Desert dust remote sensing with the new zenith looking narrow band radiometer

Transcription

1 Desert dust remote sensing with the new zenith looking narrow band radiometer based system (ZEN) A. F. Almansa 1,2,5, E. Cuevas 1, B. Torres 3, A. Barreto 1,2, R. D. García 1,4, V. E. Cachorro 5, C. Guirado 1,5, A. M. de Frutos 5, C. López 6 and R. Ramos 1 1 Izaña Atmospheric Reseach Center, AEMET, Spain 2 Cimel Electronique, France 3 Laboratoire d Optique Atmospherique, Université des Sciences et Technologies de Lille, Villeneuve d Ascq, France 4 Air Liquide España, Delegación Canarias, Candelaria, Spain 5 Grupo de Óptica Atmosférica, Universidad de Valladolid, Valladolid, Spain 6 Sieltec Canarias S. L., La Laguna, Spain Madrid, September 2016

2 LIST OF CONTENTS INTRODUCTION THE ZEN SYSTEM ZEN R41 radiometer ZEN LUT methodology IZAÑA AND TAMANRASSET STATIONS RESULTS ZEN LUT performance evaluation at Tamanrasset ( ) ZEN system performance evaluation at Tamanrasset (2015) ZEN system performance evaluation at Izaña ( ) ONGOING ACTIVITIES CONCLUSIONS

3 INTRODUCTION AEROSOL IMPORTANCE

4 INTRODUCTION SATELLITE MONITORING Advantages: global and long term aerosol monitoring (key importance for numerical climate models and model assimilation). Drawbacks: Low temporal resolution, cloud contamination and correction of ground reflectivity.

5 INTRODUCTION GROUND BASED MONITORING Optical and mycrophysical properties (key importance in model evaluation and assimilation and satellite products validation). Accurate aerosol monitoring (ΔAOD<0.02), high temporal resolution but low spatial coverage. AERONET is the most extended network of ground based photometers. CIMEL CE-318 photometer

6 INTRODUCTION GROUND BASED MONITORING OVER DESERTS AERONET (and other networks) has a lack of coverage in desert regions. Reasons: Manpower: maintenance (trained staff) High cost Power consumption Poor description of dust cycles and lack of information of aerosol properties in dust source regions

7 THE ZEN SYSTEM ZEN R41 RADIOMETER + ZEN LUT METHODOLOGY = AOD RETRIEVAL FROM ZSR (zenith sky radiances) Published in AMTD: Almansa et al., 2016.

8 THE ZEN SYSTEM ZEN R41 RADIOMETER Robust external case No moving parts Four silicon detectors and four optical 10 nm filters (440, 500, 675 and 870nm) Operational temperature range: 40 Cand85 C Internal sensors for humidity and temperature monitoring Optional external blower for dust removal Solar panels Internal electronics (autocheck and product) Simple, robust and low cost instrument with low maintenance is suitable to be deployed in remote desert areas

9 THE ZEN SYSTEM ZEN LUT Methodology Calibration ZSR measurement Earth Sun distance corrected measured signal at four spectral bands ZSR and AOD simulation Atmosphere vertical profile definition: P, T, gases Surface reflectance definition Four spectral ranges: 10 nm FWHM filter function Aerosol definition: N vertical profiles of OPAC components Solar position: θ sun L m λ(θ sun,θ v =0) λ (spectral band index) L c λ,i(θ sun,θ v =0) AOD c λ,i λ (spectral band index) i(aerosol profile index),,,, Minimum(ε i ) AOD r λ Almansa et al., 2016.

10 IZAÑA AND TAMANRASSET STATIONS Izaña high mountain station (the Canary Islands, Spain, 28.3 N, 16.5 W, 2373 m a.s.l). Most of the time under atmospheric background conditions. Ocassional influence of mineral dust due to the proximity to Saharan desert (mainly in summertime). Tamanrasset station (Algeria, 22.8 N, 5.5 E, 1377 m a.s.l). Key location near the most important dust sources of Mali, Algeria, Libya and Chad. Dust is the main aerosol type. Prevailing clear sky conditions in winter and high turbidity events in summer.

11 RESULTS

12 RESULTS ZEN LUT performance evaluation at Tamanrasset ( ) Just with CE318 information YEAR R 2 RMSE

13 RESULTS ZEN system performance evaluation at Tamanrasset (2015) Device R 2 RMSE ZEN R CE318 LUT

14 RESULTS ZEN system performance evaluation at Izaña ( ) R 2 =0.97; RMSE=0.02

15 ONGOING ACTIVITIES Autonomous cloud screening ZEN LUT methodology for different aerosol conditions Total column water vapour estimation

16 CONCLUSIONS We have shown the good performance of the ZEN LUT method and ZEN R41 radiometer for AOD estimation, by comparing with the CE318 AERONET in Tamanrasset (R , RMSE 0.015) and in Izaña (R and RMSEs up to 0.023). These results indicate that ZEN system is appropriated to monitor atmospheric dust with little maintenance in remote desert locations, allowing us to fill important observational gaps and improve our knowledge on dust cycles in key regions near dust sources. This system could also play an important role in dust model assimilation, satellite validation and early warning within the World Meteorological Organization (WMO) Sand and Dust Storm Warning Advisory and Assessment System (SDS WAS).

17 Thanks for your attention!