Dr. Andrew Wald Profile

Dr. Andrew Wald

at Global Science & Technology Inc

SPIE Involvement:

Author

Publications (4)

Proceedings Article | 17 May 2016 Paper

Estimating terra MODIS polarization effect using ocean data

Andrew Wald, Jake Brinkmann, Aisheng Wu, Jack Xiong

Proceedings Volume 9827, 98270V (2016) https://doi.org/10.1117/12.2222585

KEYWORDS: MODIS, Polarization, Calibration, Reflectivity, Mirrors, Bidirectional reflectance transmission function, Rayleigh scattering, Atmospheric modeling, Data modeling, Clouds

Read Abstract +

Proceedings Article | 17 May 2016 Paper

Impact of MODIS SWIR band calibration improvements on Level-3 atmospheric products

Andrew Wald, Robert Levy, Amit Angal, Xu Geng, Jack Xiong, Kurt Hoffman

Proceedings Volume 9827, 98270Y (2016) https://doi.org/10.1117/12.2222594

KEYWORDS: MODIS, Atmospheric particles, Atmospheric optics, Short wave infrared radiation, Calibration, Aerosols, Reflectivity, Diffusers, Clouds, Atmospheric sciences

Read Abstract +

Proceedings Article | 2 May 2016 Paper

On-orbit performance and calibration improvements for the reflective solar bands of Terra and Aqua MODIS

Amit Angal, Xiaoxiong (Jack) Xiong, Aisheng Wu, Hongda Chen, Xu Geng, Daniel Link, Yonghong Li, Andrew Wald, Jake Brinkmann

Proceedings Volume 9881, 98811F (2016) https://doi.org/10.1117/12.2223912

KEYWORDS: MODIS, Calibration, Reflectivity, Diffusers, Sensors, Mirrors, Short wave infrared radiation, Signal to noise ratio, Neodymium, Detection and tracking algorithms

Read Abstract +

Moderate Resolution Imaging Spectroradiometer (MODIS) is the keystone instrument for NASA’s EOS Terra and Aqua missions, designed to extend and improve heritage sensor measurements and data records of the land, oceans and atmosphere. The reflective solar bands (RSB) of MODIS covering wavelengths from 0.41 μm to 2.2 μm, are calibrated on-orbit using a solar diffuser (SD), with its on-orbit bi-directional reflectance factor (BRF) changes tracked using a solar diffuser stability monitor (SDSM). MODIS is a scanning radiometer using a two-sided paddle-wheel mirror to collect earth view (EV) data over a range of ±55° off instrument nadir. In addition to the solar calibration provided by the SD and SDSM system, lunar observations at nearly constant phase angles are regularly scheduled to monitor the RSB calibration stability. For both Terra and Aqua MODIS, the SD and lunar observations are used together to track the on-orbit changes of RSB response versus scan angle (RVS) as the SD and SV port are viewed at different angles of incidence (AOI) on the scan mirror. The MODIS Level 1B (L1B) Collection 6 (C6) algorithm incorporated several enhancements over its predecessor Collection 5 (C5) algorithm. A notable improvement was the use of the earth-view (EV) response trends from pseudo-invariant desert targets to characterize the on-orbit RVS for select RSB (Terra bands 1-4, 8, 9 and Aqua bands 8, 9) and the time, AOI, and wavelength-dependent uncertainty. The MODIS Characterization Support Team (MCST) has been maintaining and enhancing the C6 algorithm since its first update in November, 2011 for Aqua MODIS, and February, 2012 for Terra MODIS. Several calibration improvements have been incorporated that include extending the EV-based RVS approach to other RSB, additional correction for SD degradation at SWIR wavelengths, and alternative approaches for on-orbit RVS characterization. In addition to the on-orbit performance of the MODIS RSB, this paper also discusses in detail the recent calibration improvements implemented in the MODIS L1B C6.

Proceedings Article | 12 October 2015 Paper

Tracking Terra MODIS on-orbit polarization sensitivity using pseudo-invariant desert sites

Aisheng Wu, Xu Geng, Andrew Wald, Amit Angal, Xiaoxiong Xiong

Proceedings Volume 9639, 963914 (2015) https://doi.org/10.1117/12.2196473

KEYWORDS: Polarization, MODIS, Reflectivity, Mirrors, Satellites, Calibration, Bidirectional reflectance transmission function, Imaging systems, Radiative transfer, Sensors

Read Abstract +

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years