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Kaitlin Harbeck

Publications and source records attributed to Kaitlin Harbeck.

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

On-Orbit Radiometric Performance on ICESat-2

NASA’s ICESat-2 mission measures Earth’s elevation with the Advanced Topographic Laser Altimeter System (ATLAS), a 6-beam photon-counting laser altimeter. The Global Geolocated Photon data product (ATL03) is the primary source of photon information used by surface-type-specific higher-level products, along with the Atmospheric Layer Characteristics product (ATL09). ATL03 provides time-tagged, geolocated photon heights referenced to the ellipsoid and a parameter providing an initial classification of photon events as signal or background. We use this classification to evaluate ATLAS radiometry (number of signal photons per transmitted laser pulse) over short time scales and over the mission to date. The radiometric performance of ATLAS will in part determine what differences in the signal and background photon rates are significant and indicate geophysical, rather than instrumental, changes. We find the ATLAS radiometry is very stable over short time scales and exhibits a long-term decrease of ∼1 signal photon per laser pulse (∼-12%) in the strong spots over the first 1.5 years of the mission.

Aimee Gibbons↗
NASA NTRS2020

Pervasive ice sheet mass loss reflects competing ocean and atmosphere processes

Quantifying changes in Earth’s ice sheets and identifying the climate drivers are central to improving sea level projections. We provide unified estimates of grounded and floating ice mass change from 2003 to 2019 using NASA’s Ice, Cloud and land Elevation Satellite (ICESat) and ICESat-2 satellite laser altimetry. Our data reveal patterns likely linked to competing climate processes: Ice loss from coastal Greenland (increased surface melt), Antarctic ice shelves (increased ocean melting), and Greenland and Antarctic outlet glaciers (dynamic response to ocean melting) was partially compensated by mass gains over ice sheet interiors (increased snow accumulation). Losses outpaced gains, with grounded-ice loss from Greenland (200 billion tonnes per year) and Antarctica (118 billion tonnes per year) contributing 14 millimeters to sea level. Mass lost from West Antarctica’s ice shelves accounted for more than 30% of that region’s total.

Ben Smith↗
NASA NTRS2019

The Ice, Cloud, and Land Elevation Satellite-2 Mission: A Global Geolocated Photon Product Derived from the Advanced Topographic Laser Altimeter System

The Ice, Cloud, and land Elevation Satellite – 2 (ICESat-2) observatory was launched on 15 September 2018 to measure ice sheet and glacier elevation change, sea ice freeboard, and enable the determination of the heights of Earth’s forests. ICESat-2’s laser altimeter, the Advanced Topographic Laser Altimeter System (ATLAS) uses green (532 nm) laser light and single-photon sensitive detection to measure time of flight and subsequently surface height along each of its six beams. In this paper, we describe the major components of ATLAS, including the transmitter, the receiver and the components of the timing system. We present the major components of the ICESat-2 observatory, including the Global Positioning System, star trackers and inertial measurement unit. The ICESat-2 Level 1B data product (ATL02) provides the precise photon round-trip time of flight, among other data. The ICESat-2 Level 2A data product (ATL03) combines the photon times of flight with the observatory position and attitude to determine the geodetic location (i.e. the latitude, longitude and height) of the ground bounce point of photons detected by ATLAS. The ATL03 data product is used by higher-level (Level 3A) surface-specific data products to determine glacier and ice sheet height, sea ice freeboard, vegetation canopy height, ocean surface topography, and inland water body height.

ICESat-2↗
NASA NTRS2019

Land ice height-retrieval algorithm for NASA's ICESat-2 photon-counting laser altimeter

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) and its sole scientific instrument, the Advanced Topographic Laser Altimeter System (ATLAS), was launched on 15 September 2018 with a primary goal of measuring changes in the surface of the Earth's land ice (glaciers and ice sheets). ATLAS is a photon-counting laser altimeter, which records the transit time of individual photons in order to reconstruct surface height along track. The ground-track pattern repeats every 91 days such that changes in ice sheet surface height can be estimated through time. In this paper, we describe the set of algorithms that have been developed for ICESat-2 to retrieve ice sheet surface height from the geolocated photons for the Land Ice Along-Track Height Product (ATL06), and demonstrate their output and performance using a synthetic dataset over various land-ice surfaces and under different cloud conditions. We show that the ATL06 algorithm is expected to perform at the level required to meet the ICESat-2 science objectives for land ice.

ICESat-2↗
NASA NTRSDate not supplied

NASA Earth Science Division’s Commitment to Increasing Safety in the Field

NASA's Earth Science Division (ESD) has led and supported field campaign research over many decades focused on advancing fundamental research, testing new instrument technologies, and promoting career development. ESD field campaign research is conducted over a wide range of projects that vary in size, science focus area, location, platform type, and people. ESD leadership has created a task team to address campaign physical and mental safety, with the goal of providing all participants in NASA field campaign research with an environment that promotes research, safety, inclusivity, and a positive experience. Building on resources that have been developed both within and outside NASA, we report on the task team’s accomplishments and near-term plans, including the recent establishment of a best practices document and guidelines for the development of “agreement of behaviors” document for field teams. We also describe progress in the development of an online training module for field campaign participation, the incorporation of campaign safety language in forthcoming NASA ROSES solicitations, and outreach activities. Finally, we report on recent joint interactions with the NASA Planetary Science Division’s Ethics in Fieldwork team.

Ocean-based measurements↗