1. 95 th AMS Annual Meeting 13 th Symposium on the Coastal Environment Coastal clouds along northern Chile: climatology and trends Ricardo C. Muñoz Dept. Geophysics, University of Chile Juan Quintana Chilean National Weather Service (DMC) Mark Falvey Dept. Geophysics, University of Chile Acknowledgment: Partial funding by Project Fondecyt-Chile 1130111

2. Arica Iquique Antofagasta Key geographic/climate elements: Andes Cordillera (Z>5000 m) Atacama Desert SE Pacific Anticyclone Cold Chile-Peru surface current Extensive Sc cloud layer from: www.nrlmry.navy.mil/nexsat-bin/

3. taken from Mechoso et al., BAMS, 2014. Importance of SE Pacific Sc clouds: local: coastal clouds affect transport and local weather global: impact in Earth´s radiation budget (e.g. Exp. VOCALS-REx 2008)

4. Objective of this presentation: to document climatology and trends of coastal clouds based on long-term databases: hourly surface observations (SYNOP/METAR): 1969-2013 T, RH, WS, WD, P clouds: layers, type, fraction, height sunshine hours (Campbell-Stokes heliograph) upper air: 1979-2013 12 UTC ( 8 AM LT ) radiosondes

5. Thermodynamic structure of this coastal boundary layer: full description in Muñoz et al., J.Climate, 2011, p. 1013-1033 Subsidence inversion cool and humid boundary layer

6. Cloud observations: most typical conditions: 1-layer Sc clouds with bases below 1 km and various cloud fractions

7. Annual/Diurnal cycles of cloud properties: frequency: time fraction with low clouds fraction: spatial coverage of low clouds (oktas) height: cloud base height

8. Trends of low clouds: cloud frequency: slight increase cloud fraction: slight decrease cloud height: significant decrease

9. Inversion Base Cloud base Surface LCL Divergence in trends of inversion and cloud bases suggests cloud deepening Convergence in trends of cloud base and LCL suggests ABL coupling Increase in correlation between LCL and cloud base reaffirms coupling

10. Consistent trends: decrease in AM sunshine hours decrease in cloud base heights in other stations along the coast Antofagasta Iquique Arica

11. Not-as-consistent trends: slight decrease in winds not consistent with mechanical coupling of ABL: decrease of radiosonde relative humidity not consistent with cloud deepening: RH in ABL RH aloft

12. Conclusions

13. Work in progress: continuous measurements of cloud properties: CL31 Ceilometer Total Sky Imager 3 Automatic weather stations additional 16 UTC radiosoundings WRF modeling and validation TSI image see Poster 314