ENTICE Satellite Orbital Simulator to Study Ice Clouds

Abstract

Ice clouds play a critical role in Earth's weather and climate. They significantly impact the global hydrological cycle (Stubenrauch et al., 2013) and the global energy balance (Stephens et al., 2012), making them crucial for life on Earth. Weather and climate anomalies are tightly associated with the radiative heating related to ice clouds (Albern et al., 2020). Tropical anvil clouds are at the heart of large uncertainties on cloud-climate feedback (Hartmann & Berry, 2017). Anvil clouds are defined as clouds with convective cores and spreading clouds at upper levels that look like a blacksmith's anvil (Hartmann, 2016). Competing theories exist on the formation and evolution of tropical anvil clouds, which makes anvil clouds one of the least well-understood aspects of current atmospheric models (Yue et al., 2020). Specifically, anvil cloud duration and coverage as well as the processes that govern those factors are not well understood. For example, the global circulation model (GCM) simulation of high-altitude ice clouds does not match observational data (Jiang et al., 2012(Jiang et al., , 2021Li et al., 2012;Waliser et al., 2009). Moreover, a recent review article has shown that tropical anvil clouds are one of the main sources of uncertainty in climate models (Sherwood et al., 2020). In fact, the 2017 Decadal Survey states that one of its most important science goals is to reduce the uncertainty in low and high cloud feedback by a factor of 2 (ESAS, 2017). To better understand these processes, accurate measurements on vertical structures of cloud Abstract Clouds play a significant role in the Earth's energy balance and hydrologic cycle through their effects on radiation and precipitation, and therefore are crucial for life on Earth. Earth's NexT-generation ICE mission (ENTICE) is proposed to measure diurnally resolved global vertical profiles of cloud ice particle size, ice water content, and in-cloud humidity and temperature combining a 94 GHz cloud radar and multi-frequency sub-millimeter (sub-mm) microwave radiometers from space. The scientific objective of ENTICE is to identify the important processes by which anvil clouds evolve and interact with ambient thermodynamic conditions to advance our fundamental understanding of clouds and reduce uncertainties in cloud climate feedback. Whether such a science objective could be achieved depends on the orbital sampling characteristics of the mission. In this study, ENTICE sampling statistics are simulated with more than 1 billion (10 9 ) profiles and using five different scanning methods in a 400 km altitude precession orbit with an inclination of 65°: nadir, forward pointing, side scanning, and conical scanning for the radiometers, and nadir pointing for the radar. These statistics can then be used to help with future mission planning efforts. Using the GEOS-5 model atmosphere (produced by nature-run at 7-km and 30-min resolution), the simulator calculates sampling statistics related to cloud types and overpass times with enhancement from radar. The wide swath of...