.881017

wue

-37.158598 mg CO2 / g H2O

A flux partitioning solution for this data can found with:

from fluxpart.partition import fvspart_interval
from fluxpart.containers import WQCData

# Note converting input to SI units

wue = -37.158598e-3
interval_data = WQCData(
    var_q=0.411163e-3 ** 2,
    var_c=5.182580e-6 ** 2,
    wq=0.033140e-3,
    wc=-0.472108e-6,
    corr_qc=-0.881017,
)
massfluxes, fvsp = fvspart_interval(interval_data, wue, wipe_if_invalid=True)

print(fvsp)
print()
print(massfluxes)

which produces:

-------------
FVSP Solution
-------------
  valid_partition: True
  fvsp_mssg:
  Wavelet filtering level: nan
  var_q = 0.1691 (g/m^3)^2
  var_c = 26.86 (mg/m^3)^2
  corr_qc = -0.881
  cov_w_q = 0.03314 g/m^2/s
  cov_w_c = -0.4721 mg/m^2/s
  corr_cp_cr = -0.7585
  var_cp = 27.36 (mg/m^3)^2
  sig_cr = 0.06352 mg/m^3
  co2soln_id = 1
  valid_root = True
  root_mssg =

MassFluxes(
    Fq = 0.03314 g/m^2/s,
    Fqt = 0.01282 g/m^2/s,
    Fqe = 0.02032 g/m^2/s,
    Fc = -0.4721 mg/m^2/s,
    Fcp = -0.4765 mg/m^2/s,
    Fcr = 0.004389 mg/m^2/s)

The obtained results match closely those reported in [PRV14]:

[PRV14]

fluxpart

var(cp) (mg/m^3)^2

27.358130

27.36

corr(cp,cr)

-0.757626

-0.7585

<w’qt’> (g/m^3/s)

0.012878

0.01282

<w’qe’> (g/m^3/s)

0.020262

0.02032

<w’cp’> (mg/m^3/s)

-0.476489

-0.4765

<w’cr’> (mg/m^3/s)

0.004381

0.004389