Mod Parcel Theory
get_scale_factor_theory_numerical(temp_surf_ref, temp_surf_quant, r_ref, r_quant, temp_ft_quant, lapse_mod_D_quant, lapse_mod_M_quant, p_ft_ref, p_surf_ref, p_surf_quant=None, lapse_mod_D_ref=None, lapse_mod_M_ref=None, temp_surf_lcl_calc=300, guess_lapse=lapse_dry, valid_range=100)
Calculates the theoretical near-surface temperature change for percentile \(x\), \(\delta \hat{T}_s(x)\), relative to the reference temperature change, \(\delta \tilde{T}_s\). The theoretical scale factor is given by the linear sum of mechanisms assumed independent: either anomalous values in current climate, \(\Delta\), or due to the variation in that parameter with warming, \(\delta\).
Reference Quantities
The reference quantities, \(\tilde{\chi}\) are free to be chosen by the user. For ease of interpretation, I propose the following, where \(\overline{\chi}\) is the mean value of \(\chi\) across all days:
- \(\tilde{T}_s = \overline{T_s}; \delta \tilde{T}_s = \delta \overline{T_s}\)
- \(\tilde{r}_s = \overline{r_s}; \delta \tilde{r}_s = 0\)
- \(\tilde{p}_s = \overline{p_s}; \delta \tilde{p}_s = 0\)
- \(\tilde{\eta_D} = 0; \delta \tilde{\eta_D} = 0\)
- \(\tilde{\eta_M} = 0; \delta \tilde{\eta_M} = 0\)
Given the choice of these five reference variables and their changes with warming, the reference free troposphere temperature, \(\tilde{T}_{FT}\), can be computed according to the definition of \(\tilde{h}^{\dagger}\):
\(\tilde{h}^{\dagger} = (c_p - R^{\dagger})\tilde{T}_{sP} + L_v \tilde{q}_s = (c_p + R^{\dagger}) \tilde{T}_{FT} + L_v q^*(\tilde{T}_{FTP}, p_{FT})\)
Poor choice of reference quantities may cause the theoretical scale factor to be a bad approximation. If this
is the case, get_approx_terms can be used to investigate what is causing the theory to break down.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
temp_surf_ref
|
ndarray
|
|
required |
temp_surf_quant
|
ndarray
|
|
required |
r_ref
|
ndarray
|
|
required |
r_quant
|
ndarray
|
|
required |
temp_ft_quant
|
ndarray
|
|
required |
lapse_mod_D_quant
|
ndarray
|
|
required |
lapse_mod_M_quant
|
ndarray
|
|
required |
p_ft_ref
|
float
|
Pressure at free troposphere level for reference day, \(p_{FT}\), in Pa. |
required |
p_surf_ref
|
ndarray
|
Pressure at near-surface for reference day, \(p_s\), in Pa. |
required |
p_surf_quant
|
Optional[ndarray]
|
|
None
|
lapse_mod_D_ref
|
Optional[ndarray]
|
|
None
|
lapse_mod_M_ref
|
Optional[ndarray]
|
|
None
|
temp_surf_lcl_calc
|
float
|
Surface temperature to use when computing \(\sigma_{LCL}\). If |
300
|
guess_lapse
|
float
|
Initial guess for parcel temperature will be found assuming this bulk lapse rate
from |
lapse_dry
|
valid_range
|
float
|
Valid temperature range in Kelvin for temperature. Allow +/- this much from the initial guess. |
100
|
Returns:
| Name | Type | Description |
|---|---|---|
scale_factor |
ndarray
|
|
scale_factor_linear |
ndarray
|
|
info_cont |
dict
|
Dictionary containing a contribution from each mechanism. This gives the contribution from each physical mechanism to the overall scale factor. |
Source code in isca_tools/thesis/mod_parcel_theory.py
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get_temp_mod_parcel(rh_surf, p_surf, p_ft, lapse_mod_D=0, lapse_mod_M=0, temp_surf=None, temp_ft=None, temp_surf_lcl_calc=300, guess_lapse=lapse_dry, valid_range=100, method='add')
This returns the free tropospheric (or surface) temperature \(T_{FT}\) (\(T_s\)), such that the parcel modified MSE, \(h_{\mathrm{p}}^{\dagger}\) is equal at the surface and free troposphere.
The parcel temperature can be obtained with both lapse_mod_D and lapse_mod_M set to zero.
If any variable given is a numpy array, the returned value will be a numpy array of the same shape. If more than one variable is a numpy array, they must be the same shape.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
rh_surf
|
float
|
Environmental pseudo relative humidity, \(q_s/q^*(T_s, p_s)\) at |
required |
p_surf
|
float
|
Pressure at near-surface, \(p_s\), in Pa. Either a single value or one for each temperature. |
required |
p_ft
|
float
|
Pressure at free troposphere level, \(p_{FT}\), in Pa. Either a single value or one for each temperature. |
required |
lapse_mod_D
|
float
|
The quantity \(\eta_D\) such that the lapse rate between \(p_s\) and LCL is \(\Gamma_D + \eta_D\) with \(\Gamma_D\) being the dry adiabatic lapse rate. Either a single value or one for each temperature. Units: K/m |
0
|
lapse_mod_M
|
float
|
The quantity \(\eta_M\) such that the lapse rate above the LCL is \(\Gamma_M(p) + \eta_M\) with
\(\Gamma_M(p)\) being the moist adiabatic lapse rate at pressure \(p\).
Either a single value or one for each temperature.
Units: K/m
If |
0
|
temp_surf
|
Optional[float]
|
Environmental temperature at |
None
|
temp_ft
|
Optional[float]
|
Environmental temperature at |
None
|
temp_surf_lcl_calc
|
Optional[float]
|
Surface temperature to use when computing \(\sigma_{LCL}\). If |
300
|
guess_lapse
|
float
|
Initial guess for temperature will be found assuming this bulk lapse rate
from |
lapse_dry
|
valid_range
|
float
|
Valid temperature range in Kelvin for temperature. Allow +/- this much from the initial guess. |
100
|
method
|
Literal['add', 'multiply']
|
How to modify moist adiabat lapse rate using |
'add'
|
Returns:
| Name | Type | Description |
|---|---|---|
temp |
Union[float, ndarray]
|
Environmental temperature in Kelvin at the pressure level |
Source code in isca_tools/thesis/mod_parcel_theory.py
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temp_mod_parcel_fit_func(temp_ft, temp_surf, rh_surf, p_surf, p_ft, lapse_mod_D=0, lapse_mod_M=0, temp_surf_lcl_calc=300, method='add')
In the modified parcel framework, equating surface and free tropospheric moist static energy leads to the exact vertical coupling equation:
where \(R^{\dagger} = R\ln(p_s/p_{FT})/2\) and the parcel temperatures are related to the environmental temperatures by:
- \(T_{\mathrm{sp}} = \sigma_{LCL}^{R\eta_D/g} T_s\)
- \(T_{\mathrm{FTp}} = (\sigma_{LCL} / \sigma_{FT})^{R\eta_M/g} T_{FT}\)
And an approximate formula derived from Bolton 1980 is used to relate \(\sigma_{LCL}\) to surface relative humidity.
Note that in this definition of parcel, we neglect the error in relating \(z\) to temperature.
This function returns the RHS minus the LHS of this equation to then give to scipy.optimize.fsolve to find
\(T_{\mathrm{FTp}}\) or \(T_{\mathrm{sp}}\).
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
temp_ft
|
float
|
float
Environmental temperature at |
required |
temp_surf
|
float
|
Environmental temperature at |
required |
rh_surf
|
float
|
Environmental pseudo relative humidity, \(q_s/q^*(T_s, p_s)\) at |
required |
p_surf
|
float
|
Pressure at near-surface, \(p_s\), in Pa. |
required |
p_ft
|
float
|
Pressure at free troposphere level, \(p_{FT}\), in Pa. |
required |
lapse_mod_D
|
float
|
The quantity \(\eta_D\) such that the lapse rate between \(p_s\) and LCL is \(\Gamma_D + \eta_D\) with \(\Gamma_D\) being the dry adiabatic lapse rate. Units: K/m |
0
|
lapse_mod_M
|
float
|
The quantity \(\eta_M\) such that the lapse rate above the LCL is \(\Gamma_M(p) + \eta_M\) with
\(\Gamma_M(p)\) being the moist adiabatic lapse rate at pressure \(p\).
Units: K/m
If |
0
|
temp_surf_lcl_calc
|
Optional[float]
|
Surface temperature to use when computing \(\sigma_{LCL}\). If |
300
|
method
|
Literal['add', 'multiply']
|
How to modify moist adiabat lapse rate using |
'add'
|
Returns:
| Name | Type | Description |
|---|---|---|
modMSE_diff |
float
|
difference between parcel surface and free troposphere saturated modified MSE. |
Source code in isca_tools/thesis/mod_parcel_theory.py
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