REMOTE SENSING OF PRECIPITATION IN A WARMING CLIMATE CLEMENS - PowerPoint PPT Presentation

CCC CONFERENCE COLOGNE 2018 REMOTE SENSING OF PRECIPITATION IN A WARMING CLIMATE CLEMENS SIMMER METEOROLOGICAL INSTITUTE

CONTENT • Precipitation as element of the global water cycle • Special characteristics of precipitation as a climate variable • Current and predicted trends in precipitation • Monitoring of precipitation – ground ‐ based and from space • Quality of climate models simulating precipitation • PROM – a new initiative combining models and remote sensing for improved precipitation monitoring and simulation • Conclusions & Outlook CCC Conference, April 19, 2018, Cologne 2

THE WATER CYCLE IN NUMBERS water vapor transport 40 Uncertainties of the individual 746 480 1176 58 evapo ‐ evapo ‐ evapo ‐ components are precipitation 37 92 1066 transpiration transpiration transpiration 111 425 71 83 precipitation between melt ‐ 385 water 5 and 10%. infiltration lake river land Precipitation back 40 amounts to about flow ocean 1m per year on groundwater flow average Observations from Baumgartner and Reichel, 1975 red: W/m 2 black: in 1000 km 3 /year blue: mm/year 3

SPECIAL CHARACTERISTICS OF PRECIPITATION AS A CLIMATE VARIABLE • Precipitation is not a continuous variable ‐ but an event. • Its impact is more dependent on the type of event – e.g. its extremeness ‐ than on average measures. • Typical measures besides mean and variance: − Wet day/hour/… occurrence and duration − Mean intensities − Frequencies of exceedance or change of return levels CCC Conference, April 19, 2018, Cologne 4

CPEX-LAB: CPEX-LAB: 3D COMPOSIT RADARS BONN UND JÜLICH REFLECTIVITY 4. JUNI 2016 MESZ = UTC + 2 hours

5 (2)-HOUR SUM OVER WACHTBERG JUNE 4, 2016 CCC Conference, April 19, 2018, Cologne 6

OBSERVED CHANGES IN PRECIPITATION ARE EXTREMELY INHOMOGENEOUS (IPPC AR5) CCC Conference, April 19, 2018, Cologne 7

CLIMATE PREDICTIONS UNTIL END OF CENTURY Change in average precipitation (1986 ‐ 2005) to (2081 ‐ 2100) RCP 2.6 RCP 8.5 Predicted precipitation changes are inhomogeneous and differ between models for stronger anthropogenic forcings. CCC Conference, April 19, 2018, Cologne 8

Today ca. 2050 ca. 2090 Summer CENTRAL EUROPE MEAN (from Knist et al. 2018) SEASONAL PRECIPITATION  Less precipitation in summer  In winter small changes in the next 30 years but increases by up to 30% Winter towards the end of the century, except the Mediterranean CCC Conference, April 19, 2018, Cologne 9

Today ca. 2050 ca. 2090 Summer PROJECTED CHANGES IN (from Knist et al. 2018) EXTREME PRECIPITATION Extreme hourly precipitation (upper 1/1000) increase especially in summer, but later also in winter Winter CCC Conference, April 19, 2018, Cologne 10

HOW DO GAUGES MONITOR EXTREMES? CCC Conference, April 19, 2018, Cologne 11

(from Trenberth et al., 2014, Nature Climate Change ) LAND PRECIPITATION UNCERTAINTIES FROM DIFFERENT DATA SETS CCC Conference, April 19, 2018, Cologne 12

UNCERTAIN EUROPEAN TRENDS 1968 - 2010 IN MM GPCP U Del. CRU, GPCC, U Del agree in wetter North/dryer South Europe over past 4 decades. Differences between two sources (bottom right) are in the same order of CRU magnitude as the GPCP – U Del. estimated changes (same(!) color bar used for changes and differences) CCC Conference, April 19, 2018, Cologne 13

REMOTE SENSING (from Encyclopediea of Atmospheric Science, 2002, S. 1973) OF PRECIPITATION − Different sensors deployed on an aircraft flying over a hurricane − Only radar remote sensing detects precipitation − VIS, IR and passive microwaves provide only very indirect information CCC Conference, April 19, 2018, Cologne 14

COMPARISON OF SEVERAL PRECIPITATION DATA SETS Over oceans large differences between TRMM observations and other satellite estimates Over land products correlate much better due to gauges. https://climatedataguide.ucar.edu/sites/default/files/styles/ node_lightbox_display/public/key_figures/climate_data_set/ PRECIP_TimeSeries.png?itok=H ‐ HW0No4 CCC Conference, April 19, 2018, Cologne 15

summer winter DATA SET PURE GAUGE-BASED E-OBS GPCP1DD AGAINST THE (Lockhoff et al. 2014) CCC Conference, April 19, 2018, Cologne 16

THE GLOBAL PRECIPITATION MEASUREMENT (GPM) MISSION LAUNCHED ON FEB 28, 2014 Constellation radiometers from any agency are calibrated by the core satellite product to achieve a more frequent sampling. NASA/JAXA contribute Core Satellite - a dual- frequency radar & - a passive microwave imager with high frequency capabilities CCC Conference, April 19, 2018, Cologne 17

CLOUDS AND PRECIPITATION EXPLORATION LABORATORY - GPM VALIDATION SITE CCC Conference, April 19, 2018, Cologne 18

CPEX-LAB – GPM COMPARISONS (1) Overpass : 2014.10.07 – 02:35:00 UTC Comparison with RADOLAN reflectivities CCC Conference, April 19, 2018, Cologne 19

CPEX-LAB – GPM COMPARISONS (2) 3 years RADOLAN - GPM CCC Conference, April 19, 2018, Cologne 20

CPEX-LAB – GPM COMPARISONS (3) CCC Conference, April 19, 2018, Cologne 21

UNCERTAINTY OF CMIP MODELS IN REPRESENTING PRECIPITATION − for models 10 ‐ year running means − 22% spread between the models − Models overestimate precipitation (from Trenberth et al. 2014, Eumetsat Climate Symposium) CCC Conference, April 19, 2018, Cologne 22

wet areas TREND IN OBSERVATIONS AND MODELS FOR THE TROPICS dry areas from Liu & Allan (2013) gauges satellites models CCC Conference, April 19, 2018, Cologne 23

PRECIPITATION REQUIRES HIGH MODEL RESOLUTIONS (from Knist et al. 2018) 3 km resolution improves the daily cycle and the intensity distribution of precipitation compared to 12 km resolution simulations. CCC Conference, April 19, 2018, Cologne 24

INCREASE OF EXTREME PRECIPITATION WITH NEAR-SURFACE TEMPERATURE mm/h 100 99% Quantile od hourly precipitation Clausisus-Clapeyron Scaling (~7%/ ° C) Stratiform precipitation Super-C-C Skalierung convective precipitation Decrease due to missing moisture at 10 very high temperatures 1 Daily mean near ‐ surface temperature °C (Sebastian Knist) March 19, 2018 Extreme Niederschläge ‐ heute und morgen 25

PRIORITY PROGRAMME By courtesy of A. Ryzhov and A. Khain SPP 2115 Fusion of Radar Polarimetry and Numerical Atmospheric Modelling Towards an Improved Understanding of Cloud and Precipitation Processes Polarimetric Radar Observations meet Atmospheric Modelling (PROM) coordinated by Silke Trömel, Johannes Quaas, Susanne Crewell, and Clemens Simmer CCC Conference, April 19, 2018, Cologne 26

MOTIVATION FOR PROM • Cloud and precipitation processes are still the main source of uncertainties in weather prediction and climate change projections since decades • One reason are missing observations, which constrain the models • Since March 2015 Germany is covered by 16 state ‐ of ‐ the ‐ art polarimetric C ‐ band radars CPEX ‐ Lab (JOYCE) and other supersites embedded in • polarimetric radar network provide ideal data base for SPP ‐ PROM CCC Conference, April 19, 2018, Cologne 27

POLARIMETRIC SIGNATURES OF MICROPHYSICAL PROCESSES Z H Z DR Z H ⍴ HV Z H Z DR K DP CCC Conference, April 19, 2018, Cologne 28

CONCLUSIONS • Precipitation is a difficult climate variable for observation and modeling due to its event ‐ like multi ‐ scale nature. • Climate warming intensifies the water cycle and thus precipitation and its extremes. • Radar methods give the best results for area covering quantitative precipitation estimation. Other satellite observations are better used by assimilation into atmospheric models i.e. in the form of reanalyses. • Climate models need to be run at convection ‐ permitting resolution to correctly simulate the scaling of precipitation with near ‐ surface temperature, which is a prerequisite for predicting impact ‐ oriented precipitation quantities like extremes. CCC Conference, April 19, 2018, Cologne 29

OUTLOOK • Quantitatively observing precipitation amounts is a “mission impossible”; its quantification can only be achieved by combining models with observations via model improvements and data assimilation. • Polarimetric radar observations will provide the strongest constraints on micro and macrophysical precipitation processes. • Radar polarimetry from space should be explored to better monitor precipitation processes over the whole globe. CCC Conference, April 19, 2018, Cologne 30