Aerosol Optical Depth measurements in the Azores

Aerosol Optical Depth measurements in the Azores Fernanda Carvalho Diamantino Henriques Paulo Fialho Instituto de Meteorologia Universidade dos Açores

GAW Global Atmosphere Watch BSR Baseline Station Radation etwork WMO World Meteorological Organisation The José Agostinho Observatory, located in Angra do Heroísmo town, is part of the regional station GAW network since 99 and proposed to BSR station in 8. The very first global irradiance measurements in Portugal using conventional instruments and methods were done in this Observatory in 97.

Aerosol Optical Depth (τa,λ) computations τ a,λ = -(/m) ln( E λ / E,λ ) - τ R,λ - τ O,λ - τ HO ((./(cos(za*pi/8.)+.*(9.88-za)**(-. = m mr=m*p/p ( vdo=./cdo(λ (. mr*7.99*(vdo**.)/(9.799e8-.7e9*vdo** = τ R,λ τ O,λ =ao(λ)*o*mo mo=./(.*(cos(za*pi/8.)**)+.)**. τ HO =.8*aHO(λ)*(w+(.-w)*.)*m/(.+7*aHO(λ)*m)**.

Aerosol Optical Depth (τa,λ) computations (. Cont ) Wavelength (nm) 7 8 Extraterrestrial const (E) 77 O absorption coef. (ao) 9 9 HO absorption coef. (aho) 7 9 Precipitable water (w):. cm Total ozone (o): Brewer observed nearest value

Data acquisition and processing Acquisition system: DTK ( avg;std ) Integration: s Filter data with: signal < night background (zero); signal noise: std/ avg > ( 9 < night readings (za should not be considered. minute AOD averages computed only with n >= readings

AOD( nm) - Angra do Heroísmo - AOD( nm) - Angra do Heroísmo - AOD( nm)..9.8.7...... AOD( nm)..9.8.7...... 7 Month 8 9 7 Month 8 9 AOD( nm) - Angra do Heroísmo - AOD( nm) - Angra do Heroísmo - 7 AOD( nm)..9.8.7...... 7 Month 8 9 AOD( nm)..9.8.7...... 7 Month 8 9

AOD (Aug-Dec ) - Angra do Heroísmo AOD () - Angra do Heroísmo AOD( nm)*time 9 AOD( nm)*time 8 AOD( nm)*time 9 AOD( nm)*time 8.8...7.... AOD(7 nm)*time AOD(8 nm)*time AOD(7 nm)*time AOD(8 nm)*time.8....7... 9 8 Time (UTC) 9 8 Time (UTC) AOD () - Angra do Heroísmo AOD (7) - Angra do Heroísmo AOD( nm)*time 9 AOD( nm)*time 8..7 AOD( nm)*time 9 8 AOD( nm)*time.8.......7 AOD(7 nm)*time AOD(8 nm)*time.8. AOD(7 nm)*time AOD(8 nm)*time.... 9 8 Time (UTC) 9 8 Time (UTC)

Frequency distribution of AOD - Angra do Heroismo (Aug-Dec ) Frequency distribution of AOD - Angra do Heroísmo () AOD( nm) 7....7. AOD( nm) AOD( nm) 7....7. AOD( nm) Percent AOD(7 nm) AOD(8 nm) Percent AOD(7 nm) AOD(8 nm) 7....7. 7....7. Frequency distribution of AOD - Angra do Heroísmo () Frequency distribution of AOD - Angra do Heroísmo (7) AOD( nm) 7....7. AOD( nm) AOD( nm) 7....7. AOD( nm) Percent AOD(7 nm) AOD(8 nm) Percent AOD(7 nm) AOD(8 nm) 7....7. 7....7.

and - Angra do Heroísmo - and - Angra do Heroísmo -.. Variable.. Variable...... -. -. - 7 Month 8 9-7 Month 8 9 and - Angra do Heroísmo - and - Angra do Heroísmo - 7.. Variable.. Variable...... -. -. - 7 Month 8 9-7 8 Month 9

and - Angra do Heroísmo - and - Angra do Heroísmo -.... 8...... 8 - - 8.. Time (UTC) -. -. -7. 8.. Time (UTC) and - Angra do Heroísmo - and - Angra do Heroísmo - 7 *Time. *Time 8 *Time. *Time 8...... -.. -.. - 8 Time (UTC) - 8 Time (UTC)

Frequency distribution - alpha & beta - Angra do Heroísmo () Frequency distribution - alpha & beta - Angra do Heroísmo ()..9..8..7..9..8..7 Percent Percent....8. -..... Frequency distribution - alpha & beta - Angra do Heroísmo () Frequency distribution - alpha & beta - Angra do Heroísmo (7)..9..8..7..9..8..7 Percent Percent....8. -.....

vs - Angra do Heroísmo - vs - Angra do Heroísmo - - - -...... -...... vs - Angra do Heroísmo - vs - Angra do Heroísmo - 7 - - -...... -......

; vs AOD( nm) - Angra do Heroísmo - ; vs AOD( nm) - Angra do Heroísmo -.....8....7....... -.. -.. -....8 AOD( nm) -...7. AOD( nm) ; vs AOD( nm) - Angra do Heroísmo - ; vs AOD( nm) - Angra do Heroísmo - 7................ -.. -.. -.... AOD( nm) -.... AOD( nm)

AOD( nm) vs V; U - Angra do Heroísmo - AOD( nm) vs V; U - Angra do Heroísmo -.. A OD( nm) <.. -.. -.. -.8 >.8.. AOD( nm) <.. -.. -.. -.8 >.8 V -. V -. -. -. -7. -7. - - U - U AOD( nm) vs V; U - Angra do Heroísmo - AOD( nm) vs V; U - Angra do Heroísmo - 7 A OD( nm) <.. -.. -.. -.8 >.8.. A OD( nm) <.. -.. -.. -.8 >.8 V V -. - -. -7. - - U -. -. U.. 7.

AOD @ nm Azores ( Horta / Cimel (AEROET SP (AZOET/ Angra do Heroismo..... AOD.... Jan- Fev- Mar- Abr- Mai- Jun- Jul- Ago- Set- Out- ov- Dez- Data

... AOD: -8- Angra do Heroísmo (SP) and Horta (Cimel) Horta nm (Cimel) 8 nm (Cimel) nm (SP) nm (Cimel) nm (SP) nm (Cimel) 7 nm (SP) 7 nm (Cimel) 8 nm (SP) 87 nm (Cimel) nm (Cimel) AOD.. Angra do Heroismo : 7: 8: 9: : : : : : : : 7: 8: 9: : : Time (UTC)

Azores

Faial Is. Terceira Is.

Horta Angra do Heroismo

CIMEL Horta

SP Angra do Heroísmo

,,9, 8, 8,,9, 8, 8 Obs. P. A. Mónaco,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8 Junho () Obs. P. A. Mónaco Julho () Obs. P. A. Mónaco Agosto () Obs. P. A. Mónaco Setembro (),,, W,7, 9,77 7, Wind Speed (m/s), 9, 8,9,,,8 E,8,9,8, S Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,8% of observations were missing.,8,9, W,89, 8,, Wind Speed (m/s),9,,7 S, 9,7,, 9 E,7,,7 Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,% of observations were missing.,,, W, 7, 7,8, Wind Speed (m/s), 7,,8,,, E,9,7,, S Calms in clud ed a t center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,78% of observations were missing.,8,,9 W,9,8 8,7, Wind Speed (m/s),,7 8, S,,7,8, E,,,9 Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown. 7,% of observations were missing. H O R T A DIR,,9, 8, 8 DIR,,9, 8, 8,,,7,9,, S,,,,,, E,,9,99,,97, SSW,9,,7,,9, E,9,,,,, SW,7,,8,,8,9 EE,,88,9,,, WSW,8,9,9 8,8,,7 E,,9,,,, W,,99,9,,, ESE,,,,,, WW,,8,9,,, SE,7,9,9,,, W,,,,,, SSE,,7,,,, W,,8,,,, TOTAL OBS = MISSIG OBS = CALM OBS = 9 PERCET CALM =, DIR,,9, 8, 8 DIR,,9, 8, 8,,,,,, S,7,,8,,, E,8,,9,,7, SSW,8,,7,,, E,8,8,,,77,9 SW,,9,8,8,9, EE,7,,,78,, WSW,,7,88,,, E,,,9,,, W,7,9,,,, ES E,9,7,,,, WW,9,,8,,, SE,,9,9,,, W,87,8,,,, SSE,,,7,,, W,,,,7,, TOTAL OBS = MISSIG OBS = 9 CALM OBS = PERCET CALM =, DIR,,9, 8, 8 DIR,,9, 8, 8,8,,,9,, S,,,,,, E,8,,8,,, SSW,,,,,, E,7,8,,9,8, SW,,,8,,, EE,7,,,,, WSW,,8 7, 7,,, E,,,,,, W,,,,,7, ESE,,,9,,, WW,,8,,,, SE,,,,,, W,,,8,,, SSE,,,,,, W,,,9,9,, TOTAL OBS = MISSIG OBS = CALM OBS = 9 PERCET CALM =, DIR,,9, 8, 8 DIR,,9, 8, 8,9,9,9,,, S,8,8,9,,9, E,8,7,,,, SSW,,8,,,, E,7,,,,8, SW,7,9,7,,, EE,,8,79,9,9, WSW,,,8,7,, E,8,,,,, W,,8,9,,, ES E,,,,,, WW,,,,,, SE,,7,,9,, W,,8,,,, SSE,79, 9,88,,8, W,8,,,,, TOTAL OBS = MISSIG OBS = 77 CALM OBS = 7 PERCET CALM =,7 Obs. José Agostinho Junho () Obs. José Agostinho Julho () Obs. José Agostinho Agosto () Obs. José Agostinho Setembro (),,9,9 W, 8,7 9,,77 Wind Speed (m/s),,,7 S,9,,,9 E,,8, Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown. o observations were missing. 7,8,9,8 W,7 9,,,8 Wind Speed (m/s) 7,,8, S 7,8,97,, 8 E,7,, Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,7% of observations were missing. 8, 8, 9 7, W,87,,9, Wind Speed (m/s) 7,,9, S,9,,78, E,,, Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,% of observations were missing.,9,8, W,9 8,,,8 Wind Speed (m/s),7, 8,7 S 7,8 9,7 7,8, E,9,, Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,% of observations were missing. A G R A DIR,,9, 8, 8 DIR,,9, 8, 8,7,7,,9,, S,,8,7,,, E,,,8,,, SSW,,7,,9,, E,9,,,9,, SW,,7,78,88,9, EE,8,8,,7,, WSW,, 7,,,, E,9,9,7,,, W,,8,8,,, ESE,8,,88,,, WW,8,,,9,, SE,8,,,7,, W,7,,,,, SSE,,,9,,, W,9,9,,,, TOTAL OBS = MISSIG OBS = CALM OBS = PERCET CALM =, DIR,,9, 8, 8 DIR,,9, 8, 8,8,7,77,,, S,,8,,,, E,,,,,, SSW,7,,,,, E,8,8,,,, SW,9,9,,7,8, EE,,,,,, WSW,, 9,,,, E,7,,9,8,, W,,,99,,, ES E,,78,,,, WW,9,,87,,, SE,8,,8,,, W,88,7,7,8,, SSE,9,,,,, W,77,,,8,, TOTAL OBS = MISSIG OBS = CALM OBS = PERCET CALM =,8 DIR,,9, 8, 8 DIR,,9, 8, 8,99,9,99,,, S,,,,,, E,,,,,, SSW,,,7,,, E,9,97,,87,, SW,,,8,,, EE,,,,8,, WSW,79,88 7,,,, E,9,9,,,, W,9,9,7,,8, ESE,9,,9,,, WW,,8,7 8,8,, SE,,8,,,, W,9,,,8,7, SSE,,9,,,, W,,,,,, TOTAL OBS = MISSIG OBS = CALM OBS = PERCET CALM =,9 DIR,,9, 8, 8 DIR,,9, 8, 8,,8,,,, S,9,9,9,7,, E,,,,,, SSW,,,,9,, E,7,9,7,,, SW,7,,,,, EE,9,,99,8,, WSW,,7,8,7,, E,,,,,, W,,,9,9,, ES E,7,,9,,, WW,,9,7,,, SE,,7,9,,, W,7,,,,, SSE, 7,7,7,,, W,7,7,,,, TOTAL OBS = MISSIG OBS = 8 CALM OBS = 9 PERCET CALM =, June July August September

,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8,,9, 8, 8 Obs. P. A. Mónaco Outubro () Obs. P. A. Mónaco ovembro () Obs. P. A. Mónaco Dezembro (),,, W,8 9, 7,9 7,9 Wind Speed (m/s),89,8, S 8,,8,8,9 E,9, 9, Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,8% of observations were missing.,,, W,8,8,7, Wind Speed (m/s),9, 8,7 S,,,,77 E,,8,9 Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,7% of observations were missing.,9,, W,8,7 8, 8, Wind Speed (m/s), 8,,,,, 99 E,,,, S Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown.,% of observations were missing. H O R T A DIR,,9, 8, 8 DIR,,9, 8, 8,,8,7,,,8 S,,78,,8,, E,,7,97,7,87,8 SSW,,99,8,,, E,,,87,9,98, SW,,,,,9, EE,7,,,7,,7 WSW,9,9,,7,8,8 E,7,9,,,8,8 W,9,99,,,8, ESE,9,7,9,,, WW,,9,87,78,, SE,,9,,,, W,,,,,, SSE,,,9,9,, W,8,,8,7,7, TOTAL OBS = MISSIG OBS = 8 CALM OBS = 8 PERCET CALM =,8 DIR,,9, 8, 8 DIR,,9, 8, 8,7,7,,7,, S,,,,,8,7 E,79,,,9,, SSW,88,,7,7,8,8 E,,,,,98,8 SW,,88,9,,, EE,9,8,,9,9,7 WSW,,9,,97,7, E,8,,9,,, W,,,7,,, ESE,9,9,,,9, WW,8,,,,, SE,,9,,9,9, W,,,,,, SSE,,9,77,9,9, W,,9,9,,, TOTAL OBS = MISSIG OBS = 9 CALM OBS = PERCET CALM =, DIR,,9, 8, 8 DIR,,9, 8, 8,,,,7,9, S,8,99,7,9,7, E,,7,9,89,,8 SSW,7,8 7,,,, E,8,7,,88,, SW,,,,8,, EE,7,7,,8,79,9 WSW,8,,,,, E,,7,8,,, W,9,,,,, ES E,,9,7,9,, WW,,9,,7,7, SE,,,,,, W,,87,,,, SSE,,7,,79,, W,7,7,,9,,9 TOTAL OBS = MISSIG OBS = CALM OBS = 9 PERCET CALM =, Obs. José Agostinho Outubro () Obs. José Agostinho ovembro () Obs. José Agostinho Dezembro () 9,,,9,9 7,,78 7, 7,8 W 9,,,89 E,,,9,,,99,7 S Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown. Wind Speed (m/s),% of observations were missing. DIR,,9, 8, 8 DIR,,9, 8, 8,7,7,,,, S,,9,,,7, E,,9,,,, SSW,,,7,7,, E,8,,,88,9, SW,,8,7,,, EE,,9,8,8,8, WSW,8,8,,87,78,8 E,8,,7 8,,8, W,,97,8,,, ESE,,,8,7,9, WW,,8,9,,, SE,,8,7,,, W,,8,,7,, SSE,,,9,9,, W,,7,7,,, TOTAL OBS = MISSIG OBS = 9 CALM OBS = PERCET CALM =,,,88, 7,9,7,,7 W,99,, E,8 7,,,8,,, S Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown. Wind Speed (m/s),% of observations were missing. DIR,,9, 8, 8 DIR,,9, 8, 8,,87,,,, S,9,,,,, E,7,87,,,9, SSW,9,,8,,9, E,9,7,8,,9, SW,,,97,,, EE,,,9,,88, WSW,,,8,,, E,,8, 9,8,, W,,9,,,, ESE,,9,9,89,, WW,9,7,9,,, SE,,,,9,, W,9,,9,,, SSE,,,,7,, W,,7,,,, TOTAL OBS = MISSIG OBS = CALM OBS = PERCET CALM =, 7,97,7 8,,,,7 W,, 7,8 E,79,8, 7,,, 9, S Calms included at center. Rings drawn at % intervals. Wind flow is FROM the directions shown. Wind Speed (m/s),7% of observations were missing. DIR,,9, 8, 8 DIR,,9, 8, 8,7,8,8,9,,9 S,,8,,7,, E,8,7,7,9,, SSW,9,,,8,,7 E,88,9,8,9,, SW,,,,,9, EE,9,9,,7,, WSW,8,9,99,8,, E,9,9,8,89,, W,8,,9,,, ES E,,8,,9,, WW,79,,,9,, SE,8,8,,,, W,7,,9,,, SSE,8,,7,,, W,97,9,,,,7 TOTAL OBS = MISSIG OBS = CALM OBS = PERCET CALM =, A G R A October ovember December

Acknowledgements Sun-photometer and tracking systems funded by projects CLIMAAT (MAC./A) and CLIMAAT II (/MAC/./A) from ITERREG IIIB program. Special thanks to Dr. Christoph Wehrli from PMOD (Physikalisch-Meteorologisches Observatorium Davos).