Climate indices: ONI, PDO, QBO, degree heating weeks, cyclone energy, Hadley edge, scaling and downscaling
Source:R/ClimateIndices.R
OniIndex.RdOniIndex: Oceanic Nino Index (NOAA CPC), the centred 3-month mean of
the Nino-3.4 anomaly from the calendar-month climatology of the months
base (index range, default all); El Nino (La Nina) episodes are at
least min_run consecutive seasons with ONI at or above
threshold (at or below minus threshold).
PdoIndex: Pacific Decadal Oscillation, the standardised leading
principal component of monthly North Pacific SST anomalies (minus the
global-mean anomaly when global_mean is given, columns scaled by
sqrt(weights)); the largest loading is made negative.
QboIndex: deseasonalised equatorial 30 hPa zonal wind, its phase,
westerly onsets and periods. DegreeHeatingWeeks: Coral Reef Watch
HotSpots max(SST - MMM, 0), degree heating weeks over the trailing
84 days counting HotSpots of at least 1 degree, and alert levels 0 to 4.
CycloneEnergy: accumulated cyclone energy 1e-4 sum v^2
(fixes at or above threshold) and power dissipation index
sum v^3 dt. HurricaneTrack: haversine step lengths,
translation speeds, bearings and the recurvature fix.
HadleyEdge: mean meridional mass streamfunction
psi = (2 pi a cos(phi) / g) int v dp (trapezoid rule from the top
level) and the zero crossings of psi at level poleward of its
northern maximum and southern minimum. CcScaling: binned
Clausius-Clapeyron scaling, the regression of the log q quantile of
precipitation on bin-centre temperature, rate 100 (exp(b) - 1)
percent per degree, and the Bolton (1980) theoretical rate.
SeaLevelSemiEmpirical: Rahmstorf (2007) dH/dt = a (T - T0)
by least squares on mid-step temperatures, with projection.
EmpiricalQuantileMap: Q_obs(F_hist(x)) with type 7
quantiles. BcsdDownscale: quantile-mapped coarse series, anomalies
from the observed climatology interpolated by inverse distance to fine
points and applied to the fine climatology. ProbabilityRatio:
exceedance probabilities, probability ratio and fraction of attributable risk.
Usage
OniIndex(sst, start_month = 1, base = NULL, threshold = 0.5, min_run = 5)
PdoIndex(sst, start_month = 1, weights = NULL, global_mean = NULL)
QboIndex(u30, start_month = 1)
DegreeHeatingWeeks(sst, mmm, days_per_obs = 1, window_days = 84)
CycloneEnergy(vmax, dt_hours = 6, threshold = 35)
HurricaneTrack(lat, lon, dt_hours = 6, radius_km = 6371)
HadleyEdge(lat, p, v, level = 50000, radius = 6371000, g = 9.80665)
CcScaling(temp, precip, bin_width = 2, q = 0.99, min_count = 10)
SeaLevelSemiEmpirical(temp, sea_level, dt = 1, future_temp = NULL)
EmpiricalQuantileMap(obs, model_hist, model_future)
BcsdDownscale(
obs_coarse,
gcm_hist,
gcm_future,
coarse_xy,
fine_xy,
fine_clim,
multiplicative = FALSE,
power = 2
)
ProbabilityRatio(factual, counterfactual, threshold)Arguments
- sst
Numeric monthly (or daily for
DegreeHeatingWeeks) series, or forPdoIndexaT x Nmatrix.- start_month
Calendar month of the first value.
- base
Length-2 index range (0-based start, end exclusive) of the climatology months.
- threshold
ONI episode threshold, or ACE wind threshold, or exceedance threshold.
- min_run
Minimum episode length in seasons.
- weights
Area weights per column.
- global_mean
Global-mean SST series subtracted after deseasonalising.
- u30
Monthly 30 hPa equatorial zonal wind.
- mmm
Maximum monthly mean climatology.
- days_per_obs
Days between observations.
- window_days
Accumulation window in days.
- vmax
Maximum sustained winds of one storm.
- dt_hours
Hours between fixes.
- lat, lon
Latitudes and longitudes (degrees).
- radius_km
Earth radius (km).
- p
Pressure levels (Pa, increasing downward).
- v
Zonal-mean meridional wind, levels by latitudes.
- level
Pressure level of the edge metric.
- radius
Earth radius (m).
- g
Gravity.
- temp
Temperatures.
- precip
Precipitation.
- bin_width
Temperature bin width.
- q
Quantile level.
- min_count
Minimum values per bin.
- sea_level
Sea-level series.
- dt
Time step.
- future_temp
Future temperature path.
- obs, model_hist, model_future
Observed, model-historical and model-future series.
- obs_coarse, gcm_hist, gcm_future
Lists of coarse-cell series.
- coarse_xy, fine_xy
Coordinate matrices of coarse cells and fine points.
- fine_clim
Fine-scale climatology.
- multiplicative
Ratio anomalies (precipitation) instead of differences.
- power
Inverse-distance exponent.
- factual, counterfactual
Samples of the factual and counterfactual climates.
References
Mantua, N. J. et al. (1997). A Pacific interdecadal climate oscillation with impacts on salmon production. BAMS 78, 1069-1079. Reed, R. J. et al. (1961). J. Geophys. Res. 66, 813-818. Liu, G., Strong, A. E. and Skirving, W. (2003). Eos 84, 137-144. Emanuel, K. (2005). Nature 436, 686-688. Davis, S. M. and Rosenlof, K. H. (2012). J. Climate 25, 1061-1078. Lenderink, G. and van Meijgaard, E. (2008). Nature Geoscience 1, 511-514. Rahmstorf, S. (2007). Science 315, 368-370. Wood, A. W. et al. (2004). Climatic Change 62, 189-216. Stott, P. A., Stone, D. A. and Allen, M. R. (2004). Nature 432, 610-614.