Dr. Michael D. Obland Profile

Dr. Michael D. Obland

Senior Research Scientist at NASA Langley Research Ctr

SPIE Involvement:

Author

Publications (9)

Proceedings Article | 14 May 2019 Presentation + Paper

SAGE IV Pathfinder multi-spectral imaging spectrometer telescope paves the way for semi-custom CubeSat imaging missions

Alexander Cheff Halterman, Robert Damadeo, Charles Hill, Christine Buleri, Luke Murchison, Michael Obland, Adam Phenis, Shimshone Yacoby

Proceedings Volume 10986, 109860H (2019) https://doi.org/10.1117/12.2518971

KEYWORDS: Telescopes, Space operations, Stray light, Mirrors, Ozone, Optical design, Optical instrument design, Aerosols, Optical filters, Satellite imaging, Imaging spectrometry, Multispectral imaging, Optical analysis, Thermal analysis

Read Abstract +

Proceedings Article | 25 September 2018 Paper

Advancements towards active remote sensing of CO2 from space using intensity-modulated, continuous-Wave (IM-CW) lidar

Michael Obland, Abigail Corbett, Bing Lin, Byron Meadows, Joel Campbell, Susan Kooi, Tai-fang Fan, William Carrion, Jonathan Hicks, Joseph Sparrow, Edward Browell, Jeremy Dobler, Josh DiGangi

Proceedings Volume 10785, 1078509 (2018) https://doi.org/10.1117/12.2325816

KEYWORDS: LIDAR, Sensors, Carbon monoxide, Optical amplifiers, Continuous wave operation, Fiber lasers, In situ metrology, Active remote sensing, Carbon dioxide, Space operations

Read Abstract +

Proceedings Article | 5 December 2016 Presentation

Optical depth distribution of optically thin clouds and surface elevation variability derived from CALIPSO lidar measurements (Conference Presentation)

Zhaoyan Liu, Bing Lin, Michael Obland, Joel Campbell

Proceedings Volume 10006, 1000606 (2016) https://doi.org/10.1117/12.2240080

KEYWORDS: Carbon dioxide, LIDAR, Clouds, Aerosols, Earth's atmosphere, Atmospheric sensing, Passive sensors, Satellites, Atmospheric particles, Atmospheric optics

Read Abstract +

Atmospheric carbon dioxide (CO2) is one of the major greenhouse gases in the Earth’s climate system. The CO2 concentration in the atmosphere has been significantly increased over the last 150 years, due mainly to anthropogenic activities. Comprehensive measurements of global atmospheric CO2 distributions are urgently needed to develop a more complete understanding of CO2 sources and sinks. Because of the importance of the atmospheric CO2 measurements, satellite missions with passive sensors such as GOSAT and OCO-2 have been launched, and those with active sensors like Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) using an integrated path differential absorption (IPDA) lidar are being studied. The required accuracy and precision for the column-integrated CO2 mixing ratios (XCO2) is high, within 1.0 ppm or approximately 0.26%, which calls for unbiased CO2 measurements and accurate determinations of the path length. The presence of clouds and aerosols can make the measurement complicated, especially for passive instruments. The heterogeneity generated by the surface elevation changes within the field of view of the sensors and the grid boxes of averaged values of atmospheric CO2 would also cause significant uncertainties in XCO2 estimates if the path length is not accurately known. Thus, it is required to study the cloud and aerosol distributions as well as the surface elevation variability in assessing the performance of the CO2 measurements from both active and passive instruments. The CALIPSO lidar has acquired nearly 10 years of global measurement data. It provides a great opportunity to study the global distribution of clouds and aerosols as well as the statistics of the surface elevation variations. In this study we have analyzed multiple years of the CALIPSO Level 2 data to derive the global occurrence of aerosols and optically thin clouds. The results show that clear sky does not occur as frequently as expected. The global average occurrence is only about 8% for very clean air with columnar OD at 532 nm < 0.01. It increases to ~29% when OD < 0.1, and ~42% when OD < 0.3, which is close the clear atmospheric threshold from regular passive remote sensing instruments. This calls for a capability to make precise retrievals in the presence of relatively dense aerosols or thin clouds. Multiple years of surface elevation data derived from the CALIPSO lidar has also been used in the assessment of surface elevation variability for passive sensor observations. It is shown that the variability of the surface elevation generally increases with increases in footprint size and surface elevation. For a footprint of 1-2 km typical for passive sensors, the mean standard deviation is 5-10 meters when elevation < 1 km and can reach 100 meters as the elevation increases. The occurrence frequency for a standard deviation < 10 m is greater than 20%, which can cause significant biases in the CO2 retrieval if the presence of the cloud and/or aerosol cannot be identified and corrected. With ranging capability, the ASCENDS lidar system supported by NASA will reliably measure CO2 even in the presence of multiple backscatter targets (surface and transparent clouds) as shown during the experiments of recent airborne system demonstrations. However, it is very challenging for passive satellites to make reliable retrievals in the multiple-layer target case, because of the lack of path length information.

Proceedings Article | 20 October 2015 Paper

Advanced intensity-modulation continuous-wave lidar techniques for ASCENDS CO2 column measurements

Joel Campbell, Bing Lin, Amin Nehrir, F. Harrison, Michael Obland, Byron Meadows

Proceedings Volume 9645, 964504 (2015) https://doi.org/10.1117/12.2194442

KEYWORDS: LIDAR, Clouds, Modulation, Carbon dioxide, Teeth, Point spread functions, Absorption, Continuous wave operation, Sensors, Atmospheric sensing

Read Abstract +

SPIE Journal Paper | 1 March 2010

Development of a widely tunable amplified diode laser differential absorption lidar for profiling atmospheric water vapor

Michael Obland, Kevin Repasky, Amin Nehrir, John Carlsten, Joseph Shaw

JARS, Vol. 4, Issue 01, 043515, (March 2010) https://doi.org/10.1117/12.10.1117/1.3383156

KEYWORDS: Absorption, Transmitters, Semiconductor lasers, Optical amplifiers, LIDAR, Sensors, Avalanche photodetectors, Diodes, Receivers, Pulsed laser operation

Read Abstract +

Proceedings Article | 26 September 2007 Paper

Initial results from a water vapor differential absorption lidar (DIAL) using a widely tunable amplified diode laser source

Michael Obland, Amin Nehrir, Kevin Repasky, Joseph Shaw, John Carlsten

Proceedings Volume 6681, 66810I (2007) https://doi.org/10.1117/12.731877

KEYWORDS: Absorption, Transmitters, Receivers, LIDAR, Semiconductor lasers, Optical filters, Avalanche photodetectors, Sensors, Telescopes, Mirrors

Read Abstract +

SPIE Journal Paper | 1 August 2007

Application of extended tuning range for external cavity diode lasers to water vapor differential absorption measurements

Michael Obland, Amin Nehrir, Kevin Repasky, John Carlsten, Joseph Shaw

OE, Vol. 46, Issue 08, 084301, (August 2007) https://doi.org/10.1117/12.10.1117/1.2771654

KEYWORDS: Absorption, Semiconductor lasers, Feedback loops, Laser systems engineering, Prisms, Ferroelectric materials, Diodes, Temperature metrology, Computing systems, Humidity

Read Abstract +