Langematz, Oberländer, Kunze Ulrike Langematz, Sophie Oberländer and Markus Kunze Institut für...

Langematz, Oberländer, Kunze

Ulrike Langematz, Sophie Oberländer and Markus Kunze Institut für Meteorologie, Freie Universität Berlin, Germany

The effects of different solar irradiance datasets on stratospheric

heating rates and temperatures

Workshop on "Recent variability of the solar spectral irradiance and its impact on climate modelling”, Berlin, 15.5.2012

Langematz, Oberländer, Kunze 2

Largest solar cycle variations in short wavelengths – up to several tens of percent in the ultraviolet (UV) spectral range

Lean et al., 1997

>50% in 121,6 nm (Lyman-α)

5-12% in 175-240 nm

3-5% in 240-260 nm

0.1 % change in TSI

11-year solar max minus min


SPARC (Stratospheric Processes and their Role in Climate) CCMVal (Chemistry-Climate Model Validation Activity), Chapter 3 (Radiation)

(Figure 17, from Forster et al., 2011)

Simulation of the stratospheric solar signal requires …

Solar only O3 only Solar + O3

spectrally resolved short-wave radiation scheme

Heating rate differences solar max-min


Simulation of the stratospheric solar signal requires …

spectrally resolved solar fluxes at TOA

Spectral solar fluxes need to be prescribed at top of a GCM or CCM

Standard data set: NRLSSI (Lean, 2000; Lean et al., 2005)

Several new spectral solar irradiance data sets from different measurement platforms exist.

To which extent is the simulated solar signal affected by the prescribed solar fluxes at the top of the atmosphere?


NRLSSI: Standard spectral irradiance data set

Alternative irradiance data sets

Effects of irradiance data sets on shortwave heating and temperature

Solar signal from SIM data set

Uncertainty factors

Outline


NRLSSI: Standard spectral irradiance data set

• First daily spectral solar flux data set from Naval Research Laboratory, Washington D.C.

• Based on empirical model adjusted to measurements from

TIMED/SEE (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Solar EUV Experiment),

SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on board UARS (Upper Atmosphere Research Satellite),

completed with SOLSPEC (Solar Spectral Irradiance Measurements) on ISS

• Most widely used dataset

• Input for SPARC CCMVal climate scenario simulations

• First daily spectral solar flux data set from Naval Research Laboratory, Washington D.C.

• Based on empirical model adjusted to measurements from

TIMED/SEE (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Solar EUV Experiment),

SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on board UARS (Upper Atmosphere Research Satellite),

completed with SOLSPEC (Solar Spectral Irradiance Measurements) on ISS

• Most widely used dataset

• Input for SPARC CCMVal climate scenario simulations

Maximum heating (~14 K/day) at summer

stratopause (~1 hPa)

Shortwave Heating Rates in K/day from FUBRad* scheme with NRLSSI data

(Lean, 2000; Lean et al., 2005)

15 Jan

* Nissen et al., 2007


Alternative Irradiance Data Sets I

NRLSSI

Lean, 2000; Lean et al., 2005

• Naval Research Laboratory, Washington D.C.

• TIMED/SEE (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Solar EUV Experiment), SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on board UARS, completed with SOLSPEC (Solar Spectral Irradiance Measurements)

• Empirical model

• Spectral range: 0 - 3000 nm

• Sampling: 1-5 nm

NRLSSI

Lean, 2000; Lean et al., 2005

• Naval Research Laboratory, Washington D.C.

• TIMED/SEE (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Solar EUV Experiment), SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on board UARS, completed with SOLSPEC (Solar Spectral Irradiance Measurements)

• Empirical model


• Sampling: 1-5 nm

MPS

Krivova et al., 2009, 2011

• MPl für Sonnensystem-forschung, Katlenburg-L.

• KPNSO (Kitt Peak National Solar Observatory) magnetograms and SOHO (Solar and Heliospheric Observatory) MDI (Michelson Doppler Imager) images

• SATIRE model


• Sampling: 1 nm

MPS

Krivova et al., 2009, 2011

• MPl für Sonnensystem-forschung, Katlenburg-L.

• KPNSO (Kitt Peak National Solar Observatory) magnetograms and SOHO (Solar and Heliospheric Observatory) MDI (Michelson Doppler Imager) images

• SATIRE model


• Sampling: 1 nm

IUP

Pagaran et al., 2009

• Institut für Umweltphysik, Universität Bremen

• SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) on ENVISAT (Environmental Satellite)

• Empirical SCIA proxy model

• Wavelength range: 230 – 1750 nm

• Sampling: 1 nm

IUP


• Institut für Umweltphysik, Universität Bremen

• SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) on ENVISAT (Environmental Satellite)

• Empirical SCIA proxy model

• Wavelength range: 230 – 1750 nm

• Sampling: 1 nm


10 – 20% differences between data sets in multi-annual mean (1978-2005) in ultraviolet (UV), less than 5% in visible (VIS) and infrared (IR)

Differences in incoming spectral solar flux

(Fig. 16 and 17 from Pagaran et al., 2011)



• Slightly higher incomingfluxes in the Hartley bands for the IUP data set

• Largest incoming fluxes for the MPS data set in main parts of the Huggins bands, relevant for ozone absorption

TOA solar flux in the Hartley and Huggins bands from IUP, NRLSSI and MPS data at solar minimum, September 1986.


Central wavelengths of FUBRad spectral intervals [nm]

integrated to 49 spectral intervals of FUBRad SW CCM radiation scheme


Effects of different spectral input data on radiative heating I

Zhong et al., 2008:

Two different solar irradiance spectra in line-by-line radiative transfer code

1. Spectral data from a theoretical spectral line model (Kurucz spectrum)

2. NRLSSI data

Significant differences of up to 1.1 K/day in

shortwave (SW) heating rates between spectra

• Heating rates in 200-320nm region (ozone Hartley band) for mid-latitude summer atmosphere

• Thick: line-by-line model• Thin: broad-band model

(Figure 2 from Zhong et al., 2008)


Changes in SW heating rates

• offline calculations with FUBRad shortwave radiation parameterisation (Nissen et al., 2007)

high resolution CCM SW radiation scheme

49 spectral intervals: 121.56 -683nm

• 15th January conditions for solar zenith angle and orbital parameters

• mean O3-climatology (for January)

Changes in temperatures and circulation

• GCM-type experiments with the Chemistry-Climate Model EMAC (ECHAM/MESSy Atmospheric Chemistry) (Jöckel et al., 2006) in EMAC-FUB configuration

FUBRad included horizontal resolution: T42 39 levels (up to 0.01hPa)

• January conditions for zenith angle and orbital parameters

• mean O3-climatology (for January)11-Year Solar Cycle number

22:• Solar minimum: September

1986• Solar maximum: November

1989

Effects of irradiance data sets on shortwave heating and temperature II


• Largest heating rates for MPS data set around 1 – 10 hPa (Huggins bands)

• Slightly higher values for IUP data set around 0.1 – 1 hPa (Hartley bands)

• MPS data set produces up to 5% higher SW heating rates than NRLSSI in global mean

SW heating rate differences for solar minimum [K/day]Global mean

(Oberländer et al., 2012, GRL)


Temperature signal – MPS minus NRLSSISolar Minimum 11-Year Solar Cycle Differences

• No significant effect on solar temperature signal

• Large dynamical variability in winter hemisphere

• Significantly warmer stratosphere for MPS data

• Impact of enhanced solar fluxes in MPS data directly reflected in temperature changes



11-Year solar cycle signal SW heating rate differences [K/day], (Cycle 22: Max: Nov 1989; Min: Sep 1986)

NRLSSI • ‚reference‘ data set• 15th January conditions


• Stratospheric solar signal up to 0.2K/day at the summer stratopause (~50km)↔ Hartley/Huggins bands (O3)

• Strong increase in heating rates in upper mesosphere↔ Lyman-α-line (O2)


MPS

• Strongest solar signal (max to min)

• 0.03 K/day higher than NRLSSI in global mean; up to 0.05 K/day at summer stratopause

IUP(/MPS)• 20-40% higher global mean

solar heating signal in lower and middle stratosphere

• 10-20% higher for upper strato-sphere and mesosphere

Global mean


11-Year solar cycle signal: Differences between data sets


Temperature signal – MPS minus NRLSSISolar Minimum 11-Year Solar Cycle Differences

• No significant effect on solar temperature signal

• Large dynamical variability in winter hemisphere

• Significantly warmer stratosphere for MPS data

• Impact of enhanced solar fluxes in MPS data directly reflected in temperature changes



Solar signal from SIM data set

SIM data Harder et al., 2009• SIM (Spectral Irradiance Monitor)

on board SORCE (Solar Radiation and Climate Experiment)

• Available wavelength range:115-2412 nm

• Sampling: 1-34 nm• Available since April 2004

• Up to six times larger changes in UV than NRLSSI from 2004 to 2007

Variations in the visible (VIS) and near-infrared (NIR) out of phase to changes in TSI and UV with increasing irradiance towards the minimum of solar cycle 23

(Figure 1 from Haigh et al., 2010)

Differences in spectral irradiance:April 2004 minus November 2007


• SIM data show larger SSI changes• SIM data changes out-of-phase in VIS compared to SCIA, SATIRE and

NRLSSI• SIM and SCIA proxy changes out-of-phase in NIR for decending solar

cycle 23 in contrast to NRLSSI and SATIRE


(Figure 18 from Pagaran et al., 2011)

(Pagaran et al., 2011)


• Prescribed solar flux: mean (May 2004) to minimum phase (Nov 2007) of SC 23

• Modelling setup as before for NRLSSI, IUP, MPS (January conditions, O3 fixed)

• Wavelengths < 200nm from SOLSTICE

Solar Signal from SIM-data – modelling studies at FUB

SW heating rate differences [K/day] at solar minimum

• SIM: lower absolute irradiance → weaker heating in UV bands (up to 0.5 K/day at summer polar stratopause, 0.3 K/day in global mean)

• SIM: slightly higher VIS heating at solar min


SIM-NRLSSI


Temperature signal – SIM minus NRLSSISolar Minimum 2007

• Significantly cooler stratosphere and mesosphere in summer for SIM data due to weaker UV-heating

• Significantly warmer summer upper stratosphere in 2004 compared to 2007 for SIM than for NRLSSI data

• Negative contribution from VIS flux more than compensated

May 2004 minus November 2007


Solar cycle signal difference SIM NRLSSI

SW heating rates [K/day], May 2004 minus November 2007

• SIM solar signal exceeds NRLSSI by 0.28 K/day at summer stratopause(0.18 K/day in global mean)

• SIM produces lower VIS heating for 2004 (solar mean) compared to 2007 (solar minimum), opposite to NRLSSI data



Temperature signal – SIM minus NRLSSISolar Minimum 2007

• Significantly cooler stratosphere and mesosphere in summer for SIM data due to weaker UV-heating

• Significantly stronger warming in summer upper stratosphere in 2004 compared to 2007 for SIM than for NRLSSI data

• Negative contribution from VIS flux more than compensated

May 2004 minus November 2007


Haigh et al., 2010:

• 2D CTM

• SIM data produces lower O3 above 45 km in 2004

• Very different temperature structure compared to NRLSSI

Solar Signal from SIM Data Set – Haigh et al., 2010

(Fig. 2 (left) and Supp. Fig. 1 (right), from Haigh et al., 2010)

December 2004 minus 2007

NR

LS

SI

SIM

ΔO3 ΔT

0.3 K

1.6 K


Integrating spectral flux data sets into spectral radiation codes

• Spectral flux data sets have individual spectral resolution.

• SW radiation parameterization have individual spectral resolution.

Spectral flux data need to be integrated to spectral intervals of SW radiation codes.

2 examples:


1. Effect of increased spectral resolution in SW radiation codeFUBRad: Increase of spectral resolution in Chappuis band from 1 to 57 bands

49 FUBRad bands 106 FUBRad bands

VIS:SIM > NRLSSI

VIS:NRLSSI > SIM

Global mean SW heating rate differences, Nov. 2007NRLSSI SIM


2. Effect of integration method

Comparison of two integration procedures to calculate spectrally integrated solar fluxes for SW radiation code form solar flux input data:

• int_tabulated (idl)• bin_trapez SIM data


SW heating rates for different integration methods

Chappuis bandsUV + Chappuis bands

• Int_tab (idl) produces wrong integrated fluxes for input data sets with insufficient spectral resolution


11-year solar signal [K/day] for different integration methods and spectral

resolutions

• Solar signal is not strongly affected due to the dominance of the UV.

• Work in progress

Langematz, Oberländer, Kunze Ulrike Langematz, Sophie Oberländer and Markus Kunze Institut für...

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