Exercise 1 Spectral global Irradiance in W/m 2 /nm Spec1 Spec2 Calculate : 1)Total integrated UV irradiance 2)UVA irradiance 3)UVB irradiance 4)UV Index

Calc.m Spec2: UV=17.0 W/m 2 UVA=16.8 W/m 2 UVB=0.16 W/m 2 UVIndex=0.95 (0.024 W/m 2 ) Spec1: UV=52.80 W/m 2 UVA=51.4 W/m 2 UVB=1.37 W/m 2 UVIndex=7.2 (0.179 W/m 2 ) % load the two spectra spec1=load('spec1.dat'); spec2=load('spec2.dat'); wl=spec1(:,1); spec=[spec1(:,2) spec2(:,2)]; figure;plot(wl,spec);grid xlabel('Wavelength /nm'); ylabel('Global irradiance /Wm^{-2}nm^{-1}'); legend('Spectrum1','Spectrum 2'); % Exercise 1: Calculate UV-weighted irradiance iuv=wl>=280 & wl<=400; % choose wavelength range UV=trapz(wl(iuv),spec(iuv,:)); disp(sprintf('\nExercise 1')); disp(sprintf('UV Irradiance for Spectrum Nb 1=%5.3f W/m^2',UV(1))); disp(sprintf('UV Irradiance for Spectrum Nb 2=%5.3f W/m^2',UV(2))); iuv=wl>=280 & wl<=400; iuva=wl>315 & wl<=400; iuvb=wl>=280 & wl<=315; uvindex=trapz(wl,spec.*repmat(erythema(wl),1,2))*40; function [f,fori]=erythema(wl) f=zeros(size(wl)); f(wl<=298)=1; ind=wl>298 & wl<=328;f(ind)=10.^(0.094*(298-wl(ind))); ind=wl>328 & wl<=400;f(ind)=10.^(0.015*(139-wl(ind)));

Integration issue The units are given in W/m 2 /nm. In the numerical integration, remember to apply the right ∆λ (here it is 4) Summation versus Trapezoidal integration: UV=trapz(wl,spec); Or UV=sum(spec)/deltawl; i.e. overestimation of 0.3%

Programming issues always returns 1...

Exercise 1 cont Calculate the time needed to reach 1 MED for a person with standard skin type (II) for spectra 1 and 2 Time until 1 MED for Spectrum Nb 1=23.2 minutes Time until 1 MED for Spectrum Nb 2=176 minutes Time [s]=MED [J/m 2 ] / doserate [J/s/m 2 ]

Exercise 1 cont 5)Calculate the time needed to reach a sufficient dose of VitD for spectra 1 and 2 for the following assumptions: 1)All body exposure (100%) 2)Arms, Hands and Face (27%) Assumption: A sufficient dose of VitD is reached in one minute for a standard skin type II at UV Index=10 Dosis: 2*60*10/40 = 30 Jm -2

Exercise 1 cont 5)Calculate the time needed to reach a sufficient dose of VitD for spectra 1 and 2 for the following assumptions: 1)All body exposure (100%) 2)Arms, Hands and Face (27%) Assumption: A sufficient dose of VitD is reached in one minute for a standard skin type II at UV Index=10

Exercise 1 cont 5)Calculate the time needed to reach a sufficient dose of VitD for spectra 1 and 2 for the following assumptions: 1)All body exposure (100%) 2)Arms, Hands and Face (27%) Assumption: A sufficient dose of VitD is reached in one minute for a standard skin type II at UV Index=10 % Assume UV Index of 10, multiply by 2 to transform from Erythemal weighted % irradiance to VitD weighted irradiance, and multiply by 1 minute dose=10/40*2*60 = 30 J m -2 Time until 1 Vit D3 Dose for Spectrum Nb 1 FULL BODY=1.449 minutes Time until 1 Vit D3 Dose for Spectrum Nb 2 FULL BODY= minutes Time until 1 Vit D3 Dose for Spectrum Nb 1 Arms & face=5.366 minutes Time until 1 Vit D3 Dose for Spectrum Nb 2 Arms & face= minutes Time [s]=RequiredDose(VitD) [J/m 2 ] / doserate [J/s/m 2 ]

Calculate the photolysis rate of ozone to oxygen (1D) for the two solar spectra of exercise 1. You can also use the provided mat file (variables wl, spec, comment) to obtain the diurnal variation The actinic flux needs to be converted to number of photons (per m 2 /sec) Energy of one photon=hc/λ x-sections [cm 2 ] Actinic flux [photons/m 2 /sec] quantum yield

h=6.62e-34; c=2.998e8; QY=load('shet_qy.dat'); QS=load('Ozone_bass_243_k.p.txt'); QS(:,1)=QS(:,1)/10; act=ACTINIC./1e3.*repmat(wl*1e-9,1,size(actinic,2))/(h*c)/1e4; %from mW/m^2 to photons/cm^2 o1d=nansum((act.*qy.*qs))*dwl; J(O1D) spring= s -1 J(O1D) summer= s -1

UV Dose rate from OMI Satellite Altiplano di Bolivia Salar di Chalviri Six sites with Max UVI =22.8 All are at altitudes above 4000 m Yareta, alt 4500 m

Halley Bay - Antarctica Data from Ozone hole FallSpring

New Zealand versus Europe

Halley Bay - Antarctica Fall Spring

Higher UV in the southern hemisphere? From McKenzie, UV Workshop New Zealand, 2010 UV Radiation is much higher in the southern hemisphere. These hemispherical differences are attributable to seasonal changes in Sun- Earth separation (7%), lower ozone amounts and cleaner atmosphere. From Bodecker, UV Workshop New Zealand, 2010

Higher UV due to the Antarctic ozonehole WMO Ozone Assessment, 2006