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SEMI-ANNUAL REPORT (for July - December 1998), Contract Number N_'3_ OCEAN OBSERVATIONS WITH EOS/MODIS: Algorithm Development and Post Launch Studies Howard R. Gordon University of Miami I Department of Physics Coral Gables, FL 33124 (Submitted January 1, 1999) P .¥ /' /'_/ r Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 Preamble As in earlier reports, we will continue to break our effort into six distinct units: • Atmospheric Correction Algorithm Development • Whitecap Correction Algorithm • In-water Radiance Distribution • Residual Instrument Polarization • Pre-launch/Post-launch Atmospheric Correction Validation • Detached Coccolith Algorithm and Post-launch Studies This separation has been logical thus far; however, as launch of AM-1 approaches, it must be rec- ognized that many of these activities will shift emphasis from algorithm development to validation. For example, the second, third, and fifth bullets will become almost totally validation-focussed activities in the post-launch era, providing the core of our experimental validation effort. Work under the first bullet will continue into the post-launch time frame, driven in part by algorithm _ deficiencies revealed as a result of validation activities. An addition to this report is a description of our planned activities for FY99 (Appendix 1). Our next Semi-Annual Report will address the progress made on this plan. Semi-Annual Report (1 July- 31 December 1998) NAS5-31363 Abstract Significant accomplishments made during the present reporting period: • Installed spectral optimization algorithm in the SeaI)as image processing environment and successfully processed SeaWiFS imagery. The results were superior to the standard SeaWiFS algorithm (the MODIS prototype). in a turbid atmosphere offthe US East Coast, but similar in a clear (typical) oceanic atmosphere. Inverted ACE-2 LIDAR measurements coupled with sun photometer-derived aerosol optical thickness to obtain the vertical profile of aerosol optical thickness. The profile was validated with simultaneous aircraft measure- ments. Obtained LIDAR and CIMEL measurements of typical maritime and min- eral dust-dominated marine atmosphere in the U.S. Virgin Islands. Con- temporaneous SeaWiFS imagery were also acquired. £ Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 L 1. Atmospheric Correction Algorithm Development. a. Task Objectives: During CY 1998 there are seven objectives under this task. Objectives (i) and (ii) below are considered to be the most critical. If the work planned under objective (i) is successful, a module that enables the algorithm to distinguish between weakly- and strongly-absorbing aerosols will be includedin the atmospheric correctionalgorithm. " - (i)We willcontinuethe study ofthe "spectraloptimization"algorithm.The initialrealization ofthe algorithmwillbe toprovidea flagthat willsignaltheprobablepresenceofabsorbingaerosols, and indicatethat the qualityof the derivedproducts cannot be assured. Later realizationswill provide an atmospheric correctionin the presenceof absorbingas wellas nonabsorbing aerosols. (ii)We need to testthe basicimplementation of the MODIS atmospheric correctionalgorithm with actualocean colorimagery. We willdo thiswith SeaWiFS imagery. 0ii)We must implement our strategyfor adding the cirruscloudcorrectioninto the existing atmospheric correctionalgorithm. Specificissuesinclude (1) the phase function to be used for the cirrusclouds,(2) the detailsof making two passes through the correctionalgorithm, and (3) preparationof the requiredtables.These issueswillbe addressed as time permits in CY 1998. (iv)The basic correctionalgorithm yieldsthe product of the diffusetransmittance and the water-leavingreflectance.However, we have shown that the transmittancedepends on the angular distributionofthe reflectanceonly when the pigment concentrationisvery low and then only in the blue. We need to develop a model to includethe effectsofthe subsurfaceBRDF for,low-pigment waters in the blue. (v)We need to study the efficacyofthe presentatmospheric correctionalgorithm forremoval of the aerosoleffectfrom the measurement ofthe fluorescenceline height. (vi)We need to examine methods for efficiently includingearth-curvatureeffectsinto the atmospheric correctionalgorithm.This willmost likelybe a modificationof the look-up tablesfor the top-of-the'-atmosphere contributionfrom Rayleigh scattering. (vii)We willexamine the necessityofimplementing out-of-bandcorrectionsto MODIS. I Semi-Annual Report (1 July-3i December 1998) NAS5'31363 b. Work Accomplished: i .. (i) We consider this task to be one of our most important atmospheric correction activities of 1998 [the other is item (fi) above: testing MODIS algorithms with SeaWiFS _imagery], and as such, the major part of our effort on atmospheric correction will be focussed on it. We have implemented the spectral optimization algorithm described by Chomko and Gordon lit. Chomko and H.it. Gordon, Atmospheric correction of ocean color imagery: Use of the, Junge power-law aerosol size distribution with variable refractive index to handle aerosol absorption, Applied Optics, 37, 5560-5572 (1998)], in which power-law size distributions are utilized, in the SEADAS image processing environment. The power-law distribution allows a straightforward interpolation to size distributions that are not part of the candidate set. We also interpolate on the real and imaginary parts of the complex refractive index. Thus, a complete spectrum of models can be generated from a relatively small candidate set. We then use standard optimization techniques to find the best fitting set of parameters. Although incomplete, the first test of the spectral optimization algorithm (S OA) is v'ery encour- aging. The figure on the next page compares the performance of the SOA wRh the NASA standard SeaWiFS algorithm (NSSA) over the Middle Atlantic Bight (MAB) for days 279 and 281 of 1997. The atmosphere over the MAB was very clear on day 281 and the NSSA and SOA yielded com- parable phytoplankton pigment concentrations. In contrast, on day 279 the atmosphere over the MAB was very tttrbid, and there were significant differences between theNSSA- and SOA-derived pigment concentrations. Since the pigment concentration is unlikely to undergo gross changes in the MAB in two days at this time of the year, and since tlle SOA pigment concentrations are con- sistent for the two days, while the NSSA concentrations are not, these images suggest a superior performance for the SOA. We are in the process of preparing a detailed report c)f _these results and will included it in the next semi-annual report. We started a major effort to understand the optical properties of desert dust transported over the oceans. This is being carried out in conjunction with It. Evans. Cyril Moulin has started as a postdoc on the project in August, and is working nearly full time on this problem. The plan is to use SeaWiFS imagery from the Tropical Atlantic acquired this summer, along with the resets from the Virgin Islands field experiment (see 5.b.ii, and Appendix 2), to delineate the dust properties. In addition, we are using imagery from the Mediterranean (closer to the dust source) in conjunction with LIDAIt data acquired in Rome. r_ (ii) We are acquiring SeaWiFS imagery on a regular basis and, with It. Evans, prepared an end-to-end test of the performance of the MODIS algorithm in its present state. To effect this we created a set of SeaWiFS-specific LUTs, but in a format required by the MODIS code. Evans' Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 group has reformated SeaWiFS imagery intothe MODIS format,and thus,we can testthe MODIS codes usingSeaWIFS-simulated MODIS data. Thus farthe testshave been successful,i.e.,MODIS code running SeaWiFS data in the MODIS format reproduceclwellthe SeaWiFS code processing SeaWiFS data. : (iii)None. In the lightof the successof our spectralOptimizationalgorithm,we may have to make significant modificationsin our originalstrategy.This task has been put .onhold to free resourcesforexamination of task (i).The issueswillbe addressed during CY 1999 with the goal of having a post-launchimplementation strategyin placeduring CY 1999. (iv) We continued the development of an oceanicBRDF model SpecificaUy,the magnitude of the Raman component has been computed as a functionofthe pigment concentration. (v) No work was CarriedOut on thistask. (vi) No work was carriedout on thistask. •_ (vii)Now that we have the MODIS relativespectralresponse(RSR) functions,We have started to incorporatethem intothe algorithmsfollowingthe proceduresdescribedby Gordon (1995) ["Re- mote sensingof ocean color:a methodology for dealingwith broad spectralbands and significant out-of-band response", Applied Optics,34 8363-8374 (1995)]. We have computed the band- Table I: Band-averaged quantitiesneeded to compute the Rayleigh reflectanceand the Ozone transmittancefor the MODIS bands. A Band (nm) (i) 412 8 0.3167 443 9 0.2377 488 10 0.1610 531 11 0.1135 551 12 0.0999 667 13 0.0446 678 14 0.0417 748 15 0.0286 869 16 0.0156 mW/cm'pm sr (xlO00) 170.37 186.50 191.82 188.57' 187.16 154.15 149.88 128.07 97.30 1.47 3.78 22.21 65.66 83.22 48.69 39.95 12.02 3.75 averaged quantitiesrequired to compute the Rayleigh reflectance[(r_(A))FoS,and (F0(A))s,(See . . . Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 Gordon (1995) forthe notation)]and the Ozone transmittance[(hoz(A))F0S_].These are provided in Table 1. In addition, we examined the influence of the water vapor absorption bands on the computation of the Rayleigh reflectance. For MODIS, the error in ignoring water vapor (up to a concentration of 3.3 g_cm 2) is a maximum of 0.25% (for Band 15)i For the other spectral bands_ the error is 0.1%. In contrast, for SeaWiFS the maximum error is 0.55%. c. Data/Analysis/Interpretation: See item b above. d. Anticipated Future Actions: (i)We willcontinuetestingthe new spectraloptimizationalgorithmusing SeaWiFS imagery. In particular,we need _toevaluateitwith more imagery and differentaerosoltypes. Also, we need to understand the reason for the dramatic imProvement of the SOA over the NSSA in the figurefollowingpage 4, along with understanding why the performance ofthe NSSA (the MODIS prototype)isso poor in thiscase. (ii)We shallcontinue testingtheprototype MODIS algorithm with SeaWiFS imagery until MODIS imagery becomes available. (iii)None. The cirruscloudissueinthe presenceofour "spectraloptimization"method needs to be explored.We willresolvethe "spectraloptimization"questionsfirst. (iv) An ocean BRDF model isbeing testedby comparison with experimental data obtained at the MOBY siteand during MOCE-4. This testingwillContinueintoCY 1999. (See 5 below). (v) None. (vi) None. (vii)We will derive the functionsneeded to incorporatethe out-of-band influenceon the aerosolcomponent ofthe atmospheric correctionalgorithm (Gordon, 1995),and provideLUT's for Rayleigh reflectancethat are specificto the MODIS band characteristics. f. Publications: R. Chovako and H.R. Gordon, Atmospheric correctionof ocean colorimagery: Use of.the Junge power-law aerosolsizedistributionwith variablerefractiveindex to handle aerosolabsorption, Applied Optics,37, 5560-5572 (1998). . Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 H.R. Gordon, Contribution of raman scattering to water-leaving radiance: A reexamination. (Sub- mitred to Applied Optics.) Semi-Annual Report (1 July- 31 December 1998).NAS5-31363 2. Whitecap Correction Algorithm (with K.J. Voss). As the basic objectives of the experimental portion of this task have been realized (acquiring whitecap radiometric data at sea), exPerimental work is being suspended until the validation phase, except insofar as the radiometer is being operated at sea when it is sufHciehtly important to do so, e.g., the SeaWiFS Initialization Cruise (MOCE-4). Our goal is to maintain experience in operating and maintaining the insfrumentation in preparation for the validation phase of the contract. In addition, we need to reanalyze the Tropical Pacific whitecap data because Of the surprisingly low reflectance increase due to whitecaps that we measured there. This is a unique data set, as it was acquired in the trade winds with moderately high winds (8-12 m/s) and practically unlimited fetch and duration. This will better bound the limits of oceanic whitecap reflectance. a. Near-term Objectives: . Operate the radiometer at sea to maintain experience in preparation for the validation phase. Reanalyze data acquired during the Tropical Pacific cruise. b. Task Progress: A strategy has been developed that we believewill improve the analysis of the whitecap data; however, the postdoc identified for the reanalysis has accepted a position elsewhere (due to uncertainties in MODIS funding), so no progress has been made on whitecap data analysis of either the Tropical Pacific or MOCE-4 cruises. c. Data/Analysis/Interpretation: See item b above. Z. d. Anticipated Future Actions: We will begin the reanalysis of the Tropical Pacific data with the goal of submitting a revised manuscript on whitecap reflectance by the end of the summer. e. Publications: None. 9 Semi-Annual Report (1 July- 31 Decemberi1998) NAS5-31363 3. In-waterRadiance Distribution (with K.J. Voss). a. Task Objectives: The main objective in this task is to obtain upwelling radiance distribution data at sea for a variety of solar zenith angles to understand how the _water-leaving radiance varies with viewing angle and sun angle. This is the experimental component of our BtLDF modeling. b. Work accomplished: No new measurements were made of oceanic BI_DF's during this reporting period. c. Data/AnalysisfInterpretation: None (but see 1 .b.(iv)). d. Anticipated future actions: We will be participating in INDOEX during January to April of 1999, as wellas the MODIS initalization cruise. Oceanic BRDF's will be included in our stdte of measurements. We will concentrate on data analysis after INDOEX. e. Problems/Corrective actions: None. f. Publications: None. 10 . II _Li -L ; •_UOhI :suoDe:n.lqu d "5 _ ouo/_ :suo:_a v OADaa.x.mD/Smalqo.xd "a :- "_lq_ .I_A_ amo_aq _aq_ uaq_ '_l_PO m uo!_a_oa uo!_z!_iod _._sN_ aq_ o_. _p _!x!_!swos-uo!_z!_tod ,T,SDIAI/S_S aq_ _m_od.zo_m s_ su,rema_ _q_ IIV ._aldmo_ ,¢lTe_s_q Mou s_ _s_ s.nt,T, • " .), ' • -,, " . . :suoDav a_a_neI pa_edlaDuv "p •auolq :uoDe_aadaa_ui/s!s,(l_uV/e_(i "a "auolq :poqstldmoaa V _IaOA& "q _ i'i " , .auol q :saADaarq 0 _lse.T' .u /,s_jSa asay_ •oj _aa_oa a,_ tn_a _oq pwe 'uo!_aazzoa a.t_aqdsom_ _o_ m'q_Ho_l'a aq_ jo aam_maoj_ad aq_ ap_ap s.rq__._ cpam txoq ,zosuas a_i_._o so!_s!za_o_tp £_!_,!_!suas-uo!_z!zeIod a_[_ _a_t_ 'aou-e.rp_z _uap_.au! aq_ jo a_s uo!_z!z_Iod jo a_s aq_ o_ spuodsaz SICIOIAI aq_ _. :s! azaq uoDsanb _!s=q aq_ •uoBez!JelOd luotunJlsul ICnp!soH "lz 1_9fIl_-ggVl_I (966I .xaqmaaa(I I£ - Xlnf I) _;toda_I lunuuv-.ttuaS Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 5. Pre-launclVPost-launch Atmospheric Correction Validation (with K.J. Voss). a. Task Objectives: The long-term objectives of this task are four-fold: '_: (i) First, we need to study aerosol optical properties over the oceans to assess the applicability of the aerosol models used in the atmospheric correction algorithm. Effecting this required obtaining long-term time series of the aerosol optical properties in typical maritime environments. This was achieved using a CIMEL sun/sky radiometer. This radiometer is identical to those used in the AERONET Network (inwhich we are a participant). (ii) Second, we must be able to measure the a_rosol optical properties from aship during the initialization/calibration/validation cruises. The CIMEL-type instrumentation could not be used (due to the motion of the ship) for this purpose. The required instrumentation consisted of an all-sky camera (which can measure the entire sky radiance, With the exception of the solar aureole region) from a moving ship, an aureole camera (specifically designed for ship use) and a hand-held sun photometer. _..... In the case of strongly-absorbing aerosols, we have shown that knowledge of the aerosol verti- cal structure is critical. Thus, we need to be able to measure the vertical distribution of aerosols during validation exercises as well as to build a climatology of the vertical distribution of absorbing aerosols. This is accomplished with a LIDAR system, which we have modified for ship opera- tions. This LIDAR is also needed to detect the presence (or ab_s_uce) of thin cirrus during the initialization/calibration/validation cruises. (ill) The third objective was to determine how'accu.rately the radiance at the top of the atmo- sphere can be determined based on measurements of sky radiance and aerosol optical thickness at the sea surface. This required a critical examination of the effect of radi.ative transfer on "vicarious" calibration exercises. (iv) The forth objective is to utilize data from other sensors that have achieved orbit (OCTS, POLDER, SeaWiFS ...) to validate and fine-tune the correction algorithm. =_ 12 Semi-Annual Report (1 July- 31 December 1998) NAS5-31363 b. Work Accomplished: (i)We have been operating the CIMEL instrument in the Dry Tortugas continuouslyduring most of 1998. Ithas worked well(even survivingHurricane Georges). These data are avaliableas part of AERONET, and have been used by othersto study the validityof aerosolretrievalswith SeaWiFS, e.g.,Wang et al.,"Remote sensingof the aerosolopticalthicknessfrom SeaWiFS in comparison with insitumeasurements," Submitted to _PLS99, 18-22Jan.,1999,Meribel,France. (ii)The Micro Pulse Lidar (MPL) along with a CIMEL were deployed in the U.S. Virgin Islandsduring June and July 1998 to tryto observethe verticaldistributionand opticalproperties of Saharan dust. Successfulobservationswere made during both dus_tand dust-freeperiods. A reportdescribingthe experiment isprovidedinAppendix 2. We had tohave the MPL unitrepaired (itfailedafterthe Virgin Islandsexperiment) and have procured a spare power supply to ensure againstsimilarfailuresin the winter-springINDOEX expe_hnent. The unit isnow back in Miami being prepared forINDOEX. Aureole and sky camera data acquiredduring the MOCE-4 cruiseare stillbeing reduced. A paper describingour aureolecamera has been prepared and submitted forpublicationto JAOT. It isincludedas Appendix 3. , o (iii)The theoreticalaspectsofthiswork have been coihpleted.The next phase isto use surface measurements to predicttop-of-atmosphereradiance. (iv) We have prepared a duplicateversionofthe MODIS algorithm code to use the SeaWiFS spectralbands. This isbeing used totestthe MODIS codewith SeaWiFS data. (See Section1-ii.) c. Data/Analysls/Interpretatlon: (i)A paper based on a long-term study of aerosolsover the ocean has been submitted to JGR and isincluded here as Appendix 4. It confirms the notion that high aerosolopticalthicknesses over the TropicalAtlanticv.ndCaribbean are almost always due to mineral dust. (ii)Preliminary analysisofour MPL data from the U.S. VirginIslandsdeployment isprovided in Appendix 2. Analysis of the data resultingfrom our participationin ACE-2 (June-July i997)'isnearly complete, and severalpublicationsare being prepared. Our main contributionwas in providing calibratedMPL and CIMF, L data to delineatethe verticaldistributionof the aerosoland the opticalproperties.Appendix 5 isa draftofa :papercomp_ing our MPL predictionofthe vertical 13 . r_. - • Semi-Annual Report (1 July = 31 December 1998) NAS5-31363 distribution of the aerosol optical depth with direct aircraft measurements. It is being submitted to a special issue of Tellu8 devoted to ACE-2. As far as .we know,i_this is the first such successful comparison. It shows thatlthe profile of optical depth can be retrieved from the MPL given surface optical depth measurements, e.g., by a sun photometer. d. Anticipated Future Actions: (i) We will continue to keep the CIMEL oPerating in the Dry Tortugas, including the monthly maintenance checks. " _ • " (ii) Our main focus will be our participation in INDOEX. Reduction of the data from the Virgin Islands, as well as MOCE-4 will be suspended until the end of INDOEX. (i!i) We attempt to use data acquired during MOCE-4 (once th e analysis is complete) to effect the vicariouscalibrationSeaWiFS Band 8 (865 nm). (iv) See Section1.d.(ii) e. Problems/correctly e actions: None. , - . _ " f. Publications: .... :: ' . A. Smirnov, B. Holben, I. Slutsker, E.J. Welton, and P. Formenti; "Optical properties of Saharan dust during ACE.2," Jour. Geophys. Res., 103D 28,079-28,092 (1998). E.J. Welton, K.J. Voss, D.L. Savoie, and J.M. Prospero, "Measurements of Aerosol Optical Depth over the North Atlantic Ocean: Correlations with Surface Aerosol Concentrations" (Submitted to .]'our. Geophys. Res.). J.M. Ritter and K.J. Voss, " A new instrument to measure ttie solar aureole from an unstable ,L platform." (Submitted to Jour. Atmos. Ocean. Tech.). B. Schmid, P.B. Russell,J.M. Livingston,S.Gasso, D.A. Hegg, D.R. Collins,R.C. Flagah,J.H. Se- infeld,E. Ostrom, K.J. Noone, P.A. Durkee, H.H. Jonsson,E.J.Welton, K.JI Voss,H_R_:Gordon, P. Formenti, M.O. Andreae, V.N. Kapustin, T.S. Bates,and P.K. Quinn, "Clear column closurestud- iesofurban-marine and mineral-dustaerosolsusingaircraft, ship,and ground-based measurements .inACE-2," (Submitted to ALPS99, 18-22 January 1999,Meribel,France). B. Schmid, J.M. Livingston,P.B. Russell,P.A. Durkee, H.H. Jonsson, D.R. Collins,R.C. Flagan, J.H. Sehtfeld, S.A. Gasso,D.A. Hegg, E. Ostrom,K.J. Noone, E.•J. Welton, K.J. Voss, H.R. Gordon, 14 _r ' Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 ? P. Formenti, and M.O. Andreae, "Clear sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 using airborne sunphotometer, airborne in-situ, space-borne, and ground-based measurements." (To be submitted to Tellu8 Special Issue on ACE-2) E.J. Welton, K.J. Voss, H.R. Gordon, H. Maring, A_ smirnov, s. Holben, B. Schmid, J.M. Liv- ingston, P.B. Russell, P.A. Durkee, P. Formenti, and M.O.-Andreae, "Ground-based Lidar Measure- ments of Aerosols During ACE-2: Instrument Description, Results, and Comparisons with other Ground-based and Airborne Measurements." (To be submitted to Tellu8 Special Issue on ACE-2) x _- • L _ _ , • J! . • Semi-Annual R'eport (1 July - 31 December 1998) NAS5-31363 6. Detached Coccolith Algorithm and Post Launch Studies (W.M. Balch). a. Task Objectives: T Our MODIS work during involvesunderstanding allaspectsof the influenceof suspended calcium carbonate particleson inherentopticalpropertiesin the sea. Work during thisreporting period focused on severalareas:processingcellcount sampleS;merging atomic absorptiondata, particulateorganiccarbon data,and scatteringdata from MODIS pre-launch cruisesin the Gulf of Maine; preparation,submission,or revisionof threeMODIS-related manuscripts;participating in another MODIS pre-launchcruiseto the Gulfof Maine to examine in situpropertiesof calcite particle;and analysisofcalciteopticalpropertiesfrom the Ar_ibiansea. The algorithm forretrievalofthe detached coccolithconcentrationfrom the coccolithophorid, E. huxleyiisdescribedin detailinour ATBD. The key isquantificationofthe backscatteringcoef- ficientofthe detached coccoliths.Our earlierstudiesfocusedon laboratoryculturesto understand factorsaffectingthe calcite-specific backscatteringcoei_cient.A thorough understanding of the relationshipbetween calciteabmidance and lightscattering,in situ,Willprovide the basisfor a genericsuspended calcitealgorithm.As with algorithmsforchlorophyll,and primary productivity, the naturalvariancebetween growth relatedparameters and opticalpropert'ies needs to be under- stood before the accuracy of the algorithm can be determined.To thisend, the objectivesof our coccolithstudiesduring thisreportingperiod have been: (1) Working up data from our June '98MODIS Gulf of Maine cruise. (2) Final pre-publicationformatting of JGR m_muscript on coccolith scatteringproperties. _ (3) Continued microscope cell/coccolith counts forlatestsamples from the Gulf of Maine. (4) Final publicationof a paper on coccolithopticalproperties(with Ken Voss and Katherine Kilpatrick. (5) Completion of11 one-day pre-launchcruisesinthe Gulf OfMaine in ' which samples forcoccolithconcentration,suspended calcium car- bonate and opticalpropertiesoftheseparticulateswere enumerated. For perspectiveon the directionsofour work, we providean overview ofour previousactivities: Semi-Annual Report (I July - 31 DeCember 1998) NAS5-31363 Jan-J_une 1995: Research focus - chemostat cultures(in whim algal growth rate was preciselycontrolled)and"we examiziedhow the optical propertiesofthese calcifyingalgaechanged as a functi°n°fgrowth. July-Dec 1995: Research focus - shipbbard measurements of suspended calciteand estimatesofopticalbackscatteringas validationofthe labo- ratory.measurements.We participated.0ntwo month-long cruisesto the Arabian Sea;measuring coccolithophoreabundance, production,and op- ticalproperties. Jan-June 1996: Research focus- fieldc_cite distributions, during two Gulf ofMaine cruises,one in March and one in June. ' :_ July-Dec 1996: Research focus - participatedon anothercruise to the Gulf ofMaine and processedsamples from the Gulf of Maine. Jan-June 1997: Research focus- continued prbcessingsamples from our previouscruises,upgraded our laserlighi scatteringpl10t0meterused in allOfthe calcitescatteringmeasurements, performed another pre-launch cruiseon calciteparticleopticsin the Gulf of Maine, and analyzed our resultsfrom the MODIS-funded flow cytometer work, July-December 1997: Research focus continuedbuildingour data base on calcite-dependentscatteringwith a cruiseto the Gulf of Maine in November 1997. Work was alsoperformed on processingthe data from the June 1997 cruise.The resultsfromlthe flow cytometer work were submitted forpublication. "." Jan-June 1998: Research focus - worked-up resultsfrom our Novem- ber '97 Cruise,participatedin a pre-launchcruisein June '98,finalized data merging and processingforallprev_iouscruises,integrated.thedata stream for surfaceradiance into the suiteof opticalparameters which• we measure [which was one ofthe issuesfrom our MODIS ATBD review " that was suggested forconnectingthe inherentopticalproperties(which we measure) to the water-leavingradiance (which the satellite willmea- ; -,i', sure)].Lastly,we put considerabletime intopreparationand publishing ofearlierresults. Semi-Annual Report (1 July - 31 December 1998)NAS5-31363 • b. July-December 1998: We completed work-up of our June 1998 cruise in tl_e Gulf of Maine aboard the tt/V Alba- tross. As with the November 1997 cruise, calcite-dependent backscattering commonly accounted for 10-20% of t0tal backscattering. Even with the low light:concUtions, coccolithophores were still remarkably abundant in the Gulf of Maine. We formerly interpreted strong coccolith influence on particle optics as a "summer-only" issue but it now can be clearly considered a year-round phe- nomenon. Specifically, we encountered a coccolith patch in 8°C water SW of Nova Scotia. This is the last place we ever expected to see coccoHthophores, given the strong mixing and cool temper- atures. Since we collected AC-9 data of absorption and attenuation (which by difference gave us scattering), then we have been processing the data to calculate bb (the backscattering probability bb/b) and see how this varies with the standing stock of chlorophyll and calcium carbonate. i .i f', Given the future plan for more Gulf of Maine cruises, as:weH as our SI1VIBIOS activities, we have written new software to merge the various data sets into one file that can be submitted to NASA's SeaBass data archive. The software (which performs vicarious calibrations, offset corrections, plus calculating "derived quantities" has now been through 3 sets_of revisions to streamline it and make it more efficient. This software will considerably reduce the time currently required to quality control the numbers and produce hydrographic plots of the _inherent optical properties (a, b, c, bb, calcite-dependent backscattering, bb, temperature, s_ilnlty,:and fluorescence). c. Data/Analysis/Interpretation: See b.' : d. Anticipated Future Actions: Work in the next reportingperiod will adc_ess several/areas:, _• (1) Suspended calcite analyses from the Gulf of Maine cruise series. (2) Publication of JGR manuscript on coccolith scattering properties : (January 1999 issue). ' (3) Completion of a cruise in the Gulf of Mexico, doing a line between Tampa and Progresso, Mexico, followed by a trip up the entire east- ern U.S., back to the Gulf of Maine (March and April !999). This will be a one month campaign. (4) Continuation of microscope cell/coccolith-counts for latest samples from the Gulf of Maine, and Gulf of Mexico. 18 i__:_i • Semi-Annual Report (1 July-31 December 1998) NAS5-31363 (5) Utilization of 20 more days 'at sea in the Gulf of Maine during the summer and fall of 1999. e. Problems/Corrective Actions: None f. Publications: Voss, K., W. M. Balch, and K. A. Kilpatriek, "Scattering and attenuation properties of Emiliania huxleyi cells and their detached eoeeoliths," Limnol. Oeeanoor. 43 870-876 (1998). Balch, William M., David T. Drapeau, Terry L. Cucci, and Robert D. Vaillancourt, Katherine A. Kilpatrick, Jennifer J. Fritz. "Optical backscattering by calcifying algae-Separating the contribution by particulate inorganic and organic carbon fractions," Jour. Geoph_s. Res. (In press). Milliman, J., P.J. Troy, W. Balch, A.K. Adams,'Y.-H. Li, and F.T. MacKenzie, "Biologically- mediated dissolution of calcium carbonate above the chemical lysocline?" Deep Sea Res. (In press). Graziano, L., W. Balch, D. Drapeau, B. Bowler, and S. Dunford, 'iOrganic and inorganic carbon production in the Gulf of. Maine" Cont. Shelf Res. (Submitted). . Balch_ W. M., D. Drapeau, J. Fritz, and B. Bowler, "Calcification rates in the Arabian SeaP," Submitted to Deep Sea Res. Special Issue on the Arabian Sea (Submitted). T -- 19 Semi-Annual Report (1 July - 31 December 1998) NAS5-31363 7. Other Activities. The PI participated in the MODIS Science Team meeting at University of Maryland (December 15 and 16, 1998). He also presented the following papers at scientific meetings. H.R. Gordon, K.J. Voss, J.W. Brown, P.V.F. Banzon, R.E. Evans, D.K. Clark, L. Kovar, M. Yuen, M. Feinholz, and M. Yarbrough, SeaWiFS Calibrat'ion Initaliz'ation: Pr_ary Results. Ocean Optics XIV, Kona, Hawaii, November 11-13, 1998. H.R. Gordon, The NIMBUS-7 Coastal Zone Color Scanner: A Retrospective. Invited paper, Amer- ical Geophysical Union Fall Meeting, San Francisco, CA, December 6-10, 1998. ; .' • - r f- 20 - Semi-Annual Report (1 July -31 December 1998) NAS5-31363 8. Publications and Submissions 1998. H.R. Gordon, Vicarious calibration of bcean color sensors, Remote Sensing of Environment, 63, 265-278(1998). H. Yang and H.R, Gordon, Retrieval of the Columnar Aerosol Phase Function and Single Scattering Albedo from Sky Radiance over Land: Simulations, Applied Optics, 37, 978-997 (1998). K.D. Moore, K.J. Voss,. and H.R. Gordon, Spectral reflectance of whitecaps: Instrumentation, calibration, and performance in coastal waters, Jour. Atmos. "'Ocean. Tech., 15,496-509 (1998). D.J. Diner, J.C. Beckert, T.H. Reilly, C.J. Bruegge , J.E. Conel, R.A. Kahn, J.V. Martonchik, T.P. Ackerman, R. Davies_ G.A.W. Gerstl, H.R. Gordon,. J-P. Muller, R. Myneni, P.J. Sellers, B. Pinty, and M:M. Vestraete, Multi-angle Imaging SpectroRadiometer (MISR) Instrument De- scription and Experiment Overview, IEEE Transactions on Geoscience and Remote Sensing, 36, 1072-1087 (1998). J.V. Martonchik, D.J. Diner, R.A. Katm, T.P. Ackerman, M.M. Verstrate, B. Pinty, and H.R. Gordon, Techni.'ques for the Reetrieval of Aerosol Properties Over Land and Ocean Using Multiangle Imaging_' IEEE Transactions on Geoscience and'Remote Sensing, 36, 1212-1227 (1998). W.E. Esaias,M.R. Abbott, Otis B. Brown, J.W. Campbel, K.L. Carder, D.K. Clark,R.L. Evans, F.E. Hoge, H.R. Gordon, W.M. Balch; R. Letelier,and P. Minnett, An overview of MODIS capa- bilities forocean scienceobservations,IEEE Transactionson Geoscience and Remote Sensing,36, 1250-1265 (1998i. J.V. Martonchik, D.J. Diner, B. Pinty,M.M. Verstrate,R.B. Myneni, Y. Knyazikhim, and H.R. Gordon, 'DeterminationofLand and Ocean Reflective, Radiative,and BiophysicalPropertiesUsing MultiangleImaging, IEEE Transactionson GeoseienceandRemote Sensing,36, 1266-1281 (1998). R. Chomko and Ii.R.Gordon, Atmospheric correctionof ocean :colorimageryi Use of the Junge power-law aerosolsizedistributionwith variablerefractiveindex to handle aerosolabsorption, Applied Optics,37, 5560-5572 (1998). Voss,K., W. M. Balch, and K. A. Kilpatrick,"Scatteringand attenuationpropertiesofEmiliania huxleyicellsand theirdetached coccoliths,"Limnol. Oceanogr. 43 870-876 (1998). A. Smirnov, B. H01ben ,I.S1utsker,E.J. Welton, and P. Formenti, "Opticalpropertiesof Saharan dust during ACE 2," Jour. Geophys. Res.,103D 28,079-28;092"(1998). o 21 Semi-Annual Report (1 July - 31 December11998) _NAS5-31363 Balch, William M., David T. Dral_ean, Terry L. Cucci, and Robert D. Vaillancourt, Katherine A. Kilpatrick, Jennifer J. Fritz. "Optical backscattering by calcifying algae-Separating the contribution by partic_ate inorganic and organic carbon fractions," Jour. Geophys. Res. (In press). Milliman, J., P.J. Troy, W. Balch, A.K. Adams, Y.-H. Li, and F.T. MacKenzie, "Biologically- mediated dissolution of calcium carbonate above the chemical lysocline?" Deep Sea Res. (In press). -_-_ _ H.R. Gordon, Contribution of raman scattering to water-leaving radiance: A reexamination. (Sub- mitted to Applied Optics.) _ o E.J. Welton, K.J. Voss, D:L. Savoie, and J.M. Prospero, "Measurements of Aerosol Optical Depth over the North Atlantic Ocean: ,Correlations with Surface Aerosol Concentrations" (Submitted to Jour. Geophys. Res.)_ B. Schmid, P.B. Russell, J.M. Livingston, S. Gasso, D.A. Hegg, D_R. Collins, K.C. Flagan, J.H. Se- infeld, E. Ostrom, K._J. Noone, P.A. Durkee, H.H. Jonsson, E.J. W_iton, K.J. Voss, H.R. Gordon, P. Formenti, M.O. Andreae, V.N. Kapustin, T.S. Bates, and P.K. Quinn, "Clear column closure stud- ies of urban-marine and mineral-dust aerosols using aircraft, ship, and ground-based measurements in ACE-2," (Submitted to ALPS99, 18-22 January 1999, Meribel, France). J.M. Bitter and K.J. Voss, " A new instrument to measure the solar aureole from an unstable platform." (Submitte d to Jour: Atmos. Ocean. Tech.). Graziano, L., W. Balch, D. Drapeau, B. Bowler, and S. Dunford, "Organic and inorganic carbon production in the Gulf of Maine" Cont. Shelf Res. (Submitted).. Balch, W. M., D. Drapeau, J. Fritz, and B. Bowler, "Calcification rates in the Arabian Sea," Submitted to Deep Sea Res." Special Issue on the Arabian Sea (Submitted). r B. Schmid, J.M. Livingston, P.B. Russell, P.A. Durkee, H.H. Jonsson, D.R. Collins, R.C. Flagan, J.H. Seinfeld, S.A. Gasso, D.A. Hegg, E. Ostrom, K.J. Noone, E.J. Welton, K.J. Voss, H.R. Gordon, P. Formenti, and M.O. Andreae, "Clear sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 Using airborne sunphotometer, airborne in-sitU, Space-borne, and ground-based measurements." (To be submitted to Tellus Special Issue on ACE-2) E.J. Welton, K.J. Voss, H.tt. Gordon, H. Mating, A. Smirnov, B. Holben, B. Schmid:i J.M. Liv- ingston, P.B. Russell, P.A. Durkee, P. Formenti, and M.O. Andreae, "Ground:based Lidar Measure- _ 22 ,.." . L. ,i (8"_[OV uo anss I I_!_ads _nlla _ o_ pa_.mlqns aq O.T.) ,,'s_uamaaaS_al/g au.toq .a_ pu_ p_s_q-puno_ D _q_o y_!_ suos!_dmoo_pm_ 's_ins_i 'uo!id!_s_(I _u_m'_su I :g'_IOY _m.a'n(I SlOSO_V jo s_u_m gO¢Ig-_SVlq (g66I aoqmo_o(I Ig -£lnr _) _aodo_I l_nuuv-.maoS Plans for FY 99 NASA/GSFC NAS5-31363• H.R. Gordon 12/15/98 I : APPENDIX 1 ! NASA/GSFC Contract No. NAS5-31363 OCEAN OBSERVATIONS WITH EOS/MODIS Algorithm Development and Post Launch Studies - t Howard R. Gordon : University of Miami Department of Physics Coral Gables, FL 33124 • k Plans for FY 99 xL • Plans for FY 99 NASA/GSFC NAS5-31363 H.R. Gordon 12/15/98 Preamble The coming Fiscal Year (1999) was to be heavily focused on validation of MODIS-derived products. However, the delay of the launch of EOS AM1 requires some modification of the plan. Our approach for the coming year is to use SeaWiFS for validating algorithms (rather than MODIS-derived products) in a manner similar to the way the MODIS Land and Atmospheres Groups have already been using the MAS. In addition, the delay in the launch will allow us additional time to enhance the already existing algorithms prior to launch. We break our effort for FY 99 into five distinct (although interrelated) units: • Atmospheric Correction Algorithm Development • Whitecap Correction Algorithm • In-water Radiance Distribution (BRDF) • " Preqaunch/Post-launch Atmospheric Correction Validation * Detached Coccolith Algorithm In what follows, it will be seen that addressing the various tasks within these units requires fundamental studies, a through examination of SeaWiFS imagerY, use of SeaWiFS imagery as a tool, and a maintenance of measurement and data-analysis capability through the prelaunch era into the formal validation phase. Developing the required capability of, and experience in, processing SeaWiFS imagery will also facilitate the efficient handling of MODIS imagery (e.g., for QA) in the post-launch era. Atmospheric correction Algorithm Development Objectives and Proposed Activities (FY '99) During FY '99 there are several objectives under this task. They are focused on ensuring the correctness of the basic correction algorithm and its:implementation, improving the basic algorithm to provide for an accurate correction in the presence of strongly-absorbing aerosols, and addressing several MODIS-specific issues. 1. Validate