LBA MONITORING SITES  5 MONITORING SITES (2 SINCE JAN. 1999, 3 SINCE NOV. 1999)

1. EFFECT OF CLOUDS AND AEROSOLS ON SOLAR RADIATION IN THE AMAZON BASIN: OBSERVED REDUCTIONS IN DAILY INTEGRATED IRRADIATION AND MODELED SMOKE AEROSOL ABSORPTION PROPERTIES J.S. Schafer, B.N. Holben, T.F. Eck, M.A. Yamasoe, P. Artaxo LBA MONITORING SITES  5 MONITORING SITES (2 SINCE JAN. 1999, 3 SINCE NOV. 1999) (ALTA FLORESTA, JI PARANA,BALBINA, BELTERRA, BRASILIA)  CIMEL SUNPHOTOMETER DATA (AOT, SIZE DIST, WATER VAPOR)  1-MINUTE INSTANTANEOUS FLUX [PAR,PYR,(UVA,UVB)]  INTEGRATED DAILY TOTALS SSA ESTIMATES FROM 1-MINUTE PAR MEASUREMENTS CLOUD-SCREENED CIMEL AOT, WV OBS MATCHED TO PAR (±2.5 MIN) FOR: SZ < 40; AOT440 > 0.8; WXP > 1.0 6S RUN FOR OBSERVED COND. WITH N(i) RANGE (0.0-0.06) FOR 434 CASES AOT SIZE DISTRIBUTIONS DERIVED FROM 1999 VALID CIMEL RETRIEVALS GROUPED BY AOT (15 BINS) APPROPRIATE SIZE DIST. AUTOMATICALLY INPUT TO 6S FOR OBS. AOT EACH 6S FLUX, SSA TREND USED TO INTERPOLATE SSA FOR OBS. PAR GENERAL AGREEMENT WITH CIMEL RETR. (SZ > 45; ERR < 0.05; AOT > 0.5) 24 DAYS WITH RETRIEVALS, WITH AVG. OF 20 OBS / DAY; SOME 40-50 434 PAR RETRIVALS; AVG: 0.91 INDIVIDUAL CASES TREND CIMEL FRACTION OF EXPECTED CLEAR SKY IRRADIATION PAR, PYR FLUX MODELED FOR FULL DAY (15 MIN INT) FOR LOW AOT, CLEAR SKY CASE WITH 6S RADIATIVE MODEL MODELED FLUX INTEGRATED FOR EACH DAY & SITE, EVERY 2 WEEKS ANNUAL TREND ESTIMATED FROM BI-MONTHLY INTEGRATED VALUES OBS. TOTALS NORMALIZED BY THE EXPECTED FOR GIVEN DAY & SITE