Cloud base height determination in rain, snow, and fog with a low-cost eye-safe lidar

Author(s):  
Christoph Muenkel
Measurement ◽  
2014 ◽  
Vol 51 ◽  
pp. 429-440 ◽  
Author(s):  
Fernando M. Janeiro ◽  
Filipe Carretas ◽  
Konrad Kandler ◽  
Frank Wagner ◽  
Pedro M. Ramos

Measurement ◽  
2010 ◽  
Vol 43 (5) ◽  
pp. 684-689 ◽  
Author(s):  
Fernando M. Janeiro ◽  
Pedro M. Ramos ◽  
Frank Wagner ◽  
A.M. Silva

2018 ◽  
Vol 76 (1) ◽  
pp. 87-94 ◽  
Author(s):  
PW Miller ◽  
TL Mote ◽  
CA Ramseyer ◽  
AE Van Beusekom ◽  
M Scholl ◽  
...  

2015 ◽  
Vol 15 (8) ◽  
pp. 4131-4144 ◽  
Author(s):  
P. Wang ◽  
M. Allaart ◽  
W. H. Knap ◽  
P. Stammes

Abstract. A green light sensor has been developed at KNMI to measure actinic flux profiles using an ozonesonde balloon. In total, 63 launches with ascending and descending profiles were performed between 2006 and 2010. The measured uncalibrated actinic flux profiles are analysed using the Doubling–Adding KNMI (DAK) radiative transfer model. Values of the cloud optical thickness (COT) along the flight track were taken from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) Cloud Physical Properties (CPP) product. The impact of clouds on the actinic flux profile is evaluated on the basis of the cloud modification factor (CMF) at the cloud top and cloud base, which is the ratio between the actinic fluxes for cloudy and clear-sky scenes. The impact of clouds on the actinic flux is clearly detected: the largest enhancement occurs at the cloud top due to multiple scattering. The actinic flux decreases almost linearly from cloud top to cloud base. Above the cloud top the actinic flux also increases compared to clear-sky scenes. We find that clouds can increase the actinic flux to 2.3 times the clear-sky value at cloud top and decrease it to about 0.05 at cloud base. The relationship between CMF and COT agrees well with DAK simulations, except for a few outliers. Good agreement is found between the DAK-simulated actinic flux profiles and the observations for single-layer clouds in fully overcast scenes. The instrument is suitable for operational balloon measurements because of its simplicity and low cost. It is worth further developing the instrument and launching it together with atmospheric chemistry composition sensors.


2021 ◽  
Author(s):  
Bjorn Stevens ◽  
Ilya Serikov ◽  
Anna Lea Albright ◽  
Sandrine Bony ◽  
Geet George ◽  
...  

<p>Cloud free skies are rare in the trades.  We analyze conditions in which cloud-free conditions prevail.  For this purpose Raman water vapor measurements from the Barbados Cloud Observatory, complemented by ship-based measurements during EUREC4A are used to explore water vapor variability in the marine boundary layer.   We explore the consistency of the inferred cloud base height with estimates of temperature and water vapor from the lidar signal, and examine the co-variability of these quantities.  After having established the properties of these measurements, we seek to use them as well as others, to explain in what ways periods of cloud-free conditions are maintained, investigating the hypothesis that only when the wind stills is it simply sunny.</p>


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