Retrieving temperature and relative humidity profiles from hyperspectral
radiations via deep learning
Wei Gao
USDA UV-B Monitoring and Research Program, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado 80523, USA; Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, Colorado 80523, USA
Author ProfileAbstract
Atmospheric temperature and relative humidity profiles are fundamental
for atmospheric research such as numerical weather prediction and
climate change assessment. Hyperspectral satellite data contain a wealth
of relevant information and have been used in many algorithms (e.g.
regression-based methods) to retrieve these profiles. Deep Learning or
Deep Neural Network (DNN) is capable of finding complex relationships
(functions) between pairs of input and output variables by assembling
many simple non-linear modules together and learning the parameters
therein from large amounts of observations. DNN has been successfully
applied in many fields (such as image classification, object detection,
language translation). In this study, we explored the potential of
retrieving atmospheric profiles from hyperspectral satellite radiation
data using DNN. The requirement for applying the DNN technique is
satisfied with large amount of hyperspectral radiance data provided by
United States Suomi National Polar (NPP) Cross-track Infrared Sounder
(CrIS) and the reanalyzed atmospheric profiles data provided by the
European Centre for Medium-Range Weather Forecasts (ECMWF). The proposed
DNN consists of two consecutive parts. In the first part, the first 1245
bands of the NPP CrIS hyperspectral radiance data (648.75 to 2555 cm-1)
are compressed into a 300-element vector representing their key features
by stacked AutoEncoders. Then, in the second part, the multi-layer
Self-Normalizing Neural Network (SNN) is used to map the compressed
vector (of 300 elements) into 55-layer temperature and relative humidity
profiles. The DNN trainable variables are optimized by minimizing the
difference of its predictions and the matched ECMWF temperature and
humidity profiles (53230 samples). Finally, the DNN retrieved
atmospheric temperature and relative humidity profiles and those
provided by the NOAA Unique Combined Atmospheric Processing System
(NUCAPS, the official retrieval products for CrIS) are compared with the
matched radiosonde observations at one location.