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Papers by Charles Booth

An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Su... more An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs) are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds have little impact at both sites, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at 345 nm by 4-6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20-80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10-25% smaller than in the summer. Maximum UV Indices ever observed at Summit and South Pole are 6.7 and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9-2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow. 1 Introduction Solar ultraviolet (UV) radiation reaching the Earth's surface has a wide range of effects on humans, aquatic and terrestrial ecosystems (UNEP, 2003; ACIA, 2006). For humans, exposure to UV radiation has been linked to sunburn, skin cancer, corneal 4950

In response to the need for oceanographers to be able to make atmospheric and oceanic observation... more In response to the need for oceanographers to be able to make atmospheric and oceanic observations during mission calibration exercises, NASA partnered with Biospherical Instruments Inc to develop a new class of instruments based on very small and highly accurate microradiometers. These innovative radiometers have been developed as part of a new vicarious calibration paradigm called the Optical Sensors for Planetary Radiant Energy (OSPREy) project with emphasis on achieving greater spectral resolution in optically complex (coastal) waters. An OSPREy sensor suite includes radiometers equipped with cosine diffusers and robotic shadow bands to measure global and diffuse irradiance, as well as radiometers with 2.5° field-of-view radiance optics mounted on pointing units to measure the Sun, Moon, sky, and sea. OSPREy sensors are temperature-stabilized, hybrid instruments consisting of up to 19 fixed-wavelength (filter) microradiometers (spanning 320 to 1640 nm) and a Zeiss spectrograph (...

The use of general descriptive names, registered names, trademarks, etc. in this publication does... more The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Eos, Transactions American Geophysical Union, 1990

UV spectral irradiance incident at the United States bases at McMurdo, Palmer, and the South Pole... more UV spectral irradiance incident at the United States bases at McMurdo, Palmer, and the South Pole, in Antarctica, and at an Argentina Laboratory in Ushuaia is being routinely monitored by the NSF UV Spectroradiometer Network. Coverage includes the 1988 and 1989 ozone hole seasons and show marked differences between these two years. Many different methods of assessing UV irradiance or exposure are found in the literature. The degree of contrast between the 1988 and 1989 seasons varies widely depending upon the UV assessment method chosen. Data will be presented describing how different assessment methods present this time series.

As part of a long-term perspective of supporting both current and next-generation calibration and... more As part of a long-term perspective of supporting both current and next-generation calibration and validation activities for ocean color satellites, incremental modifications to existing COTS sensors were undertaken to reduce the uncertainties in AOP measurements. A principal concern was improving observations made in shallow, optically complex waters, wherein above-water methods have an advantage because they are not subjected to self-shading effects. The primary objective of the BioSORS development was to fit the capabilities of the state-of-the-art COTS PRR series of sensors into a smaller form factor that is more compatible with existing deployment capabilities, and to characterize the new sensors more fully than is the usual practice. The results of these two activities are presented.

The advances and new findings that have occurred in the ultraviolet (UV) radiation field since th... more The advances and new findings that have occurred in the ultraviolet (UV) radiation field since the publication of the previous Assessment (WMO, 1995) include the fo llowing: The inverse relationship between decreasing ozone amount and increasing UV-B radiation has been reconfirmed and firmly established in both theory and measurements. The measured effects of ozone, albedo, altitude, clouds and aerosols, and geographic differences are much better understood. The number, distribution, and quality of UV-irradiance (energy per unit area per unit time) instruments have greatly improved throughout the world. However, there are still regions of sparse coverage. Well-calibrated UV-irradiance spectral time series are now available at some ground sites for periods of up to 9 years, where changes in UV-B irradiance have been detected (e.g., 1.5% per year at 300 nm, 0.8% per year at 305 nm) at midlatitudes (near 40 ') that are consistent with expected changes fr om the decreasing amounts of ozone. However, the long-term stability needed for trend estimates has been demonstrated for only a few ground based UV instruments. Either the records are not long enough or the instrument stability is insufficient to reliably determine decadal change at most midlatitude sites. Other factors limiting the detection of long-term trends are that clouds, albedo, aerosols, and short-term ozone changes produce local daily, monthly, and interannual changes that are larger than the long-term trend. It is important for long-term trend detection that both UV-A and UV-B be measured separately along with ancillary data (e.g., ozone and aerosols). The anomalous UV-trend estimates fr om the Robertson-Berger (RB) meter network located in the United States are now understood. Corrections have been applied to the data, which now show no significant trends for the latitude range of the instruments' locations. It was concluded that the data fr om the U.S. RB network alone are unsuitable for trend detection. Public interest related to UV exposure has been addressed by establishing a standardized UV index in many countries, based on estimates of ozone and, in some cases, cloud cover and surface albedo, to provide daily information about the intensity of UV radiation.

The C-OPS instrument successfully integrates a number of new technologies, each focused on differ... more The C-OPS instrument successfully integrates a number of new technologies, each focused on different aspects of the practical problem of resolving the optical complexity of the near-shore water column. Although C-OPS represents a significant improvement over BioPRO and other legacy profilers, C-OPS was designed from inception specifically to operate in shallow coastal waters and from a wide variety of deployment platforms. In terms of the mechanics of operating the instrumentation and its behavior during descent, the most significant improvement was to change the basic design for mounting the light sensors from a rocket-shaped deployment system, used in legacy profilers, to the kite-shaped backplane developed for SuBOPS (Chap. 2). This change allowed the flotation to be distributed as a primary hydrobaric buoyancy chamber along the top of the profiler, plus an adjustable secondary set of one or more movable floats immediately below. The primary set provides the upward buoyant thrust...

In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and... more In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and chlorophyll in the ocean. Biospherical Instruments Inc. responded to this call with a proposal first to study a variety of approaches to this problem. A second phase of research was then funded to pursue instrumentation to measure the sunlight stimulated naturally occurring fluorescence of chlorophyll in marine phytoplankton. The monitoring of global productivity, global fisheries resources, application of above surface-to-underwater optical communications systems, submarine detection applications, correlation, and calibration of remote sensing systems are but some of the reasons for developing inexpensive sensors to measure chlorophyll and productivity. Normally, productivity measurements are manpower and cost intensive and, with the exception of a very few expensive multiship research experiments, provide no contemporaneous data. We feel that the patented, simple sensors that we have ...

Offshore Technology Conference, 1991

Natural fluorescence is the flux of fluoresced light emitted from chlorophyll a during photosynth... more Natural fluorescence is the flux of fluoresced light emitted from chlorophyll a during photosynthesis. This signal is centered in the red region of the spectrum around 683 nm and a number of studies have indicated that it is sufficiently strong to be detected throughout the euphotic zone. Since it was first identified in the late 1970's, natural fluorescence has been investigated as a means for rapidly determining the distribution and abundance of marine phytoplankton, particularly since it is one of the few measurements that can be made without perturbing the crop. Moreover, this in situ measurement is rapid, yields information that is of high spatial and temporal resolution and may made from a number of different platforms. Most recently, research on natural fluorescence has determined that this signal can be related not only to the standing crop of phytoplankton, but to instantaneous rates of gross primary production. The first natural fluorescence field instruments were intr...

Scientific Assessment of …, 1994

Photochemical & Photobiological Sciences, 2011

Ultraviolet radiation (UVR) plays a key role in several biological functions, including human hea... more Ultraviolet radiation (UVR) plays a key role in several biological functions, including human health. Skin exposure to UVR is the main factor in vitamin D photoconversion. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostate, as well as other diseases. Several epidemiological studies have shown an inverse relationship between the above-mentioned diseases and latitude, in accordance with the ultraviolet radiation latitudinal gradient. The aim of this study is to determine whether UV irradiance levels in the southern South America are sufficient to produce suitable levels of vitamin D year around. For this purpose, vitamin D photoconversion weighted-irradiance was analyzed between S.S. de Jujuy (24.17°S, 65.02°W) and Ushuaia (54° 50'S, 68° 18'W). In addition to irradiance, skin type and area of body exposed to sunlight are critical factors in vitamin D epidemiology. Due to a broad ethnic variability, it was assumed that the skin type in this region varies between II and V (from the most to the less sensitive). All sites except South Patagonia indicate that skin II under any condition of body area exposure and skin V when exposing head, hands, arms and legs, would produce suitable levels of vitamin D year round (except for some days in winter at North Patagonian sites). At South Patagonian sites, minimum healthy levels of vitamin D year round can be reached only by the more sensitive skin II type, if exposing head, hands, arms and legs, which is not a realistic scenario during winter. At these southern latitudes, healthy vitamin D levels would not be obtained between mid May and beginning of August if exposing only the head. Skin V with head exposure is the most critical situation; with the exception of the tropics, sun exposure would not produce suitable levels of vitamin D around winter, during a time period that varies with latitude. Analyzing the best exposure time during the day in order to obtain a suitable level of vitamin D without risk of sunburn, it was concluded that noon is best during winter, as determined previously. For skin type II when exposing head, exposure period in winter varies between 30 and 130 min, according to latitude, except for South Patagonian sites. During summer, noon seems to be a good time of day for short periods of exposure, while during leisure times, longer periods of exposure without risk of sunburn are possible at mid-morning and mid-afternoon. At 3 h from noon, solar zenith angles are almost the same for sites between the tropics and North Patagonia, and at 4 h from noon, for all sites. Then, in these cases, the necessary exposure periods varied slightly between sites, only due to meteorological differences.

Effects of sensor characteristics on the inferred vertical structure of the diffuse attenuation c... more Effects of sensor characteristics on the inferred vertical structure of the diffuse attenuation coefficient spectrum

Biospherical Instruments has successfully completed a NASA sponsored SBIR (Small Business Innovat... more Biospherical Instruments has successfully completed a NASA sponsored SBIR (Small Business Innovational Research Program) project to develop spectroradiometers capable of being deployed in the ocean for long periods of time. The completion of this project adds a valuable tool for the calibration of future spaceborne ocean color sensors and enables oceanographers to extend remote sensing optical techniques beyond the intermittent coverage of spaceborne sensors. Highlights of the project include two moorings totalling 8 months generating extensive sets of optical, biological, and physical data sets in the ocean off La Jolla, California, and a 70 day operational deployment of the resulting commercial product by the ONR and NASA sponsored BIOWATT program. Based on experience gained in these moorings, Biospherical Instruments has developed a new line of spectroradiometers designed to support the oceanographic remote sensing missions of NASA, the Navy, and various oceanographers.

Deep Sea Research Part A. Oceanographic Research Papers, 1990

To test the proposal that the natural or solar-induced fluorescence of chlorophyll a in the sea p... more To test the proposal that the natural or solar-induced fluorescence of chlorophyll a in the sea provides a purely optical measure of chlorophyll and the rate of photosynthesis in the sea, we studied the relationship between natural fluorescence and photosynthesis in several environments including the central South Pacific, the western Sargasso Sea, and two sheltered bays. The results of 76 such measurements between 2 and 150 m depth and covering a 1500-fold range in production indicate that photosynthesis is highly correlated (r > 0.9) with natural fluorescence. Furthermore, a substantial portion of the remaining variability can be explained by an examination of the relationships of the quantum yields of photosynthesis and fluorescence as a function of light level. Specifically, the quantum yield of photosynthesis decreases more rapidly than the quantum yield of natural fluorescence with increasing irradiance. Predicted rates of primary production from measures of natural fluorescence and PAR fad within +30% for half of the samples, and within +75% for 90% of the cases (assuming that the carbon fixation measurements were without error). The prediction of chlorophyll from natural fluorescence and PAR exhibit similar correlations. This suggests that natural fluorescence measurements, either as a supplement to direct measurements or as independent optical measurements, provide a new and rapid means of estimating gross photosynthesis in the sea,

An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Su... more An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs) are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds have little impact at both sites, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at 345 nm by 4-6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20-80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10-25% smaller than in the summer. Maximum UV Indices ever observed at Summit and South Pole are 6.7 and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9-2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow. 1 Introduction Solar ultraviolet (UV) radiation reaching the Earth's surface has a wide range of effects on humans, aquatic and terrestrial ecosystems (UNEP, 2003; ACIA, 2006). For humans, exposure to UV radiation has been linked to sunburn, skin cancer, corneal 4950

In response to the need for oceanographers to be able to make atmospheric and oceanic observation... more In response to the need for oceanographers to be able to make atmospheric and oceanic observations during mission calibration exercises, NASA partnered with Biospherical Instruments Inc to develop a new class of instruments based on very small and highly accurate microradiometers. These innovative radiometers have been developed as part of a new vicarious calibration paradigm called the Optical Sensors for Planetary Radiant Energy (OSPREy) project with emphasis on achieving greater spectral resolution in optically complex (coastal) waters. An OSPREy sensor suite includes radiometers equipped with cosine diffusers and robotic shadow bands to measure global and diffuse irradiance, as well as radiometers with 2.5° field-of-view radiance optics mounted on pointing units to measure the Sun, Moon, sky, and sea. OSPREy sensors are temperature-stabilized, hybrid instruments consisting of up to 19 fixed-wavelength (filter) microradiometers (spanning 320 to 1640 nm) and a Zeiss spectrograph (...

The use of general descriptive names, registered names, trademarks, etc. in this publication does... more The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Eos, Transactions American Geophysical Union, 1990

UV spectral irradiance incident at the United States bases at McMurdo, Palmer, and the South Pole... more UV spectral irradiance incident at the United States bases at McMurdo, Palmer, and the South Pole, in Antarctica, and at an Argentina Laboratory in Ushuaia is being routinely monitored by the NSF UV Spectroradiometer Network. Coverage includes the 1988 and 1989 ozone hole seasons and show marked differences between these two years. Many different methods of assessing UV irradiance or exposure are found in the literature. The degree of contrast between the 1988 and 1989 seasons varies widely depending upon the UV assessment method chosen. Data will be presented describing how different assessment methods present this time series.

As part of a long-term perspective of supporting both current and next-generation calibration and... more As part of a long-term perspective of supporting both current and next-generation calibration and validation activities for ocean color satellites, incremental modifications to existing COTS sensors were undertaken to reduce the uncertainties in AOP measurements. A principal concern was improving observations made in shallow, optically complex waters, wherein above-water methods have an advantage because they are not subjected to self-shading effects. The primary objective of the BioSORS development was to fit the capabilities of the state-of-the-art COTS PRR series of sensors into a smaller form factor that is more compatible with existing deployment capabilities, and to characterize the new sensors more fully than is the usual practice. The results of these two activities are presented.

The advances and new findings that have occurred in the ultraviolet (UV) radiation field since th... more The advances and new findings that have occurred in the ultraviolet (UV) radiation field since the publication of the previous Assessment (WMO, 1995) include the fo llowing: The inverse relationship between decreasing ozone amount and increasing UV-B radiation has been reconfirmed and firmly established in both theory and measurements. The measured effects of ozone, albedo, altitude, clouds and aerosols, and geographic differences are much better understood. The number, distribution, and quality of UV-irradiance (energy per unit area per unit time) instruments have greatly improved throughout the world. However, there are still regions of sparse coverage. Well-calibrated UV-irradiance spectral time series are now available at some ground sites for periods of up to 9 years, where changes in UV-B irradiance have been detected (e.g., 1.5% per year at 300 nm, 0.8% per year at 305 nm) at midlatitudes (near 40 ') that are consistent with expected changes fr om the decreasing amounts of ozone. However, the long-term stability needed for trend estimates has been demonstrated for only a few ground based UV instruments. Either the records are not long enough or the instrument stability is insufficient to reliably determine decadal change at most midlatitude sites. Other factors limiting the detection of long-term trends are that clouds, albedo, aerosols, and short-term ozone changes produce local daily, monthly, and interannual changes that are larger than the long-term trend. It is important for long-term trend detection that both UV-A and UV-B be measured separately along with ancillary data (e.g., ozone and aerosols). The anomalous UV-trend estimates fr om the Robertson-Berger (RB) meter network located in the United States are now understood. Corrections have been applied to the data, which now show no significant trends for the latitude range of the instruments' locations. It was concluded that the data fr om the U.S. RB network alone are unsuitable for trend detection. Public interest related to UV exposure has been addressed by establishing a standardized UV index in many countries, based on estimates of ozone and, in some cases, cloud cover and surface albedo, to provide daily information about the intensity of UV radiation.

The C-OPS instrument successfully integrates a number of new technologies, each focused on differ... more The C-OPS instrument successfully integrates a number of new technologies, each focused on different aspects of the practical problem of resolving the optical complexity of the near-shore water column. Although C-OPS represents a significant improvement over BioPRO and other legacy profilers, C-OPS was designed from inception specifically to operate in shallow coastal waters and from a wide variety of deployment platforms. In terms of the mechanics of operating the instrumentation and its behavior during descent, the most significant improvement was to change the basic design for mounting the light sensors from a rocket-shaped deployment system, used in legacy profilers, to the kite-shaped backplane developed for SuBOPS (Chap. 2). This change allowed the flotation to be distributed as a primary hydrobaric buoyancy chamber along the top of the profiler, plus an adjustable secondary set of one or more movable floats immediately below. The primary set provides the upward buoyant thrust...

In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and... more In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and chlorophyll in the ocean. Biospherical Instruments Inc. responded to this call with a proposal first to study a variety of approaches to this problem. A second phase of research was then funded to pursue instrumentation to measure the sunlight stimulated naturally occurring fluorescence of chlorophyll in marine phytoplankton. The monitoring of global productivity, global fisheries resources, application of above surface-to-underwater optical communications systems, submarine detection applications, correlation, and calibration of remote sensing systems are but some of the reasons for developing inexpensive sensors to measure chlorophyll and productivity. Normally, productivity measurements are manpower and cost intensive and, with the exception of a very few expensive multiship research experiments, provide no contemporaneous data. We feel that the patented, simple sensors that we have ...

Offshore Technology Conference, 1991

Natural fluorescence is the flux of fluoresced light emitted from chlorophyll a during photosynth... more Natural fluorescence is the flux of fluoresced light emitted from chlorophyll a during photosynthesis. This signal is centered in the red region of the spectrum around 683 nm and a number of studies have indicated that it is sufficiently strong to be detected throughout the euphotic zone. Since it was first identified in the late 1970's, natural fluorescence has been investigated as a means for rapidly determining the distribution and abundance of marine phytoplankton, particularly since it is one of the few measurements that can be made without perturbing the crop. Moreover, this in situ measurement is rapid, yields information that is of high spatial and temporal resolution and may made from a number of different platforms. Most recently, research on natural fluorescence has determined that this signal can be related not only to the standing crop of phytoplankton, but to instantaneous rates of gross primary production. The first natural fluorescence field instruments were intr...

Scientific Assessment of …, 1994

Photochemical & Photobiological Sciences, 2011

Ultraviolet radiation (UVR) plays a key role in several biological functions, including human hea... more Ultraviolet radiation (UVR) plays a key role in several biological functions, including human health. Skin exposure to UVR is the main factor in vitamin D photoconversion. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostate, as well as other diseases. Several epidemiological studies have shown an inverse relationship between the above-mentioned diseases and latitude, in accordance with the ultraviolet radiation latitudinal gradient. The aim of this study is to determine whether UV irradiance levels in the southern South America are sufficient to produce suitable levels of vitamin D year around. For this purpose, vitamin D photoconversion weighted-irradiance was analyzed between S.S. de Jujuy (24.17°S, 65.02°W) and Ushuaia (54° 50'S, 68° 18'W). In addition to irradiance, skin type and area of body exposed to sunlight are critical factors in vitamin D epidemiology. Due to a broad ethnic variability, it was assumed that the skin type in this region varies between II and V (from the most to the less sensitive). All sites except South Patagonia indicate that skin II under any condition of body area exposure and skin V when exposing head, hands, arms and legs, would produce suitable levels of vitamin D year round (except for some days in winter at North Patagonian sites). At South Patagonian sites, minimum healthy levels of vitamin D year round can be reached only by the more sensitive skin II type, if exposing head, hands, arms and legs, which is not a realistic scenario during winter. At these southern latitudes, healthy vitamin D levels would not be obtained between mid May and beginning of August if exposing only the head. Skin V with head exposure is the most critical situation; with the exception of the tropics, sun exposure would not produce suitable levels of vitamin D around winter, during a time period that varies with latitude. Analyzing the best exposure time during the day in order to obtain a suitable level of vitamin D without risk of sunburn, it was concluded that noon is best during winter, as determined previously. For skin type II when exposing head, exposure period in winter varies between 30 and 130 min, according to latitude, except for South Patagonian sites. During summer, noon seems to be a good time of day for short periods of exposure, while during leisure times, longer periods of exposure without risk of sunburn are possible at mid-morning and mid-afternoon. At 3 h from noon, solar zenith angles are almost the same for sites between the tropics and North Patagonia, and at 4 h from noon, for all sites. Then, in these cases, the necessary exposure periods varied slightly between sites, only due to meteorological differences.

Effects of sensor characteristics on the inferred vertical structure of the diffuse attenuation c... more Effects of sensor characteristics on the inferred vertical structure of the diffuse attenuation coefficient spectrum

Biospherical Instruments has successfully completed a NASA sponsored SBIR (Small Business Innovat... more Biospherical Instruments has successfully completed a NASA sponsored SBIR (Small Business Innovational Research Program) project to develop spectroradiometers capable of being deployed in the ocean for long periods of time. The completion of this project adds a valuable tool for the calibration of future spaceborne ocean color sensors and enables oceanographers to extend remote sensing optical techniques beyond the intermittent coverage of spaceborne sensors. Highlights of the project include two moorings totalling 8 months generating extensive sets of optical, biological, and physical data sets in the ocean off La Jolla, California, and a 70 day operational deployment of the resulting commercial product by the ONR and NASA sponsored BIOWATT program. Based on experience gained in these moorings, Biospherical Instruments has developed a new line of spectroradiometers designed to support the oceanographic remote sensing missions of NASA, the Navy, and various oceanographers.

Deep Sea Research Part A. Oceanographic Research Papers, 1990

To test the proposal that the natural or solar-induced fluorescence of chlorophyll a in the sea p... more To test the proposal that the natural or solar-induced fluorescence of chlorophyll a in the sea provides a purely optical measure of chlorophyll and the rate of photosynthesis in the sea, we studied the relationship between natural fluorescence and photosynthesis in several environments including the central South Pacific, the western Sargasso Sea, and two sheltered bays. The results of 76 such measurements between 2 and 150 m depth and covering a 1500-fold range in production indicate that photosynthesis is highly correlated (r > 0.9) with natural fluorescence. Furthermore, a substantial portion of the remaining variability can be explained by an examination of the relationships of the quantum yields of photosynthesis and fluorescence as a function of light level. Specifically, the quantum yield of photosynthesis decreases more rapidly than the quantum yield of natural fluorescence with increasing irradiance. Predicted rates of primary production from measures of natural fluorescence and PAR fad within +30% for half of the samples, and within +75% for 90% of the cases (assuming that the carbon fixation measurements were without error). The prediction of chlorophyll from natural fluorescence and PAR exhibit similar correlations. This suggests that natural fluorescence measurements, either as a supplement to direct measurements or as independent optical measurements, provide a new and rapid means of estimating gross photosynthesis in the sea,